basic_string.h source code [include/c++/9/bits/basic_string.h]

1	// Components for manipulating sequences of characters -- C++ --
2
3	// Copyright (C) 1997-2019 Free Software Foundation, Inc.
4	//
5	// This file is part of the GNU ISO C++ Library. This library is free
6	// software; you can redistribute it and/or modify it under the
7	// terms of the GNU General Public License as published by the
8	// Free Software Foundation; either version 3, or (at your option)
9	// any later version.
10
11	// This library is distributed in the hope that it will be useful,
12	// but WITHOUT ANY WARRANTY; without even the implied warranty of
13	// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14	// GNU General Public License for more details.
15
16	// Under Section 7 of GPL version 3, you are granted additional
17	// permissions described in the GCC Runtime Library Exception, version
18	// 3.1, as published by the Free Software Foundation.
19
20	// You should have received a copy of the GNU General Public License and
21	// a copy of the GCC Runtime Library Exception along with this program;
22	// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23	// <http://www.gnu.org/licenses/>.
24
25	/* @file bits/basic_string.h*
26	* This is an internal header file, included by other library headers.
27	* Do not attempt to use it directly. @headername{string}
28	*/
29
30	//
31	// ISO C++ 14882: 21 Strings library
32	//
33
34	#ifndef _BASIC_STRING_H
35	#define _BASIC_STRING_H 1
36
37	#pragma GCC system_header
38
39	#include <ext/atomicity.h>
40	#include <ext/alloc_traits.h>
41	#include <debug/debug.h>
42
43	#if __cplusplus >= 201103L
44	#include <initializer_list>
45	#endif
46
47	#if __cplusplus >= 201703L
48	# include <string_view>
49	#endif
50
51
52	namespace std _GLIBCXX_VISIBILITY(default)
53	{
54	_GLIBCXX_BEGIN_NAMESPACE_VERSION
55
56	#if _GLIBCXX_USE_CXX11_ABI
57	_GLIBCXX_BEGIN_NAMESPACE_CXX11
58	/**
59	* @class basic_string basic_string.h <string>
60	* @brief Managing sequences of characters and character-like objects.
61	*
62	* @ingroup strings
63	* @ingroup sequences
64	*
65	* @tparam _CharT Type of character
66	* @tparam _Traits Traits for character type, defaults to
67	* char_traits<_CharT>.
68	* @tparam _Alloc Allocator type, defaults to allocator<_CharT>.
69	*
70	* Meets the requirements of a <a href="tables.html#65">container</a>, a
71	* <a href="tables.html#66">reversible container</a>, and a
72	* <a href="tables.html#67">sequence</a>. Of the
73	* <a href="tables.html#68">optional sequence requirements</a>, only
74	* @c push_back, @c at, and @c %array access are supported.
75	*/
76	template<typename _CharT, typename _Traits, typename _Alloc>
77	class basic_string
78	{
79	typedef typename __gnu_cxx::__alloc_traits<_Alloc>::template
80	rebind<_CharT>::other _Char_alloc_type;
81	typedef __gnu_cxx::__alloc_traits<_Char_alloc_type> _Alloc_traits;
82
83	// Types:
84	public:
85	typedef _Traits traits_type;
86	typedef typename _Traits::char_type value_type;
87	typedef _Char_alloc_type allocator_type;
88	typedef typename _Alloc_traits::size_type size_type;
89	typedef typename _Alloc_traits::difference_type difference_type;
90	typedef typename _Alloc_traits::reference reference;
91	typedef typename _Alloc_traits::const_reference const_reference;
92	typedef typename _Alloc_traits::pointer pointer;
93	typedef typename _Alloc_traits::const_pointer const_pointer;
94	typedef __gnu_cxx::__normal_iterator<pointer, basic_string> iterator;
95	typedef __gnu_cxx::__normal_iterator<const_pointer, basic_string>
96	const_iterator;
97	typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
98	typedef std::reverse_iterator<iterator> reverse_iterator;
99
100	/// Value returned by various member functions when they fail.
101	static const size_type npos = static_cast<size_type>(-`1`);
102
103	protected:
104	// type used for positions in insert, erase etc.
105	#if __cplusplus < 201103L
106	typedef iterator __const_iterator;
107	#else
108	typedef const_iterator __const_iterator;
109	#endif
110
111	private:
112	#if __cplusplus >= 201703L
113	// A helper type for avoiding boiler-plate.
114	typedef basic_string_view<_CharT, _Traits> __sv_type;
115
116	template<typename _Tp, typename _Res>
117	using _If_sv = enable_if_t<
118	__and_<is_convertible<const _Tp&, __sv_type>,
119	__not_<is_convertible<const _Tp, const* basic_string*>>,
120	__not_<is_convertible<const _Tp&, const _CharT*>>>::value,
121	_Res>;
122
123	// Allows an implicit conversion to __sv_type.
124	static __sv_type
125	_S_to_string_view(__sv_type __svt) noexcept
126	{ return __svt; }
127
128	// Wraps a string_view by explicit conversion and thus
129	// allows to add an internal constructor that does not
130	// participate in overload resolution when a string_view
131	// is provided.
132	struct __sv_wrapper
133	{
134	explicit __sv_wrapper(__sv_type __sv) noexcept : _M_sv(__sv) { }
135	__sv_type _M_sv;
136	};
137
138	/**
139	* @brief Only internally used: Construct string from a string view
140	* wrapper.
141	* @param __svw string view wrapper.
142	* @param __a Allocator to use.
143	*/
144	explicit
145	basic_string(__sv_wrapper __svw, const _Alloc& __a)
146	: basic_string(__svw._M_sv.data(), __svw._M_sv.size(), __a) { }
147	#endif
148
149	// Use empty-base optimization: http://www.cantrip.org/emptyopt.html
150	struct _Alloc_hider : allocator_type // TODO check __is_final
151	{
152	#if __cplusplus < 201103L
153	_Alloc_hider(pointer __dat, const _Alloc& __a = _Alloc())
154	: allocator_type(__a), _M_p(__dat) { }
155	#else
156	_Alloc_hider(pointer __dat, const _Alloc& __a)
157	: allocator_type(__a), _M_p(__dat) { }
158
159	_Alloc_hider(pointer __dat, _Alloc&& __a = _Alloc())
160	: allocator_type(std::move(__a)), _M_p(__dat) { }
161	#endif
162
163	pointer _M_p; // The actual data.
164	};
165
166	_Alloc_hider _M_dataplus;
167	size_type _M_string_length;
168
169	enum { _S_local_capacity = `15` / sizeof(_CharT) };
170
171	union
172	{
173	_CharT _M_local_buf[_S_local_capacity + `1`];
174	size_type _M_allocated_capacity;
175	};
176
177	void
178	_M_data(pointer __p)
179	{ _M_dataplus._M_p = __p; }
180
181	void
182	_M_length(size_type __length)
183	{ _M_string_length = __length; }
184
185	pointer
186	_M_data() const
187	{ return _M_dataplus._M_p; }
188
189	pointer
190	_M_local_data()
191	{
192	#if __cplusplus >= 201103L
193	return std::pointer_traits<pointer>::pointer_to(*_M_local_buf);
194	#else
195	return pointer(_M_local_buf);
196	#endif
197	}
198
199	const_pointer
200	_M_local_data() const
201	{
202	#if __cplusplus >= 201103L
203	return std::pointer_traits<const_pointer>::pointer_to(*_M_local_buf);
204	#else
205	return const_pointer(_M_local_buf);
206	#endif
207	}
208
209	void
210	_M_capacity(size_type __capacity)
211	{ _M_allocated_capacity = __capacity; }
212
213	void
214	_M_set_length(size_type __n)
215	{
216	_M_length(__n);
217	traits_type::assign(_M_data()[__n], _CharT());
218	}
219
220	bool
221	_M_is_local() const
222	{ return _M_data() == _M_local_data(); }
223
224	// Create & Destroy
225	pointer
226	_M_create(size_type&, size_type);
227
228	void
229	_M_dispose()
230	{
231	if (!_M_is_local())
232	_M_destroy(_M_allocated_capacity);
233	}
234
235	void
236	_M_destroy(size_type __size) throw()
237	{ _Alloc_traits::deallocate(_M_get_allocator(), _M_data(), __size + `1`); }
238
239	// _M_construct_aux is used to implement the 21.3.1 para 15 which
240	// requires special behaviour if _InIterator is an integral type
241	template<typename _InIterator>
242	void
243	_M_construct_aux(_InIterator __beg, _InIterator __end,
244	std::__false_type)
245	{
246	typedef typename iterator_traits<_InIterator>::iterator_category _Tag;
247	_M_construct(__beg, __end, _Tag());
248	}
249
250	// _GLIBCXX_RESOLVE_LIB_DEFECTS
251	// 438. Ambiguity in the "do the right thing" clause
252	template<typename _Integer>
253	void
254	_M_construct_aux(_Integer __beg, _Integer __end, std::__true_type)
255	{ _M_construct_aux_2(static_cast<size_type>(__beg), __end); }
256
257	void
258	_M_construct_aux_2(size_type __req, _CharT __c)
259	{ _M_construct(__req, __c); }
260
261	template<typename _InIterator>
262	void
263	_M_construct(_InIterator __beg, _InIterator __end)
264	{
265	typedef typename std::__is_integer<_InIterator>::__type _Integral;
266	_M_construct_aux(__beg, __end, _Integral());
267	}
268
269	// For Input Iterators, used in istreambuf_iterators, etc.
270	template<typename _InIterator>
271	void
272	_M_construct(_InIterator __beg, _InIterator __end,
273	std::input_iterator_tag);
274
275	// For forward_iterators up to random_access_iterators, used for
276	// string::iterator, _CharT, etc.*
277	template<typename _FwdIterator>
278	void
279	_M_construct(_FwdIterator __beg, _FwdIterator __end,
280	std::forward_iterator_tag);
281
282	void
283	_M_construct(size_type __req, _CharT __c);
284
285	allocator_type&
286	_M_get_allocator()
287	{ return _M_dataplus; }
288
289	const allocator_type&
290	_M_get_allocator() const
291	{ return _M_dataplus; }
292
293	private:
294
295	#ifdef _GLIBCXX_DISAMBIGUATE_REPLACE_INST
296	// The explicit instantiations in misc-inst.cc require this due to
297	// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64063
298	template<typename _Tp, bool _Requires =
299	!__are_same<_Tp, _CharT*>::__value
300	&& !__are_same<_Tp, const _CharT*>::__value
301	&& !__are_same<_Tp, iterator>::__value
302	&& !__are_same<_Tp, const_iterator>::__value>
303	struct __enable_if_not_native_iterator
304	{ typedef basic_string& __type; };
305	template<typename _Tp>
306	struct __enable_if_not_native_iterator<_Tp, false> { };
307	#endif
308
309	size_type
310	_M_check(size_type __pos, const char* __s) const
311	{
312	if (__pos > this->size())
313	__throw_out_of_range_fmt(__N("%s: __pos (which is %zu) > "
314	"this->size() (which is %zu)"),
315	__s, __pos, this->size());
316	return __pos;
317	}
318
319	void
320	_M_check_length(size_type __n1, size_type __n2, const char* __s) const
321	{
322	if (this->max_size() - (this->size() - __n1) < __n2)
323	__throw_length_error(__N(__s));
324	}
325
326
327	// NB: _M_limit doesn't check for a bad __pos value.
328	size_type
329	_M_limit(size_type __pos, size_type __off) const _GLIBCXX_NOEXCEPT
330	{
331	const bool __testoff = __off < this->size() - __pos;
332	return __testoff ? __off : this->size() - __pos;
333	}
334
335	// True if _Rep and source do not overlap.
336	bool
337	_M_disjunct(const _CharT* __s) const _GLIBCXX_NOEXCEPT
338	{
339	return (less<const _CharT*>()(__s, _M_data())
340	\|\| less<const _CharT>()(_M_data() + this*->size(), __s));
341	}
342
343	// When __n = 1 way faster than the general multichar
344	// traits_type::copy/move/assign.
345	static void
346	_S_copy(_CharT* __d, const _CharT* __s, size_type __n)
347	{
348	if (__n == `1`)
349	traits_type::assign(__d, __s);
350	else
351	traits_type::copy(__d, __s, __n);
352	}
353
354	static void
355	_S_move(_CharT* __d, const _CharT* __s, size_type __n)
356	{
357	if (__n == `1`)
358	traits_type::assign(__d, __s);
359	else
360	traits_type::move(__d, __s, __n);
361	}
362
363	static void
364	_S_assign(_CharT* __d, size_type __n, _CharT __c)
365	{
366	if (__n == `1`)
367	traits_type::assign(*__d, __c);
368	else
369	traits_type::assign(__d, __n, __c);
370	}
371
372	// _S_copy_chars is a separate template to permit specialization
373	// to optimize for the common case of pointers as iterators.
374	template<class _Iterator>
375	static void
376	_S_copy_chars(_CharT* __p, _Iterator __k1, _Iterator __k2)
377	{
378	for (; __k1 != __k2; ++__k1, (void)++__p)
379	traits_type::assign(__p, __k1); // These types are off.
380	}
381
382	static void
383	_S_copy_chars(_CharT* __p, iterator __k1, iterator __k2) _GLIBCXX_NOEXCEPT
384	{ _S_copy_chars(__p, __k1.base(), __k2.base()); }
385
386	static void
387	_S_copy_chars(_CharT* __p, const_iterator __k1, const_iterator __k2)
388	_GLIBCXX_NOEXCEPT
389	{ _S_copy_chars(__p, __k1.base(), __k2.base()); }
390
391	static void
392	_S_copy_chars(_CharT* __p, _CharT* __k1, _CharT* __k2) _GLIBCXX_NOEXCEPT
393	{ _S_copy(__p, __k1, __k2 - __k1); }
394
395	static void
396	_S_copy_chars(_CharT* __p, const _CharT* __k1, const _CharT* __k2)
397	_GLIBCXX_NOEXCEPT
398	{ _S_copy(__p, __k1, __k2 - __k1); }
399
400	static int
401	_S_compare(size_type __n1, size_type __n2) _GLIBCXX_NOEXCEPT
402	{
403	const difference_type __d = difference_type(__n1 - __n2);
404
405	if (__d > __gnu_cxx::__numeric_traits<int>::__max)
406	return __gnu_cxx::__numeric_traits<int>::__max;
407	else if (__d < __gnu_cxx::__numeric_traits<int>::__min)
408	return __gnu_cxx::__numeric_traits<int>::__min;
409	else
410	return int(__d);
411	}
412
413	void
414	_M_assign(const basic_string&);
415
416	void
417	_M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
418	size_type __len2);
419
420	void
421	_M_erase(size_type __pos, size_type __n);
422
423	public:
424	// Construct/copy/destroy:
425	// NB: We overload ctors in some cases instead of using default
426	// arguments, per 17.4.4.4 para. 2 item 2.
427
428	/**
429	* @brief Default constructor creates an empty string.
430	*/
431	basic_string()
432	_GLIBCXX_NOEXCEPT_IF(is_nothrow_default_constructible<_Alloc>::value)
433	: _M_dataplus(_M_local_data())
434	{ _M_set_length(`0`); }
435
436	/**
437	* @brief Construct an empty string using allocator @a a.
438	*/
439	explicit
440	basic_string(const _Alloc& __a) _GLIBCXX_NOEXCEPT
441	: _M_dataplus(_M_local_data(), __a)
442	{ _M_set_length(`0`); }
443
444	/**
445	* @brief Construct string with copy of value of @a __str.
446	* @param __str Source string.
447	*/
448	basic_string(const basic_string& __str)
449	: _M_dataplus(_M_local_data(),
450	_Alloc_traits::_S_select_on_copy(__str._M_get_allocator()))
451	{ _M_construct(__str._M_data(), __str._M_data() + __str.length()); }
452
453	// _GLIBCXX_RESOLVE_LIB_DEFECTS
454	// 2583. no way to supply an allocator for basic_string(str, pos)
455	/**
456	* @brief Construct string as copy of a substring.
457	* @param __str Source string.
458	* @param __pos Index of first character to copy from.
459	* @param __a Allocator to use.
460	*/
461	basic_string(const basic_string& __str, size_type __pos,
462	const _Alloc& __a = _Alloc())
463	: _M_dataplus(_M_local_data(), __a)
464	{
465	const _CharT* __start = __str._M_data()
466	+ __str._M_check(__pos, "basic_string::basic_string");
467	_M_construct(__start, __start + __str._M_limit(__pos, npos));
468	}
469
470	/**
471	* @brief Construct string as copy of a substring.
472	* @param __str Source string.
473	* @param __pos Index of first character to copy from.
474	* @param __n Number of characters to copy.
475	*/
476	basic_string(const basic_string& __str, size_type __pos,
477	size_type __n)
478	: _M_dataplus(_M_local_data())
479	{
480	const _CharT* __start = __str._M_data()
481	+ __str._M_check(__pos, "basic_string::basic_string");
482	_M_construct(__start, __start + __str._M_limit(__pos, __n));
483	}
484
485	/**
486	* @brief Construct string as copy of a substring.
487	* @param __str Source string.
488	* @param __pos Index of first character to copy from.
489	* @param __n Number of characters to copy.
490	* @param __a Allocator to use.
491	*/
492	basic_string(const basic_string& __str, size_type __pos,
493	size_type __n, const _Alloc& __a)
494	: _M_dataplus(_M_local_data(), __a)
495	{
496	const _CharT* __start
497	= __str._M_data() + __str._M_check(__pos, "string::string");
498	_M_construct(__start, __start + __str._M_limit(__pos, __n));
499	}
500
501	/**
502	* @brief Construct string initialized by a character %array.
503	* @param __s Source character %array.
504	* @param __n Number of characters to copy.
505	* @param __a Allocator to use (default is default allocator).
506	*
507	* NB: @a __s must have at least @a __n characters, '\\0'
508	* has no special meaning.
509	*/
510	basic_string(const _CharT* __s, size_type __n,
511	const _Alloc& __a = _Alloc())
512	: _M_dataplus(_M_local_data(), __a)
513	{ _M_construct(__s, __s + __n); }
514
515	/**
516	* @brief Construct string as copy of a C string.
517	* @param __s Source C string.
518	* @param __a Allocator to use (default is default allocator).
519	*/
520	#if __cpp_deduction_guides && ! defined _GLIBCXX_DEFINING_STRING_INSTANTIATIONS
521	// _GLIBCXX_RESOLVE_LIB_DEFECTS
522	// 3076. basic_string CTAD ambiguity
523	template<typename = _RequireAllocator<_Alloc>>
524	#endif
525	basic_string(const _CharT* __s, const _Alloc& __a = _Alloc())
526	: _M_dataplus(_M_local_data(), __a)
527	{ _M_construct(__s, __s ? __s + traits_type::length(__s) : __s+npos); }
528
529	/**
530	* @brief Construct string as multiple characters.
531	* @param __n Number of characters.
532	* @param __c Character to use.
533	* @param __a Allocator to use (default is default allocator).
534	*/
535	#if __cpp_deduction_guides && ! defined _GLIBCXX_DEFINING_STRING_INSTANTIATIONS
536	// _GLIBCXX_RESOLVE_LIB_DEFECTS
537	// 3076. basic_string CTAD ambiguity
538	template<typename = _RequireAllocator<_Alloc>>
539	#endif
540	basic_string(size_type __n, _CharT __c, const _Alloc& __a = _Alloc())
541	: _M_dataplus(_M_local_data(), __a)
542	{ _M_construct(__n, __c); }
543
544	#if __cplusplus >= 201103L
545	/**
546	* @brief Move construct string.
547	* @param __str Source string.
548	*
549	* The newly-created string contains the exact contents of @a __str.
550	* @a __str is a valid, but unspecified string.
551	**/
552	basic_string(basic_string&& __str) noexcept
553	: _M_dataplus(_M_local_data(), std::move(__str._M_get_allocator()))
554	{
555	if (__str._M_is_local())
556	{
557	traits_type::copy(_M_local_buf, __str._M_local_buf,
558	_S_local_capacity + `1`);
559	}
560	else
561	{
562	_M_data(__str._M_data());
563	_M_capacity(__str._M_allocated_capacity);
564	}
565
566	// Must use _M_length() here not _M_set_length() because
567	// basic_stringbuf relies on writing into unallocated capacity so
568	// we mess up the contents if we put a '\0' in the string.
569	_M_length(__str.length());
570	__str._M_data(__str._M_local_data());
571	__str._M_set_length(`0`);
572	}
573
574	/**
575	* @brief Construct string from an initializer %list.
576	* @param __l std::initializer_list of characters.
577	* @param __a Allocator to use (default is default allocator).
578	*/
579	basic_string(initializer_list<_CharT> __l, const _Alloc& __a = _Alloc())
580	: _M_dataplus(_M_local_data(), __a)
581	{ _M_construct(__l.begin(), __l.end()); }
582
583	basic_string(const basic_string& __str, const _Alloc& __a)
584	: _M_dataplus(_M_local_data(), __a)
585	{ _M_construct(__str.begin(), __str.end()); }
586
587	basic_string(basic_string&& __str, const _Alloc& __a)
588	noexcept(_Alloc_traits::_S_always_equal())
589	: _M_dataplus(_M_local_data(), __a)
590	{
591	if (__str._M_is_local())
592	{
593	traits_type::copy(_M_local_buf, __str._M_local_buf,
594	_S_local_capacity + `1`);
595	_M_length(__str.length());
596	__str._M_set_length(`0`);
597	}
598	else if (_Alloc_traits::_S_always_equal()
599	\|\| __str.get_allocator() == __a)
600	{
601	_M_data(__str._M_data());
602	_M_length(__str.length());
603	_M_capacity(__str._M_allocated_capacity);
604	__str._M_data(__str._M_local_buf);
605	__str._M_set_length(`0`);
606	}
607	else
608	_M_construct(__str.begin(), __str.end());
609	}
610
611	#endif // C++11
612
613	/**
614	* @brief Construct string as copy of a range.
615	* @param __beg Start of range.
616	* @param __end End of range.
617	* @param __a Allocator to use (default is default allocator).
618	*/
619	#if __cplusplus >= 201103L
620	template<typename _InputIterator,
621	typename = std::_RequireInputIter<_InputIterator>>
622	#else
623	template<typename _InputIterator>
624	#endif
625	basic_string(_InputIterator __beg, _InputIterator __end,
626	const _Alloc& __a = _Alloc())
627	: _M_dataplus(_M_local_data(), __a)
628	{ _M_construct(__beg, __end); }
629
630	#if __cplusplus >= 201703L
631	/**
632	* @brief Construct string from a substring of a string_view.
633	* @param __t Source object convertible to string view.
634	* @param __pos The index of the first character to copy from __t.
635	* @param __n The number of characters to copy from __t.
636	* @param __a Allocator to use.
637	*/
638	template<typename _Tp, typename = _If_sv<_Tp, void>>
639	basic_string(const _Tp& __t, size_type __pos, size_type __n,
640	const _Alloc& __a = _Alloc())
641	: basic_string(_S_to_string_view(__t).substr(__pos, __n), __a) { }
642
643	/**
644	* @brief Construct string from a string_view.
645	* @param __t Source object convertible to string view.
646	* @param __a Allocator to use (default is default allocator).
647	*/
648	template<typename _Tp, typename = _If_sv<_Tp, void>>
649	explicit
650	basic_string(const _Tp& __t, const _Alloc& __a = _Alloc())
651	: basic_string(__sv_wrapper(_S_to_string_view(__t)), __a) { }
652	#endif // C++17
653
654	/**
655	* @brief Destroy the string instance.
656	*/
657	~basic_string()
658	{ _M_dispose(); }
659
660	/**
661	* @brief Assign the value of @a str to this string.
662	* @param __str Source string.
663	*/
664	basic_string&
665	operator=(const basic_string& __str)
666	{
667	#if __cplusplus >= 201103L
668	if (_Alloc_traits::_S_propagate_on_copy_assign())
669	{
670	if (!_Alloc_traits::_S_always_equal() && !_M_is_local()
671	&& _M_get_allocator() != __str._M_get_allocator())
672	{
673	// Propagating allocator cannot free existing storage so must
674	// deallocate it before replacing current allocator.
675	if (__str.size() <= _S_local_capacity)
676	{
677	_M_destroy(_M_allocated_capacity);
678	_M_data(_M_local_data());
679	_M_set_length(`0`);
680	}
681	else
682	{
683	const auto __len = __str.size();
684	auto __alloc = __str._M_get_allocator();
685	// If this allocation throws there are no effects:
686	auto __ptr = _Alloc_traits::allocate(__alloc, __len + `1`);
687	_M_destroy(_M_allocated_capacity);
688	_M_data(__ptr);
689	_M_capacity(__len);
690	_M_set_length(__len);
691	}
692	}
693	std::__alloc_on_copy(_M_get_allocator(), __str._M_get_allocator());
694	}
695	#endif
696	return this->assign(__str);
697	}
698
699	/**
700	* @brief Copy contents of @a s into this string.
701	* @param __s Source null-terminated string.
702	*/
703	basic_string&
704	operator=(const _CharT* __s)
705	{ return this->assign(__s); }
706
707	/**
708	* @brief Set value to string of length 1.
709	* @param __c Source character.
710	*
711	* Assigning to a character makes this string length 1 and
712	* (*this)[0] == @a c.
713	*/
714	basic_string&
715	operator=(_CharT __c)
716	{
717	this->assign(`1`, __c);
718	return *this;
719	}
720
721	#if __cplusplus >= 201103L
722	/**
723	* @brief Move assign the value of @a str to this string.
724	* @param __str Source string.
725	*
726	* The contents of @a str are moved into this string (without copying).
727	* @a str is a valid, but unspecified string.
728	**/
729	// _GLIBCXX_RESOLVE_LIB_DEFECTS
730	// 2063. Contradictory requirements for string move assignment
731	basic_string&
732	operator=(basic_string&& __str)
733	noexcept(_Alloc_traits::_S_nothrow_move())
734	{
735	if (!_M_is_local() && _Alloc_traits::_S_propagate_on_move_assign()
736	&& !_Alloc_traits::_S_always_equal()
737	&& _M_get_allocator() != __str._M_get_allocator())
738	{
739	// Destroy existing storage before replacing allocator.
740	_M_destroy(_M_allocated_capacity);
741	_M_data(_M_local_data());
742	_M_set_length(`0`);
743	}
744	// Replace allocator if POCMA is true.
745	std::__alloc_on_move(_M_get_allocator(), __str._M_get_allocator());
746
747	if (__str._M_is_local())
748	{
749	// We've always got room for a short string, just copy it.
750	if (__str.size())
751	this->_S_copy(_M_data(), __str._M_data(), __str.size());
752	_M_set_length(__str.size());
753	}
754	else if (_Alloc_traits::_S_propagate_on_move_assign()
755	\|\| _Alloc_traits::_S_always_equal()
756	\|\| _M_get_allocator() == __str._M_get_allocator())
757	{
758	// Just move the allocated pointer, our allocator can free it.
759	pointer __data = nullptr;
760	size_type __capacity;
761	if (!_M_is_local())
762	{
763	if (_Alloc_traits::_S_always_equal())
764	{
765	// __str can reuse our existing storage.
766	__data = _M_data();
767	__capacity = _M_allocated_capacity;
768	}
769	else // __str can't use it, so free it.
770	_M_destroy(_M_allocated_capacity);
771	}
772
773	_M_data(__str._M_data());
774	_M_length(__str.length());
775	_M_capacity(__str._M_allocated_capacity);
776	if (__data)
777	{
778	__str._M_data(__data);
779	__str._M_capacity(__capacity);
780	}
781	else
782	__str._M_data(__str._M_local_buf);
783	}
784	else // Need to do a deep copy
785	assign(__str);
786	__str.clear();
787	return *this;
788	}
789
790	/**
791	* @brief Set value to string constructed from initializer %list.
792	* @param __l std::initializer_list.
793	*/
794	basic_string&
795	operator=(initializer_list<_CharT> __l)
796	{
797	this->assign(__l.begin(), __l.size());
798	return *this;
799	}
800	#endif // C++11
801
802	#if __cplusplus >= 201703L
803	/**
804	* @brief Set value to string constructed from a string_view.
805	* @param __svt An object convertible to string_view.
806	*/
807	template<typename _Tp>
808	_If_sv<_Tp, basic_string&>
809	operator=(const _Tp& __svt)
810	{ return this->assign(__svt); }
811
812	/**
813	* @brief Convert to a string_view.
814	* @return A string_view.
815	*/
816	operator __sv_type() const noexcept
817	{ return __sv_type(data(), size()); }
818	#endif // C++17
819
820	// Iterators:
821	/**
822	* Returns a read/write iterator that points to the first character in
823	* the %string.
824	*/
825	iterator
826	begin() _GLIBCXX_NOEXCEPT
827	{ return iterator(_M_data()); }
828
829	/**
830	* Returns a read-only (constant) iterator that points to the first
831	* character in the %string.
832	*/
833	const_iterator
834	begin() const _GLIBCXX_NOEXCEPT
835	{ return const_iterator(_M_data()); }
836
837	/**
838	* Returns a read/write iterator that points one past the last
839	* character in the %string.
840	*/
841	iterator
842	end() _GLIBCXX_NOEXCEPT
843	{ return iterator(_M_data() + this->size()); }
844
845	/**
846	* Returns a read-only (constant) iterator that points one past the
847	* last character in the %string.
848	*/
849	const_iterator
850	end() const _GLIBCXX_NOEXCEPT
851	{ return const_iterator(_M_data() + this->size()); }
852
853	/**
854	* Returns a read/write reverse iterator that points to the last
855	* character in the %string. Iteration is done in reverse element
856	* order.
857	*/
858	reverse_iterator
859	rbegin() _GLIBCXX_NOEXCEPT
860	{ return reverse_iterator(this->end()); }
861
862	/**
863	* Returns a read-only (constant) reverse iterator that points
864	* to the last character in the %string. Iteration is done in
865	* reverse element order.
866	*/
867	const_reverse_iterator
868	rbegin() const _GLIBCXX_NOEXCEPT
869	{ return const_reverse_iterator(this->end()); }
870
871	/**
872	* Returns a read/write reverse iterator that points to one before the
873	* first character in the %string. Iteration is done in reverse
874	* element order.
875	*/
876	reverse_iterator
877	rend() _GLIBCXX_NOEXCEPT
878	{ return reverse_iterator(this->begin()); }
879
880	/**
881	* Returns a read-only (constant) reverse iterator that points
882	* to one before the first character in the %string. Iteration
883	* is done in reverse element order.
884	*/
885	const_reverse_iterator
886	rend() const _GLIBCXX_NOEXCEPT
887	{ return const_reverse_iterator(this->begin()); }
888
889	#if __cplusplus >= 201103L
890	/**
891	* Returns a read-only (constant) iterator that points to the first
892	* character in the %string.
893	*/
894	const_iterator
895	cbegin() const noexcept
896	{ return const_iterator(this->_M_data()); }
897
898	/**
899	* Returns a read-only (constant) iterator that points one past the
900	* last character in the %string.
901	*/
902	const_iterator
903	cend() const noexcept
904	{ return const_iterator(this->_M_data() + this->size()); }
905
906	/**
907	* Returns a read-only (constant) reverse iterator that points
908	* to the last character in the %string. Iteration is done in
909	* reverse element order.
910	*/
911	const_reverse_iterator
912	crbegin() const noexcept
913	{ return const_reverse_iterator(this->end()); }
914
915	/**
916	* Returns a read-only (constant) reverse iterator that points
917	* to one before the first character in the %string. Iteration
918	* is done in reverse element order.
919	*/
920	const_reverse_iterator
921	crend() const noexcept
922	{ return const_reverse_iterator(this->begin()); }
923	#endif
924
925	public:
926	// Capacity:
927	/// Returns the number of characters in the string, not including any
928	/// null-termination.
929	size_type
930	size() const _GLIBCXX_NOEXCEPT
931	{ return _M_string_length; }
932
933	/// Returns the number of characters in the string, not including any
934	/// null-termination.
935	size_type
936	length() const _GLIBCXX_NOEXCEPT
937	{ return _M_string_length; }
938
939	/// Returns the size() of the largest possible %string.
940	size_type
941	max_size() const _GLIBCXX_NOEXCEPT
942	{ return (_Alloc_traits::max_size(_M_get_allocator()) - `1`) / `2`; }
943
944	/**
945	* @brief Resizes the %string to the specified number of characters.
946	* @param __n Number of characters the %string should contain.
947	* @param __c Character to fill any new elements.
948	*
949	* This function will %resize the %string to the specified
950	* number of characters. If the number is smaller than the
951	* %string's current size the %string is truncated, otherwise
952	* the %string is extended and new elements are %set to @a __c.
953	*/
954	void
955	resize(size_type __n, _CharT __c);
956
957	/**
958	* @brief Resizes the %string to the specified number of characters.
959	* @param __n Number of characters the %string should contain.
960	*
961	* This function will resize the %string to the specified length. If
962	* the new size is smaller than the %string's current size the %string
963	* is truncated, otherwise the %string is extended and new characters
964	* are default-constructed. For basic types such as char, this means
965	* setting them to 0.
966	*/
967	void
968	resize(size_type __n)
969	{ this->resize(__n, _CharT()); }
970
971	#if __cplusplus >= 201103L
972	/// A non-binding request to reduce capacity() to size().
973	void
974	shrink_to_fit() noexcept
975	{
976	#if __cpp_exceptions
977	if (capacity() > size())
978	{
979	try
980	{ reserve(`0`); }
981	catch(...)
982	{ }
983	}
984	#endif
985	}
986	#endif
987
988	/**
989	* Returns the total number of characters that the %string can hold
990	* before needing to allocate more memory.
991	*/
992	size_type
993	capacity() const _GLIBCXX_NOEXCEPT
994	{
995	return _M_is_local() ? size_type(_S_local_capacity)
996	: _M_allocated_capacity;
997	}
998
999	/**
1000	* @brief Attempt to preallocate enough memory for specified number of
1001	* characters.
1002	* @param __res_arg Number of characters required.
1003	* @throw std::length_error If @a __res_arg exceeds @c max_size().
1004	*
1005	* This function attempts to reserve enough memory for the
1006	* %string to hold the specified number of characters. If the
1007	* number requested is more than max_size(), length_error is
1008	* thrown.
1009	*
1010	* The advantage of this function is that if optimal code is a
1011	* necessity and the user can determine the string length that will be
1012	* required, the user can reserve the memory in %advance, and thus
1013	* prevent a possible reallocation of memory and copying of %string
1014	* data.
1015	*/
1016	void
1017	reserve(size_type __res_arg = `0`);
1018
1019	/**
1020	* Erases the string, making it empty.
1021	*/
1022	void
1023	clear() _GLIBCXX_NOEXCEPT
1024	{ _M_set_length(`0`); }
1025
1026	/**
1027	* Returns true if the %string is empty. Equivalent to
1028	* <code>*this == ""</code>.
1029	*/
1030	_GLIBCXX_NODISCARD bool
1031	empty() const _GLIBCXX_NOEXCEPT
1032	{ return this->size() == `0`; }
1033
1034	// Element access:
1035	/**
1036	* @brief Subscript access to the data contained in the %string.
1037	* @param __pos The index of the character to access.
1038	* @return Read-only (constant) reference to the character.
1039	*
1040	* This operator allows for easy, array-style, data access.
1041	* Note that data access with this operator is unchecked and
1042	* out_of_range lookups are not defined. (For checked lookups
1043	* see at().)
1044	*/
1045	const_reference
1046	operator[] (size_type __pos) const _GLIBCXX_NOEXCEPT
1047	{
1048	__glibcxx_assert(__pos <= size());
1049	return _M_data()[__pos];
1050	}
1051
1052	/**
1053	* @brief Subscript access to the data contained in the %string.
1054	* @param __pos The index of the character to access.
1055	* @return Read/write reference to the character.
1056	*
1057	* This operator allows for easy, array-style, data access.
1058	* Note that data access with this operator is unchecked and
1059	* out_of_range lookups are not defined. (For checked lookups
1060	* see at().)
1061	*/
1062	reference
1063	operator[](size_type __pos)
1064	{
1065	// Allow pos == size() both in C++98 mode, as v3 extension,
1066	// and in C++11 mode.
1067	__glibcxx_assert(__pos <= size());
1068	// In pedantic mode be strict in C++98 mode.
1069	_GLIBCXX_DEBUG_PEDASSERT(__cplusplus >= `201103L` \|\| __pos < size());
1070	return _M_data()[__pos];
1071	}
1072
1073	/**
1074	* @brief Provides access to the data contained in the %string.
1075	* @param __n The index of the character to access.
1076	* @return Read-only (const) reference to the character.
1077	* @throw std::out_of_range If @a n is an invalid index.
1078	*
1079	* This function provides for safer data access. The parameter is
1080	* first checked that it is in the range of the string. The function
1081	* throws out_of_range if the check fails.
1082	*/
1083	const_reference
1084	at(size_type __n) const
1085	{
1086	if (__n >= this->size())
1087	__throw_out_of_range_fmt(__N("basic_string::at: __n "
1088	"(which is %zu) >= this->size() "
1089	"(which is %zu)"),
1090	__n, this->size());
1091	return _M_data()[__n];
1092	}
1093
1094	/**
1095	* @brief Provides access to the data contained in the %string.
1096	* @param __n The index of the character to access.
1097	* @return Read/write reference to the character.
1098	* @throw std::out_of_range If @a n is an invalid index.
1099	*
1100	* This function provides for safer data access. The parameter is
1101	* first checked that it is in the range of the string. The function
1102	* throws out_of_range if the check fails.
1103	*/
1104	reference
1105	at(size_type __n)
1106	{
1107	if (__n >= size())
1108	__throw_out_of_range_fmt(__N("basic_string::at: __n "
1109	"(which is %zu) >= this->size() "
1110	"(which is %zu)"),
1111	__n, this->size());
1112	return _M_data()[__n];
1113	}
1114
1115	#if __cplusplus >= 201103L
1116	/**
1117	* Returns a read/write reference to the data at the first
1118	* element of the %string.
1119	*/
1120	reference
1121	front() noexcept
1122	{
1123	__glibcxx_assert(!empty());
1124	return operator[](`0`);
1125	}
1126
1127	/**
1128	* Returns a read-only (constant) reference to the data at the first
1129	* element of the %string.
1130	*/
1131	const_reference
1132	front() const noexcept
1133	{
1134	__glibcxx_assert(!empty());
1135	return operator[](`0`);
1136	}
1137
1138	/**
1139	* Returns a read/write reference to the data at the last
1140	* element of the %string.
1141	*/
1142	reference
1143	back() noexcept
1144	{
1145	__glibcxx_assert(!empty());
1146	return operator[](this->size() - `1`);
1147	}
1148
1149	/**
1150	* Returns a read-only (constant) reference to the data at the
1151	* last element of the %string.
1152	*/
1153	const_reference
1154	back() const noexcept
1155	{
1156	__glibcxx_assert(!empty());
1157	return operator[](this->size() - `1`);
1158	}
1159	#endif
1160
1161	// Modifiers:
1162	/**
1163	* @brief Append a string to this string.
1164	* @param __str The string to append.
1165	* @return Reference to this string.
1166	*/
1167	basic_string&
1168	operator+=(const basic_string& __str)
1169	{ return this->append(__str); }
1170
1171	/**
1172	* @brief Append a C string.
1173	* @param __s The C string to append.
1174	* @return Reference to this string.
1175	*/
1176	basic_string&
1177	operator+=(const _CharT* __s)
1178	{ return this->append(__s); }
1179
1180	/**
1181	* @brief Append a character.
1182	* @param __c The character to append.
1183	* @return Reference to this string.
1184	*/
1185	basic_string&
1186	operator+=(_CharT __c)
1187	{
1188	this->push_back(__c);
1189	return *this;
1190	}
1191
1192	#if __cplusplus >= 201103L
1193	/**
1194	* @brief Append an initializer_list of characters.
1195	* @param __l The initializer_list of characters to be appended.
1196	* @return Reference to this string.
1197	*/
1198	basic_string&
1199	operator+=(initializer_list<_CharT> __l)
1200	{ return this->append(__l.begin(), __l.size()); }
1201	#endif // C++11
1202
1203	#if __cplusplus >= 201703L
1204	/**
1205	* @brief Append a string_view.
1206	* @param __svt An object convertible to string_view to be appended.
1207	* @return Reference to this string.
1208	*/
1209	template<typename _Tp>
1210	_If_sv<_Tp, basic_string&>
1211	operator+=(const _Tp& __svt)
1212	{ return this->append(__svt); }
1213	#endif // C++17
1214
1215	/**
1216	* @brief Append a string to this string.
1217	* @param __str The string to append.
1218	* @return Reference to this string.
1219	*/
1220	basic_string&
1221	append(const basic_string& __str)
1222	{ return _M_append(__str._M_data(), __str.size()); }
1223
1224	/**
1225	* @brief Append a substring.
1226	* @param __str The string to append.
1227	* @param __pos Index of the first character of str to append.
1228	* @param __n The number of characters to append.
1229	* @return Reference to this string.
1230	* @throw std::out_of_range if @a __pos is not a valid index.
1231	*
1232	* This function appends @a __n characters from @a __str
1233	* starting at @a __pos to this string. If @a __n is is larger
1234	* than the number of available characters in @a __str, the
1235	* remainder of @a __str is appended.
1236	*/
1237	basic_string&
1238	append(const basic_string& __str, size_type __pos, size_type __n = npos)
1239	{ return _M_append(__str._M_data()
1240	+ __str._M_check(__pos, "basic_string::append"),
1241	__str._M_limit(__pos, __n)); }
1242
1243	/**
1244	* @brief Append a C substring.
1245	* @param __s The C string to append.
1246	* @param __n The number of characters to append.
1247	* @return Reference to this string.
1248	*/
1249	basic_string&
1250	append(const _CharT* __s, size_type __n)
1251	{
1252	__glibcxx_requires_string_len(__s, __n);
1253	_M_check_length(size_type(`0`), __n, "basic_string::append");
1254	return _M_append(__s, __n);
1255	}
1256
1257	/**
1258	* @brief Append a C string.
1259	* @param __s The C string to append.
1260	* @return Reference to this string.
1261	*/
1262	basic_string&
1263	append(const _CharT* __s)
1264	{
1265	__glibcxx_requires_string(__s);
1266	const size_type __n = traits_type::length(__s);
1267	_M_check_length(size_type(`0`), __n, "basic_string::append");
1268	return _M_append(__s, __n);
1269	}
1270
1271	/**
1272	* @brief Append multiple characters.
1273	* @param __n The number of characters to append.
1274	* @param __c The character to use.
1275	* @return Reference to this string.
1276	*
1277	* Appends __n copies of __c to this string.
1278	*/
1279	basic_string&
1280	append(size_type __n, _CharT __c)
1281	{ return _M_replace_aux(this->size(), size_type(`0`), __n, __c); }
1282
1283	#if __cplusplus >= 201103L
1284	/**
1285	* @brief Append an initializer_list of characters.
1286	* @param __l The initializer_list of characters to append.
1287	* @return Reference to this string.
1288	*/
1289	basic_string&
1290	append(initializer_list<_CharT> __l)
1291	{ return this->append(__l.begin(), __l.size()); }
1292	#endif // C++11
1293
1294	/**
1295	* @brief Append a range of characters.
1296	* @param __first Iterator referencing the first character to append.
1297	* @param __last Iterator marking the end of the range.
1298	* @return Reference to this string.
1299	*
1300	* Appends characters in the range [__first,__last) to this string.
1301	*/
1302	#if __cplusplus >= 201103L
1303	template<class _InputIterator,
1304	typename = std::_RequireInputIter<_InputIterator>>
1305	#else
1306	template<class _InputIterator>
1307	#endif
1308	basic_string&
1309	append(_InputIterator __first, _InputIterator __last)
1310	{ return this->replace(end(), end(), __first, __last); }
1311
1312	#if __cplusplus >= 201703L
1313	/**
1314	* @brief Append a string_view.
1315	* @param __svt An object convertible to string_view to be appended.
1316	* @return Reference to this string.
1317	*/
1318	template<typename _Tp>
1319	_If_sv<_Tp, basic_string&>
1320	append(const _Tp& __svt)
1321	{
1322	__sv_type __sv = __svt;
1323	return this->append(__sv.data(), __sv.size());
1324	}
1325
1326	/**
1327	* @brief Append a range of characters from a string_view.
1328	* @param __svt An object convertible to string_view to be appended from.
1329	* @param __pos The position in the string_view to append from.
1330	* @param __n The number of characters to append from the string_view.
1331	* @return Reference to this string.
1332	*/
1333	template<typename _Tp>
1334	_If_sv<_Tp, basic_string&>
1335	append(const _Tp& __svt, size_type __pos, size_type __n = npos)
1336	{
1337	__sv_type __sv = __svt;
1338	return _M_append(__sv.data()
1339	+ std::__sv_check(__sv.size(), __pos, "basic_string::append"),
1340	std::__sv_limit(__sv.size(), __pos, __n));
1341	}
1342	#endif // C++17
1343
1344	/**
1345	* @brief Append a single character.
1346	* @param __c Character to append.
1347	*/
1348	void
1349	push_back(_CharT __c)
1350	{
1351	const size_type __size = this->size();
1352	if (__size + `1` > this->capacity())
1353	this->_M_mutate(__size, size_type(`0`), `0`, size_type(`1`));
1354	traits_type::assign(this->_M_data()[__size], __c);
1355	this->_M_set_length(__size + `1`);
1356	}
1357
1358	/**
1359	* @brief Set value to contents of another string.
1360	* @param __str Source string to use.
1361	* @return Reference to this string.
1362	*/
1363	basic_string&
1364	assign(const basic_string& __str)
1365	{
1366	this->_M_assign(__str);
1367	return *this;
1368	}
1369
1370	#if __cplusplus >= 201103L
1371	/**
1372	* @brief Set value to contents of another string.
1373	* @param __str Source string to use.
1374	* @return Reference to this string.
1375	*
1376	* This function sets this string to the exact contents of @a __str.
1377	* @a __str is a valid, but unspecified string.
1378	*/
1379	basic_string&
1380	assign(basic_string&& __str)
1381	noexcept(_Alloc_traits::_S_nothrow_move())
1382	{
1383	// _GLIBCXX_RESOLVE_LIB_DEFECTS
1384	// 2063. Contradictory requirements for string move assignment
1385	return *this = std::move(__str);
1386	}
1387	#endif // C++11
1388
1389	/**
1390	* @brief Set value to a substring of a string.
1391	* @param __str The string to use.
1392	* @param __pos Index of the first character of str.
1393	* @param __n Number of characters to use.
1394	* @return Reference to this string.
1395	* @throw std::out_of_range if @a pos is not a valid index.
1396	*
1397	* This function sets this string to the substring of @a __str
1398	* consisting of @a __n characters at @a __pos. If @a __n is
1399	* is larger than the number of available characters in @a
1400	* __str, the remainder of @a __str is used.
1401	*/
1402	basic_string&
1403	assign(const basic_string& __str, size_type __pos, size_type __n = npos)
1404	{ return _M_replace(size_type(`0`), this->size(), __str._M_data()
1405	+ __str._M_check(__pos, "basic_string::assign"),
1406	__str._M_limit(__pos, __n)); }
1407
1408	/**
1409	* @brief Set value to a C substring.
1410	* @param __s The C string to use.
1411	* @param __n Number of characters to use.
1412	* @return Reference to this string.
1413	*
1414	* This function sets the value of this string to the first @a __n
1415	* characters of @a __s. If @a __n is is larger than the number of
1416	* available characters in @a __s, the remainder of @a __s is used.
1417	*/
1418	basic_string&
1419	assign(const _CharT* __s, size_type __n)
1420	{
1421	__glibcxx_requires_string_len(__s, __n);
1422	return _M_replace(size_type(`0`), this->size(), __s, __n);
1423	}
1424
1425	/**
1426	* @brief Set value to contents of a C string.
1427	* @param __s The C string to use.
1428	* @return Reference to this string.
1429	*
1430	* This function sets the value of this string to the value of @a __s.
1431	* The data is copied, so there is no dependence on @a __s once the
1432	* function returns.
1433	*/
1434	basic_string&
1435	assign(const _CharT* __s)
1436	{
1437	__glibcxx_requires_string(__s);
1438	return _M_replace(size_type(`0`), this->size(), __s,
1439	traits_type::length(__s));
1440	}
1441
1442	/**
1443	* @brief Set value to multiple characters.
1444	* @param __n Length of the resulting string.
1445	* @param __c The character to use.
1446	* @return Reference to this string.
1447	*
1448	* This function sets the value of this string to @a __n copies of
1449	* character @a __c.
1450	*/
1451	basic_string&
1452	assign(size_type __n, _CharT __c)
1453	{ return _M_replace_aux(size_type(`0`), this->size(), __n, __c); }
1454
1455	/**
1456	* @brief Set value to a range of characters.
1457	* @param __first Iterator referencing the first character to append.
1458	* @param __last Iterator marking the end of the range.
1459	* @return Reference to this string.
1460	*
1461	* Sets value of string to characters in the range [__first,__last).
1462	*/
1463	#if __cplusplus >= 201103L
1464	template<class _InputIterator,
1465	typename = std::_RequireInputIter<_InputIterator>>
1466	#else
1467	template<class _InputIterator>
1468	#endif
1469	basic_string&
1470	assign(_InputIterator __first, _InputIterator __last)
1471	{ return this->replace(begin(), end(), __first, __last); }
1472
1473	#if __cplusplus >= 201103L
1474	/**
1475	* @brief Set value to an initializer_list of characters.
1476	* @param __l The initializer_list of characters to assign.
1477	* @return Reference to this string.
1478	*/
1479	basic_string&
1480	assign(initializer_list<_CharT> __l)
1481	{ return this->assign(__l.begin(), __l.size()); }
1482	#endif // C++11
1483
1484	#if __cplusplus >= 201703L
1485	/**
1486	* @brief Set value from a string_view.
1487	* @param __svt The source object convertible to string_view.
1488	* @return Reference to this string.
1489	*/
1490	template<typename _Tp>
1491	_If_sv<_Tp, basic_string&>
1492	assign(const _Tp& __svt)
1493	{
1494	__sv_type __sv = __svt;
1495	return this->assign(__sv.data(), __sv.size());
1496	}
1497
1498	/**
1499	* @brief Set value from a range of characters in a string_view.
1500	* @param __svt The source object convertible to string_view.
1501	* @param __pos The position in the string_view to assign from.
1502	* @param __n The number of characters to assign.
1503	* @return Reference to this string.
1504	*/
1505	template<typename _Tp>
1506	_If_sv<_Tp, basic_string&>
1507	assign(const _Tp& __svt, size_type __pos, size_type __n = npos)
1508	{
1509	__sv_type __sv = __svt;
1510	return _M_replace(size_type(`0`), this->size(),
1511	__sv.data()
1512	+ std::__sv_check(__sv.size(), __pos, "basic_string::assign"),
1513	std::__sv_limit(__sv.size(), __pos, __n));
1514	}
1515	#endif // C++17
1516
1517	#if __cplusplus >= 201103L
1518	/**
1519	* @brief Insert multiple characters.
1520	* @param __p Const_iterator referencing location in string to
1521	* insert at.
1522	* @param __n Number of characters to insert
1523	* @param __c The character to insert.
1524	* @return Iterator referencing the first inserted char.
1525	* @throw std::length_error If new length exceeds @c max_size().
1526	*
1527	* Inserts @a __n copies of character @a __c starting at the
1528	* position referenced by iterator @a __p. If adding
1529	* characters causes the length to exceed max_size(),
1530	* length_error is thrown. The value of the string doesn't
1531	* change if an error is thrown.
1532	*/
1533	iterator
1534	insert(const_iterator __p, size_type __n, _CharT __c)
1535	{
1536	_GLIBCXX_DEBUG_PEDASSERT(__p >= begin() && __p <= end());
1537	const size_type __pos = __p - begin();
1538	this->replace(__p, __p, __n, __c);
1539	return iterator(this->_M_data() + __pos);
1540	}
1541	#else
1542	/**
1543	* @brief Insert multiple characters.
1544	* @param __p Iterator referencing location in string to insert at.
1545	* @param __n Number of characters to insert
1546	* @param __c The character to insert.
1547	* @throw std::length_error If new length exceeds @c max_size().
1548	*
1549	* Inserts @a __n copies of character @a __c starting at the
1550	* position referenced by iterator @a __p. If adding
1551	* characters causes the length to exceed max_size(),
1552	* length_error is thrown. The value of the string doesn't
1553	* change if an error is thrown.
1554	*/
1555	void
1556	insert(iterator __p, size_type __n, _CharT __c)
1557	{ this->replace(__p, __p, __n, __c); }
1558	#endif
1559
1560	#if __cplusplus >= 201103L
1561	/**
1562	* @brief Insert a range of characters.
1563	* @param __p Const_iterator referencing location in string to
1564	* insert at.
1565	* @param __beg Start of range.
1566	* @param __end End of range.
1567	* @return Iterator referencing the first inserted char.
1568	* @throw std::length_error If new length exceeds @c max_size().
1569	*
1570	* Inserts characters in range [beg,end). If adding characters
1571	* causes the length to exceed max_size(), length_error is
1572	* thrown. The value of the string doesn't change if an error
1573	* is thrown.
1574	*/
1575	template<class _InputIterator,
1576	typename = std::_RequireInputIter<_InputIterator>>
1577	iterator
1578	insert(const_iterator __p, _InputIterator __beg, _InputIterator __end)
1579	{
1580	_GLIBCXX_DEBUG_PEDASSERT(__p >= begin() && __p <= end());
1581	const size_type __pos = __p - begin();
1582	this->replace(__p, __p, __beg, __end);
1583	return iterator(this->_M_data() + __pos);
1584	}
1585	#else
1586	/**
1587	* @brief Insert a range of characters.
1588	* @param __p Iterator referencing location in string to insert at.
1589	* @param __beg Start of range.
1590	* @param __end End of range.
1591	* @throw std::length_error If new length exceeds @c max_size().
1592	*
1593	* Inserts characters in range [__beg,__end). If adding
1594	* characters causes the length to exceed max_size(),
1595	* length_error is thrown. The value of the string doesn't
1596	* change if an error is thrown.
1597	*/
1598	template<class _InputIterator>
1599	void
1600	insert(iterator __p, _InputIterator __beg, _InputIterator __end)
1601	{ this->replace(__p, __p, __beg, __end); }
1602	#endif
1603
1604	#if __cplusplus >= 201103L
1605	/**
1606	* @brief Insert an initializer_list of characters.
1607	* @param __p Iterator referencing location in string to insert at.
1608	* @param __l The initializer_list of characters to insert.
1609	* @throw std::length_error If new length exceeds @c max_size().
1610	*/
1611	iterator
1612	insert(const_iterator __p, initializer_list<_CharT> __l)
1613	{ return this->insert(__p, __l.begin(), __l.end()); }
1614
1615	#ifdef _GLIBCXX_DEFINING_STRING_INSTANTIATIONS
1616	// See PR libstdc++/83328
1617	void
1618	insert(iterator __p, initializer_list<_CharT> __l)
1619	{
1620	_GLIBCXX_DEBUG_PEDASSERT(__p >= begin() && __p <= end());
1621	this->insert(__p - begin(), __l.begin(), __l.size());
1622	}
1623	#endif
1624	#endif // C++11
1625
1626	/**
1627	* @brief Insert value of a string.
1628	* @param __pos1 Iterator referencing location in string to insert at.
1629	* @param __str The string to insert.
1630	* @return Reference to this string.
1631	* @throw std::length_error If new length exceeds @c max_size().
1632	*
1633	* Inserts value of @a __str starting at @a __pos1. If adding
1634	* characters causes the length to exceed max_size(),
1635	* length_error is thrown. The value of the string doesn't
1636	* change if an error is thrown.
1637	*/
1638	basic_string&
1639	insert(size_type __pos1, const basic_string& __str)
1640	{ return this->replace(__pos1, size_type(`0`),
1641	__str._M_data(), __str.size()); }
1642
1643	/**
1644	* @brief Insert a substring.
1645	* @param __pos1 Iterator referencing location in string to insert at.
1646	* @param __str The string to insert.
1647	* @param __pos2 Start of characters in str to insert.
1648	* @param __n Number of characters to insert.
1649	* @return Reference to this string.
1650	* @throw std::length_error If new length exceeds @c max_size().
1651	* @throw std::out_of_range If @a pos1 > size() or
1652	* @a __pos2 > @a str.size().
1653	*
1654	* Starting at @a pos1, insert @a __n character of @a __str
1655	* beginning with @a __pos2. If adding characters causes the
1656	* length to exceed max_size(), length_error is thrown. If @a
1657	* __pos1 is beyond the end of this string or @a __pos2 is
1658	* beyond the end of @a __str, out_of_range is thrown. The
1659	* value of the string doesn't change if an error is thrown.
1660	*/
1661	basic_string&
1662	insert(size_type __pos1, const basic_string& __str,
1663	size_type __pos2, size_type __n = npos)
1664	{ return this->replace(__pos1, size_type(`0`), __str._M_data()
1665	+ __str._M_check(__pos2, "basic_string::insert"),
1666	__str._M_limit(__pos2, __n)); }
1667
1668	/**
1669	* @brief Insert a C substring.
1670	* @param __pos Iterator referencing location in string to insert at.
1671	* @param __s The C string to insert.
1672	* @param __n The number of characters to insert.
1673	* @return Reference to this string.
1674	* @throw std::length_error If new length exceeds @c max_size().
1675	* @throw std::out_of_range If @a __pos is beyond the end of this
1676	* string.
1677	*
1678	* Inserts the first @a __n characters of @a __s starting at @a
1679	* __pos. If adding characters causes the length to exceed
1680	* max_size(), length_error is thrown. If @a __pos is beyond
1681	* end(), out_of_range is thrown. The value of the string
1682	* doesn't change if an error is thrown.
1683	*/
1684	basic_string&
1685	insert(size_type __pos, const _CharT* __s, size_type __n)
1686	{ return this->replace(__pos, size_type(`0`), __s, __n); }
1687
1688	/**
1689	* @brief Insert a C string.
1690	* @param __pos Iterator referencing location in string to insert at.
1691	* @param __s The C string to insert.
1692	* @return Reference to this string.
1693	* @throw std::length_error If new length exceeds @c max_size().
1694	* @throw std::out_of_range If @a pos is beyond the end of this
1695	* string.
1696	*
1697	* Inserts the first @a n characters of @a __s starting at @a __pos. If
1698	* adding characters causes the length to exceed max_size(),
1699	* length_error is thrown. If @a __pos is beyond end(), out_of_range is
1700	* thrown. The value of the string doesn't change if an error is
1701	* thrown.
1702	*/
1703	basic_string&
1704	insert(size_type __pos, const _CharT* __s)
1705	{
1706	__glibcxx_requires_string(__s);
1707	return this->replace(__pos, size_type(`0`), __s,
1708	traits_type::length(__s));
1709	}
1710
1711	/**
1712	* @brief Insert multiple characters.
1713	* @param __pos Index in string to insert at.
1714	* @param __n Number of characters to insert
1715	* @param __c The character to insert.
1716	* @return Reference to this string.
1717	* @throw std::length_error If new length exceeds @c max_size().
1718	* @throw std::out_of_range If @a __pos is beyond the end of this
1719	* string.
1720	*
1721	* Inserts @a __n copies of character @a __c starting at index
1722	* @a __pos. If adding characters causes the length to exceed
1723	* max_size(), length_error is thrown. If @a __pos > length(),
1724	* out_of_range is thrown. The value of the string doesn't
1725	* change if an error is thrown.
1726	*/
1727	basic_string&
1728	insert(size_type __pos, size_type __n, _CharT __c)
1729	{ return _M_replace_aux(_M_check(__pos, "basic_string::insert"),
1730	size_type(`0`), __n, __c); }
1731
1732	/**
1733	* @brief Insert one character.
1734	* @param __p Iterator referencing position in string to insert at.
1735	* @param __c The character to insert.
1736	* @return Iterator referencing newly inserted char.
1737	* @throw std::length_error If new length exceeds @c max_size().
1738	*
1739	* Inserts character @a __c at position referenced by @a __p.
1740	* If adding character causes the length to exceed max_size(),
1741	* length_error is thrown. If @a __p is beyond end of string,
1742	* out_of_range is thrown. The value of the string doesn't
1743	* change if an error is thrown.
1744	*/
1745	iterator
1746	insert(__const_iterator __p, _CharT __c)
1747	{
1748	_GLIBCXX_DEBUG_PEDASSERT(__p >= begin() && __p <= end());
1749	const size_type __pos = __p - begin();
1750	_M_replace_aux(__pos, size_type(`0`), size_type(`1`), __c);
1751	return iterator(_M_data() + __pos);
1752	}
1753
1754	#if __cplusplus >= 201703L
1755	/**
1756	* @brief Insert a string_view.
1757	* @param __pos Iterator referencing position in string to insert at.
1758	* @param __svt The object convertible to string_view to insert.
1759	* @return Reference to this string.
1760	*/
1761	template<typename _Tp>
1762	_If_sv<_Tp, basic_string&>
1763	insert(size_type __pos, const _Tp& __svt)
1764	{
1765	__sv_type __sv = __svt;
1766	return this->insert(__pos, __sv.data(), __sv.size());
1767	}
1768
1769	/**
1770	* @brief Insert a string_view.
1771	* @param __pos Iterator referencing position in string to insert at.
1772	* @param __svt The object convertible to string_view to insert from.
1773	* @param __pos Iterator referencing position in string_view to insert
1774	* from.
1775	* @param __n The number of characters to insert.
1776	* @return Reference to this string.
1777	*/
1778	template<typename _Tp>
1779	_If_sv<_Tp, basic_string&>
1780	insert(size_type __pos1, const _Tp& __svt,
1781	size_type __pos2, size_type __n = npos)
1782	{
1783	__sv_type __sv = __svt;
1784	return this->replace(__pos1, size_type(`0`),
1785	__sv.data()
1786	+ std::__sv_check(__sv.size(), __pos2, "basic_string::insert"),
1787	std::__sv_limit(__sv.size(), __pos2, __n));
1788	}
1789	#endif // C++17
1790
1791	/**
1792	* @brief Remove characters.
1793	* @param __pos Index of first character to remove (default 0).
1794	* @param __n Number of characters to remove (default remainder).
1795	* @return Reference to this string.
1796	* @throw std::out_of_range If @a pos is beyond the end of this
1797	* string.
1798	*
1799	* Removes @a __n characters from this string starting at @a
1800	* __pos. The length of the string is reduced by @a __n. If
1801	* there are < @a __n characters to remove, the remainder of
1802	* the string is truncated. If @a __p is beyond end of string,
1803	* out_of_range is thrown. The value of the string doesn't
1804	* change if an error is thrown.
1805	*/
1806	basic_string&
1807	erase(size_type __pos = `0`, size_type __n = npos)
1808	{
1809	_M_check(__pos, "basic_string::erase");
1810	if (__n == npos)
1811	this->_M_set_length(__pos);
1812	else if (__n != `0`)
1813	this->_M_erase(__pos, _M_limit(__pos, __n));
1814	return *this;
1815	}
1816
1817	/**
1818	* @brief Remove one character.
1819	* @param __position Iterator referencing the character to remove.
1820	* @return iterator referencing same location after removal.
1821	*
1822	* Removes the character at @a __position from this string. The value
1823	* of the string doesn't change if an error is thrown.
1824	*/
1825	iterator
1826	erase(__const_iterator __position)
1827	{
1828	_GLIBCXX_DEBUG_PEDASSERT(__position >= begin()
1829	&& __position < end());
1830	const size_type __pos = __position - begin();
1831	this->_M_erase(__pos, size_type(`1`));
1832	return iterator(_M_data() + __pos);
1833	}
1834
1835	/**
1836	* @brief Remove a range of characters.
1837	* @param __first Iterator referencing the first character to remove.
1838	* @param __last Iterator referencing the end of the range.
1839	* @return Iterator referencing location of first after removal.
1840	*
1841	* Removes the characters in the range [first,last) from this string.
1842	* The value of the string doesn't change if an error is thrown.
1843	*/
1844	iterator
1845	erase(__const_iterator __first, __const_iterator __last)
1846	{
1847	_GLIBCXX_DEBUG_PEDASSERT(__first >= begin() && __first <= __last
1848	&& __last <= end());
1849	const size_type __pos = __first - begin();
1850	if (__last == end())
1851	this->_M_set_length(__pos);
1852	else
1853	this->_M_erase(__pos, __last - __first);
1854	return iterator(this->_M_data() + __pos);
1855	}
1856
1857	#if __cplusplus >= 201103L
1858	/**
1859	* @brief Remove the last character.
1860	*
1861	* The string must be non-empty.
1862	*/
1863	void
1864	pop_back() noexcept
1865	{
1866	__glibcxx_assert(!empty());
1867	_M_erase(size() - `1`, `1`);
1868	}
1869	#endif // C++11
1870
1871	/**
1872	* @brief Replace characters with value from another string.
1873	* @param __pos Index of first character to replace.
1874	* @param __n Number of characters to be replaced.
1875	* @param __str String to insert.
1876	* @return Reference to this string.
1877	* @throw std::out_of_range If @a pos is beyond the end of this
1878	* string.
1879	* @throw std::length_error If new length exceeds @c max_size().
1880	*
1881	* Removes the characters in the range [__pos,__pos+__n) from
1882	* this string. In place, the value of @a __str is inserted.
1883	* If @a __pos is beyond end of string, out_of_range is thrown.
1884	* If the length of the result exceeds max_size(), length_error
1885	* is thrown. The value of the string doesn't change if an
1886	* error is thrown.
1887	*/
1888	basic_string&
1889	replace(size_type __pos, size_type __n, const basic_string& __str)
1890	{ return this->replace(__pos, __n, __str._M_data(), __str.size()); }
1891
1892	/**
1893	* @brief Replace characters with value from another string.
1894	* @param __pos1 Index of first character to replace.
1895	* @param __n1 Number of characters to be replaced.
1896	* @param __str String to insert.
1897	* @param __pos2 Index of first character of str to use.
1898	* @param __n2 Number of characters from str to use.
1899	* @return Reference to this string.
1900	* @throw std::out_of_range If @a __pos1 > size() or @a __pos2 >
1901	* __str.size().
1902	* @throw std::length_error If new length exceeds @c max_size().
1903	*
1904	* Removes the characters in the range [__pos1,__pos1 + n) from this
1905	* string. In place, the value of @a __str is inserted. If @a __pos is
1906	* beyond end of string, out_of_range is thrown. If the length of the
1907	* result exceeds max_size(), length_error is thrown. The value of the
1908	* string doesn't change if an error is thrown.
1909	*/
1910	basic_string&
1911	replace(size_type __pos1, size_type __n1, const basic_string& __str,
1912	size_type __pos2, size_type __n2 = npos)
1913	{ return this->replace(__pos1, __n1, __str._M_data()
1914	+ __str._M_check(__pos2, "basic_string::replace"),
1915	__str._M_limit(__pos2, __n2)); }
1916
1917	/**
1918	* @brief Replace characters with value of a C substring.
1919	* @param __pos Index of first character to replace.
1920	* @param __n1 Number of characters to be replaced.
1921	* @param __s C string to insert.
1922	* @param __n2 Number of characters from @a s to use.
1923	* @return Reference to this string.
1924	* @throw std::out_of_range If @a pos1 > size().
1925	* @throw std::length_error If new length exceeds @c max_size().
1926	*
1927	* Removes the characters in the range [__pos,__pos + __n1)
1928	* from this string. In place, the first @a __n2 characters of
1929	* @a __s are inserted, or all of @a __s if @a __n2 is too large. If
1930	* @a __pos is beyond end of string, out_of_range is thrown. If
1931	* the length of result exceeds max_size(), length_error is
1932	* thrown. The value of the string doesn't change if an error
1933	* is thrown.
1934	*/
1935	basic_string&
1936	replace(size_type __pos, size_type __n1, const _CharT* __s,
1937	size_type __n2)
1938	{
1939	__glibcxx_requires_string_len(__s, __n2);
1940	return _M_replace(_M_check(__pos, "basic_string::replace"),
1941	_M_limit(__pos, __n1), __s, __n2);
1942	}
1943
1944	/**
1945	* @brief Replace characters with value of a C string.
1946	* @param __pos Index of first character to replace.
1947	* @param __n1 Number of characters to be replaced.
1948	* @param __s C string to insert.
1949	* @return Reference to this string.
1950	* @throw std::out_of_range If @a pos > size().
1951	* @throw std::length_error If new length exceeds @c max_size().
1952	*
1953	* Removes the characters in the range [__pos,__pos + __n1)
1954	* from this string. In place, the characters of @a __s are
1955	* inserted. If @a __pos is beyond end of string, out_of_range
1956	* is thrown. If the length of result exceeds max_size(),
1957	* length_error is thrown. The value of the string doesn't
1958	* change if an error is thrown.
1959	*/
1960	basic_string&
1961	replace(size_type __pos, size_type __n1, const _CharT* __s)
1962	{
1963	__glibcxx_requires_string(__s);
1964	return this->replace(__pos, __n1, __s, traits_type::length(__s));
1965	}
1966
1967	/**
1968	* @brief Replace characters with multiple characters.
1969	* @param __pos Index of first character to replace.
1970	* @param __n1 Number of characters to be replaced.
1971	* @param __n2 Number of characters to insert.
1972	* @param __c Character to insert.
1973	* @return Reference to this string.
1974	* @throw std::out_of_range If @a __pos > size().
1975	* @throw std::length_error If new length exceeds @c max_size().
1976	*
1977	* Removes the characters in the range [pos,pos + n1) from this
1978	* string. In place, @a __n2 copies of @a __c are inserted.
1979	* If @a __pos is beyond end of string, out_of_range is thrown.
1980	* If the length of result exceeds max_size(), length_error is
1981	* thrown. The value of the string doesn't change if an error
1982	* is thrown.
1983	*/
1984	basic_string&
1985	replace(size_type __pos, size_type __n1, size_type __n2, _CharT __c)
1986	{ return _M_replace_aux(_M_check(__pos, "basic_string::replace"),
1987	_M_limit(__pos, __n1), __n2, __c); }
1988
1989	/**
1990	* @brief Replace range of characters with string.
1991	* @param __i1 Iterator referencing start of range to replace.
1992	* @param __i2 Iterator referencing end of range to replace.
1993	* @param __str String value to insert.
1994	* @return Reference to this string.
1995	* @throw std::length_error If new length exceeds @c max_size().
1996	*
1997	* Removes the characters in the range [__i1,__i2). In place,
1998	* the value of @a __str is inserted. If the length of result
1999	* exceeds max_size(), length_error is thrown. The value of
2000	* the string doesn't change if an error is thrown.
2001	*/
2002	basic_string&
2003	replace(__const_iterator __i1, __const_iterator __i2,
2004	const basic_string& __str)
2005	{ return this->replace(__i1, __i2, __str._M_data(), __str.size()); }
2006
2007	/**
2008	* @brief Replace range of characters with C substring.
2009	* @param __i1 Iterator referencing start of range to replace.
2010	* @param __i2 Iterator referencing end of range to replace.
2011	* @param __s C string value to insert.
2012	* @param __n Number of characters from s to insert.
2013	* @return Reference to this string.
2014	* @throw std::length_error If new length exceeds @c max_size().
2015	*
2016	* Removes the characters in the range [__i1,__i2). In place,
2017	* the first @a __n characters of @a __s are inserted. If the
2018	* length of result exceeds max_size(), length_error is thrown.
2019	* The value of the string doesn't change if an error is
2020	* thrown.
2021	*/
2022	basic_string&
2023	replace(__const_iterator __i1, __const_iterator __i2,
2024	const _CharT* __s, size_type __n)
2025	{
2026	_GLIBCXX_DEBUG_PEDASSERT(begin() <= __i1 && __i1 <= __i2
2027	&& __i2 <= end());
2028	return this->replace(__i1 - begin(), __i2 - __i1, __s, __n);
2029	}
2030
2031	/**
2032	* @brief Replace range of characters with C string.
2033	* @param __i1 Iterator referencing start of range to replace.
2034	* @param __i2 Iterator referencing end of range to replace.
2035	* @param __s C string value to insert.
2036	* @return Reference to this string.
2037	* @throw std::length_error If new length exceeds @c max_size().
2038	*
2039	* Removes the characters in the range [__i1,__i2). In place,
2040	* the characters of @a __s are inserted. If the length of
2041	* result exceeds max_size(), length_error is thrown. The
2042	* value of the string doesn't change if an error is thrown.
2043	*/
2044	basic_string&
2045	replace(__const_iterator __i1, __const_iterator __i2, const _CharT* __s)
2046	{
2047	__glibcxx_requires_string(__s);
2048	return this->replace(__i1, __i2, __s, traits_type::length(__s));
2049	}
2050
2051	/**
2052	* @brief Replace range of characters with multiple characters
2053	* @param __i1 Iterator referencing start of range to replace.
2054	* @param __i2 Iterator referencing end of range to replace.
2055	* @param __n Number of characters to insert.
2056	* @param __c Character to insert.
2057	* @return Reference to this string.
2058	* @throw std::length_error If new length exceeds @c max_size().
2059	*
2060	* Removes the characters in the range [__i1,__i2). In place,
2061	* @a __n copies of @a __c are inserted. If the length of
2062	* result exceeds max_size(), length_error is thrown. The
2063	* value of the string doesn't change if an error is thrown.
2064	*/
2065	basic_string&
2066	replace(__const_iterator __i1, __const_iterator __i2, size_type __n,
2067	_CharT __c)
2068	{
2069	_GLIBCXX_DEBUG_PEDASSERT(begin() <= __i1 && __i1 <= __i2
2070	&& __i2 <= end());
2071	return _M_replace_aux(__i1 - begin(), __i2 - __i1, __n, __c);
2072	}
2073
2074	/**
2075	* @brief Replace range of characters with range.
2076	* @param __i1 Iterator referencing start of range to replace.
2077	* @param __i2 Iterator referencing end of range to replace.
2078	* @param __k1 Iterator referencing start of range to insert.
2079	* @param __k2 Iterator referencing end of range to insert.
2080	* @return Reference to this string.
2081	* @throw std::length_error If new length exceeds @c max_size().
2082	*
2083	* Removes the characters in the range [__i1,__i2). In place,
2084	* characters in the range [__k1,__k2) are inserted. If the
2085	* length of result exceeds max_size(), length_error is thrown.
2086	* The value of the string doesn't change if an error is
2087	* thrown.
2088	*/
2089	#if __cplusplus >= 201103L
2090	template<class _InputIterator,
2091	typename = std::_RequireInputIter<_InputIterator>>
2092	basic_string&
2093	replace(const_iterator __i1, const_iterator __i2,
2094	_InputIterator __k1, _InputIterator __k2)
2095	{
2096	_GLIBCXX_DEBUG_PEDASSERT(begin() <= __i1 && __i1 <= __i2
2097	&& __i2 <= end());
2098	__glibcxx_requires_valid_range(__k1, __k2);
2099	return this->_M_replace_dispatch(__i1, __i2, __k1, __k2,
2100	std::__false_type ());
2101	}
2102	#else
2103	template<class _InputIterator>
2104	#ifdef _GLIBCXX_DISAMBIGUATE_REPLACE_INST
2105	typename __enable_if_not_native_iterator<_InputIterator>::__type
2106	#else
2107	basic_string&
2108	#endif
2109	replace(iterator __i1, iterator __i2,
2110	_InputIterator __k1, _InputIterator __k2)
2111	{
2112	_GLIBCXX_DEBUG_PEDASSERT(begin() <= __i1 && __i1 <= __i2
2113	&& __i2 <= end());
2114	__glibcxx_requires_valid_range(__k1, __k2);
2115	typedef typename std::__is_integer<_InputIterator>::__type _Integral;
2116	return _M_replace_dispatch(__i1, __i2, __k1, __k2, _Integral());
2117	}
2118	#endif
2119
2120	// Specializations for the common case of pointer and iterator:
2121	// useful to avoid the overhead of temporary buffering in _M_replace.
2122	basic_string&
2123	replace(__const_iterator __i1, __const_iterator __i2,
2124	_CharT* __k1, _CharT* __k2)
2125	{
2126	_GLIBCXX_DEBUG_PEDASSERT(begin() <= __i1 && __i1 <= __i2
2127	&& __i2 <= end());
2128	__glibcxx_requires_valid_range(__k1, __k2);
2129	return this->replace(__i1 - begin(), __i2 - __i1,
2130	__k1, __k2 - __k1);
2131	}
2132
2133	basic_string&
2134	replace(__const_iterator __i1, __const_iterator __i2,
2135	const _CharT* __k1, const _CharT* __k2)
2136	{
2137	_GLIBCXX_DEBUG_PEDASSERT(begin() <= __i1 && __i1 <= __i2
2138	&& __i2 <= end());
2139	__glibcxx_requires_valid_range(__k1, __k2);
2140	return this->replace(__i1 - begin(), __i2 - __i1,
2141	__k1, __k2 - __k1);
2142	}
2143
2144	basic_string&
2145	replace(__const_iterator __i1, __const_iterator __i2,
2146	iterator __k1, iterator __k2)
2147	{
2148	_GLIBCXX_DEBUG_PEDASSERT(begin() <= __i1 && __i1 <= __i2
2149	&& __i2 <= end());
2150	__glibcxx_requires_valid_range(__k1, __k2);
2151	return this->replace(__i1 - begin(), __i2 - __i1,
2152	__k1.base(), __k2 - __k1);
2153	}
2154
2155	basic_string&
2156	replace(__const_iterator __i1, __const_iterator __i2,
2157	const_iterator __k1, const_iterator __k2)
2158	{
2159	_GLIBCXX_DEBUG_PEDASSERT(begin() <= __i1 && __i1 <= __i2
2160	&& __i2 <= end());
2161	__glibcxx_requires_valid_range(__k1, __k2);
2162	return this->replace(__i1 - begin(), __i2 - __i1,
2163	__k1.base(), __k2 - __k1);
2164	}
2165
2166	#if __cplusplus >= 201103L
2167	/**
2168	* @brief Replace range of characters with initializer_list.
2169	* @param __i1 Iterator referencing start of range to replace.
2170	* @param __i2 Iterator referencing end of range to replace.
2171	* @param __l The initializer_list of characters to insert.
2172	* @return Reference to this string.
2173	* @throw std::length_error If new length exceeds @c max_size().
2174	*
2175	* Removes the characters in the range [__i1,__i2). In place,
2176	* characters in the range [__k1,__k2) are inserted. If the
2177	* length of result exceeds max_size(), length_error is thrown.
2178	* The value of the string doesn't change if an error is
2179	* thrown.
2180	*/
2181	basic_string& replace(const_iterator __i1, const_iterator __i2,
2182	initializer_list<_CharT> __l)
2183	{ return this->replace(__i1, __i2, __l.begin(), __l.size()); }
2184	#endif // C++11
2185
2186	#if __cplusplus >= 201703L
2187	/**
2188	* @brief Replace range of characters with string_view.
2189	* @param __pos The position to replace at.
2190	* @param __n The number of characters to replace.
2191	* @param __svt The object convertible to string_view to insert.
2192	* @return Reference to this string.
2193	*/
2194	template<typename _Tp>
2195	_If_sv<_Tp, basic_string&>
2196	replace(size_type __pos, size_type __n, const _Tp& __svt)
2197	{
2198	__sv_type __sv = __svt;
2199	return this->replace(__pos, __n, __sv.data(), __sv.size());
2200	}
2201
2202	/**
2203	* @brief Replace range of characters with string_view.
2204	* @param __pos1 The position to replace at.
2205	* @param __n1 The number of characters to replace.
2206	* @param __svt The object convertible to string_view to insert from.
2207	* @param __pos2 The position in the string_view to insert from.
2208	* @param __n2 The number of characters to insert.
2209	* @return Reference to this string.
2210	*/
2211	template<typename _Tp>
2212	_If_sv<_Tp, basic_string&>
2213	replace(size_type __pos1, size_type __n1, const _Tp& __svt,
2214	size_type __pos2, size_type __n2 = npos)
2215	{
2216	__sv_type __sv = __svt;
2217	return this->replace(__pos1, __n1,
2218	__sv.data()
2219	+ std::__sv_check(__sv.size(), __pos2, "basic_string::replace"),
2220	std::__sv_limit(__sv.size(), __pos2, __n2));
2221	}
2222
2223	/**
2224	* @brief Replace range of characters with string_view.
2225	* @param __i1 An iterator referencing the start position
2226	to replace at.
2227	* @param __i2 An iterator referencing the end position
2228	for the replace.
2229	* @param __svt The object convertible to string_view to insert from.
2230	* @return Reference to this string.
2231	*/
2232	template<typename _Tp>
2233	_If_sv<_Tp, basic_string&>
2234	replace(const_iterator __i1, const_iterator __i2, const _Tp& __svt)
2235	{
2236	__sv_type __sv = __svt;
2237	return this->replace(__i1 - begin(), __i2 - __i1, __sv);
2238	}
2239	#endif // C++17
2240
2241	private:
2242	template<class _Integer>
2243	basic_string&
2244	_M_replace_dispatch(const_iterator __i1, const_iterator __i2,
2245	_Integer __n, _Integer __val, __true_type)
2246	{ return _M_replace_aux(__i1 - begin(), __i2 - __i1, __n, __val); }
2247
2248	template<class _InputIterator>
2249	basic_string&
2250	_M_replace_dispatch(const_iterator __i1, const_iterator __i2,
2251	_InputIterator __k1, _InputIterator __k2,
2252	__false_type);
2253
2254	basic_string&
2255	_M_replace_aux(size_type __pos1, size_type __n1, size_type __n2,
2256	_CharT __c);
2257
2258	basic_string&
2259	_M_replace(size_type __pos, size_type __len1, const _CharT* __s,
2260	const size_type __len2);
2261
2262	basic_string&
2263	_M_append(const _CharT* __s, size_type __n);
2264
2265	public:
2266
2267	/**
2268	* @brief Copy substring into C string.
2269	* @param __s C string to copy value into.
2270	* @param __n Number of characters to copy.
2271	* @param __pos Index of first character to copy.
2272	* @return Number of characters actually copied
2273	* @throw std::out_of_range If __pos > size().
2274	*
2275	* Copies up to @a __n characters starting at @a __pos into the
2276	* C string @a __s. If @a __pos is %greater than size(),
2277	* out_of_range is thrown.
2278	*/
2279	size_type
2280	copy(_CharT* __s, size_type __n, size_type __pos = `0`) const;
2281
2282	/**
2283	* @brief Swap contents with another string.
2284	* @param __s String to swap with.
2285	*
2286	* Exchanges the contents of this string with that of @a __s in constant
2287	* time.
2288	*/
2289	void
2290	swap(basic_string& __s) _GLIBCXX_NOEXCEPT;
2291
2292	// String operations:
2293	/**
2294	* @brief Return const pointer to null-terminated contents.
2295	*
2296	* This is a handle to internal data. Do not modify or dire things may
2297	* happen.
2298	*/
2299	const _CharT*
2300	c_str() const _GLIBCXX_NOEXCEPT
2301	{ return _M_data(); }
2302
2303	/**
2304	* @brief Return const pointer to contents.
2305	*
2306	* This is a pointer to internal data. It is undefined to modify
2307	* the contents through the returned pointer. To get a pointer that
2308	* allows modifying the contents use @c &str[0] instead,
2309	* (or in C++17 the non-const @c str.data() overload).
2310	*/
2311	const _CharT*
2312	data() const _GLIBCXX_NOEXCEPT
2313	{ return _M_data(); }
2314
2315	#if __cplusplus >= 201703L
2316	/**
2317	* @brief Return non-const pointer to contents.
2318	*
2319	* This is a pointer to the character sequence held by the string.
2320	* Modifying the characters in the sequence is allowed.
2321	*/
2322	_CharT*
2323	data() noexcept
2324	{ return _M_data(); }
2325	#endif
2326
2327	/**
2328	* @brief Return copy of allocator used to construct this string.
2329	*/
2330	allocator_type
2331	get_allocator() const _GLIBCXX_NOEXCEPT
2332	{ return _M_get_allocator(); }
2333
2334	/**
2335	* @brief Find position of a C substring.
2336	* @param __s C string to locate.
2337	* @param __pos Index of character to search from.
2338	* @param __n Number of characters from @a s to search for.
2339	* @return Index of start of first occurrence.
2340	*
2341	* Starting from @a __pos, searches forward for the first @a
2342	* __n characters in @a __s within this string. If found,
2343	* returns the index where it begins. If not found, returns
2344	* npos.
2345	*/
2346	size_type
2347	find(const _CharT* __s, size_type __pos, size_type __n) const
2348	_GLIBCXX_NOEXCEPT;
2349
2350	/**
2351	* @brief Find position of a string.
2352	* @param __str String to locate.
2353	* @param __pos Index of character to search from (default 0).
2354	* @return Index of start of first occurrence.
2355	*
2356	* Starting from @a __pos, searches forward for value of @a __str within
2357	* this string. If found, returns the index where it begins. If not
2358	* found, returns npos.
2359	*/
2360	size_type
2361	find(const basic_string& __str, size_type __pos = `0`) const
2362	_GLIBCXX_NOEXCEPT
2363	{ return this->find(__str.data(), __pos, __str.size()); }
2364
2365	#if __cplusplus >= 201703L
2366	/**
2367	* @brief Find position of a string_view.
2368	* @param __svt The object convertible to string_view to locate.
2369	* @param __pos Index of character to search from (default 0).
2370	* @return Index of start of first occurrence.
2371	*/
2372	template<typename _Tp>
2373	_If_sv<_Tp, size_type>
2374	find(const _Tp& __svt, size_type __pos = `0`) const
2375	noexcept(is_same<_Tp, __sv_type>::value)
2376	{
2377	__sv_type __sv = __svt;
2378	return this->find(__sv.data(), __pos, __sv.size());
2379	}
2380	#endif // C++17
2381
2382	/**
2383	* @brief Find position of a C string.
2384	* @param __s C string to locate.
2385	* @param __pos Index of character to search from (default 0).
2386	* @return Index of start of first occurrence.
2387	*
2388	* Starting from @a __pos, searches forward for the value of @a
2389	* __s within this string. If found, returns the index where
2390	* it begins. If not found, returns npos.
2391	*/
2392	size_type
2393	find(const _CharT* __s, size_type __pos = `0`) const _GLIBCXX_NOEXCEPT
2394	{
2395	__glibcxx_requires_string(__s);
2396	return this->find(__s, __pos, traits_type::length(__s));
2397	}
2398
2399	/**
2400	* @brief Find position of a character.
2401	* @param __c Character to locate.
2402	* @param __pos Index of character to search from (default 0).
2403	* @return Index of first occurrence.
2404	*
2405	* Starting from @a __pos, searches forward for @a __c within
2406	* this string. If found, returns the index where it was
2407	* found. If not found, returns npos.
2408	*/
2409	size_type
2410	find(_CharT __c, size_type __pos = `0`) const _GLIBCXX_NOEXCEPT;
2411
2412	/**
2413	* @brief Find last position of a string.
2414	* @param __str String to locate.
2415	* @param __pos Index of character to search back from (default end).
2416	* @return Index of start of last occurrence.
2417	*
2418	* Starting from @a __pos, searches backward for value of @a
2419	* __str within this string. If found, returns the index where
2420	* it begins. If not found, returns npos.
2421	*/
2422	size_type
2423	rfind(const basic_string& __str, size_type __pos = npos) const
2424	_GLIBCXX_NOEXCEPT
2425	{ return this->rfind(__str.data(), __pos, __str.size()); }
2426
2427	#if __cplusplus >= 201703L
2428	/**
2429	* @brief Find last position of a string_view.
2430	* @param __svt The object convertible to string_view to locate.
2431	* @param __pos Index of character to search back from (default end).
2432	* @return Index of start of last occurrence.
2433	*/
2434	template<typename _Tp>
2435	_If_sv<_Tp, size_type>
2436	rfind(const _Tp& __svt, size_type __pos = npos) const
2437	noexcept(is_same<_Tp, __sv_type>::value)
2438	{
2439	__sv_type __sv = __svt;
2440	return this->rfind(__sv.data(), __pos, __sv.size());
2441	}
2442	#endif // C++17
2443
2444	/**
2445	* @brief Find last position of a C substring.
2446	* @param __s C string to locate.
2447	* @param __pos Index of character to search back from.
2448	* @param __n Number of characters from s to search for.
2449	* @return Index of start of last occurrence.
2450	*
2451	* Starting from @a __pos, searches backward for the first @a
2452	* __n characters in @a __s within this string. If found,
2453	* returns the index where it begins. If not found, returns
2454	* npos.
2455	*/
2456	size_type
2457	rfind(const _CharT* __s, size_type __pos, size_type __n) const
2458	_GLIBCXX_NOEXCEPT;
2459
2460	/**
2461	* @brief Find last position of a C string.
2462	* @param __s C string to locate.
2463	* @param __pos Index of character to start search at (default end).
2464	* @return Index of start of last occurrence.
2465	*
2466	* Starting from @a __pos, searches backward for the value of
2467	* @a __s within this string. If found, returns the index
2468	* where it begins. If not found, returns npos.
2469	*/
2470	size_type
2471	rfind(const _CharT* __s, size_type __pos = npos) const
2472	{
2473	__glibcxx_requires_string(__s);
2474	return this->rfind(__s, __pos, traits_type::length(__s));
2475	}
2476
2477	/**
2478	* @brief Find last position of a character.
2479	* @param __c Character to locate.
2480	* @param __pos Index of character to search back from (default end).
2481	* @return Index of last occurrence.
2482	*
2483	* Starting from @a __pos, searches backward for @a __c within
2484	* this string. If found, returns the index where it was
2485	* found. If not found, returns npos.
2486	*/
2487	size_type
2488	rfind(_CharT __c, size_type __pos = npos) const _GLIBCXX_NOEXCEPT;
2489
2490	/**
2491	* @brief Find position of a character of string.
2492	* @param __str String containing characters to locate.
2493	* @param __pos Index of character to search from (default 0).
2494	* @return Index of first occurrence.
2495	*
2496	* Starting from @a __pos, searches forward for one of the
2497	* characters of @a __str within this string. If found,
2498	* returns the index where it was found. If not found, returns
2499	* npos.
2500	*/
2501	size_type
2502	find_first_of(const basic_string& __str, size_type __pos = `0`) const
2503	_GLIBCXX_NOEXCEPT
2504	{ return this->find_first_of(__str.data(), __pos, __str.size()); }
2505
2506	#if __cplusplus >= 201703L
2507	/**
2508	* @brief Find position of a character of a string_view.
2509	* @param __svt An object convertible to string_view containing
2510	* characters to locate.
2511	* @param __pos Index of character to search from (default 0).
2512	* @return Index of first occurrence.
2513	*/
2514	template<typename _Tp>
2515	_If_sv<_Tp, size_type>
2516	find_first_of(const _Tp& __svt, size_type __pos = `0`) const
2517	noexcept(is_same<_Tp, __sv_type>::value)
2518	{
2519	__sv_type __sv = __svt;
2520	return this->find_first_of(__sv.data(), __pos, __sv.size());
2521	}
2522	#endif // C++17
2523
2524	/**
2525	* @brief Find position of a character of C substring.
2526	* @param __s String containing characters to locate.
2527	* @param __pos Index of character to search from.
2528	* @param __n Number of characters from s to search for.
2529	* @return Index of first occurrence.
2530	*
2531	* Starting from @a __pos, searches forward for one of the
2532	* first @a __n characters of @a __s within this string. If
2533	* found, returns the index where it was found. If not found,
2534	* returns npos.
2535	*/
2536	size_type
2537	find_first_of(const _CharT* __s, size_type __pos, size_type __n) const
2538	_GLIBCXX_NOEXCEPT;
2539
2540	/**
2541	* @brief Find position of a character of C string.
2542	* @param __s String containing characters to locate.
2543	* @param __pos Index of character to search from (default 0).
2544	* @return Index of first occurrence.
2545	*
2546	* Starting from @a __pos, searches forward for one of the
2547	* characters of @a __s within this string. If found, returns
2548	* the index where it was found. If not found, returns npos.
2549	*/
2550	size_type
2551	find_first_of(const _CharT* __s, size_type __pos = `0`) const
2552	_GLIBCXX_NOEXCEPT
2553	{
2554	__glibcxx_requires_string(__s);
2555	return this->find_first_of(__s, __pos, traits_type::length(__s));
2556	}
2557
2558	/**
2559	* @brief Find position of a character.
2560	* @param __c Character to locate.
2561	* @param __pos Index of character to search from (default 0).
2562	* @return Index of first occurrence.
2563	*
2564	* Starting from @a __pos, searches forward for the character
2565	* @a __c within this string. If found, returns the index
2566	* where it was found. If not found, returns npos.
2567	*
2568	* Note: equivalent to find(__c, __pos).
2569	*/
2570	size_type
2571	find_first_of(_CharT __c, size_type __pos = `0`) const _GLIBCXX_NOEXCEPT
2572	{ return this->find(__c, __pos); }
2573
2574	/**
2575	* @brief Find last position of a character of string.
2576	* @param __str String containing characters to locate.
2577	* @param __pos Index of character to search back from (default end).
2578	* @return Index of last occurrence.
2579	*
2580	* Starting from @a __pos, searches backward for one of the
2581	* characters of @a __str within this string. If found,
2582	* returns the index where it was found. If not found, returns
2583	* npos.
2584	*/
2585	size_type
2586	find_last_of(const basic_string& __str, size_type __pos = npos) const
2587	_GLIBCXX_NOEXCEPT
2588	{ return this->find_last_of(__str.data(), __pos, __str.size()); }
2589
2590	#if __cplusplus >= 201703L
2591	/**
2592	* @brief Find last position of a character of string.
2593	* @param __svt An object convertible to string_view containing
2594	* characters to locate.
2595	* @param __pos Index of character to search back from (default end).
2596	* @return Index of last occurrence.
2597	*/
2598	template<typename _Tp>
2599	_If_sv<_Tp, size_type>
2600	find_last_of(const _Tp& __svt, size_type __pos = npos) const
2601	noexcept(is_same<_Tp, __sv_type>::value)
2602	{
2603	__sv_type __sv = __svt;
2604	return this->find_last_of(__sv.data(), __pos, __sv.size());
2605	}
2606	#endif // C++17
2607
2608	/**
2609	* @brief Find last position of a character of C substring.
2610	* @param __s C string containing characters to locate.
2611	* @param __pos Index of character to search back from.
2612	* @param __n Number of characters from s to search for.
2613	* @return Index of last occurrence.
2614	*
2615	* Starting from @a __pos, searches backward for one of the
2616	* first @a __n characters of @a __s within this string. If
2617	* found, returns the index where it was found. If not found,
2618	* returns npos.
2619	*/
2620	size_type
2621	find_last_of(const _CharT* __s, size_type __pos, size_type __n) const
2622	_GLIBCXX_NOEXCEPT;
2623
2624	/**
2625	* @brief Find last position of a character of C string.
2626	* @param __s C string containing characters to locate.
2627	* @param __pos Index of character to search back from (default end).
2628	* @return Index of last occurrence.
2629	*
2630	* Starting from @a __pos, searches backward for one of the
2631	* characters of @a __s within this string. If found, returns
2632	* the index where it was found. If not found, returns npos.
2633	*/
2634	size_type
2635	find_last_of(const _CharT* __s, size_type __pos = npos) const
2636	_GLIBCXX_NOEXCEPT
2637	{
2638	__glibcxx_requires_string(__s);
2639	return this->find_last_of(__s, __pos, traits_type::length(__s));
2640	}
2641
2642	/**
2643	* @brief Find last position of a character.
2644	* @param __c Character to locate.
2645	* @param __pos Index of character to search back from (default end).
2646	* @return Index of last occurrence.
2647	*
2648	* Starting from @a __pos, searches backward for @a __c within
2649	* this string. If found, returns the index where it was
2650	* found. If not found, returns npos.
2651	*
2652	* Note: equivalent to rfind(__c, __pos).
2653	*/
2654	size_type
2655	find_last_of(_CharT __c, size_type __pos = npos) const _GLIBCXX_NOEXCEPT
2656	{ return this->rfind(__c, __pos); }
2657
2658	/**
2659	* @brief Find position of a character not in string.
2660	* @param __str String containing characters to avoid.
2661	* @param __pos Index of character to search from (default 0).
2662	* @return Index of first occurrence.
2663	*
2664	* Starting from @a __pos, searches forward for a character not contained
2665	* in @a __str within this string. If found, returns the index where it
2666	* was found. If not found, returns npos.
2667	*/
2668	size_type
2669	find_first_not_of(const basic_string& __str, size_type __pos = `0`) const
2670	_GLIBCXX_NOEXCEPT
2671	{ return this->find_first_not_of(__str.data(), __pos, __str.size()); }
2672
2673	#if __cplusplus >= 201703L
2674	/**
2675	* @brief Find position of a character not in a string_view.
2676	* @param __svt A object convertible to string_view containing
2677	* characters to avoid.
2678	* @param __pos Index of character to search from (default 0).
2679	* @return Index of first occurrence.
2680	*/
2681	template<typename _Tp>
2682	_If_sv<_Tp, size_type>
2683	find_first_not_of(const _Tp& __svt, size_type __pos = `0`) const
2684	noexcept(is_same<_Tp, __sv_type>::value)
2685	{
2686	__sv_type __sv = __svt;
2687	return this->find_first_not_of(__sv.data(), __pos, __sv.size());
2688	}
2689	#endif // C++17
2690
2691	/**
2692	* @brief Find position of a character not in C substring.
2693	* @param __s C string containing characters to avoid.
2694	* @param __pos Index of character to search from.
2695	* @param __n Number of characters from __s to consider.
2696	* @return Index of first occurrence.
2697	*
2698	* Starting from @a __pos, searches forward for a character not
2699	* contained in the first @a __n characters of @a __s within
2700	* this string. If found, returns the index where it was
2701	* found. If not found, returns npos.
2702	*/
2703	size_type
2704	find_first_not_of(const _CharT* __s, size_type __pos,
2705	size_type __n) const _GLIBCXX_NOEXCEPT;
2706
2707	/**
2708	* @brief Find position of a character not in C string.
2709	* @param __s C string containing characters to avoid.
2710	* @param __pos Index of character to search from (default 0).
2711	* @return Index of first occurrence.
2712	*
2713	* Starting from @a __pos, searches forward for a character not
2714	* contained in @a __s within this string. If found, returns
2715	* the index where it was found. If not found, returns npos.
2716	*/
2717	size_type
2718	find_first_not_of(const _CharT* __s, size_type __pos = `0`) const
2719	_GLIBCXX_NOEXCEPT
2720	{
2721	__glibcxx_requires_string(__s);
2722	return this->find_first_not_of(__s, __pos, traits_type::length(__s));
2723	}
2724
2725	/**
2726	* @brief Find position of a different character.
2727	* @param __c Character to avoid.
2728	* @param __pos Index of character to search from (default 0).
2729	* @return Index of first occurrence.
2730	*
2731	* Starting from @a __pos, searches forward for a character
2732	* other than @a __c within this string. If found, returns the
2733	* index where it was found. If not found, returns npos.
2734	*/
2735	size_type
2736	find_first_not_of(_CharT __c, size_type __pos = `0`) const
2737	_GLIBCXX_NOEXCEPT;
2738
2739	/**
2740	* @brief Find last position of a character not in string.
2741	* @param __str String containing characters to avoid.
2742	* @param __pos Index of character to search back from (default end).
2743	* @return Index of last occurrence.
2744	*
2745	* Starting from @a __pos, searches backward for a character
2746	* not contained in @a __str within this string. If found,
2747	* returns the index where it was found. If not found, returns
2748	* npos.
2749	*/
2750	size_type
2751	find_last_not_of(const basic_string& __str, size_type __pos = npos) const
2752	_GLIBCXX_NOEXCEPT
2753	{ return this->find_last_not_of(__str.data(), __pos, __str.size()); }
2754
2755	#if __cplusplus >= 201703L
2756	/**
2757	* @brief Find last position of a character not in a string_view.
2758	* @param __svt An object convertible to string_view containing
2759	* characters to avoid.
2760	* @param __pos Index of character to search back from (default end).
2761	* @return Index of last occurrence.
2762	*/
2763	template<typename _Tp>
2764	_If_sv<_Tp, size_type>
2765	find_last_not_of(const _Tp& __svt, size_type __pos = npos) const
2766	noexcept(is_same<_Tp, __sv_type>::value)
2767	{
2768	__sv_type __sv = __svt;
2769	return this->find_last_not_of(__sv.data(), __pos, __sv.size());
2770	}
2771	#endif // C++17
2772
2773	/**
2774	* @brief Find last position of a character not in C substring.
2775	* @param __s C string containing characters to avoid.
2776	* @param __pos Index of character to search back from.
2777	* @param __n Number of characters from s to consider.
2778	* @return Index of last occurrence.
2779	*
2780	* Starting from @a __pos, searches backward for a character not
2781	* contained in the first @a __n characters of @a __s within this string.
2782	* If found, returns the index where it was found. If not found,
2783	* returns npos.
2784	*/
2785	size_type
2786	find_last_not_of(const _CharT* __s, size_type __pos,
2787	size_type __n) const _GLIBCXX_NOEXCEPT;
2788	/**
2789	* @brief Find last position of a character not in C string.
2790	* @param __s C string containing characters to avoid.
2791	* @param __pos Index of character to search back from (default end).
2792	* @return Index of last occurrence.
2793	*
2794	* Starting from @a __pos, searches backward for a character
2795	* not contained in @a __s within this string. If found,
2796	* returns the index where it was found. If not found, returns
2797	* npos.
2798	*/
2799	size_type
2800	find_last_not_of(const _CharT* __s, size_type __pos = npos) const
2801	_GLIBCXX_NOEXCEPT
2802	{
2803	__glibcxx_requires_string(__s);
2804	return this->find_last_not_of(__s, __pos, traits_type::length(__s));
2805	}
2806
2807	/**
2808	* @brief Find last position of a different character.
2809	* @param __c Character to avoid.
2810	* @param __pos Index of character to search back from (default end).
2811	* @return Index of last occurrence.
2812	*
2813	* Starting from @a __pos, searches backward for a character other than
2814	* @a __c within this string. If found, returns the index where it was
2815	* found. If not found, returns npos.
2816	*/
2817	size_type
2818	find_last_not_of(_CharT __c, size_type __pos = npos) const
2819	_GLIBCXX_NOEXCEPT;
2820
2821	/**
2822	* @brief Get a substring.
2823	* @param __pos Index of first character (default 0).
2824	* @param __n Number of characters in substring (default remainder).
2825	* @return The new string.
2826	* @throw std::out_of_range If __pos > size().
2827	*
2828	* Construct and return a new string using the @a __n
2829	* characters starting at @a __pos. If the string is too
2830	* short, use the remainder of the characters. If @a __pos is
2831	* beyond the end of the string, out_of_range is thrown.
2832	*/
2833	basic_string
2834	substr(size_type __pos = `0`, size_type __n = npos) const
2835	{ return basic_string(*this,
2836	_M_check(__pos, "basic_string::substr"), __n); }
2837
2838	/**
2839	* @brief Compare to a string.
2840	* @param __str String to compare against.
2841	* @return Integer < 0, 0, or > 0.
2842	*
2843	* Returns an integer < 0 if this string is ordered before @a
2844	* __str, 0 if their values are equivalent, or > 0 if this
2845	* string is ordered after @a __str. Determines the effective
2846	* length rlen of the strings to compare as the smallest of
2847	* size() and str.size(). The function then compares the two
2848	* strings by calling traits::compare(data(), str.data(),rlen).
2849	* If the result of the comparison is nonzero returns it,
2850	* otherwise the shorter one is ordered first.
2851	*/
2852	int
2853	compare(const basic_string& __str) const
2854	{
2855	const size_type __size = this->size();
2856	const size_type __osize = __str.size();
2857	const size_type __len = std::min(__size, __osize);
2858
2859	int __r = traits_type::compare(_M_data(), __str.data(), __len);
2860	if (!__r)
2861	__r = _S_compare(__size, __osize);
2862	return __r;
2863	}
2864
2865	#if __cplusplus >= 201703L
2866	/**
2867	* @brief Compare to a string_view.
2868	* @param __svt An object convertible to string_view to compare against.
2869	* @return Integer < 0, 0, or > 0.
2870	*/
2871	template<typename _Tp>
2872	_If_sv<_Tp, int>
2873	compare(const _Tp& __svt) const
2874	noexcept(is_same<_Tp, __sv_type>::value)
2875	{
2876	__sv_type __sv = __svt;
2877	const size_type __size = this->size();
2878	const size_type __osize = __sv.size();
2879	const size_type __len = std::min(__size, __osize);
2880
2881	int __r = traits_type::compare(_M_data(), __sv.data(), __len);
2882	if (!__r)
2883	__r = _S_compare(__size, __osize);
2884	return __r;
2885	}
2886
2887	/**
2888	* @brief Compare to a string_view.
2889	* @param __pos A position in the string to start comparing from.
2890	* @param __n The number of characters to compare.
2891	* @param __svt An object convertible to string_view to compare
2892	* against.
2893	* @return Integer < 0, 0, or > 0.
2894	*/
2895	template<typename _Tp>
2896	_If_sv<_Tp, int>
2897	compare(size_type __pos, size_type __n, const _Tp& __svt) const
2898	noexcept(is_same<_Tp, __sv_type>::value)
2899	{
2900	__sv_type __sv = __svt;
2901	return __sv_type(*this).substr(__pos, __n).compare(__sv);
2902	}
2903
2904	/**
2905	* @brief Compare to a string_view.
2906	* @param __pos1 A position in the string to start comparing from.
2907	* @param __n1 The number of characters to compare.
2908	* @param __svt An object convertible to string_view to compare
2909	* against.
2910	* @param __pos2 A position in the string_view to start comparing from.
2911	* @param __n2 The number of characters to compare.
2912	* @return Integer < 0, 0, or > 0.
2913	*/
2914	template<typename _Tp>
2915	_If_sv<_Tp, int>
2916	compare(size_type __pos1, size_type __n1, const _Tp& __svt,
2917	size_type __pos2, size_type __n2 = npos) const
2918	noexcept(is_same<_Tp, __sv_type>::value)
2919	{
2920	__sv_type __sv = __svt;
2921	return __sv_type(*this)
2922	.substr(__pos1, __n1).compare(__sv.substr(__pos2, __n2));
2923	}
2924	#endif // C++17
2925
2926	/**
2927	* @brief Compare substring to a string.
2928	* @param __pos Index of first character of substring.
2929	* @param __n Number of characters in substring.
2930	* @param __str String to compare against.
2931	* @return Integer < 0, 0, or > 0.
2932	*
2933	* Form the substring of this string from the @a __n characters
2934	* starting at @a __pos. Returns an integer < 0 if the
2935	* substring is ordered before @a __str, 0 if their values are
2936	* equivalent, or > 0 if the substring is ordered after @a
2937	* __str. Determines the effective length rlen of the strings
2938	* to compare as the smallest of the length of the substring
2939	* and @a __str.size(). The function then compares the two
2940	* strings by calling
2941	* traits::compare(substring.data(),str.data(),rlen). If the
2942	* result of the comparison is nonzero returns it, otherwise
2943	* the shorter one is ordered first.
2944	*/
2945	int
2946	compare(size_type __pos, size_type __n, const basic_string& __str) const;
2947
2948	/**
2949	* @brief Compare substring to a substring.
2950	* @param __pos1 Index of first character of substring.
2951	* @param __n1 Number of characters in substring.
2952	* @param __str String to compare against.
2953	* @param __pos2 Index of first character of substring of str.
2954	* @param __n2 Number of characters in substring of str.
2955	* @return Integer < 0, 0, or > 0.
2956	*
2957	* Form the substring of this string from the @a __n1
2958	* characters starting at @a __pos1. Form the substring of @a
2959	* __str from the @a __n2 characters starting at @a __pos2.
2960	* Returns an integer < 0 if this substring is ordered before
2961	* the substring of @a __str, 0 if their values are equivalent,
2962	* or > 0 if this substring is ordered after the substring of
2963	* @a __str. Determines the effective length rlen of the
2964	* strings to compare as the smallest of the lengths of the
2965	* substrings. The function then compares the two strings by
2966	* calling
2967	* traits::compare(substring.data(),str.substr(pos2,n2).data(),rlen).
2968	* If the result of the comparison is nonzero returns it,
2969	* otherwise the shorter one is ordered first.
2970	*/
2971	int
2972	compare(size_type __pos1, size_type __n1, const basic_string& __str,
2973	size_type __pos2, size_type __n2 = npos) const;
2974
2975	/**
2976	* @brief Compare to a C string.
2977	* @param __s C string to compare against.
2978	* @return Integer < 0, 0, or > 0.
2979	*
2980	* Returns an integer < 0 if this string is ordered before @a __s, 0 if
2981	* their values are equivalent, or > 0 if this string is ordered after
2982	* @a __s. Determines the effective length rlen of the strings to
2983	* compare as the smallest of size() and the length of a string
2984	* constructed from @a __s. The function then compares the two strings
2985	* by calling traits::compare(data(),s,rlen). If the result of the
2986	* comparison is nonzero returns it, otherwise the shorter one is
2987	* ordered first.
2988	*/
2989	int
2990	compare(const _CharT* __s) const _GLIBCXX_NOEXCEPT;
2991
2992	// _GLIBCXX_RESOLVE_LIB_DEFECTS
2993	// 5 String::compare specification questionable
2994	/**
2995	* @brief Compare substring to a C string.
2996	* @param __pos Index of first character of substring.
2997	* @param __n1 Number of characters in substring.
2998	* @param __s C string to compare against.
2999	* @return Integer < 0, 0, or > 0.
3000	*
3001	* Form the substring of this string from the @a __n1
3002	* characters starting at @a pos. Returns an integer < 0 if
3003	* the substring is ordered before @a __s, 0 if their values
3004	* are equivalent, or > 0 if the substring is ordered after @a
3005	* __s. Determines the effective length rlen of the strings to
3006	* compare as the smallest of the length of the substring and
3007	* the length of a string constructed from @a __s. The
3008	* function then compares the two string by calling
3009	* traits::compare(substring.data(),__s,rlen). If the result of
3010	* the comparison is nonzero returns it, otherwise the shorter
3011	* one is ordered first.
3012	*/
3013	int
3014	compare(size_type __pos, size_type __n1, const _CharT* __s) const;
3015
3016	/**
3017	* @brief Compare substring against a character %array.
3018	* @param __pos Index of first character of substring.
3019	* @param __n1 Number of characters in substring.
3020	* @param __s character %array to compare against.
3021	* @param __n2 Number of characters of s.
3022	* @return Integer < 0, 0, or > 0.
3023	*
3024	* Form the substring of this string from the @a __n1
3025	* characters starting at @a __pos. Form a string from the
3026	* first @a __n2 characters of @a __s. Returns an integer < 0
3027	* if this substring is ordered before the string from @a __s,
3028	* 0 if their values are equivalent, or > 0 if this substring
3029	* is ordered after the string from @a __s. Determines the
3030	* effective length rlen of the strings to compare as the
3031	* smallest of the length of the substring and @a __n2. The
3032	* function then compares the two strings by calling
3033	* traits::compare(substring.data(),s,rlen). If the result of
3034	* the comparison is nonzero returns it, otherwise the shorter
3035	* one is ordered first.
3036	*
3037	* NB: s must have at least n2 characters, '\\0' has
3038	* no special meaning.
3039	*/
3040	int
3041	compare(size_type __pos, size_type __n1, const _CharT* __s,
3042	size_type __n2) const;
3043
3044	#if __cplusplus > 201703L
3045	bool
3046	starts_with(basic_string_view<_CharT, _Traits> __x) const noexcept
3047	{ return __sv_type(this->data(), this->size()).starts_with(__x); }
3048
3049	bool
3050	starts_with(_CharT __x) const noexcept
3051	{ return __sv_type(this->data(), this->size()).starts_with(__x); }
3052
3053	bool
3054	starts_with(const _CharT* __x) const noexcept
3055	{ return __sv_type(this->data(), this->size()).starts_with(__x); }
3056
3057	bool
3058	ends_with(basic_string_view<_CharT, _Traits> __x) const noexcept
3059	{ return __sv_type(this->data(), this->size()).ends_with(__x); }
3060
3061	bool
3062	ends_with(_CharT __x) const noexcept
3063	{ return __sv_type(this->data(), this->size()).ends_with(__x); }
3064
3065	bool
3066	ends_with(const _CharT* __x) const noexcept
3067	{ return __sv_type(this->data(), this->size()).ends_with(__x); }
3068	#endif // C++20
3069
3070	// Allow basic_stringbuf::__xfer_bufptrs to call _M_length:
3071	template<typename, typename, typename> friend class basic_stringbuf;
3072	};
3073	_GLIBCXX_END_NAMESPACE_CXX11
3074	#else // !_GLIBCXX_USE_CXX11_ABI
3075	// Reference-counted COW string implentation
3076
3077	/**
3078	* @class basic_string basic_string.h <string>
3079	* @brief Managing sequences of characters and character-like objects.
3080	*
3081	* @ingroup strings
3082	* @ingroup sequences
3083	*
3084	* @tparam _CharT Type of character
3085	* @tparam _Traits Traits for character type, defaults to
3086	* char_traits<_CharT>.
3087	* @tparam _Alloc Allocator type, defaults to allocator<_CharT>.
3088	*
3089	* Meets the requirements of a <a href="tables.html#65">container</a>, a
3090	* <a href="tables.html#66">reversible container</a>, and a
3091	* <a href="tables.html#67">sequence</a>. Of the
3092	* <a href="tables.html#68">optional sequence requirements</a>, only
3093	* @c push_back, @c at, and @c %array access are supported.
3094	*
3095	* @doctodo
3096	*
3097	*
3098	* Documentation? What's that?
3099	* Nathan Myers <ncm@cantrip.org>.
3100	*
3101	* A string looks like this:
3102	*
3103	* @code
3104	* [_Rep]
3105	* _M_length
3106	* [basic_string<char_type>] _M_capacity
3107	* _M_dataplus _M_refcount
3108	* _M_p ----------------> unnamed array of char_type
3109	* @endcode
3110	*
3111	* Where the _M_p points to the first character in the string, and
3112	* you cast it to a pointer-to-_Rep and subtract 1 to get a
3113	* pointer to the header.
3114	*
3115	* This approach has the enormous advantage that a string object
3116	* requires only one allocation. All the ugliness is confined
3117	* within a single %pair of inline functions, which each compile to
3118	* a single @a add instruction: _Rep::_M_data(), and
3119	* string::_M_rep(); and the allocation function which gets a
3120	* block of raw bytes and with room enough and constructs a _Rep
3121	* object at the front.
3122	*
3123	* The reason you want _M_data pointing to the character %array and
3124	* not the _Rep is so that the debugger can see the string
3125	* contents. (Probably we should add a non-inline member to get
3126	* the _Rep for the debugger to use, so users can check the actual
3127	* string length.)
3128	*
3129	* Note that the _Rep object is a POD so that you can have a
3130	* static <em>empty string</em> _Rep object already @a constructed before
3131	* static constructors have run. The reference-count encoding is
3132	* chosen so that a 0 indicates one reference, so you never try to
3133	* destroy the empty-string _Rep object.
3134	*
3135	* All but the last paragraph is considered pretty conventional
3136	* for a C++ string implementation.
3137	*/
3138	// 21.3 Template class basic_string
3139	template<typename _CharT, typename _Traits, typename _Alloc>
3140	class basic_string
3141	{
3142	typedef typename _Alloc::template rebind<_CharT>::other _CharT_alloc_type;
3143
3144	// Types:
3145	public:
3146	typedef _Traits traits_type;
3147	typedef typename _Traits::char_type value_type;
3148	typedef _Alloc allocator_type;
3149	typedef typename _CharT_alloc_type::size_type size_type;
3150	typedef typename _CharT_alloc_type::difference_type difference_type;
3151	#if __cplusplus < 201103L
3152	typedef typename _CharT_alloc_type::reference reference;
3153	typedef typename _CharT_alloc_type::const_reference const_reference;
3154	#else
3155	typedef value_type& reference;
3156	typedef const value_type& const_reference;
3157	#endif
3158	typedef typename _CharT_alloc_type::pointer pointer;
3159	typedef typename _CharT_alloc_type::const_pointer const_pointer;
3160	typedef __gnu_cxx::__normal_iterator<pointer, basic_string> iterator;
3161	typedef __gnu_cxx::__normal_iterator<const_pointer, basic_string>
3162	const_iterator;
3163	typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
3164	typedef std::reverse_iterator<iterator> reverse_iterator;
3165
3166	protected:
3167	// type used for positions in insert, erase etc.
3168	typedef iterator __const_iterator;
3169
3170	private:
3171	// _Rep: string representation
3172	// Invariants:
3173	// 1. String really contains _M_length + 1 characters: due to 21.3.4
3174	// must be kept null-terminated.
3175	// 2. _M_capacity >= _M_length
3176	// Allocated memory is always (_M_capacity + 1) sizeof(_CharT).*
3177	// 3. _M_refcount has three states:
3178	// -1: leaked, one reference, no ref-copies allowed, non-const.
3179	// 0: one reference, non-const.
3180	// n>0: n + 1 references, operations require a lock, const.
3181	// 4. All fields==0 is an empty string, given the extra storage
3182	// beyond-the-end for a null terminator; thus, the shared
3183	// empty string representation needs no constructor.
3184
3185	struct _Rep_base
3186	{
3187	size_type _M_length;
3188	size_type _M_capacity;
3189	_Atomic_word _M_refcount;
3190	};
3191
3192	struct _Rep : _Rep_base
3193	{
3194	// Types:
3195	typedef typename _Alloc::template rebind<char>::other _Raw_bytes_alloc;
3196
3197	// (Public) Data members:
3198
3199	// The maximum number of individual char_type elements of an
3200	// individual string is determined by _S_max_size. This is the
3201	// value that will be returned by max_size(). (Whereas npos
3202	// is the maximum number of bytes the allocator can allocate.)
3203	// If one was to divvy up the theoretical largest size string,
3204	// with a terminating character and m _CharT elements, it'd
3205	// look like this:
3206	// npos = sizeof(_Rep) + (m sizeof(_CharT)) + sizeof(_CharT)*
3207	// Solving for m:
3208	// m = ((npos - sizeof(_Rep))/sizeof(CharT)) - 1
3209	// In addition, this implementation quarters this amount.
3210	static const size_type _S_max_size;
3211	static const _CharT _S_terminal;
3212
3213	// The following storage is init'd to 0 by the linker, resulting
3214	// (carefully) in an empty string with one reference.
3215	static size_type _S_empty_rep_storage[];
3216
3217	static _Rep&
3218	_S_empty_rep() _GLIBCXX_NOEXCEPT
3219	{
3220	// NB: Mild hack to avoid strict-aliasing warnings. Note that
3221	// _S_empty_rep_storage is never modified and the punning should
3222	// be reasonably safe in this case.
3223	void* __p = reinterpret_cast<void*>(&_S_empty_rep_storage);
3224	return *reinterpret_cast<_Rep*>(__p);
3225	}
3226
3227	bool
3228	_M_is_leaked() const _GLIBCXX_NOEXCEPT
3229	{
3230	#if defined(__GTHREADS)
3231	// _M_refcount is mutated concurrently by _M_refcopy/_M_dispose,
3232	// so we need to use an atomic load. However, _M_is_leaked
3233	// predicate does not change concurrently (i.e. the string is either
3234	// leaked or not), so a relaxed load is enough.
3235	return __atomic_load_n(&this->_M_refcount, __ATOMIC_RELAXED) < `0`;
3236	#else
3237	return this->_M_refcount < `0`;
3238	#endif
3239	}
3240
3241	bool
3242	_M_is_shared() const _GLIBCXX_NOEXCEPT
3243	{
3244	#if defined(__GTHREADS)
3245	// _M_refcount is mutated concurrently by _M_refcopy/_M_dispose,
3246	// so we need to use an atomic load. Another thread can drop last
3247	// but one reference concurrently with this check, so we need this
3248	// load to be acquire to synchronize with release fetch_and_add in
3249	// _M_dispose.
3250	return __atomic_load_n(&this->_M_refcount, __ATOMIC_ACQUIRE) > `0`;
3251	#else
3252	return this->_M_refcount > `0`;
3253	#endif
3254	}
3255
3256	void
3257	_M_set_leaked() _GLIBCXX_NOEXCEPT
3258	{ this->_M_refcount = -`1`; }
3259
3260	void
3261	_M_set_sharable() _GLIBCXX_NOEXCEPT
3262	{ this->_M_refcount = `0`; }
3263
3264	void
3265	_M_set_length_and_sharable(size_type __n) _GLIBCXX_NOEXCEPT
3266	{
3267	#if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
3268	if (__builtin_expect(this != &_S_empty_rep(), false))
3269	#endif
3270	{
3271	this->_M_set_sharable(); // One reference.
3272	this->_M_length = __n;
3273	traits_type::assign(this->_M_refdata()[__n], _S_terminal);
3274	// grrr. (per 21.3.4)
3275	// You cannot leave those LWG people alone for a second.
3276	}
3277	}
3278
3279	_CharT*
3280	_M_refdata() throw()
3281	{ return reinterpret_cast<_CharT>(this* + `1`); }
3282
3283	_CharT*
3284	_M_grab(const _Alloc& __alloc1, const _Alloc& __alloc2)
3285	{
3286	return (!_M_is_leaked() && __alloc1 == __alloc2)
3287	? _M_refcopy() : _M_clone(__alloc1);
3288	}
3289
3290	// Create & Destroy
3291	static _Rep*
3292	_S_create(size_type, size_type, const _Alloc&);
3293
3294	void
3295	_M_dispose(const _Alloc& __a) _GLIBCXX_NOEXCEPT
3296	{
3297	#if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
3298	if (__builtin_expect(this != &_S_empty_rep(), false))
3299	#endif
3300	{
3301	// Be race-detector-friendly. For more info see bits/c++config.
3302	_GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&this->_M_refcount);
3303	// Decrement of _M_refcount is acq_rel, because:
3304	// - all but last decrements need to release to synchronize with
3305	// the last decrement that will delete the object.
3306	// - the last decrement needs to acquire to synchronize with
3307	// all the previous decrements.
3308	// - last but one decrement needs to release to synchronize with
3309	// the acquire load in _M_is_shared that will conclude that
3310	// the object is not shared anymore.
3311	if (__gnu_cxx::__exchange_and_add_dispatch(&this->_M_refcount,
3312	-`1`) <= `0`)
3313	{
3314	_GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&this->_M_refcount);
3315	_M_destroy(__a);
3316	}
3317	}
3318	} // XXX MT
3319
3320	void
3321	_M_destroy(const _Alloc&) throw();
3322
3323	_CharT*
3324	_M_refcopy() throw()
3325	{
3326	#if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
3327	if (__builtin_expect(this != &_S_empty_rep(), false))
3328	#endif
3329	__gnu_cxx::__atomic_add_dispatch(&this->_M_refcount, `1`);
3330	return _M_refdata();
3331	} // XXX MT
3332
3333	_CharT*
3334	_M_clone(const _Alloc&, size_type __res = `0`);
3335	};
3336
3337	// Use empty-base optimization: http://www.cantrip.org/emptyopt.html
3338	struct _Alloc_hider : _Alloc
3339	{
3340	_Alloc_hider(_CharT* __dat, const _Alloc& __a) _GLIBCXX_NOEXCEPT
3341	: _Alloc(__a), _M_p(__dat) { }
3342
3343	_CharT* _M_p; // The actual data.
3344	};
3345
3346	public:
3347	// Data Members (public):
3348	// NB: This is an unsigned type, and thus represents the maximum
3349	// size that the allocator can hold.
3350	/// Value returned by various member functions when they fail.
3351	static const size_type npos = static_cast<size_type>(-`1`);
3352
3353	private:
3354	// Data Members (private):
3355	mutable _Alloc_hider _M_dataplus;
3356
3357	_CharT*
3358	_M_data() const _GLIBCXX_NOEXCEPT
3359	{ return _M_dataplus._M_p; }
3360
3361	_CharT*
3362	_M_data(_CharT* __p) _GLIBCXX_NOEXCEPT
3363	{ return (_M_dataplus._M_p = __p); }
3364
3365	_Rep*
3366	_M_rep() const _GLIBCXX_NOEXCEPT
3367	{ return &((reinterpret_cast<_Rep*> (_M_data()))[-`1`]); }
3368
3369	// For the internal use we have functions similar to `begin'/`end'
3370	// but they do not call _M_leak.
3371	iterator
3372	_M_ibegin() const _GLIBCXX_NOEXCEPT
3373	{ return iterator(_M_data()); }
3374
3375	iterator
3376	_M_iend() const _GLIBCXX_NOEXCEPT
3377	{ return iterator(_M_data() + this->size()); }
3378
3379	void
3380	_M_leak() // for use in begin() & non-const op[]
3381	{
3382	if (!_M_rep()->_M_is_leaked())
3383	_M_leak_hard();
3384	}
3385
3386	size_type
3387	_M_check(size_type __pos, const char* __s) const
3388	{
3389	if (__pos > this->size())
3390	__throw_out_of_range_fmt(__N("%s: __pos (which is %zu) > "
3391	"this->size() (which is %zu)"),
3392	__s, __pos, this->size());
3393	return __pos;
3394	}
3395
3396	void
3397	_M_check_length(size_type __n1, size_type __n2, const char* __s) const
3398	{
3399	if (this->max_size() - (this->size() - __n1) < __n2)
3400	__throw_length_error(__N(__s));
3401	}
3402
3403	// NB: _M_limit doesn't check for a bad __pos value.
3404	size_type
3405	_M_limit(size_type __pos, size_type __off) const _GLIBCXX_NOEXCEPT
3406	{
3407	const bool __testoff = __off < this->size() - __pos;
3408	return __testoff ? __off : this->size() - __pos;
3409	}
3410
3411	// True if _Rep and source do not overlap.
3412	bool
3413	_M_disjunct(const _CharT* __s) const _GLIBCXX_NOEXCEPT
3414	{
3415	return (less<const _CharT*>()(__s, _M_data())
3416	\|\| less<const _CharT>()(_M_data() + this*->size(), __s));
3417	}
3418
3419	// When __n = 1 way faster than the general multichar
3420	// traits_type::copy/move/assign.
3421	static void
3422	_M_copy(_CharT* __d, const _CharT* __s, size_type __n) _GLIBCXX_NOEXCEPT
3423	{
3424	if (__n == `1`)
3425	traits_type::assign(__d, __s);
3426	else
3427	traits_type::copy(__d, __s, __n);
3428	}
3429
3430	static void
3431	_M_move(_CharT* __d, const _CharT* __s, size_type __n) _GLIBCXX_NOEXCEPT
3432	{
3433	if (__n == `1`)
3434	traits_type::assign(__d, __s);
3435	else
3436	traits_type::move(__d, __s, __n);
3437	}
3438
3439	static void
3440	_M_assign(_CharT* __d, size_type __n, _CharT __c) _GLIBCXX_NOEXCEPT
3441	{
3442	if (__n == `1`)
3443	traits_type::assign(*__d, __c);
3444	else
3445	traits_type::assign(__d, __n, __c);
3446	}
3447
3448	// _S_copy_chars is a separate template to permit specialization
3449	// to optimize for the common case of pointers as iterators.
3450	template<class _Iterator>
3451	static void
3452	_S_copy_chars(_CharT* __p, _Iterator __k1, _Iterator __k2)
3453	{
3454	for (; __k1 != __k2; ++__k1, (void)++__p)
3455	traits_type::assign(__p, __k1); // These types are off.
3456	}
3457
3458	static void
3459	_S_copy_chars(_CharT* __p, iterator __k1, iterator __k2) _GLIBCXX_NOEXCEPT
3460	{ _S_copy_chars(__p, __k1.base(), __k2.base()); }
3461
3462	static void
3463	_S_copy_chars(_CharT* __p, const_iterator __k1, const_iterator __k2)
3464	_GLIBCXX_NOEXCEPT
3465	{ _S_copy_chars(__p, __k1.base(), __k2.base()); }
3466
3467	static void
3468	_S_copy_chars(_CharT* __p, _CharT* __k1, _CharT* __k2) _GLIBCXX_NOEXCEPT
3469	{ _M_copy(__p, __k1, __k2 - __k1); }
3470
3471	static void
3472	_S_copy_chars(_CharT* __p, const _CharT* __k1, const _CharT* __k2)
3473	_GLIBCXX_NOEXCEPT
3474	{ _M_copy(__p, __k1, __k2 - __k1); }
3475
3476	static int
3477	_S_compare(size_type __n1, size_type __n2) _GLIBCXX_NOEXCEPT
3478	{
3479	const difference_type __d = difference_type(__n1 - __n2);
3480
3481	if (__d > __gnu_cxx::__numeric_traits<int>::__max)
3482	return __gnu_cxx::__numeric_traits<int>::__max;
3483	else if (__d < __gnu_cxx::__numeric_traits<int>::__min)
3484	return __gnu_cxx::__numeric_traits<int>::__min;
3485	else
3486	return int(__d);
3487	}
3488
3489	void
3490	_M_mutate(size_type __pos, size_type __len1, size_type __len2);
3491
3492	void
3493	_M_leak_hard();
3494
3495	static _Rep&
3496	_S_empty_rep() _GLIBCXX_NOEXCEPT
3497	{ return _Rep::_S_empty_rep(); }
3498
3499	#if __cplusplus >= 201703L
3500	// A helper type for avoiding boiler-plate.
3501	typedef basic_string_view<_CharT, _Traits> __sv_type;
3502
3503	template<typename _Tp, typename _Res>
3504	using _If_sv = enable_if_t<
3505	__and_<is_convertible<const _Tp&, __sv_type>,
3506	__not_<is_convertible<const _Tp, const* basic_string*>>,
3507	__not_<is_convertible<const _Tp&, const _CharT*>>>::value,
3508	_Res>;
3509
3510	// Allows an implicit conversion to __sv_type.
3511	static __sv_type
3512	_S_to_string_view(__sv_type __svt) noexcept
3513	{ return __svt; }
3514
3515	// Wraps a string_view by explicit conversion and thus
3516	// allows to add an internal constructor that does not
3517	// participate in overload resolution when a string_view
3518	// is provided.
3519	struct __sv_wrapper
3520	{
3521	explicit __sv_wrapper(__sv_type __sv) noexcept : _M_sv(__sv) { }
3522	__sv_type _M_sv;
3523	};
3524
3525	/**
3526	* @brief Only internally used: Construct string from a string view
3527	* wrapper.
3528	* @param __svw string view wrapper.
3529	* @param __a Allocator to use.
3530	*/
3531	explicit
3532	basic_string(__sv_wrapper __svw, const _Alloc& __a)
3533	: basic_string(__svw._M_sv.data(), __svw._M_sv.size(), __a) { }
3534	#endif
3535
3536	public:
3537	// Construct/copy/destroy:
3538	// NB: We overload ctors in some cases instead of using default
3539	// arguments, per 17.4.4.4 para. 2 item 2.
3540
3541	/**
3542	* @brief Default constructor creates an empty string.
3543	*/
3544	basic_string()
3545	#if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
3546	_GLIBCXX_NOEXCEPT
3547	: _M_dataplus(_S_empty_rep()._M_refdata(), _Alloc())
3548	#else
3549	: _M_dataplus(_S_construct(size_type(), _CharT(), _Alloc()), _Alloc())
3550	#endif
3551	{ }
3552
3553	/**
3554	* @brief Construct an empty string using allocator @a a.
3555	*/
3556	explicit
3557	basic_string(const _Alloc& __a);
3558
3559	// NB: per LWG issue 42, semantics different from IS:
3560	/**
3561	* @brief Construct string with copy of value of @a str.
3562	* @param __str Source string.
3563	*/
3564	basic_string(const basic_string& __str);
3565
3566	// _GLIBCXX_RESOLVE_LIB_DEFECTS
3567	// 2583. no way to supply an allocator for basic_string(str, pos)
3568	/**
3569	* @brief Construct string as copy of a substring.
3570	* @param __str Source string.
3571	* @param __pos Index of first character to copy from.
3572	* @param __a Allocator to use.
3573	*/
3574	basic_string(const basic_string& __str, size_type __pos,
3575	const _Alloc& __a = _Alloc());
3576
3577	/**
3578	* @brief Construct string as copy of a substring.
3579	* @param __str Source string.
3580	* @param __pos Index of first character to copy from.
3581	* @param __n Number of characters to copy.
3582	*/
3583	basic_string(const basic_string& __str, size_type __pos,
3584	size_type __n);
3585	/**
3586	* @brief Construct string as copy of a substring.
3587	* @param __str Source string.
3588	* @param __pos Index of first character to copy from.
3589	* @param __n Number of characters to copy.
3590	* @param __a Allocator to use.
3591	*/
3592	basic_string(const basic_string& __str, size_type __pos,
3593	size_type __n, const _Alloc& __a);
3594
3595	/**
3596	* @brief Construct string initialized by a character %array.
3597	* @param __s Source character %array.
3598	* @param __n Number of characters to copy.
3599	* @param __a Allocator to use (default is default allocator).
3600	*
3601	* NB: @a __s must have at least @a __n characters, '\\0'
3602	* has no special meaning.
3603	*/
3604	basic_string(const _CharT* __s, size_type __n,
3605	const _Alloc& __a = _Alloc());
3606	/**
3607	* @brief Construct string as copy of a C string.
3608	* @param __s Source C string.
3609	* @param __a Allocator to use (default is default allocator).
3610	*/
3611	basic_string(const _CharT* __s, const _Alloc& __a = _Alloc());
3612	/**
3613	* @brief Construct string as multiple characters.
3614	* @param __n Number of characters.
3615	* @param __c Character to use.
3616	* @param __a Allocator to use (default is default allocator).
3617	*/
3618	basic_string(size_type __n, _CharT __c, const _Alloc& __a = _Alloc());
3619
3620	#if __cplusplus >= 201103L
3621	/**
3622	* @brief Move construct string.
3623	* @param __str Source string.
3624	*
3625	* The newly-created string contains the exact contents of @a __str.
3626	* @a __str is a valid, but unspecified string.
3627	**/
3628	basic_string(basic_string&& __str)
3629	#if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
3630	noexcept // FIXME C++11: should always be noexcept.
3631	#endif
3632	: _M_dataplus(std::move(__str._M_dataplus))
3633	{
3634	#if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
3635	__str._M_data(_S_empty_rep()._M_refdata());
3636	#else
3637	__str._M_data(_S_construct(size_type(), _CharT(), get_allocator()));
3638	#endif
3639	}
3640
3641	/**
3642	* @brief Construct string from an initializer %list.
3643	* @param __l std::initializer_list of characters.
3644	* @param __a Allocator to use (default is default allocator).
3645	*/
3646	basic_string(initializer_list<_CharT> __l, const _Alloc& __a = _Alloc());
3647
3648	basic_string(const basic_string& __str, const _Alloc& __a)
3649	: _M_dataplus(__str._M_rep()->_M_grab(__a, __str.get_allocator()), __a)
3650	{ }
3651
3652	basic_string(basic_string&& __str, const _Alloc& __a)
3653	: _M_dataplus(__str._M_data(), __a)
3654	{
3655	if (__a == __str.get_allocator())
3656	{
3657	#if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
3658	__str._M_data(_S_empty_rep()._M_refdata());
3659	#else
3660	__str._M_data(_S_construct(size_type(), _CharT(), __a));
3661	#endif
3662	}
3663	else
3664	_M_dataplus._M_p = _S_construct(__str.begin(), __str.end(), __a);
3665	}
3666	#endif // C++11
3667
3668	/**
3669	* @brief Construct string as copy of a range.
3670	* @param __beg Start of range.
3671	* @param __end End of range.
3672	* @param __a Allocator to use (default is default allocator).
3673	*/
3674	template<class _InputIterator>
3675	basic_string(_InputIterator __beg, _InputIterator __end,
3676	const _Alloc& __a = _Alloc());
3677
3678	#if __cplusplus >= 201703L
3679	/**
3680	* @brief Construct string from a substring of a string_view.
3681	* @param __t Source object convertible to string view.
3682	* @param __pos The index of the first character to copy from __t.
3683	* @param __n The number of characters to copy from __t.
3684	* @param __a Allocator to use.
3685	*/
3686	template<typename _Tp, typename = _If_sv<_Tp, void>>
3687	basic_string(const _Tp& __t, size_type __pos, size_type __n,
3688	const _Alloc& __a = _Alloc())
3689	: basic_string(_S_to_string_view(__t).substr(__pos, __n), __a) { }
3690
3691	/**
3692	* @brief Construct string from a string_view.
3693	* @param __t Source object convertible to string view.
3694	* @param __a Allocator to use (default is default allocator).
3695	*/
3696	template<typename _Tp, typename = _If_sv<_Tp, void>>
3697	explicit
3698	basic_string(const _Tp& __t, const _Alloc& __a = _Alloc())
3699	: basic_string(__sv_wrapper(_S_to_string_view(__t)), __a) { }
3700	#endif // C++17
3701
3702	/**
3703	* @brief Destroy the string instance.
3704	*/
3705	~basic_string() _GLIBCXX_NOEXCEPT
3706	{ _M_rep()->_M_dispose(this->get_allocator()); }
3707
3708	/**
3709	* @brief Assign the value of @a str to this string.
3710	* @param __str Source string.
3711	*/
3712	basic_string&
3713	operator=(const basic_string& __str)
3714	{ return this->assign(__str); }
3715
3716	/**
3717	* @brief Copy contents of @a s into this string.
3718	* @param __s Source null-terminated string.
3719	*/
3720	basic_string&
3721	operator=(const _CharT* __s)
3722	{ return this->assign(__s); }
3723
3724	/**
3725	* @brief Set value to string of length 1.
3726	* @param __c Source character.
3727	*
3728	* Assigning to a character makes this string length 1 and
3729	* (*this)[0] == @a c.
3730	*/
3731	basic_string&
3732	operator=(_CharT __c)
3733	{
3734	this->assign(`1`, __c);
3735	return *this;
3736	}
3737
3738	#if __cplusplus >= 201103L
3739	/**
3740	* @brief Move assign the value of @a str to this string.
3741	* @param __str Source string.
3742	*
3743	* The contents of @a str are moved into this string (without copying).
3744	* @a str is a valid, but unspecified string.
3745	**/
3746	basic_string&
3747	operator=(basic_string&& __str)
3748	_GLIBCXX_NOEXCEPT_IF(allocator_traits<_Alloc>::is_always_equal::value)
3749	{
3750	// NB: DR 1204.
3751	this->swap(__str);
3752	return *this;
3753	}
3754
3755	/**
3756	* @brief Set value to string constructed from initializer %list.
3757	* @param __l std::initializer_list.
3758	*/
3759	basic_string&
3760	operator=(initializer_list<_CharT> __l)
3761	{
3762	this->assign(__l.begin(), __l.size());
3763	return *this;
3764	}
3765	#endif // C++11
3766
3767	#if __cplusplus >= 201703L
3768	/**
3769	* @brief Set value to string constructed from a string_view.
3770	* @param __svt An object convertible to string_view.
3771	*/
3772	template<typename _Tp>
3773	_If_sv<_Tp, basic_string&>
3774	operator=(const _Tp& __svt)
3775	{ return this->assign(__svt); }
3776
3777	/**
3778	* @brief Convert to a string_view.
3779	* @return A string_view.
3780	*/
3781	operator __sv_type() const noexcept
3782	{ return __sv_type(data(), size()); }
3783	#endif // C++17
3784
3785	// Iterators:
3786	/**
3787	* Returns a read/write iterator that points to the first character in
3788	* the %string. Unshares the string.
3789	*/
3790	iterator
3791	begin() // FIXME C++11: should be noexcept.
3792	{
3793	_M_leak();
3794	return iterator(_M_data());
3795	}
3796
3797	/**
3798	* Returns a read-only (constant) iterator that points to the first
3799	* character in the %string.
3800	*/
3801	const_iterator
3802	begin() const _GLIBCXX_NOEXCEPT
3803	{ return const_iterator(_M_data()); }
3804
3805	/**
3806	* Returns a read/write iterator that points one past the last
3807	* character in the %string. Unshares the string.
3808	*/
3809	iterator
3810	end() // FIXME C++11: should be noexcept.
3811	{
3812	_M_leak();
3813	return iterator(_M_data() + this->size());
3814	}
3815
3816	/**
3817	* Returns a read-only (constant) iterator that points one past the
3818	* last character in the %string.
3819	*/
3820	const_iterator
3821	end() const _GLIBCXX_NOEXCEPT
3822	{ return const_iterator(_M_data() + this->size()); }
3823
3824	/**
3825	* Returns a read/write reverse iterator that points to the last
3826	* character in the %string. Iteration is done in reverse element
3827	* order. Unshares the string.
3828	*/
3829	reverse_iterator
3830	rbegin() // FIXME C++11: should be noexcept.
3831	{ return reverse_iterator(this->end()); }
3832
3833	/**
3834	* Returns a read-only (constant) reverse iterator that points
3835	* to the last character in the %string. Iteration is done in
3836	* reverse element order.
3837	*/
3838	const_reverse_iterator
3839	rbegin() const _GLIBCXX_NOEXCEPT
3840	{ return const_reverse_iterator(this->end()); }
3841
3842	/**
3843	* Returns a read/write reverse iterator that points to one before the
3844	* first character in the %string. Iteration is done in reverse
3845	* element order. Unshares the string.
3846	*/
3847	reverse_iterator
3848	rend() // FIXME C++11: should be noexcept.
3849	{ return reverse_iterator(this->begin()); }
3850
3851	/**
3852	* Returns a read-only (constant) reverse iterator that points
3853	* to one before the first character in the %string. Iteration
3854	* is done in reverse element order.
3855	*/
3856	const_reverse_iterator
3857	rend() const _GLIBCXX_NOEXCEPT
3858	{ return const_reverse_iterator(this->begin()); }
3859
3860	#if __cplusplus >= 201103L
3861	/**
3862	* Returns a read-only (constant) iterator that points to the first
3863	* character in the %string.
3864	*/
3865	const_iterator
3866	cbegin() const noexcept
3867	{ return const_iterator(this->_M_data()); }
3868
3869	/**
3870	* Returns a read-only (constant) iterator that points one past the
3871	* last character in the %string.
3872	*/
3873	const_iterator
3874	cend() const noexcept
3875	{ return const_iterator(this->_M_data() + this->size()); }
3876
3877	/**
3878	* Returns a read-only (constant) reverse iterator that points
3879	* to the last character in the %string. Iteration is done in
3880	* reverse element order.
3881	*/
3882	const_reverse_iterator
3883	crbegin() const noexcept
3884	{ return const_reverse_iterator(this->end()); }
3885
3886	/**
3887	* Returns a read-only (constant) reverse iterator that points
3888	* to one before the first character in the %string. Iteration
3889	* is done in reverse element order.
3890	*/
3891	const_reverse_iterator
3892	crend() const noexcept
3893	{ return const_reverse_iterator(this->begin()); }
3894	#endif
3895
3896	public:
3897	// Capacity:
3898	/// Returns the number of characters in the string, not including any
3899	/// null-termination.
3900	size_type
3901	size() const _GLIBCXX_NOEXCEPT
3902	{ return _M_rep()->_M_length; }
3903
3904	/// Returns the number of characters in the string, not including any
3905	/// null-termination.
3906	size_type
3907	length() const _GLIBCXX_NOEXCEPT
3908	{ return _M_rep()->_M_length; }
3909
3910	/// Returns the size() of the largest possible %string.
3911	size_type
3912	max_size() const _GLIBCXX_NOEXCEPT
3913	{ return _Rep::_S_max_size; }
3914
3915	/**
3916	* @brief Resizes the %string to the specified number of characters.
3917	* @param __n Number of characters the %string should contain.
3918	* @param __c Character to fill any new elements.
3919	*
3920	* This function will %resize the %string to the specified
3921	* number of characters. If the number is smaller than the
3922	* %string's current size the %string is truncated, otherwise
3923	* the %string is extended and new elements are %set to @a __c.
3924	*/
3925	void
3926	resize(size_type __n, _CharT __c);
3927
3928	/**
3929	* @brief Resizes the %string to the specified number of characters.
3930	* @param __n Number of characters the %string should contain.
3931	*
3932	* This function will resize the %string to the specified length. If
3933	* the new size is smaller than the %string's current size the %string
3934	* is truncated, otherwise the %string is extended and new characters
3935	* are default-constructed. For basic types such as char, this means
3936	* setting them to 0.
3937	*/
3938	void
3939	resize(size_type __n)
3940	{ this->resize(__n, _CharT()); }
3941
3942	#if __cplusplus >= 201103L
3943	/// A non-binding request to reduce capacity() to size().
3944	void
3945	shrink_to_fit() _GLIBCXX_NOEXCEPT
3946	{
3947	#if __cpp_exceptions
3948	if (capacity() > size())
3949	{
3950	try
3951	{ reserve(`0`); }
3952	catch(...)
3953	{ }
3954	}
3955	#endif
3956	}
3957	#endif
3958
3959	/**
3960	* Returns the total number of characters that the %string can hold
3961	* before needing to allocate more memory.
3962	*/
3963	size_type
3964	capacity() const _GLIBCXX_NOEXCEPT
3965	{ return _M_rep()->_M_capacity; }
3966
3967	/**
3968	* @brief Attempt to preallocate enough memory for specified number of
3969	* characters.
3970	* @param __res_arg Number of characters required.
3971	* @throw std::length_error If @a __res_arg exceeds @c max_size().
3972	*
3973	* This function attempts to reserve enough memory for the
3974	* %string to hold the specified number of characters. If the
3975	* number requested is more than max_size(), length_error is
3976	* thrown.
3977	*
3978	* The advantage of this function is that if optimal code is a
3979	* necessity and the user can determine the string length that will be
3980	* required, the user can reserve the memory in %advance, and thus
3981	* prevent a possible reallocation of memory and copying of %string
3982	* data.
3983	*/
3984	void
3985	reserve(size_type __res_arg = `0`);
3986
3987	/**
3988	* Erases the string, making it empty.
3989	*/
3990	#if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
3991	void
3992	clear() _GLIBCXX_NOEXCEPT
3993	{
3994	if (_M_rep()->_M_is_shared())
3995	{
3996	_M_rep()->_M_dispose(this->get_allocator());
3997	_M_data(_S_empty_rep()._M_refdata());
3998	}
3999	else
4000	_M_rep()->_M_set_length_and_sharable(`0`);
4001	}
4002	#else
4003	// PR 56166: this should not throw.
4004	void
4005	clear()
4006	{ _M_mutate(`0`, this->size(), `0`); }
4007	#endif
4008
4009	/**
4010	* Returns true if the %string is empty. Equivalent to
4011	* <code>*this == ""</code>.
4012	*/
4013	_GLIBCXX_NODISCARD bool
4014	empty() const _GLIBCXX_NOEXCEPT
4015	{ return this->size() == `0`; }
4016
4017	// Element access:
4018	/**
4019	* @brief Subscript access to the data contained in the %string.
4020	* @param __pos The index of the character to access.
4021	* @return Read-only (constant) reference to the character.
4022	*
4023	* This operator allows for easy, array-style, data access.
4024	* Note that data access with this operator is unchecked and
4025	* out_of_range lookups are not defined. (For checked lookups
4026	* see at().)
4027	*/
4028	const_reference
4029	operator[] (size_type __pos) const _GLIBCXX_NOEXCEPT
4030	{
4031	__glibcxx_assert(__pos <= size());
4032	return _M_data()[__pos];
4033	}
4034
4035	/**
4036	* @brief Subscript access to the data contained in the %string.
4037	* @param __pos The index of the character to access.
4038	* @return Read/write reference to the character.
4039	*
4040	* This operator allows for easy, array-style, data access.
4041	* Note that data access with this operator is unchecked and
4042	* out_of_range lookups are not defined. (For checked lookups
4043	* see at().) Unshares the string.
4044	*/
4045	reference
4046	operator[](size_type __pos)
4047	{
4048	// Allow pos == size() both in C++98 mode, as v3 extension,
4049	// and in C++11 mode.
4050	__glibcxx_assert(__pos <= size());
4051	// In pedantic mode be strict in C++98 mode.
4052	_GLIBCXX_DEBUG_PEDASSERT(__cplusplus >= `201103L` \|\| __pos < size());
4053	_M_leak();
4054	return _M_data()[__pos];
4055	}
4056
4057	/**
4058	* @brief Provides access to the data contained in the %string.
4059	* @param __n The index of the character to access.
4060	* @return Read-only (const) reference to the character.
4061	* @throw std::out_of_range If @a n is an invalid index.
4062	*
4063	* This function provides for safer data access. The parameter is
4064	* first checked that it is in the range of the string. The function
4065	* throws out_of_range if the check fails.
4066	*/
4067	const_reference
4068	at(size_type __n) const
4069	{
4070	if (__n >= this->size())
4071	__throw_out_of_range_fmt(__N("basic_string::at: __n "
4072	"(which is %zu) >= this->size() "
4073	"(which is %zu)"),
4074	__n, this->size());
4075	return _M_data()[__n];
4076	}
4077
4078	/**
4079	* @brief Provides access to the data contained in the %string.
4080	* @param __n The index of the character to access.
4081	* @return Read/write reference to the character.
4082	* @throw std::out_of_range If @a n is an invalid index.
4083	*
4084	* This function provides for safer data access. The parameter is
4085	* first checked that it is in the range of the string. The function
4086	* throws out_of_range if the check fails. Success results in
4087	* unsharing the string.
4088	*/
4089	reference
4090	at(size_type __n)
4091	{
4092	if (__n >= size())
4093	__throw_out_of_range_fmt(__N("basic_string::at: __n "
4094	"(which is %zu) >= this->size() "
4095	"(which is %zu)"),
4096	__n, this->size());
4097	_M_leak();
4098	return _M_data()[__n];
4099	}
4100
4101	#if __cplusplus >= 201103L
4102	/**
4103	* Returns a read/write reference to the data at the first
4104	* element of the %string.
4105	*/
4106	reference
4107	front()
4108	{
4109	__glibcxx_assert(!empty());
4110	return operator[](`0`);
4111	}
4112
4113	/**
4114	* Returns a read-only (constant) reference to the data at the first
4115	* element of the %string.
4116	*/
4117	const_reference
4118	front() const noexcept
4119	{
4120	__glibcxx_assert(!empty());
4121	return operator[](`0`);
4122	}
4123
4124	/**
4125	* Returns a read/write reference to the data at the last
4126	* element of the %string.
4127	*/
4128	reference
4129	back()
4130	{
4131	__glibcxx_assert(!empty());
4132	return operator[](this->size() - `1`);
4133	}
4134
4135	/**
4136	* Returns a read-only (constant) reference to the data at the
4137	* last element of the %string.
4138	*/
4139	const_reference
4140	back() const noexcept
4141	{
4142	__glibcxx_assert(!empty());
4143	return operator[](this->size() - `1`);
4144	}
4145	#endif
4146
4147	// Modifiers:
4148	/**
4149	* @brief Append a string to this string.
4150	* @param __str The string to append.
4151	* @return Reference to this string.
4152	*/
4153	basic_string&
4154	operator+=(const basic_string& __str)
4155	{ return this->append(__str); }
4156
4157	/**
4158	* @brief Append a C string.
4159	* @param __s The C string to append.
4160	* @return Reference to this string.
4161	*/
4162	basic_string&
4163	operator+=(const _CharT* __s)
4164	{ return this->append(__s); }
4165
4166	/**
4167	* @brief Append a character.
4168	* @param __c The character to append.
4169	* @return Reference to this string.
4170	*/
4171	basic_string&
4172	operator+=(_CharT __c)
4173	{
4174	this->push_back(__c);
4175	return *this;
4176	}
4177
4178	#if __cplusplus >= 201103L
4179	/**
4180	* @brief Append an initializer_list of characters.
4181	* @param __l The initializer_list of characters to be appended.
4182	* @return Reference to this string.
4183	*/
4184	basic_string&
4185	operator+=(initializer_list<_CharT> __l)
4186	{ return this->append(__l.begin(), __l.size()); }
4187	#endif // C++11
4188
4189	#if __cplusplus >= 201703L
4190	/**
4191	* @brief Append a string_view.
4192	* @param __svt The object convertible to string_view to be appended.
4193	* @return Reference to this string.
4194	*/
4195	template<typename _Tp>
4196	_If_sv<_Tp, basic_string&>
4197	operator+=(const _Tp& __svt)
4198	{ return this->append(__svt); }
4199	#endif // C++17
4200
4201	/**
4202	* @brief Append a string to this string.
4203	* @param __str The string to append.
4204	* @return Reference to this string.
4205	*/
4206	basic_string&
4207	append(const basic_string& __str);
4208
4209	/**
4210	* @brief Append a substring.
4211	* @param __str The string to append.
4212	* @param __pos Index of the first character of str to append.
4213	* @param __n The number of characters to append.
4214	* @return Reference to this string.
4215	* @throw std::out_of_range if @a __pos is not a valid index.
4216	*
4217	* This function appends @a __n characters from @a __str
4218	* starting at @a __pos to this string. If @a __n is is larger
4219	* than the number of available characters in @a __str, the
4220	* remainder of @a __str is appended.
4221	*/
4222	basic_string&
4223	append(const basic_string& __str, size_type __pos, size_type __n = npos);
4224
4225	/**
4226	* @brief Append a C substring.
4227	* @param __s The C string to append.
4228	* @param __n The number of characters to append.
4229	* @return Reference to this string.
4230	*/
4231	basic_string&
4232	append(const _CharT* __s, size_type __n);
4233
4234	/**
4235	* @brief Append a C string.
4236	* @param __s The C string to append.
4237	* @return Reference to this string.
4238	*/
4239	basic_string&
4240	append(const _CharT* __s)
4241	{
4242	__glibcxx_requires_string(__s);
4243	return this->append(__s, traits_type::length(__s));
4244	}
4245
4246	/**
4247	* @brief Append multiple characters.
4248	* @param __n The number of characters to append.
4249	* @param __c The character to use.
4250	* @return Reference to this string.
4251	*
4252	* Appends __n copies of __c to this string.
4253	*/
4254	basic_string&
4255	append(size_type __n, _CharT __c);
4256
4257	#if __cplusplus >= 201103L
4258	/**
4259	* @brief Append an initializer_list of characters.
4260	* @param __l The initializer_list of characters to append.
4261	* @return Reference to this string.
4262	*/
4263	basic_string&
4264	append(initializer_list<_CharT> __l)
4265	{ return this->append(__l.begin(), __l.size()); }
4266	#endif // C++11
4267
4268	/**
4269	* @brief Append a range of characters.
4270	* @param __first Iterator referencing the first character to append.
4271	* @param __last Iterator marking the end of the range.
4272	* @return Reference to this string.
4273	*
4274	* Appends characters in the range [__first,__last) to this string.
4275	*/
4276	template<class _InputIterator>
4277	basic_string&
4278	append(_InputIterator __first, _InputIterator __last)
4279	{ return this->replace(_M_iend(), _M_iend(), __first, __last); }
4280
4281	#if __cplusplus >= 201703L
4282	/**
4283	* @brief Append a string_view.
4284	* @param __svt The object convertible to string_view to be appended.
4285	* @return Reference to this string.
4286	*/
4287	template<typename _Tp>
4288	_If_sv<_Tp, basic_string&>
4289	append(const _Tp& __svt)
4290	{
4291	__sv_type __sv = __svt;
4292	return this->append(__sv.data(), __sv.size());
4293	}
4294
4295	/**
4296	* @brief Append a range of characters from a string_view.
4297	* @param __svt The object convertible to string_view to be appended
4298	* from.
4299	* @param __pos The position in the string_view to append from.
4300	* @param __n The number of characters to append from the string_view.
4301	* @return Reference to this string.
4302	*/
4303	template<typename _Tp>
4304	_If_sv<_Tp, basic_string&>
4305	append(const _Tp& __svt, size_type __pos, size_type __n = npos)
4306	{
4307	__sv_type __sv = __svt;
4308	return append(__sv.data()
4309	+ std::__sv_check(__sv.size(), __pos, "basic_string::append"),
4310	std::__sv_limit(__sv.size(), __pos, __n));
4311	}
4312	#endif // C++17
4313
4314	/**
4315	* @brief Append a single character.
4316	* @param __c Character to append.
4317	*/
4318	void
4319	push_back(_CharT __c)
4320	{
4321	const size_type __len = `1` + this->size();
4322	if (__len > this->capacity() \|\| _M_rep()->_M_is_shared())
4323	this->reserve(__len);
4324	traits_type::assign(_M_data()[this->size()], __c);
4325	_M_rep()->_M_set_length_and_sharable(__len);
4326	}
4327
4328	/**
4329	* @brief Set value to contents of another string.
4330	* @param __str Source string to use.
4331	* @return Reference to this string.
4332	*/
4333	basic_string&
4334	assign(const basic_string& __str);
4335
4336	#if __cplusplus >= 201103L
4337	/**
4338	* @brief Set value to contents of another string.
4339	* @param __str Source string to use.
4340	* @return Reference to this string.
4341	*
4342	* This function sets this string to the exact contents of @a __str.
4343	* @a __str is a valid, but unspecified string.
4344	*/
4345	basic_string&
4346	assign(basic_string&& __str)
4347	noexcept(allocator_traits<_Alloc>::is_always_equal::value)
4348	{
4349	this->swap(__str);
4350	return *this;
4351	}
4352	#endif // C++11
4353
4354	/**
4355	* @brief Set value to a substring of a string.
4356	* @param __str The string to use.
4357	* @param __pos Index of the first character of str.
4358	* @param __n Number of characters to use.
4359	* @return Reference to this string.
4360	* @throw std::out_of_range if @a pos is not a valid index.
4361	*
4362	* This function sets this string to the substring of @a __str
4363	* consisting of @a __n characters at @a __pos. If @a __n is
4364	* is larger than the number of available characters in @a
4365	* __str, the remainder of @a __str is used.
4366	*/
4367	basic_string&
4368	assign(const basic_string& __str, size_type __pos, size_type __n = npos)
4369	{ return this->assign(__str._M_data()
4370	+ __str._M_check(__pos, "basic_string::assign"),
4371	__str._M_limit(__pos, __n)); }
4372
4373	/**
4374	* @brief Set value to a C substring.
4375	* @param __s The C string to use.
4376	* @param __n Number of characters to use.
4377	* @return Reference to this string.
4378	*
4379	* This function sets the value of this string to the first @a __n
4380	* characters of @a __s. If @a __n is is larger than the number of
4381	* available characters in @a __s, the remainder of @a __s is used.
4382	*/
4383	basic_string&
4384	assign(const _CharT* __s, size_type __n);
4385
4386	/**
4387	* @brief Set value to contents of a C string.
4388	* @param __s The C string to use.
4389	* @return Reference to this string.
4390	*
4391	* This function sets the value of this string to the value of @a __s.
4392	* The data is copied, so there is no dependence on @a __s once the
4393	* function returns.
4394	*/
4395	basic_string&
4396	assign(const _CharT* __s)
4397	{
4398	__glibcxx_requires_string(__s);
4399	return this->assign(__s, traits_type::length(__s));
4400	}
4401
4402	/**
4403	* @brief Set value to multiple characters.
4404	* @param __n Length of the resulting string.
4405	* @param __c The character to use.
4406	* @return Reference to this string.
4407	*
4408	* This function sets the value of this string to @a __n copies of
4409	* character @a __c.
4410	*/
4411	basic_string&
4412	assign(size_type __n, _CharT __c)
4413	{ return _M_replace_aux(size_type(`0`), this->size(), __n, __c); }
4414
4415	/**
4416	* @brief Set value to a range of characters.
4417	* @param __first Iterator referencing the first character to append.
4418	* @param __last Iterator marking the end of the range.
4419	* @return Reference to this string.
4420	*
4421	* Sets value of string to characters in the range [__first,__last).
4422	*/
4423	template<class _InputIterator>
4424	basic_string&
4425	assign(_InputIterator __first, _InputIterator __last)
4426	{ return this->replace(_M_ibegin(), _M_iend(), __first, __last); }
4427
4428	#if __cplusplus >= 201103L
4429	/**
4430	* @brief Set value to an initializer_list of characters.
4431	* @param __l The initializer_list of characters to assign.
4432	* @return Reference to this string.
4433	*/
4434	basic_string&
4435	assign(initializer_list<_CharT> __l)
4436	{ return this->assign(__l.begin(), __l.size()); }
4437	#endif // C++11
4438
4439	#if __cplusplus >= 201703L
4440	/**
4441	* @brief Set value from a string_view.
4442	* @param __svt The source object convertible to string_view.
4443	* @return Reference to this string.
4444	*/
4445	template<typename _Tp>
4446	_If_sv<_Tp, basic_string&>
4447	assign(const _Tp& __svt)
4448	{
4449	__sv_type __sv = __svt;
4450	return this->assign(__sv.data(), __sv.size());
4451	}
4452
4453	/**
4454	* @brief Set value from a range of characters in a string_view.
4455	* @param __svt The source object convertible to string_view.
4456	* @param __pos The position in the string_view to assign from.
4457	* @param __n The number of characters to assign.
4458	* @return Reference to this string.
4459	*/
4460	template<typename _Tp>
4461	_If_sv<_Tp, basic_string&>
4462	assign(const _Tp& __svt, size_type __pos, size_type __n = npos)
4463	{
4464	__sv_type __sv = __svt;
4465	return assign(__sv.data()
4466	+ std::__sv_check(__sv.size(), __pos, "basic_string::assign"),
4467	std::__sv_limit(__sv.size(), __pos, __n));
4468	}
4469	#endif // C++17
4470
4471	/**
4472	* @brief Insert multiple characters.
4473	* @param __p Iterator referencing location in string to insert at.
4474	* @param __n Number of characters to insert
4475	* @param __c The character to insert.
4476	* @throw std::length_error If new length exceeds @c max_size().
4477	*
4478	* Inserts @a __n copies of character @a __c starting at the
4479	* position referenced by iterator @a __p. If adding
4480	* characters causes the length to exceed max_size(),
4481	* length_error is thrown. The value of the string doesn't
4482	* change if an error is thrown.
4483	*/
4484	void
4485	insert(iterator __p, size_type __n, _CharT __c)
4486	{ this->replace(__p, __p, __n, __c); }
4487
4488	/**
4489	* @brief Insert a range of characters.
4490	* @param __p Iterator referencing location in string to insert at.
4491	* @param __beg Start of range.
4492	* @param __end End of range.
4493	* @throw std::length_error If new length exceeds @c max_size().
4494	*
4495	* Inserts characters in range [__beg,__end). If adding
4496	* characters causes the length to exceed max_size(),
4497	* length_error is thrown. The value of the string doesn't
4498	* change if an error is thrown.
4499	*/
4500	template<class _InputIterator>
4501	void
4502	insert(iterator __p, _InputIterator __beg, _InputIterator __end)
4503	{ this->replace(__p, __p, __beg, __end); }
4504
4505	#if __cplusplus >= 201103L
4506	/**
4507	* @brief Insert an initializer_list of characters.
4508	* @param __p Iterator referencing location in string to insert at.
4509	* @param __l The initializer_list of characters to insert.
4510	* @throw std::length_error If new length exceeds @c max_size().
4511	*/
4512	void
4513	insert(iterator __p, initializer_list<_CharT> __l)
4514	{
4515	_GLIBCXX_DEBUG_PEDASSERT(__p >= _M_ibegin() && __p <= _M_iend());
4516	this->insert(__p - _M_ibegin(), __l.begin(), __l.size());
4517	}
4518	#endif // C++11
4519
4520	/**
4521	* @brief Insert value of a string.
4522	* @param __pos1 Iterator referencing location in string to insert at.
4523	* @param __str The string to insert.
4524	* @return Reference to this string.
4525	* @throw std::length_error If new length exceeds @c max_size().
4526	*
4527	* Inserts value of @a __str starting at @a __pos1. If adding
4528	* characters causes the length to exceed max_size(),
4529	* length_error is thrown. The value of the string doesn't
4530	* change if an error is thrown.
4531	*/
4532	basic_string&
4533	insert(size_type __pos1, const basic_string& __str)
4534	{ return this->insert(__pos1, __str, size_type(`0`), __str.size()); }
4535
4536	/**
4537	* @brief Insert a substring.
4538	* @param __pos1 Iterator referencing location in string to insert at.
4539	* @param __str The string to insert.
4540	* @param __pos2 Start of characters in str to insert.
4541	* @param __n Number of characters to insert.
4542	* @return Reference to this string.
4543	* @throw std::length_error If new length exceeds @c max_size().
4544	* @throw std::out_of_range If @a pos1 > size() or
4545	* @a __pos2 > @a str.size().
4546	*
4547	* Starting at @a pos1, insert @a __n character of @a __str
4548	* beginning with @a __pos2. If adding characters causes the
4549	* length to exceed max_size(), length_error is thrown. If @a
4550	* __pos1 is beyond the end of this string or @a __pos2 is
4551	* beyond the end of @a __str, out_of_range is thrown. The
4552	* value of the string doesn't change if an error is thrown.
4553	*/
4554	basic_string&
4555	insert(size_type __pos1, const basic_string& __str,
4556	size_type __pos2, size_type __n = npos)
4557	{ return this->insert(__pos1, __str._M_data()
4558	+ __str._M_check(__pos2, "basic_string::insert"),
4559	__str._M_limit(__pos2, __n)); }
4560
4561	/**
4562	* @brief Insert a C substring.
4563	* @param __pos Iterator referencing location in string to insert at.
4564	* @param __s The C string to insert.
4565	* @param __n The number of characters to insert.
4566	* @return Reference to this string.
4567	* @throw std::length_error If new length exceeds @c max_size().
4568	* @throw std::out_of_range If @a __pos is beyond the end of this
4569	* string.
4570	*
4571	* Inserts the first @a __n characters of @a __s starting at @a
4572	* __pos. If adding characters causes the length to exceed
4573	* max_size(), length_error is thrown. If @a __pos is beyond
4574	* end(), out_of_range is thrown. The value of the string
4575	* doesn't change if an error is thrown.
4576	*/
4577	basic_string&
4578	insert(size_type __pos, const _CharT* __s, size_type __n);
4579
4580	/**
4581	* @brief Insert a C string.
4582	* @param __pos Iterator referencing location in string to insert at.
4583	* @param __s The C string to insert.
4584	* @return Reference to this string.
4585	* @throw std::length_error If new length exceeds @c max_size().
4586	* @throw std::out_of_range If @a pos is beyond the end of this
4587	* string.
4588	*
4589	* Inserts the first @a n characters of @a __s starting at @a __pos. If
4590	* adding characters causes the length to exceed max_size(),
4591	* length_error is thrown. If @a __pos is beyond end(), out_of_range is
4592	* thrown. The value of the string doesn't change if an error is
4593	* thrown.
4594	*/
4595	basic_string&
4596	insert(size_type __pos, const _CharT* __s)
4597	{
4598	__glibcxx_requires_string(__s);
4599	return this->insert(__pos, __s, traits_type::length(__s));
4600	}
4601
4602	/**
4603	* @brief Insert multiple characters.
4604	* @param __pos Index in string to insert at.
4605	* @param __n Number of characters to insert
4606	* @param __c The character to insert.
4607	* @return Reference to this string.
4608	* @throw std::length_error If new length exceeds @c max_size().
4609	* @throw std::out_of_range If @a __pos is beyond the end of this
4610	* string.
4611	*
4612	* Inserts @a __n copies of character @a __c starting at index
4613	* @a __pos. If adding characters causes the length to exceed
4614	* max_size(), length_error is thrown. If @a __pos > length(),
4615	* out_of_range is thrown. The value of the string doesn't
4616	* change if an error is thrown.
4617	*/
4618	basic_string&
4619	insert(size_type __pos, size_type __n, _CharT __c)
4620	{ return _M_replace_aux(_M_check(__pos, "basic_string::insert"),
4621	size_type(`0`), __n, __c); }
4622
4623	/**
4624	* @brief Insert one character.
4625	* @param __p Iterator referencing position in string to insert at.
4626	* @param __c The character to insert.
4627	* @return Iterator referencing newly inserted char.
4628	* @throw std::length_error If new length exceeds @c max_size().
4629	*
4630	* Inserts character @a __c at position referenced by @a __p.
4631	* If adding character causes the length to exceed max_size(),
4632	* length_error is thrown. If @a __p is beyond end of string,
4633	* out_of_range is thrown. The value of the string doesn't
4634	* change if an error is thrown.
4635	*/
4636	iterator
4637	insert(iterator __p, _CharT __c)
4638	{
4639	_GLIBCXX_DEBUG_PEDASSERT(__p >= _M_ibegin() && __p <= _M_iend());
4640	const size_type __pos = __p - _M_ibegin();
4641	_M_replace_aux(__pos, size_type(`0`), size_type(`1`), __c);
4642	_M_rep()->_M_set_leaked();
4643	return iterator(_M_data() + __pos);
4644	}
4645
4646	#if __cplusplus >= 201703L
4647	/**
4648	* @brief Insert a string_view.
4649	* @param __pos Iterator referencing position in string to insert at.
4650	* @param __svt The object convertible to string_view to insert.
4651	* @return Reference to this string.
4652	*/
4653	template<typename _Tp>
4654	_If_sv<_Tp, basic_string&>
4655	insert(size_type __pos, const _Tp& __svt)
4656	{
4657	__sv_type __sv = __svt;
4658	return this->insert(__pos, __sv.data(), __sv.size());
4659	}
4660
4661	/**
4662	* @brief Insert a string_view.
4663	* @param __pos Iterator referencing position in string to insert at.
4664	* @param __svt The object convertible to string_view to insert from.
4665	* @param __pos Iterator referencing position in string_view to insert
4666	* from.
4667	* @param __n The number of characters to insert.
4668	* @return Reference to this string.
4669	*/
4670	template<typename _Tp>
4671	_If_sv<_Tp, basic_string&>
4672	insert(size_type __pos1, const _Tp& __svt,
4673	size_type __pos2, size_type __n = npos)
4674	{
4675	__sv_type __sv = __svt;
4676	return this->replace(__pos1, size_type(`0`), __sv.data()
4677	+ std::__sv_check(__sv.size(), __pos2, "basic_string::insert"),
4678	std::__sv_limit(__sv.size(), __pos2, __n));
4679	}
4680	#endif // C++17
4681
4682	/**
4683	* @brief Remove characters.
4684	* @param __pos Index of first character to remove (default 0).
4685	* @param __n Number of characters to remove (default remainder).
4686	* @return Reference to this string.
4687	* @throw std::out_of_range If @a pos is beyond the end of this
4688	* string.
4689	*
4690	* Removes @a __n characters from this string starting at @a
4691	* __pos. The length of the string is reduced by @a __n. If
4692	* there are < @a __n characters to remove, the remainder of
4693	* the string is truncated. If @a __p is beyond end of string,
4694	* out_of_range is thrown. The value of the string doesn't
4695	* change if an error is thrown.
4696	*/
4697	basic_string&
4698	erase(size_type __pos = `0`, size_type __n = npos)
4699	{
4700	_M_mutate(_M_check(__pos, "basic_string::erase"),
4701	_M_limit(__pos, __n), size_type(`0`));
4702	return *this;
4703	}
4704
4705	/**
4706	* @brief Remove one character.
4707	* @param __position Iterator referencing the character to remove.
4708	* @return iterator referencing same location after removal.
4709	*
4710	* Removes the character at @a __position from this string. The value
4711	* of the string doesn't change if an error is thrown.
4712	*/
4713	iterator
4714	erase(iterator __position)
4715	{
4716	_GLIBCXX_DEBUG_PEDASSERT(__position >= _M_ibegin()
4717	&& __position < _M_iend());
4718	const size_type __pos = __position - _M_ibegin();
4719	_M_mutate(__pos, size_type(`1`), size_type(`0`));
4720	_M_rep()->_M_set_leaked();
4721	return iterator(_M_data() + __pos);
4722	}
4723
4724	/**
4725	* @brief Remove a range of characters.
4726	* @param __first Iterator referencing the first character to remove.
4727	* @param __last Iterator referencing the end of the range.
4728	* @return Iterator referencing location of first after removal.
4729	*
4730	* Removes the characters in the range [first,last) from this string.
4731	* The value of the string doesn't change if an error is thrown.
4732	*/
4733	iterator
4734	erase(iterator __first, iterator __last);
4735
4736	#if __cplusplus >= 201103L
4737	/**
4738	* @brief Remove the last character.
4739	*
4740	* The string must be non-empty.
4741	*/
4742	void
4743	pop_back() // FIXME C++11: should be noexcept.
4744	{
4745	__glibcxx_assert(!empty());
4746	erase(size() - `1`, `1`);
4747	}
4748	#endif // C++11
4749
4750	/**
4751	* @brief Replace characters with value from another string.
4752	* @param __pos Index of first character to replace.
4753	* @param __n Number of characters to be replaced.
4754	* @param __str String to insert.
4755	* @return Reference to this string.
4756	* @throw std::out_of_range If @a pos is beyond the end of this
4757	* string.
4758	* @throw std::length_error If new length exceeds @c max_size().
4759	*
4760	* Removes the characters in the range [__pos,__pos+__n) from
4761	* this string. In place, the value of @a __str is inserted.
4762	* If @a __pos is beyond end of string, out_of_range is thrown.
4763	* If the length of the result exceeds max_size(), length_error
4764	* is thrown. The value of the string doesn't change if an
4765	* error is thrown.
4766	*/
4767	basic_string&
4768	replace(size_type __pos, size_type __n, const basic_string& __str)
4769	{ return this->replace(__pos, __n, __str._M_data(), __str.size()); }
4770
4771	/**
4772	* @brief Replace characters with value from another string.
4773	* @param __pos1 Index of first character to replace.
4774	* @param __n1 Number of characters to be replaced.
4775	* @param __str String to insert.
4776	* @param __pos2 Index of first character of str to use.
4777	* @param __n2 Number of characters from str to use.
4778	* @return Reference to this string.
4779	* @throw std::out_of_range If @a __pos1 > size() or @a __pos2 >
4780	* __str.size().
4781	* @throw std::length_error If new length exceeds @c max_size().
4782	*
4783	* Removes the characters in the range [__pos1,__pos1 + n) from this
4784	* string. In place, the value of @a __str is inserted. If @a __pos is
4785	* beyond end of string, out_of_range is thrown. If the length of the
4786	* result exceeds max_size(), length_error is thrown. The value of the
4787	* string doesn't change if an error is thrown.
4788	*/
4789	basic_string&
4790	replace(size_type __pos1, size_type __n1, const basic_string& __str,
4791	size_type __pos2, size_type __n2 = npos)
4792	{ return this->replace(__pos1, __n1, __str._M_data()
4793	+ __str._M_check(__pos2, "basic_string::replace"),
4794	__str._M_limit(__pos2, __n2)); }
4795
4796	/**
4797	* @brief Replace characters with value of a C substring.
4798	* @param __pos Index of first character to replace.
4799	* @param __n1 Number of characters to be replaced.
4800	* @param __s C string to insert.
4801	* @param __n2 Number of characters from @a s to use.
4802	* @return Reference to this string.
4803	* @throw std::out_of_range If @a pos1 > size().
4804	* @throw std::length_error If new length exceeds @c max_size().
4805	*
4806	* Removes the characters in the range [__pos,__pos + __n1)
4807	* from this string. In place, the first @a __n2 characters of
4808	* @a __s are inserted, or all of @a __s if @a __n2 is too large. If
4809	* @a __pos is beyond end of string, out_of_range is thrown. If
4810	* the length of result exceeds max_size(), length_error is
4811	* thrown. The value of the string doesn't change if an error
4812	* is thrown.
4813	*/
4814	basic_string&
4815	replace(size_type __pos, size_type __n1, const _CharT* __s,
4816	size_type __n2);
4817
4818	/**
4819	* @brief Replace characters with value of a C string.
4820	* @param __pos Index of first character to replace.
4821	* @param __n1 Number of characters to be replaced.
4822	* @param __s C string to insert.
4823	* @return Reference to this string.
4824	* @throw std::out_of_range If @a pos > size().
4825	* @throw std::length_error If new length exceeds @c max_size().
4826	*
4827	* Removes the characters in the range [__pos,__pos + __n1)
4828	* from this string. In place, the characters of @a __s are
4829	* inserted. If @a __pos is beyond end of string, out_of_range
4830	* is thrown. If the length of result exceeds max_size(),
4831	* length_error is thrown. The value of the string doesn't
4832	* change if an error is thrown.
4833	*/
4834	basic_string&
4835	replace(size_type __pos, size_type __n1, const _CharT* __s)
4836	{
4837	__glibcxx_requires_string(__s);
4838	return this->replace(__pos, __n1, __s, traits_type::length(__s));
4839	}
4840
4841	/**
4842	* @brief Replace characters with multiple characters.
4843	* @param __pos Index of first character to replace.
4844	* @param __n1 Number of characters to be replaced.
4845	* @param __n2 Number of characters to insert.
4846	* @param __c Character to insert.
4847	* @return Reference to this string.
4848	* @throw std::out_of_range If @a __pos > size().
4849	* @throw std::length_error If new length exceeds @c max_size().
4850	*
4851	* Removes the characters in the range [pos,pos + n1) from this
4852	* string. In place, @a __n2 copies of @a __c are inserted.
4853	* If @a __pos is beyond end of string, out_of_range is thrown.
4854	* If the length of result exceeds max_size(), length_error is
4855	* thrown. The value of the string doesn't change if an error
4856	* is thrown.
4857	*/
4858	basic_string&
4859	replace(size_type __pos, size_type __n1, size_type __n2, _CharT __c)
4860	{ return _M_replace_aux(_M_check(__pos, "basic_string::replace"),
4861	_M_limit(__pos, __n1), __n2, __c); }
4862
4863	/**
4864	* @brief Replace range of characters with string.
4865	* @param __i1 Iterator referencing start of range to replace.
4866	* @param __i2 Iterator referencing end of range to replace.
4867	* @param __str String value to insert.
4868	* @return Reference to this string.
4869	* @throw std::length_error If new length exceeds @c max_size().
4870	*
4871	* Removes the characters in the range [__i1,__i2). In place,
4872	* the value of @a __str is inserted. If the length of result
4873	* exceeds max_size(), length_error is thrown. The value of
4874	* the string doesn't change if an error is thrown.
4875	*/
4876	basic_string&
4877	replace(iterator __i1, iterator __i2, const basic_string& __str)
4878	{ return this->replace(__i1, __i2, __str._M_data(), __str.size()); }
4879
4880	/**
4881	* @brief Replace range of characters with C substring.
4882	* @param __i1 Iterator referencing start of range to replace.
4883	* @param __i2 Iterator referencing end of range to replace.
4884	* @param __s C string value to insert.
4885	* @param __n Number of characters from s to insert.
4886	* @return Reference to this string.
4887	* @throw std::length_error If new length exceeds @c max_size().
4888	*
4889	* Removes the characters in the range [__i1,__i2). In place,
4890	* the first @a __n characters of @a __s are inserted. If the
4891	* length of result exceeds max_size(), length_error is thrown.
4892	* The value of the string doesn't change if an error is
4893	* thrown.
4894	*/
4895	basic_string&
4896	replace(iterator __i1, iterator __i2, const _CharT* __s, size_type __n)
4897	{
4898	_GLIBCXX_DEBUG_PEDASSERT(_M_ibegin() <= __i1 && __i1 <= __i2
4899	&& __i2 <= _M_iend());
4900	return this->replace(__i1 - _M_ibegin(), __i2 - __i1, __s, __n);
4901	}
4902
4903	/**
4904	* @brief Replace range of characters with C string.
4905	* @param __i1 Iterator referencing start of range to replace.
4906	* @param __i2 Iterator referencing end of range to replace.
4907	* @param __s C string value to insert.
4908	* @return Reference to this string.
4909	* @throw std::length_error If new length exceeds @c max_size().
4910	*
4911	* Removes the characters in the range [__i1,__i2). In place,
4912	* the characters of @a __s are inserted. If the length of
4913	* result exceeds max_size(), length_error is thrown. The
4914	* value of the string doesn't change if an error is thrown.
4915	*/
4916	basic_string&
4917	replace(iterator __i1, iterator __i2, const _CharT* __s)
4918	{
4919	__glibcxx_requires_string(__s);
4920	return this->replace(__i1, __i2, __s, traits_type::length(__s));
4921	}
4922
4923	/**
4924	* @brief Replace range of characters with multiple characters
4925	* @param __i1 Iterator referencing start of range to replace.
4926	* @param __i2 Iterator referencing end of range to replace.
4927	* @param __n Number of characters to insert.
4928	* @param __c Character to insert.
4929	* @return Reference to this string.
4930	* @throw std::length_error If new length exceeds @c max_size().
4931	*
4932	* Removes the characters in the range [__i1,__i2). In place,
4933	* @a __n copies of @a __c are inserted. If the length of
4934	* result exceeds max_size(), length_error is thrown. The
4935	* value of the string doesn't change if an error is thrown.
4936	*/
4937	basic_string&
4938	replace(iterator __i1, iterator __i2, size_type __n, _CharT __c)
4939	{
4940	_GLIBCXX_DEBUG_PEDASSERT(_M_ibegin() <= __i1 && __i1 <= __i2
4941	&& __i2 <= _M_iend());
4942	return _M_replace_aux(__i1 - _M_ibegin(), __i2 - __i1, __n, __c);
4943	}
4944
4945	/**
4946	* @brief Replace range of characters with range.
4947	* @param __i1 Iterator referencing start of range to replace.
4948	* @param __i2 Iterator referencing end of range to replace.
4949	* @param __k1 Iterator referencing start of range to insert.
4950	* @param __k2 Iterator referencing end of range to insert.
4951	* @return Reference to this string.
4952	* @throw std::length_error If new length exceeds @c max_size().
4953	*
4954	* Removes the characters in the range [__i1,__i2). In place,
4955	* characters in the range [__k1,__k2) are inserted. If the
4956	* length of result exceeds max_size(), length_error is thrown.
4957	* The value of the string doesn't change if an error is
4958	* thrown.
4959	*/
4960	template<class _InputIterator>
4961	basic_string&
4962	replace(iterator __i1, iterator __i2,
4963	_InputIterator __k1, _InputIterator __k2)
4964	{
4965	_GLIBCXX_DEBUG_PEDASSERT(_M_ibegin() <= __i1 && __i1 <= __i2
4966	&& __i2 <= _M_iend());
4967	__glibcxx_requires_valid_range(__k1, __k2);
4968	typedef typename std::__is_integer<_InputIterator>::__type _Integral;
4969	return _M_replace_dispatch(__i1, __i2, __k1, __k2, _Integral());
4970	}
4971
4972	// Specializations for the common case of pointer and iterator:
4973	// useful to avoid the overhead of temporary buffering in _M_replace.
4974	basic_string&
4975	replace(iterator __i1, iterator __i2, _CharT* __k1, _CharT* __k2)
4976	{
4977	_GLIBCXX_DEBUG_PEDASSERT(_M_ibegin() <= __i1 && __i1 <= __i2
4978	&& __i2 <= _M_iend());
4979	__glibcxx_requires_valid_range(__k1, __k2);
4980	return this->replace(__i1 - _M_ibegin(), __i2 - __i1,
4981	__k1, __k2 - __k1);
4982	}
4983
4984	basic_string&
4985	replace(iterator __i1, iterator __i2,
4986	const _CharT* __k1, const _CharT* __k2)
4987	{
4988	_GLIBCXX_DEBUG_PEDASSERT(_M_ibegin() <= __i1 && __i1 <= __i2
4989	&& __i2 <= _M_iend());
4990	__glibcxx_requires_valid_range(__k1, __k2);
4991	return this->replace(__i1 - _M_ibegin(), __i2 - __i1,
4992	__k1, __k2 - __k1);
4993	}
4994
4995	basic_string&
4996	replace(iterator __i1, iterator __i2, iterator __k1, iterator __k2)
4997	{
4998	_GLIBCXX_DEBUG_PEDASSERT(_M_ibegin() <= __i1 && __i1 <= __i2
4999	&& __i2 <= _M_iend());
5000	__glibcxx_requires_valid_range(__k1, __k2);
5001	return this->replace(__i1 - _M_ibegin(), __i2 - __i1,
5002	__k1.base(), __k2 - __k1);
5003	}
5004
5005	basic_string&
5006	replace(iterator __i1, iterator __i2,
5007	const_iterator __k1, const_iterator __k2)
5008	{
5009	_GLIBCXX_DEBUG_PEDASSERT(_M_ibegin() <= __i1 && __i1 <= __i2
5010	&& __i2 <= _M_iend());
5011	__glibcxx_requires_valid_range(__k1, __k2);
5012	return this->replace(__i1 - _M_ibegin(), __i2 - __i1,
5013	__k1.base(), __k2 - __k1);
5014	}
5015
5016	#if __cplusplus >= 201103L
5017	/**
5018	* @brief Replace range of characters with initializer_list.
5019	* @param __i1 Iterator referencing start of range to replace.
5020	* @param __i2 Iterator referencing end of range to replace.
5021	* @param __l The initializer_list of characters to insert.
5022	* @return Reference to this string.
5023	* @throw std::length_error If new length exceeds @c max_size().
5024	*
5025	* Removes the characters in the range [__i1,__i2). In place,
5026	* characters in the range [__k1,__k2) are inserted. If the
5027	* length of result exceeds max_size(), length_error is thrown.
5028	* The value of the string doesn't change if an error is
5029	* thrown.
5030	*/
5031	basic_string& replace(iterator __i1, iterator __i2,
5032	initializer_list<_CharT> __l)
5033	{ return this->replace(__i1, __i2, __l.begin(), __l.end()); }
5034	#endif // C++11
5035
5036	#if __cplusplus >= 201703L
5037	/**
5038	* @brief Replace range of characters with string_view.
5039	* @param __pos The position to replace at.
5040	* @param __n The number of characters to replace.
5041	* @param __svt The object convertible to string_view to insert.
5042	* @return Reference to this string.
5043	*/
5044	template<typename _Tp>
5045	_If_sv<_Tp, basic_string&>
5046	replace(size_type __pos, size_type __n, const _Tp& __svt)
5047	{
5048	__sv_type __sv = __svt;
5049	return this->replace(__pos, __n, __sv.data(), __sv.size());
5050	}
5051
5052	/**
5053	* @brief Replace range of characters with string_view.
5054	* @param __pos1 The position to replace at.
5055	* @param __n1 The number of characters to replace.
5056	* @param __svt The object convertible to string_view to insert from.
5057	* @param __pos2 The position in the string_view to insert from.
5058	* @param __n2 The number of characters to insert.
5059	* @return Reference to this string.
5060	*/
5061	template<typename _Tp>
5062	_If_sv<_Tp, basic_string&>
5063	replace(size_type __pos1, size_type __n1, const _Tp& __svt,
5064	size_type __pos2, size_type __n2 = npos)
5065	{
5066	__sv_type __sv = __svt;
5067	return this->replace(__pos1, __n1,
5068	__sv.data()
5069	+ std::__sv_check(__sv.size(), __pos2, "basic_string::replace"),
5070	std::__sv_limit(__sv.size(), __pos2, __n2));
5071	}
5072
5073	/**
5074	* @brief Replace range of characters with string_view.
5075	* @param __i1 An iterator referencing the start position
5076	to replace at.
5077	* @param __i2 An iterator referencing the end position
5078	for the replace.
5079	* @param __svt The object convertible to string_view to insert from.
5080	* @return Reference to this string.
5081	*/
5082	template<typename _Tp>
5083	_If_sv<_Tp, basic_string&>
5084	replace(const_iterator __i1, const_iterator __i2, const _Tp& __svt)
5085	{
5086	__sv_type __sv = __svt;
5087	return this->replace(__i1 - begin(), __i2 - __i1, __sv);
5088	}
5089	#endif // C++17
5090
5091	private:
5092	template<class _Integer>
5093	basic_string&
5094	_M_replace_dispatch(iterator __i1, iterator __i2, _Integer __n,
5095	_Integer __val, __true_type)
5096	{ return _M_replace_aux(__i1 - _M_ibegin(), __i2 - __i1, __n, __val); }
5097
5098	template<class _InputIterator>
5099	basic_string&
5100	_M_replace_dispatch(iterator __i1, iterator __i2, _InputIterator __k1,
5101	_InputIterator __k2, __false_type);
5102
5103	basic_string&
5104	_M_replace_aux(size_type __pos1, size_type __n1, size_type __n2,
5105	_CharT __c);
5106
5107	basic_string&
5108	_M_replace_safe(size_type __pos1, size_type __n1, const _CharT* __s,
5109	size_type __n2);
5110
5111	// _S_construct_aux is used to implement the 21.3.1 para 15 which
5112	// requires special behaviour if _InIter is an integral type
5113	template<class _InIterator>
5114	static _CharT*
5115	_S_construct_aux(_InIterator __beg, _InIterator __end,
5116	const _Alloc& __a, __false_type)
5117	{
5118	typedef typename iterator_traits<_InIterator>::iterator_category _Tag;
5119	return _S_construct(__beg, __end, __a, _Tag());
5120	}
5121
5122	// _GLIBCXX_RESOLVE_LIB_DEFECTS
5123	// 438. Ambiguity in the "do the right thing" clause
5124	template<class _Integer>
5125	static _CharT*
5126	_S_construct_aux(_Integer __beg, _Integer __end,
5127	const _Alloc& __a, __true_type)
5128	{ return _S_construct_aux_2(static_cast<size_type>(__beg),
5129	__end, __a); }
5130
5131	static _CharT*
5132	_S_construct_aux_2(size_type __req, _CharT __c, const _Alloc& __a)
5133	{ return _S_construct(__req, __c, __a); }
5134
5135	template<class _InIterator>
5136	static _CharT*
5137	_S_construct(_InIterator __beg, _InIterator __end, const _Alloc& __a)
5138	{
5139	typedef typename std::__is_integer<_InIterator>::__type _Integral;
5140	return _S_construct_aux(__beg, __end, __a, _Integral());
5141	}
5142
5143	// For Input Iterators, used in istreambuf_iterators, etc.
5144	template<class _InIterator>
5145	static _CharT*
5146	_S_construct(_InIterator __beg, _InIterator __end, const _Alloc& __a,
5147	input_iterator_tag);
5148
5149	// For forward_iterators up to random_access_iterators, used for
5150	// string::iterator, _CharT, etc.*
5151	template<class _FwdIterator>
5152	static _CharT*
5153	_S_construct(_FwdIterator __beg, _FwdIterator __end, const _Alloc& __a,
5154	forward_iterator_tag);
5155
5156	static _CharT*
5157	_S_construct(size_type __req, _CharT __c, const _Alloc& __a);
5158
5159	public:
5160
5161	/**
5162	* @brief Copy substring into C string.
5163	* @param __s C string to copy value into.
5164	* @param __n Number of characters to copy.
5165	* @param __pos Index of first character to copy.
5166	* @return Number of characters actually copied
5167	* @throw std::out_of_range If __pos > size().
5168	*
5169	* Copies up to @a __n characters starting at @a __pos into the
5170	* C string @a __s. If @a __pos is %greater than size(),
5171	* out_of_range is thrown.
5172	*/
5173	size_type
5174	copy(_CharT* __s, size_type __n, size_type __pos = `0`) const;
5175
5176	/**
5177	* @brief Swap contents with another string.
5178	* @param __s String to swap with.
5179	*
5180	* Exchanges the contents of this string with that of @a __s in constant
5181	* time.
5182	*/
5183	void
5184	swap(basic_string& __s)
5185	_GLIBCXX_NOEXCEPT_IF(allocator_traits<_Alloc>::is_always_equal::value);
5186
5187	// String operations:
5188	/**
5189	* @brief Return const pointer to null-terminated contents.
5190	*
5191	* This is a handle to internal data. Do not modify or dire things may
5192	* happen.
5193	*/
5194	const _CharT*
5195	c_str() const _GLIBCXX_NOEXCEPT
5196	{ return _M_data(); }
5197
5198	/**
5199	* @brief Return const pointer to contents.
5200	*
5201	* This is a pointer to internal data. It is undefined to modify
5202	* the contents through the returned pointer. To get a pointer that
5203	* allows modifying the contents use @c &str[0] instead,
5204	* (or in C++17 the non-const @c str.data() overload).
5205	*/
5206	const _CharT*
5207	data() const _GLIBCXX_NOEXCEPT
5208	{ return _M_data(); }
5209
5210	#if __cplusplus >= 201703L
5211	/**
5212	* @brief Return non-const pointer to contents.
5213	*
5214	* This is a pointer to the character sequence held by the string.
5215	* Modifying the characters in the sequence is allowed.
5216	*/
5217	_CharT*
5218	data() noexcept
5219	{
5220	_M_leak();
5221	return _M_data();
5222	}
5223	#endif
5224
5225	/**
5226	* @brief Return copy of allocator used to construct this string.
5227	*/
5228	allocator_type
5229	get_allocator() const _GLIBCXX_NOEXCEPT
5230	{ return _M_dataplus; }
5231
5232	/**
5233	* @brief Find position of a C substring.
5234	* @param __s C string to locate.
5235	* @param __pos Index of character to search from.
5236	* @param __n Number of characters from @a s to search for.
5237	* @return Index of start of first occurrence.
5238	*
5239	* Starting from @a __pos, searches forward for the first @a
5240	* __n characters in @a __s within this string. If found,
5241	* returns the index where it begins. If not found, returns
5242	* npos.
5243	*/
5244	size_type
5245	find(const _CharT* __s, size_type __pos, size_type __n) const
5246	_GLIBCXX_NOEXCEPT;
5247
5248	/**
5249	* @brief Find position of a string.
5250	* @param __str String to locate.
5251	* @param __pos Index of character to search from (default 0).
5252	* @return Index of start of first occurrence.
5253	*
5254	* Starting from @a __pos, searches forward for value of @a __str within
5255	* this string. If found, returns the index where it begins. If not
5256	* found, returns npos.
5257	*/
5258	size_type
5259	find(const basic_string& __str, size_type __pos = `0`) const
5260	_GLIBCXX_NOEXCEPT
5261	{ return this->find(__str.data(), __pos, __str.size()); }
5262
5263	/**
5264	* @brief Find position of a C string.
5265	* @param __s C string to locate.
5266	* @param __pos Index of character to search from (default 0).
5267	* @return Index of start of first occurrence.
5268	*
5269	* Starting from @a __pos, searches forward for the value of @a
5270	* __s within this string. If found, returns the index where
5271	* it begins. If not found, returns npos.
5272	*/
5273	size_type
5274	find(const _CharT* __s, size_type __pos = `0`) const _GLIBCXX_NOEXCEPT
5275	{
5276	__glibcxx_requires_string(__s);
5277	return this->find(__s, __pos, traits_type::length(__s));
5278	}
5279
5280	/**
5281	* @brief Find position of a character.
5282	* @param __c Character to locate.
5283	* @param __pos Index of character to search from (default 0).
5284	* @return Index of first occurrence.
5285	*
5286	* Starting from @a __pos, searches forward for @a __c within
5287	* this string. If found, returns the index where it was
5288	* found. If not found, returns npos.
5289	*/
5290	size_type
5291	find(_CharT __c, size_type __pos = `0`) const _GLIBCXX_NOEXCEPT;
5292
5293	#if __cplusplus >= 201703L
5294	/**
5295	* @brief Find position of a string_view.
5296	* @param __svt The object convertible to string_view to locate.
5297	* @param __pos Index of character to search from (default 0).
5298	* @return Index of start of first occurrence.
5299	*/
5300	template<typename _Tp>
5301	_If_sv<_Tp, size_type>
5302	find(const _Tp& __svt, size_type __pos = `0`) const
5303	noexcept(is_same<_Tp, __sv_type>::value)
5304	{
5305	__sv_type __sv = __svt;
5306	return this->find(__sv.data(), __pos, __sv.size());
5307	}
5308	#endif // C++17
5309
5310	/**
5311	* @brief Find last position of a string.
5312	* @param __str String to locate.
5313	* @param __pos Index of character to search back from (default end).
5314	* @return Index of start of last occurrence.
5315	*
5316	* Starting from @a __pos, searches backward for value of @a
5317	* __str within this string. If found, returns the index where
5318	* it begins. If not found, returns npos.
5319	*/
5320	size_type
5321	rfind(const basic_string& __str, size_type __pos = npos) const
5322	_GLIBCXX_NOEXCEPT
5323	{ return this->rfind(__str.data(), __pos, __str.size()); }
5324
5325	/**
5326	* @brief Find last position of a C substring.
5327	* @param __s C string to locate.
5328	* @param __pos Index of character to search back from.
5329	* @param __n Number of characters from s to search for.
5330	* @return Index of start of last occurrence.
5331	*
5332	* Starting from @a __pos, searches backward for the first @a
5333	* __n characters in @a __s within this string. If found,
5334	* returns the index where it begins. If not found, returns
5335	* npos.
5336	*/
5337	size_type
5338	rfind(const _CharT* __s, size_type __pos, size_type __n) const
5339	_GLIBCXX_NOEXCEPT;
5340
5341	/**
5342	* @brief Find last position of a C string.
5343	* @param __s C string to locate.
5344	* @param __pos Index of character to start search at (default end).
5345	* @return Index of start of last occurrence.
5346	*
5347	* Starting from @a __pos, searches backward for the value of
5348	* @a __s within this string. If found, returns the index
5349	* where it begins. If not found, returns npos.
5350	*/
5351	size_type
5352	rfind(const _CharT* __s, size_type __pos = npos) const _GLIBCXX_NOEXCEPT
5353	{
5354	__glibcxx_requires_string(__s);
5355	return this->rfind(__s, __pos, traits_type::length(__s));
5356	}
5357
5358	/**
5359	* @brief Find last position of a character.
5360	* @param __c Character to locate.
5361	* @param __pos Index of character to search back from (default end).
5362	* @return Index of last occurrence.
5363	*
5364	* Starting from @a __pos, searches backward for @a __c within
5365	* this string. If found, returns the index where it was
5366	* found. If not found, returns npos.
5367	*/
5368	size_type
5369	rfind(_CharT __c, size_type __pos = npos) const _GLIBCXX_NOEXCEPT;
5370
5371	#if __cplusplus >= 201703L
5372	/**
5373	* @brief Find last position of a string_view.
5374	* @param __svt The object convertible to string_view to locate.
5375	* @param __pos Index of character to search back from (default end).
5376	* @return Index of start of last occurrence.
5377	*/
5378	template<typename _Tp>
5379	_If_sv<_Tp, size_type>
5380	rfind(const _Tp& __svt, size_type __pos = npos) const
5381	noexcept(is_same<_Tp, __sv_type>::value)
5382	{
5383	__sv_type __sv = __svt;
5384	return this->rfind(__sv.data(), __pos, __sv.size());
5385	}
5386	#endif // C++17
5387
5388	/**
5389	* @brief Find position of a character of string.
5390	* @param __str String containing characters to locate.
5391	* @param __pos Index of character to search from (default 0).
5392	* @return Index of first occurrence.
5393	*
5394	* Starting from @a __pos, searches forward for one of the
5395	* characters of @a __str within this string. If found,
5396	* returns the index where it was found. If not found, returns
5397	* npos.
5398	*/
5399	size_type
5400	find_first_of(const basic_string& __str, size_type __pos = `0`) const
5401	_GLIBCXX_NOEXCEPT
5402	{ return this->find_first_of(__str.data(), __pos, __str.size()); }
5403
5404	/**
5405	* @brief Find position of a character of C substring.
5406	* @param __s String containing characters to locate.
5407	* @param __pos Index of character to search from.
5408	* @param __n Number of characters from s to search for.
5409	* @return Index of first occurrence.
5410	*
5411	* Starting from @a __pos, searches forward for one of the
5412	* first @a __n characters of @a __s within this string. If
5413	* found, returns the index where it was found. If not found,
5414	* returns npos.
5415	*/
5416	size_type
5417	find_first_of(const _CharT* __s, size_type __pos, size_type __n) const
5418	_GLIBCXX_NOEXCEPT;
5419
5420	/**
5421	* @brief Find position of a character of C string.
5422	* @param __s String containing characters to locate.
5423	* @param __pos Index of character to search from (default 0).
5424	* @return Index of first occurrence.
5425	*
5426	* Starting from @a __pos, searches forward for one of the
5427	* characters of @a __s within this string. If found, returns
5428	* the index where it was found. If not found, returns npos.
5429	*/
5430	size_type
5431	find_first_of(const _CharT* __s, size_type __pos = `0`) const
5432	_GLIBCXX_NOEXCEPT
5433	{
5434	__glibcxx_requires_string(__s);
5435	return this->find_first_of(__s, __pos, traits_type::length(__s));
5436	}
5437
5438	/**
5439	* @brief Find position of a character.
5440	* @param __c Character to locate.
5441	* @param __pos Index of character to search from (default 0).
5442	* @return Index of first occurrence.
5443	*
5444	* Starting from @a __pos, searches forward for the character
5445	* @a __c within this string. If found, returns the index
5446	* where it was found. If not found, returns npos.
5447	*
5448	* Note: equivalent to find(__c, __pos).
5449	*/
5450	size_type
5451	find_first_of(_CharT __c, size_type __pos = `0`) const _GLIBCXX_NOEXCEPT
5452	{ return this->find(__c, __pos); }
5453
5454	#if __cplusplus >= 201703L
5455	/**
5456	* @brief Find position of a character of a string_view.
5457	* @param __svt An object convertible to string_view containing
5458	* characters to locate.
5459	* @param __pos Index of character to search from (default 0).
5460	* @return Index of first occurrence.
5461	*/
5462	template<typename _Tp>
5463	_If_sv<_Tp, size_type>
5464	find_first_of(const _Tp& __svt, size_type __pos = `0`) const
5465	noexcept(is_same<_Tp, __sv_type>::value)
5466	{
5467	__sv_type __sv = __svt;
5468	return this->find_first_of(__sv.data(), __pos, __sv.size());
5469	}
5470	#endif // C++17
5471
5472	/**
5473	* @brief Find last position of a character of string.
5474	* @param __str String containing characters to locate.
5475	* @param __pos Index of character to search back from (default end).
5476	* @return Index of last occurrence.
5477	*
5478	* Starting from @a __pos, searches backward for one of the
5479	* characters of @a __str within this string. If found,
5480	* returns the index where it was found. If not found, returns
5481	* npos.
5482	*/
5483	size_type
5484	find_last_of(const basic_string& __str, size_type __pos = npos) const
5485	_GLIBCXX_NOEXCEPT
5486	{ return this->find_last_of(__str.data(), __pos, __str.size()); }
5487
5488	/**
5489	* @brief Find last position of a character of C substring.
5490	* @param __s C string containing characters to locate.
5491	* @param __pos Index of character to search back from.
5492	* @param __n Number of characters from s to search for.
5493	* @return Index of last occurrence.
5494	*
5495	* Starting from @a __pos, searches backward for one of the
5496	* first @a __n characters of @a __s within this string. If
5497	* found, returns the index where it was found. If not found,
5498	* returns npos.
5499	*/
5500	size_type
5501	find_last_of(const _CharT* __s, size_type __pos, size_type __n) const
5502	_GLIBCXX_NOEXCEPT;
5503
5504	/**
5505	* @brief Find last position of a character of C string.
5506	* @param __s C string containing characters to locate.
5507	* @param __pos Index of character to search back from (default end).
5508	* @return Index of last occurrence.
5509	*
5510	* Starting from @a __pos, searches backward for one of the
5511	* characters of @a __s within this string. If found, returns
5512	* the index where it was found. If not found, returns npos.
5513	*/
5514	size_type
5515	find_last_of(const _CharT* __s, size_type __pos = npos) const
5516	_GLIBCXX_NOEXCEPT
5517	{
5518	__glibcxx_requires_string(__s);
5519	return this->find_last_of(__s, __pos, traits_type::length(__s));
5520	}
5521
5522	/**
5523	* @brief Find last position of a character.
5524	* @param __c Character to locate.
5525	* @param __pos Index of character to search back from (default end).
5526	* @return Index of last occurrence.
5527	*
5528	* Starting from @a __pos, searches backward for @a __c within
5529	* this string. If found, returns the index where it was
5530	* found. If not found, returns npos.
5531	*
5532	* Note: equivalent to rfind(__c, __pos).
5533	*/
5534	size_type
5535	find_last_of(_CharT __c, size_type __pos = npos) const _GLIBCXX_NOEXCEPT
5536	{ return this->rfind(__c, __pos); }
5537
5538	#if __cplusplus >= 201703L
5539	/**
5540	* @brief Find last position of a character of string.
5541	* @param __svt An object convertible to string_view containing
5542	* characters to locate.
5543	* @param __pos Index of character to search back from (default end).
5544	* @return Index of last occurrence.
5545	*/
5546	template<typename _Tp>
5547	_If_sv<_Tp, size_type>
5548	find_last_of(const _Tp& __svt, size_type __pos = npos) const
5549	noexcept(is_same<_Tp, __sv_type>::value)
5550	{
5551	__sv_type __sv = __svt;
5552	return this->find_last_of(__sv.data(), __pos, __sv.size());
5553	}
5554	#endif // C++17
5555
5556	/**
5557	* @brief Find position of a character not in string.
5558	* @param __str String containing characters to avoid.
5559	* @param __pos Index of character to search from (default 0).
5560	* @return Index of first occurrence.
5561	*
5562	* Starting from @a __pos, searches forward for a character not contained
5563	* in @a __str within this string. If found, returns the index where it
5564	* was found. If not found, returns npos.
5565	*/
5566	size_type
5567	find_first_not_of(const basic_string& __str, size_type __pos = `0`) const
5568	_GLIBCXX_NOEXCEPT
5569	{ return this->find_first_not_of(__str.data(), __pos, __str.size()); }
5570
5571	/**
5572	* @brief Find position of a character not in C substring.
5573	* @param __s C string containing characters to avoid.
5574	* @param __pos Index of character to search from.
5575	* @param __n Number of characters from __s to consider.
5576	* @return Index of first occurrence.
5577	*
5578	* Starting from @a __pos, searches forward for a character not
5579	* contained in the first @a __n characters of @a __s within
5580	* this string. If found, returns the index where it was
5581	* found. If not found, returns npos.
5582	*/
5583	size_type
5584	find_first_not_of(const _CharT* __s, size_type __pos,
5585	size_type __n) const _GLIBCXX_NOEXCEPT;
5586
5587	/**
5588	* @brief Find position of a character not in C string.
5589	* @param __s C string containing characters to avoid.
5590	* @param __pos Index of character to search from (default 0).
5591	* @return Index of first occurrence.
5592	*
5593	* Starting from @a __pos, searches forward for a character not
5594	* contained in @a __s within this string. If found, returns
5595	* the index where it was found. If not found, returns npos.
5596	*/
5597	size_type
5598	find_first_not_of(const _CharT* __s, size_type __pos = `0`) const
5599	_GLIBCXX_NOEXCEPT
5600	{
5601	__glibcxx_requires_string(__s);
5602	return this->find_first_not_of(__s, __pos, traits_type::length(__s));
5603	}
5604
5605	/**
5606	* @brief Find position of a different character.
5607	* @param __c Character to avoid.
5608	* @param __pos Index of character to search from (default 0).
5609	* @return Index of first occurrence.
5610	*
5611	* Starting from @a __pos, searches forward for a character
5612	* other than @a __c within this string. If found, returns the
5613	* index where it was found. If not found, returns npos.
5614	*/
5615	size_type
5616	find_first_not_of(_CharT __c, size_type __pos = `0`) const
5617	_GLIBCXX_NOEXCEPT;
5618
5619	#if __cplusplus >= 201703L
5620	/**
5621	* @brief Find position of a character not in a string_view.
5622	* @param __svt An object convertible to string_view containing
5623	* characters to avoid.
5624	* @param __pos Index of character to search from (default 0).
5625	* @return Index of first occurrence.
5626	*/
5627	template<typename _Tp>
5628	_If_sv<_Tp, size_type>
5629	find_first_not_of(const _Tp& __svt, size_type __pos = `0`) const
5630	noexcept(is_same<_Tp, __sv_type>::value)
5631	{
5632	__sv_type __sv = __svt;
5633	return this->find_first_not_of(__sv.data(), __pos, __sv.size());
5634	}
5635	#endif // C++17
5636
5637	/**
5638	* @brief Find last position of a character not in string.
5639	* @param __str String containing characters to avoid.
5640	* @param __pos Index of character to search back from (default end).
5641	* @return Index of last occurrence.
5642	*
5643	* Starting from @a __pos, searches backward for a character
5644	* not contained in @a __str within this string. If found,
5645	* returns the index where it was found. If not found, returns
5646	* npos.
5647	*/
5648	size_type
5649	find_last_not_of(const basic_string& __str, size_type __pos = npos) const
5650	_GLIBCXX_NOEXCEPT
5651	{ return this->find_last_not_of(__str.data(), __pos, __str.size()); }
5652
5653	/**
5654	* @brief Find last position of a character not in C substring.
5655	* @param __s C string containing characters to avoid.
5656	* @param __pos Index of character to search back from.
5657	* @param __n Number of characters from s to consider.
5658	* @return Index of last occurrence.
5659	*
5660	* Starting from @a __pos, searches backward for a character not
5661	* contained in the first @a __n characters of @a __s within this string.
5662	* If found, returns the index where it was found. If not found,
5663	* returns npos.
5664	*/
5665	size_type
5666	find_last_not_of(const _CharT* __s, size_type __pos,
5667	size_type __n) const _GLIBCXX_NOEXCEPT;
5668	/**
5669	* @brief Find last position of a character not in C string.
5670	* @param __s C string containing characters to avoid.
5671	* @param __pos Index of character to search back from (default end).
5672	* @return Index of last occurrence.
5673	*
5674	* Starting from @a __pos, searches backward for a character
5675	* not contained in @a __s within this string. If found,
5676	* returns the index where it was found. If not found, returns
5677	* npos.
5678	*/
5679	size_type
5680	find_last_not_of(const _CharT* __s, size_type __pos = npos) const
5681	_GLIBCXX_NOEXCEPT
5682	{
5683	__glibcxx_requires_string(__s);
5684	return this->find_last_not_of(__s, __pos, traits_type::length(__s));
5685	}
5686
5687	/**
5688	* @brief Find last position of a different character.
5689	* @param __c Character to avoid.
5690	* @param __pos Index of character to search back from (default end).
5691	* @return Index of last occurrence.
5692	*
5693	* Starting from @a __pos, searches backward for a character other than
5694	* @a __c within this string. If found, returns the index where it was
5695	* found. If not found, returns npos.
5696	*/
5697	size_type
5698	find_last_not_of(_CharT __c, size_type __pos = npos) const
5699	_GLIBCXX_NOEXCEPT;
5700
5701	#if __cplusplus >= 201703L
5702	/**
5703	* @brief Find last position of a character not in a string_view.
5704	* @param __svt An object convertible to string_view containing
5705	* characters to avoid.
5706	* @param __pos Index of character to search back from (default end).
5707	* @return Index of last occurrence.
5708	*/
5709	template<typename _Tp>
5710	_If_sv<_Tp, size_type>
5711	find_last_not_of(const _Tp& __svt, size_type __pos = npos) const
5712	noexcept(is_same<_Tp, __sv_type>::value)
5713	{
5714	__sv_type __sv = __svt;
5715	return this->find_last_not_of(__sv.data(), __pos, __sv.size());
5716	}
5717	#endif // C++17
5718
5719	/**
5720	* @brief Get a substring.
5721	* @param __pos Index of first character (default 0).
5722	* @param __n Number of characters in substring (default remainder).
5723	* @return The new string.
5724	* @throw std::out_of_range If __pos > size().
5725	*
5726	* Construct and return a new string using the @a __n
5727	* characters starting at @a __pos. If the string is too
5728	* short, use the remainder of the characters. If @a __pos is
5729	* beyond the end of the string, out_of_range is thrown.
5730	*/
5731	basic_string
5732	substr(size_type __pos = `0`, size_type __n = npos) const
5733	{ return basic_string(*this,
5734	_M_check(__pos, "basic_string::substr"), __n); }
5735
5736	/**
5737	* @brief Compare to a string.
5738	* @param __str String to compare against.
5739	* @return Integer < 0, 0, or > 0.
5740	*
5741	* Returns an integer < 0 if this string is ordered before @a
5742	* __str, 0 if their values are equivalent, or > 0 if this
5743	* string is ordered after @a __str. Determines the effective
5744	* length rlen of the strings to compare as the smallest of
5745	* size() and str.size(). The function then compares the two
5746	* strings by calling traits::compare(data(), str.data(),rlen).
5747	* If the result of the comparison is nonzero returns it,
5748	* otherwise the shorter one is ordered first.
5749	*/
5750	int
5751	compare(const basic_string& __str) const
5752	{
5753	const size_type __size = this->size();
5754	const size_type __osize = __str.size();
5755	const size_type __len = std::min(__size, __osize);
5756
5757	int __r = traits_type::compare(_M_data(), __str.data(), __len);
5758	if (!__r)
5759	__r = _S_compare(__size, __osize);
5760	return __r;
5761	}
5762
5763	#if __cplusplus >= 201703L
5764	/**
5765	* @brief Compare to a string_view.
5766	* @param __svt An object convertible to string_view to compare against.
5767	* @return Integer < 0, 0, or > 0.
5768	*/
5769	template<typename _Tp>
5770	_If_sv<_Tp, int>
5771	compare(const _Tp& __svt) const
5772	noexcept(is_same<_Tp, __sv_type>::value)
5773	{
5774	__sv_type __sv = __svt;
5775	const size_type __size = this->size();
5776	const size_type __osize = __sv.size();
5777	const size_type __len = std::min(__size, __osize);
5778
5779	int __r = traits_type::compare(_M_data(), __sv.data(), __len);
5780	if (!__r)
5781	__r = _S_compare(__size, __osize);
5782	return __r;
5783	}
5784
5785	/**
5786	* @brief Compare to a string_view.
5787	* @param __pos A position in the string to start comparing from.
5788	* @param __n The number of characters to compare.
5789	* @param __svt An object convertible to string_view to compare
5790	* against.
5791	* @return Integer < 0, 0, or > 0.
5792	*/
5793	template<typename _Tp>
5794	_If_sv<_Tp, int>
5795	compare(size_type __pos, size_type __n, const _Tp& __svt) const
5796	noexcept(is_same<_Tp, __sv_type>::value)
5797	{
5798	__sv_type __sv = __svt;
5799	return __sv_type(*this).substr(__pos, __n).compare(__sv);
5800	}
5801
5802	/**
5803	* @brief Compare to a string_view.
5804	* @param __pos1 A position in the string to start comparing from.
5805	* @param __n1 The number of characters to compare.
5806	* @param __svt An object convertible to string_view to compare
5807	* against.
5808	* @param __pos2 A position in the string_view to start comparing from.
5809	* @param __n2 The number of characters to compare.
5810	* @return Integer < 0, 0, or > 0.
5811	*/
5812	template<typename _Tp>
5813	_If_sv<_Tp, int>
5814	compare(size_type __pos1, size_type __n1, const _Tp& __svt,
5815	size_type __pos2, size_type __n2 = npos) const
5816	noexcept(is_same<_Tp, __sv_type>::value)
5817	{
5818	__sv_type __sv = __svt;
5819	return __sv_type(*this)
5820	.substr(__pos1, __n1).compare(__sv.substr(__pos2, __n2));
5821	}
5822	#endif // C++17
5823
5824	/**
5825	* @brief Compare substring to a string.
5826	* @param __pos Index of first character of substring.
5827	* @param __n Number of characters in substring.
5828	* @param __str String to compare against.
5829	* @return Integer < 0, 0, or > 0.
5830	*
5831	* Form the substring of this string from the @a __n characters
5832	* starting at @a __pos. Returns an integer < 0 if the
5833	* substring is ordered before @a __str, 0 if their values are
5834	* equivalent, or > 0 if the substring is ordered after @a
5835	* __str. Determines the effective length rlen of the strings
5836	* to compare as the smallest of the length of the substring
5837	* and @a __str.size(). The function then compares the two
5838	* strings by calling
5839	* traits::compare(substring.data(),str.data(),rlen). If the
5840	* result of the comparison is nonzero returns it, otherwise
5841	* the shorter one is ordered first.
5842	*/
5843	int
5844	compare(size_type __pos, size_type __n, const basic_string& __str) const;
5845
5846	/**
5847	* @brief Compare substring to a substring.
5848	* @param __pos1 Index of first character of substring.
5849	* @param __n1 Number of characters in substring.
5850	* @param __str String to compare against.
5851	* @param __pos2 Index of first character of substring of str.
5852	* @param __n2 Number of characters in substring of str.
5853	* @return Integer < 0, 0, or > 0.
5854	*
5855	* Form the substring of this string from the @a __n1
5856	* characters starting at @a __pos1. Form the substring of @a
5857	* __str from the @a __n2 characters starting at @a __pos2.
5858	* Returns an integer < 0 if this substring is ordered before
5859	* the substring of @a __str, 0 if their values are equivalent,
5860	* or > 0 if this substring is ordered after the substring of
5861	* @a __str. Determines the effective length rlen of the
5862	* strings to compare as the smallest of the lengths of the
5863	* substrings. The function then compares the two strings by
5864	* calling
5865	* traits::compare(substring.data(),str.substr(pos2,n2).data(),rlen).
5866	* If the result of the comparison is nonzero returns it,
5867	* otherwise the shorter one is ordered first.
5868	*/
5869	int
5870	compare(size_type __pos1, size_type __n1, const basic_string& __str,
5871	size_type __pos2, size_type __n2 = npos) const;
5872
5873	/**
5874	* @brief Compare to a C string.
5875	* @param __s C string to compare against.
5876	* @return Integer < 0, 0, or > 0.
5877	*
5878	* Returns an integer < 0 if this string is ordered before @a __s, 0 if
5879	* their values are equivalent, or > 0 if this string is ordered after
5880	* @a __s. Determines the effective length rlen of the strings to
5881	* compare as the smallest of size() and the length of a string
5882	* constructed from @a __s. The function then compares the two strings
5883	* by calling traits::compare(data(),s,rlen). If the result of the
5884	* comparison is nonzero returns it, otherwise the shorter one is
5885	* ordered first.
5886	*/
5887	int
5888	compare(const _CharT* __s) const _GLIBCXX_NOEXCEPT;
5889
5890	// _GLIBCXX_RESOLVE_LIB_DEFECTS
5891	// 5 String::compare specification questionable
5892	/**
5893	* @brief Compare substring to a C string.
5894	* @param __pos Index of first character of substring.
5895	* @param __n1 Number of characters in substring.
5896	* @param __s C string to compare against.
5897	* @return Integer < 0, 0, or > 0.
5898	*
5899	* Form the substring of this string from the @a __n1
5900	* characters starting at @a pos. Returns an integer < 0 if
5901	* the substring is ordered before @a __s, 0 if their values
5902	* are equivalent, or > 0 if the substring is ordered after @a
5903	* __s. Determines the effective length rlen of the strings to
5904	* compare as the smallest of the length of the substring and
5905	* the length of a string constructed from @a __s. The
5906	* function then compares the two string by calling
5907	* traits::compare(substring.data(),__s,rlen). If the result of
5908	* the comparison is nonzero returns it, otherwise the shorter
5909	* one is ordered first.
5910	*/
5911	int
5912	compare(size_type __pos, size_type __n1, const _CharT* __s) const;
5913
5914	/**
5915	* @brief Compare substring against a character %array.
5916	* @param __pos Index of first character of substring.
5917	* @param __n1 Number of characters in substring.
5918	* @param __s character %array to compare against.
5919	* @param __n2 Number of characters of s.
5920	* @return Integer < 0, 0, or > 0.
5921	*
5922	* Form the substring of this string from the @a __n1
5923	* characters starting at @a __pos. Form a string from the
5924	* first @a __n2 characters of @a __s. Returns an integer < 0
5925	* if this substring is ordered before the string from @a __s,
5926	* 0 if their values are equivalent, or > 0 if this substring
5927	* is ordered after the string from @a __s. Determines the
5928	* effective length rlen of the strings to compare as the
5929	* smallest of the length of the substring and @a __n2. The
5930	* function then compares the two strings by calling
5931	* traits::compare(substring.data(),s,rlen). If the result of
5932	* the comparison is nonzero returns it, otherwise the shorter
5933	* one is ordered first.
5934	*
5935	* NB: s must have at least n2 characters, '\\0' has
5936	* no special meaning.
5937	*/
5938	int
5939	compare(size_type __pos, size_type __n1, const _CharT* __s,
5940	size_type __n2) const;
5941
5942	#if __cplusplus > 201703L
5943	bool
5944	starts_with(basic_string_view<_CharT, _Traits> __x) const noexcept
5945	{ return __sv_type(this->data(), this->size()).starts_with(__x); }
5946
5947	bool
5948	starts_with(_CharT __x) const noexcept
5949	{ return __sv_type(this->data(), this->size()).starts_with(__x); }
5950
5951	bool
5952	starts_with(const _CharT* __x) const noexcept
5953	{ return __sv_type(this->data(), this->size()).starts_with(__x); }
5954
5955	bool
5956	ends_with(basic_string_view<_CharT, _Traits> __x) const noexcept
5957	{ return __sv_type(this->data(), this->size()).ends_with(__x); }
5958
5959	bool
5960	ends_with(_CharT __x) const noexcept
5961	{ return __sv_type(this->data(), this->size()).ends_with(__x); }
5962
5963	bool
5964	ends_with(const _CharT* __x) const noexcept
5965	{ return __sv_type(this->data(), this->size()).ends_with(__x); }
5966	#endif // C++20
5967
5968	# ifdef _GLIBCXX_TM_TS_INTERNAL
5969	friend void
5970	::_txnal_cow_string_C1_for_exceptions(void* that, const char* s,
5971	void* exc);
5972	friend const char*
5973	::_txnal_cow_string_c_str(const void *that);
5974	friend void
5975	::_txnal_cow_string_D1(void *that);
5976	friend void
5977	::_txnal_cow_string_D1_commit(void *that);
5978	# endif
5979	};
5980	#endif // !_GLIBCXX_USE_CXX11_ABI
5981
5982	#if __cpp_deduction_guides >= 201606
5983	_GLIBCXX_BEGIN_NAMESPACE_CXX11
5984	template<typename _InputIterator, typename _CharT
5985	= typename iterator_traits<_InputIterator>::value_type,
5986	typename _Allocator = allocator<_CharT>,
5987	typename = _RequireInputIter<_InputIterator>,
5988	typename = _RequireAllocator<_Allocator>>
5989	basic_string(_InputIterator, _InputIterator, _Allocator = _Allocator())
5990	-> basic_string<_CharT, char_traits<_CharT>, _Allocator>;
5991
5992	// _GLIBCXX_RESOLVE_LIB_DEFECTS
5993	// 3075. basic_string needs deduction guides from basic_string_view
5994	template<typename _CharT, typename _Traits,
5995	typename _Allocator = allocator<_CharT>,
5996	typename = _RequireAllocator<_Allocator>>
5997	basic_string(basic_string_view<_CharT, _Traits>, const _Allocator& = _Allocator())
5998	-> basic_string<_CharT, _Traits, _Allocator>;
5999
6000	template<typename _CharT, typename _Traits,
6001	typename _Allocator = allocator<_CharT>,
6002	typename = _RequireAllocator<_Allocator>>
6003	basic_string(basic_string_view<_CharT, _Traits>,
6004	typename basic_string<_CharT, _Traits, _Allocator>::size_type,
6005	typename basic_string<_CharT, _Traits, _Allocator>::size_type,
6006	const _Allocator& = _Allocator())
6007	-> basic_string<_CharT, _Traits, _Allocator>;
6008	_GLIBCXX_END_NAMESPACE_CXX11
6009	#endif
6010
6011	// operator+
6012	/**
6013	* @brief Concatenate two strings.
6014	* @param __lhs First string.
6015	* @param __rhs Last string.
6016	* @return New string with value of @a __lhs followed by @a __rhs.
6017	*/
6018	template<typename _CharT, typename _Traits, typename _Alloc>
6019	basic_string<_CharT, _Traits, _Alloc>
6020	operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6021	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6022	{
6023	basic_string<_CharT, _Traits, _Alloc> __str(__lhs);
6024	__str.append(__rhs);
6025	return __str;
6026	}
6027
6028	/**
6029	* @brief Concatenate C string and string.
6030	* @param __lhs First string.
6031	* @param __rhs Last string.
6032	* @return New string with value of @a __lhs followed by @a __rhs.
6033	*/
6034	template<typename _CharT, typename _Traits, typename _Alloc>
6035	basic_string<_CharT,_Traits,_Alloc>
6036	operator+(const _CharT* __lhs,
6037	const basic_string<_CharT,_Traits,_Alloc>& __rhs);
6038
6039	/**
6040	* @brief Concatenate character and string.
6041	* @param __lhs First string.
6042	* @param __rhs Last string.
6043	* @return New string with @a __lhs followed by @a __rhs.
6044	*/
6045	template<typename _CharT, typename _Traits, typename _Alloc>
6046	basic_string<_CharT,_Traits,_Alloc>
6047	operator+(_CharT __lhs, const basic_string<_CharT,_Traits,_Alloc>& __rhs);
6048
6049	/**
6050	* @brief Concatenate string and C string.
6051	* @param __lhs First string.
6052	* @param __rhs Last string.
6053	* @return New string with @a __lhs followed by @a __rhs.
6054	*/
6055	template<typename _CharT, typename _Traits, typename _Alloc>
6056	inline basic_string<_CharT, _Traits, _Alloc>
6057	operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6058	const _CharT* __rhs)
6059	{
6060	basic_string<_CharT, _Traits, _Alloc> __str(__lhs);
6061	__str.append(__rhs);
6062	return __str;
6063	}
6064
6065	/**
6066	* @brief Concatenate string and character.
6067	* @param __lhs First string.
6068	* @param __rhs Last string.
6069	* @return New string with @a __lhs followed by @a __rhs.
6070	*/
6071	template<typename _CharT, typename _Traits, typename _Alloc>
6072	inline basic_string<_CharT, _Traits, _Alloc>
6073	operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs, _CharT __rhs)
6074	{
6075	typedef basic_string<_CharT, _Traits, _Alloc> __string_type;
6076	typedef typename __string_type::size_type __size_type;
6077	__string_type __str(__lhs);
6078	__str.append(__size_type(`1`), __rhs);
6079	return __str;
6080	}
6081
6082	#if __cplusplus >= 201103L
6083	template<typename _CharT, typename _Traits, typename _Alloc>
6084	inline basic_string<_CharT, _Traits, _Alloc>
6085	operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
6086	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6087	{ return std::move(__lhs.append(__rhs)); }
6088
6089	template<typename _CharT, typename _Traits, typename _Alloc>
6090	inline basic_string<_CharT, _Traits, _Alloc>
6091	operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6092	basic_string<_CharT, _Traits, _Alloc>&& __rhs)
6093	{ return std::move(__rhs.insert(`0`, __lhs)); }
6094
6095	template<typename _CharT, typename _Traits, typename _Alloc>
6096	inline basic_string<_CharT, _Traits, _Alloc>
6097	operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
6098	basic_string<_CharT, _Traits, _Alloc>&& __rhs)
6099	{
6100	const auto __size = __lhs.size() + __rhs.size();
6101	const bool __cond = (__size > __lhs.capacity()
6102	&& __size <= __rhs.capacity());
6103	return __cond ? std::move(__rhs.insert(`0`, __lhs))
6104	: std::move(__lhs.append(__rhs));
6105	}
6106
6107	template<typename _CharT, typename _Traits, typename _Alloc>
6108	inline basic_string<_CharT, _Traits, _Alloc>
6109	operator+(const _CharT* __lhs,
6110	basic_string<_CharT, _Traits, _Alloc>&& __rhs)
6111	{ return std::move(__rhs.insert(`0`, __lhs)); }
6112
6113	template<typename _CharT, typename _Traits, typename _Alloc>
6114	inline basic_string<_CharT, _Traits, _Alloc>
6115	operator+(_CharT __lhs,
6116	basic_string<_CharT, _Traits, _Alloc>&& __rhs)
6117	{ return std::move(__rhs.insert(`0`, `1`, __lhs)); }
6118
6119	template<typename _CharT, typename _Traits, typename _Alloc>
6120	inline basic_string<_CharT, _Traits, _Alloc>
6121	operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
6122	const _CharT* __rhs)
6123	{ return std::move(__lhs.append(__rhs)); }
6124
6125	template<typename _CharT, typename _Traits, typename _Alloc>
6126	inline basic_string<_CharT, _Traits, _Alloc>
6127	operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
6128	_CharT __rhs)
6129	{ return std::move(__lhs.append(`1`, __rhs)); }
6130	#endif
6131
6132	// operator ==
6133	/**
6134	* @brief Test equivalence of two strings.
6135	* @param __lhs First string.
6136	* @param __rhs Second string.
6137	* @return True if @a __lhs.compare(@a __rhs) == 0. False otherwise.
6138	*/
6139	template<typename _CharT, typename _Traits, typename _Alloc>
6140	inline bool
6141	operator==(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6142	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6143	_GLIBCXX_NOEXCEPT
6144	{ return __lhs.compare(__rhs) == `0`; }
6145
6146	template<typename _CharT>
6147	inline
6148	typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value, bool>::__type
6149	operator==(const basic_string<_CharT>& __lhs,
6150	const basic_string<_CharT>& __rhs) _GLIBCXX_NOEXCEPT
6151	{ return (__lhs.size() == __rhs.size()
6152	&& !std::char_traits<_CharT>::compare(__lhs.data(), __rhs.data(),
6153	__lhs.size())); }
6154
6155	/**
6156	* @brief Test equivalence of C string and string.
6157	* @param __lhs C string.
6158	* @param __rhs String.
6159	* @return True if @a __rhs.compare(@a __lhs) == 0. False otherwise.
6160	*/
6161	template<typename _CharT, typename _Traits, typename _Alloc>
6162	inline bool
6163	operator==(const _CharT* __lhs,
6164	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6165	{ return __rhs.compare(__lhs) == `0`; }
6166
6167	/**
6168	* @brief Test equivalence of string and C string.
6169	* @param __lhs String.
6170	* @param __rhs C string.
6171	* @return True if @a __lhs.compare(@a __rhs) == 0. False otherwise.
6172	*/
6173	template<typename _CharT, typename _Traits, typename _Alloc>
6174	inline bool
6175	operator==(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6176	const _CharT* __rhs)
6177	{ return __lhs.compare(__rhs) == `0`; }
6178
6179	// operator !=
6180	/**
6181	* @brief Test difference of two strings.
6182	* @param __lhs First string.
6183	* @param __rhs Second string.
6184	* @return True if @a __lhs.compare(@a __rhs) != 0. False otherwise.
6185	*/
6186	template<typename _CharT, typename _Traits, typename _Alloc>
6187	inline bool
6188	operator!=(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6189	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6190	_GLIBCXX_NOEXCEPT
6191	{ return !(__lhs == __rhs); }
6192
6193	/**
6194	* @brief Test difference of C string and string.
6195	* @param __lhs C string.
6196	* @param __rhs String.
6197	* @return True if @a __rhs.compare(@a __lhs) != 0. False otherwise.
6198	*/
6199	template<typename _CharT, typename _Traits, typename _Alloc>
6200	inline bool
6201	operator!=(const _CharT* __lhs,
6202	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6203	{ return !(__lhs == __rhs); }
6204
6205	/**
6206	* @brief Test difference of string and C string.
6207	* @param __lhs String.
6208	* @param __rhs C string.
6209	* @return True if @a __lhs.compare(@a __rhs) != 0. False otherwise.
6210	*/
6211	template<typename _CharT, typename _Traits, typename _Alloc>
6212	inline bool
6213	operator!=(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6214	const _CharT* __rhs)
6215	{ return !(__lhs == __rhs); }
6216
6217	// operator <
6218	/**
6219	* @brief Test if string precedes string.
6220	* @param __lhs First string.
6221	* @param __rhs Second string.
6222	* @return True if @a __lhs precedes @a __rhs. False otherwise.
6223	*/
6224	template<typename _CharT, typename _Traits, typename _Alloc>
6225	inline bool
6226	operator<(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6227	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6228	_GLIBCXX_NOEXCEPT
6229	{ return __lhs.compare(__rhs) < `0`; }
6230
6231	/**
6232	* @brief Test if string precedes C string.
6233	* @param __lhs String.
6234	* @param __rhs C string.
6235	* @return True if @a __lhs precedes @a __rhs. False otherwise.
6236	*/
6237	template<typename _CharT, typename _Traits, typename _Alloc>
6238	inline bool
6239	operator<(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6240	const _CharT* __rhs)
6241	{ return __lhs.compare(__rhs) < `0`; }
6242
6243	/**
6244	* @brief Test if C string precedes string.
6245	* @param __lhs C string.
6246	* @param __rhs String.
6247	* @return True if @a __lhs precedes @a __rhs. False otherwise.
6248	*/
6249	template<typename _CharT, typename _Traits, typename _Alloc>
6250	inline bool
6251	operator<(const _CharT* __lhs,
6252	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6253	{ return __rhs.compare(__lhs) > `0`; }
6254
6255	// operator >
6256	/**
6257	* @brief Test if string follows string.
6258	* @param __lhs First string.
6259	* @param __rhs Second string.
6260	* @return True if @a __lhs follows @a __rhs. False otherwise.
6261	*/
6262	template<typename _CharT, typename _Traits, typename _Alloc>
6263	inline bool
6264	operator>(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6265	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6266	_GLIBCXX_NOEXCEPT
6267	{ return __lhs.compare(__rhs) > `0`; }
6268
6269	/**
6270	* @brief Test if string follows C string.
6271	* @param __lhs String.
6272	* @param __rhs C string.
6273	* @return True if @a __lhs follows @a __rhs. False otherwise.
6274	*/
6275	template<typename _CharT, typename _Traits, typename _Alloc>
6276	inline bool
6277	operator>(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6278	const _CharT* __rhs)
6279	{ return __lhs.compare(__rhs) > `0`; }
6280
6281	/**
6282	* @brief Test if C string follows string.
6283	* @param __lhs C string.
6284	* @param __rhs String.
6285	* @return True if @a __lhs follows @a __rhs. False otherwise.
6286	*/
6287	template<typename _CharT, typename _Traits, typename _Alloc>
6288	inline bool
6289	operator>(const _CharT* __lhs,
6290	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6291	{ return __rhs.compare(__lhs) < `0`; }
6292
6293	// operator <=
6294	/**
6295	* @brief Test if string doesn't follow string.
6296	* @param __lhs First string.
6297	* @param __rhs Second string.
6298	* @return True if @a __lhs doesn't follow @a __rhs. False otherwise.
6299	*/
6300	template<typename _CharT, typename _Traits, typename _Alloc>
6301	inline bool
6302	operator<=(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6303	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6304	_GLIBCXX_NOEXCEPT
6305	{ return __lhs.compare(__rhs) <= `0`; }
6306
6307	/**
6308	* @brief Test if string doesn't follow C string.
6309	* @param __lhs String.
6310	* @param __rhs C string.
6311	* @return True if @a __lhs doesn't follow @a __rhs. False otherwise.
6312	*/
6313	template<typename _CharT, typename _Traits, typename _Alloc>
6314	inline bool
6315	operator<=(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6316	const _CharT* __rhs)
6317	{ return __lhs.compare(__rhs) <= `0`; }
6318
6319	/**
6320	* @brief Test if C string doesn't follow string.
6321	* @param __lhs C string.
6322	* @param __rhs String.
6323	* @return True if @a __lhs doesn't follow @a __rhs. False otherwise.
6324	*/
6325	template<typename _CharT, typename _Traits, typename _Alloc>
6326	inline bool
6327	operator<=(const _CharT* __lhs,
6328	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6329	{ return __rhs.compare(__lhs) >= `0`; }
6330
6331	// operator >=
6332	/**
6333	* @brief Test if string doesn't precede string.
6334	* @param __lhs First string.
6335	* @param __rhs Second string.
6336	* @return True if @a __lhs doesn't precede @a __rhs. False otherwise.
6337	*/
6338	template<typename _CharT, typename _Traits, typename _Alloc>
6339	inline bool
6340	operator>=(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6341	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6342	_GLIBCXX_NOEXCEPT
6343	{ return __lhs.compare(__rhs) >= `0`; }
6344
6345	/**
6346	* @brief Test if string doesn't precede C string.
6347	* @param __lhs String.
6348	* @param __rhs C string.
6349	* @return True if @a __lhs doesn't precede @a __rhs. False otherwise.
6350	*/
6351	template<typename _CharT, typename _Traits, typename _Alloc>
6352	inline bool
6353	operator>=(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6354	const _CharT* __rhs)
6355	{ return __lhs.compare(__rhs) >= `0`; }
6356
6357	/**
6358	* @brief Test if C string doesn't precede string.
6359	* @param __lhs C string.
6360	* @param __rhs String.
6361	* @return True if @a __lhs doesn't precede @a __rhs. False otherwise.
6362	*/
6363	template<typename _CharT, typename _Traits, typename _Alloc>
6364	inline bool
6365	operator>=(const _CharT* __lhs,
6366	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6367	{ return __rhs.compare(__lhs) <= `0`; }
6368
6369	/**
6370	* @brief Swap contents of two strings.
6371	* @param __lhs First string.
6372	* @param __rhs Second string.
6373	*
6374	* Exchanges the contents of @a __lhs and @a __rhs in constant time.
6375	*/
6376	template<typename _CharT, typename _Traits, typename _Alloc>
6377	inline void
6378	swap(basic_string<_CharT, _Traits, _Alloc>& __lhs,
6379	basic_string<_CharT, _Traits, _Alloc>& __rhs)
6380	_GLIBCXX_NOEXCEPT_IF(noexcept(__lhs.swap(__rhs)))
6381	{ __lhs.swap(__rhs); }
6382
6383
6384	/**
6385	* @brief Read stream into a string.
6386	* @param __is Input stream.
6387	* @param __str Buffer to store into.
6388	* @return Reference to the input stream.
6389	*
6390	* Stores characters from @a __is into @a __str until whitespace is
6391	* found, the end of the stream is encountered, or str.max_size()
6392	* is reached. If is.width() is non-zero, that is the limit on the
6393	* number of characters stored into @a __str. Any previous
6394	* contents of @a __str are erased.
6395	*/
6396	template<typename _CharT, typename _Traits, typename _Alloc>
6397	basic_istream<_CharT, _Traits>&
6398	operator>>(basic_istream<_CharT, _Traits>& __is,
6399	basic_string<_CharT, _Traits, _Alloc>& __str);
6400
6401	template<>
6402	basic_istream<char>&
6403	operator>>(basic_istream<char>& __is, basic_string<char>& __str);
6404
6405	/**
6406	* @brief Write string to a stream.
6407	* @param __os Output stream.
6408	* @param __str String to write out.
6409	* @return Reference to the output stream.
6410	*
6411	* Output characters of @a __str into os following the same rules as for
6412	* writing a C string.
6413	*/
6414	template<typename _CharT, typename _Traits, typename _Alloc>
6415	inline basic_ostream<_CharT, _Traits>&
6416	operator<<(basic_ostream<_CharT, _Traits>& __os,
6417	const basic_string<_CharT, _Traits, _Alloc>& __str)
6418	{
6419	// _GLIBCXX_RESOLVE_LIB_DEFECTS
6420	// 586. string inserter not a formatted function
6421	return __ostream_insert(__os, __str.data(), __str.size());
6422	}
6423
6424	/**
6425	* @brief Read a line from stream into a string.
6426	* @param __is Input stream.
6427	* @param __str Buffer to store into.
6428	* @param __delim Character marking end of line.
6429	* @return Reference to the input stream.
6430	*
6431	* Stores characters from @a __is into @a __str until @a __delim is
6432	* found, the end of the stream is encountered, or str.max_size()
6433	* is reached. Any previous contents of @a __str are erased. If
6434	* @a __delim is encountered, it is extracted but not stored into
6435	* @a __str.
6436	*/
6437	template<typename _CharT, typename _Traits, typename _Alloc>
6438	basic_istream<_CharT, _Traits>&
6439	getline(basic_istream<_CharT, _Traits>& __is,
6440	basic_string<_CharT, _Traits, _Alloc>& __str, _CharT __delim);
6441
6442	/**
6443	* @brief Read a line from stream into a string.
6444	* @param __is Input stream.
6445	* @param __str Buffer to store into.
6446	* @return Reference to the input stream.
6447	*
6448	* Stores characters from is into @a __str until '\n' is
6449	* found, the end of the stream is encountered, or str.max_size()
6450	* is reached. Any previous contents of @a __str are erased. If
6451	* end of line is encountered, it is extracted but not stored into
6452	* @a __str.
6453	*/
6454	template<typename _CharT, typename _Traits, typename _Alloc>
6455	inline basic_istream<_CharT, _Traits>&
6456	getline(basic_istream<_CharT, _Traits>& __is,
6457	basic_string<_CharT, _Traits, _Alloc>& __str)
6458	{ return std::getline(__is, __str, __is.widen(`'\n'`)); }
6459
6460	#if __cplusplus >= 201103L
6461	/// Read a line from an rvalue stream into a string.
6462	template<typename _CharT, typename _Traits, typename _Alloc>
6463	inline basic_istream<_CharT, _Traits>&
6464	getline(basic_istream<_CharT, _Traits>&& __is,
6465	basic_string<_CharT, _Traits, _Alloc>& __str, _CharT __delim)
6466	{ return std::getline(__is, __str, __delim); }
6467
6468	/// Read a line from an rvalue stream into a string.
6469	template<typename _CharT, typename _Traits, typename _Alloc>
6470	inline basic_istream<_CharT, _Traits>&
6471	getline(basic_istream<_CharT, _Traits>&& __is,
6472	basic_string<_CharT, _Traits, _Alloc>& __str)
6473	{ return std::getline(__is, __str); }
6474	#endif
6475
6476	template<>
6477	basic_istream<char>&
6478	getline(basic_istream<char>& __in, basic_string<char>& __str,
6479	char __delim);
6480
6481	#ifdef _GLIBCXX_USE_WCHAR_T
6482	template<>
6483	basic_istream<wchar_t>&
6484	getline(basic_istream<wchar_t>& __in, basic_string<wchar_t>& __str,
6485	wchar_t __delim);
6486	#endif
6487
6488	_GLIBCXX_END_NAMESPACE_VERSION
6489	} // namespace
6490
6491	#if __cplusplus >= 201103L
6492
6493	#include <ext/string_conversions.h>
6494
6495	namespace std _GLIBCXX_VISIBILITY(default)
6496	{
6497	_GLIBCXX_BEGIN_NAMESPACE_VERSION
6498	_GLIBCXX_BEGIN_NAMESPACE_CXX11
6499
6500	#if _GLIBCXX_USE_C99_STDLIB
6501	// 21.4 Numeric Conversions [string.conversions].
6502	inline int
6503	stoi(const string& __str, size_t* __idx = `0`, int __base = `10`)
6504	{ return __gnu_cxx::__stoa<long, int>(&std::strtol, "stoi", __str.c_str(),
6505	__idx, __base); }
6506
6507	inline long
6508	stol(const string& __str, size_t* __idx = `0`, int __base = `10`)
6509	{ return __gnu_cxx::__stoa(&std::strtol, "stol", __str.c_str(),
6510	__idx, __base); }
6511
6512	inline unsigned long
6513	stoul(const string& __str, size_t* __idx = `0`, int __base = `10`)
6514	{ return __gnu_cxx::__stoa(&std::strtoul, "stoul", __str.c_str(),
6515	__idx, __base); }
6516
6517	inline long long
6518	stoll(const string& __str, size_t* __idx = `0`, int __base = `10`)
6519	{ return __gnu_cxx::__stoa(&std::strtoll, "stoll", __str.c_str(),
6520	__idx, __base); }
6521
6522	inline unsigned long long
6523	stoull(const string& __str, size_t* __idx = `0`, int __base = `10`)
6524	{ return __gnu_cxx::__stoa(&std::strtoull, "stoull", __str.c_str(),
6525	__idx, __base); }
6526
6527	// NB: strtof vs strtod.
6528	inline float
6529	stof(const string& __str, size_t* __idx = `0`)
6530	{ return __gnu_cxx::__stoa(&std::strtof, "stof", __str.c_str(), __idx); }
6531
6532	inline double
6533	stod(const string& __str, size_t* __idx = `0`)
6534	{ return __gnu_cxx::__stoa(&std::strtod, "stod", __str.c_str(), __idx); }
6535
6536	inline long double
6537	stold(const string& __str, size_t* __idx = `0`)
6538	{ return __gnu_cxx::__stoa(&std::strtold, "stold", __str.c_str(), __idx); }
6539	#endif // _GLIBCXX_USE_C99_STDLIB
6540
6541	#if _GLIBCXX_USE_C99_STDIO
6542	// NB: (v)snprintf vs sprintf.
6543
6544	// DR 1261.
6545	inline string
6546	to_string(int __val)
6547	{ return __gnu_cxx::__to_xstring<string>(&std::vsnprintf, `4` * sizeof(int),
6548	"%d", __val); }
6549
6550	inline string
6551	to_string(unsigned __val)
6552	{ return __gnu_cxx::__to_xstring<string>(&std::vsnprintf,
6553	`4` * sizeof(unsigned),
6554	"%u", __val); }
6555
6556	inline string
6557	to_string(long __val)
6558	{ return __gnu_cxx::__to_xstring<string>(&std::vsnprintf, `4` * sizeof(long),
6559	"%ld", __val); }
6560
6561	inline string
6562	to_string(unsigned long __val)
6563	{ return __gnu_cxx::__to_xstring<string>(&std::vsnprintf,
6564	`4` * sizeof(unsigned long),
6565	"%lu", __val); }
6566
6567	inline string
6568	to_string(long long __val)
6569	{ return __gnu_cxx::__to_xstring<string>(&std::vsnprintf,
6570	`4` * sizeof(long long),
6571	"%lld", __val); }
6572
6573	inline string
6574	to_string(unsigned long long __val)
6575	{ return __gnu_cxx::__to_xstring<string>(&std::vsnprintf,
6576	`4` * sizeof(unsigned long long),
6577	"%llu", __val); }
6578
6579	inline string
6580	to_string(float __val)
6581	{
6582	const int __n =
6583	__gnu_cxx::__numeric_traits<float>::__max_exponent10 + `20`;
6584	return __gnu_cxx::__to_xstring<string>(&std::vsnprintf, __n,
6585	"%f", __val);
6586	}
6587
6588	inline string
6589	to_string(double __val)
6590	{
6591	const int __n =
6592	__gnu_cxx::__numeric_traits<double>::__max_exponent10 + `20`;
6593	return __gnu_cxx::__to_xstring<string>(&std::vsnprintf, __n,
6594	"%f", __val);
6595	}
6596
6597	inline string
6598	to_string(long double __val)
6599	{
6600	const int __n =
6601	__gnu_cxx::__numeric_traits<long double>::__max_exponent10 + `20`;
6602	return __gnu_cxx::__to_xstring<string>(&std::vsnprintf, __n,
6603	"%Lf", __val);
6604	}
6605	#endif // _GLIBCXX_USE_C99_STDIO
6606
6607	#if defined(_GLIBCXX_USE_WCHAR_T) && _GLIBCXX_USE_C99_WCHAR
6608	inline int
6609	stoi(const wstring& __str, size_t* __idx = `0`, int __base = `10`)
6610	{ return __gnu_cxx::__stoa<long, int>(&std::wcstol, "stoi", __str.c_str(),
6611	__idx, __base); }
6612
6613	inline long
6614	stol(const wstring& __str, size_t* __idx = `0`, int __base = `10`)
6615	{ return __gnu_cxx::__stoa(&std::wcstol, "stol", __str.c_str(),
6616	__idx, __base); }
6617
6618	inline unsigned long
6619	stoul(const wstring& __str, size_t* __idx = `0`, int __base = `10`)
6620	{ return __gnu_cxx::__stoa(&std::wcstoul, "stoul", __str.c_str(),
6621	__idx, __base); }
6622
6623	inline long long
6624	stoll(const wstring& __str, size_t* __idx = `0`, int __base = `10`)
6625	{ return __gnu_cxx::__stoa(&std::wcstoll, "stoll", __str.c_str(),
6626	__idx, __base); }
6627
6628	inline unsigned long long
6629	stoull(const wstring& __str, size_t* __idx = `0`, int __base = `10`)
6630	{ return __gnu_cxx::__stoa(&std::wcstoull, "stoull", __str.c_str(),
6631	__idx, __base); }
6632
6633	// NB: wcstof vs wcstod.
6634	inline float
6635	stof(const wstring& __str, size_t* __idx = `0`)
6636	{ return __gnu_cxx::__stoa(&std::wcstof, "stof", __str.c_str(), __idx); }
6637
6638	inline double
6639	stod(const wstring& __str, size_t* __idx = `0`)
6640	{ return __gnu_cxx::__stoa(&std::wcstod, "stod", __str.c_str(), __idx); }
6641
6642	inline long double
6643	stold(const wstring& __str, size_t* __idx = `0`)
6644	{ return __gnu_cxx::__stoa(&std::wcstold, "stold", __str.c_str(), __idx); }
6645
6646	#ifndef _GLIBCXX_HAVE_BROKEN_VSWPRINTF
6647	// DR 1261.
6648	inline wstring
6649	to_wstring(int __val)
6650	{ return __gnu_cxx::__to_xstring<wstring>(&std::vswprintf, `4` * sizeof(int),
6651	L"%d", __val); }
6652
6653	inline wstring
6654	to_wstring(unsigned __val)
6655	{ return __gnu_cxx::__to_xstring<wstring>(&std::vswprintf,
6656	`4` * sizeof(unsigned),
6657	L"%u", __val); }
6658
6659	inline wstring
6660	to_wstring(long __val)
6661	{ return __gnu_cxx::__to_xstring<wstring>(&std::vswprintf, `4` * sizeof(long),
6662	L"%ld", __val); }
6663
6664	inline wstring
6665	to_wstring(unsigned long __val)
6666	{ return __gnu_cxx::__to_xstring<wstring>(&std::vswprintf,
6667	`4` * sizeof(unsigned long),
6668	L"%lu", __val); }
6669
6670	inline wstring
6671	to_wstring(long long __val)
6672	{ return __gnu_cxx::__to_xstring<wstring>(&std::vswprintf,
6673	`4` * sizeof(long long),
6674	L"%lld", __val); }
6675
6676	inline wstring
6677	to_wstring(unsigned long long __val)
6678	{ return __gnu_cxx::__to_xstring<wstring>(&std::vswprintf,
6679	`4` * sizeof(unsigned long long),
6680	L"%llu", __val); }
6681
6682	inline wstring
6683	to_wstring(float __val)
6684	{
6685	const int __n =
6686	__gnu_cxx::__numeric_traits<float>::__max_exponent10 + `20`;
6687	return __gnu_cxx::__to_xstring<wstring>(&std::vswprintf, __n,
6688	L"%f", __val);
6689	}
6690
6691	inline wstring
6692	to_wstring(double __val)
6693	{
6694	const int __n =
6695	__gnu_cxx::__numeric_traits<double>::__max_exponent10 + `20`;
6696	return __gnu_cxx::__to_xstring<wstring>(&std::vswprintf, __n,
6697	L"%f", __val);
6698	}
6699
6700	inline wstring
6701	to_wstring(long double __val)
6702	{
6703	const int __n =
6704	__gnu_cxx::__numeric_traits<long double>::__max_exponent10 + `20`;
6705	return __gnu_cxx::__to_xstring<wstring>(&std::vswprintf, __n,
6706	L"%Lf", __val);
6707	}
6708	#endif // _GLIBCXX_HAVE_BROKEN_VSWPRINTF
6709	#endif // _GLIBCXX_USE_WCHAR_T && _GLIBCXX_USE_C99_WCHAR
6710
6711	_GLIBCXX_END_NAMESPACE_CXX11
6712	_GLIBCXX_END_NAMESPACE_VERSION
6713	} // namespace
6714
6715	#endif /* C++11 */
6716
6717	#if __cplusplus >= 201103L
6718
6719	#include <bits/functional_hash.h>
6720
6721	namespace std _GLIBCXX_VISIBILITY(default)
6722	{
6723	_GLIBCXX_BEGIN_NAMESPACE_VERSION
6724
6725	// DR 1182.
6726
6727	#ifndef _GLIBCXX_COMPATIBILITY_CXX0X
6728	/// std::hash specialization for string.
6729	template<>
6730	struct hash<string>
6731	: public __hash_base<size_t, string>
6732	{
6733	size_t
6734	operator()(const string& __s) const noexcept
6735	{ return std::_Hash_impl::hash(__s.data(), __s.length()); }
6736	};
6737
6738	template<>
6739	struct __is_fast_hash<hash<string>> : std::false_type
6740	{ };
6741
6742	#ifdef _GLIBCXX_USE_WCHAR_T
6743	/// std::hash specialization for wstring.
6744	template<>
6745	struct hash<wstring>
6746	: public __hash_base<size_t, wstring>
6747	{
6748	size_t
6749	operator()(const wstring& __s) const noexcept
6750	{ return std::_Hash_impl::hash(__s.data(),
6751	__s.length() * sizeof(wchar_t)); }
6752	};
6753
6754	template<>
6755	struct __is_fast_hash<hash<wstring>> : std::false_type
6756	{ };
6757	#endif
6758	#endif /* _GLIBCXX_COMPATIBILITY_CXX0X */
6759
6760	#ifdef _GLIBCXX_USE_CHAR8_T
6761	/// std::hash specialization for u8string.
6762	template<>
6763	struct hash<u8string>
6764	: public __hash_base<size_t, u8string>
6765	{
6766	size_t
6767	operator()(const u8string& __s) const noexcept
6768	{ return std::_Hash_impl::hash(__s.data(),
6769	__s.length() * sizeof(char8_t)); }
6770	};
6771
6772	template<>
6773	struct __is_fast_hash<hash<u8string>> : std::false_type
6774	{ };
6775	#endif
6776
6777	/// std::hash specialization for u16string.
6778	template<>
6779	struct hash<u16string>
6780	: public __hash_base<size_t, u16string>
6781	{
6782	size_t
6783	operator()(const u16string& __s) const noexcept
6784	{ return std::_Hash_impl::hash(__s.data(),
6785	__s.length() * sizeof(char16_t)); }
6786	};
6787
6788	template<>
6789	struct __is_fast_hash<hash<u16string>> : std::false_type
6790	{ };
6791
6792	/// std::hash specialization for u32string.
6793	template<>
6794	struct hash<u32string>
6795	: public __hash_base<size_t, u32string>
6796	{
6797	size_t
6798	operator()(const u32string& __s) const noexcept
6799	{ return std::_Hash_impl::hash(__s.data(),
6800	__s.length() * sizeof(char32_t)); }
6801	};
6802
6803	template<>
6804	struct __is_fast_hash<hash<u32string>> : std::false_type
6805	{ };
6806
6807	#if __cplusplus >= 201402L
6808
6809	#define __cpp_lib_string_udls 201304
6810
6811	inline namespace literals
6812	{
6813	inline namespace string_literals
6814	{
6815	#pragma GCC diagnostic push
6816	#pragma GCC diagnostic ignored "-Wliteral-suffix"
6817	_GLIBCXX_DEFAULT_ABI_TAG
6818	inline basic_string<char>
6819	operator""s(const char* __str, size_t __len)
6820	{ return basic_string<char>{__str, __len}; }
6821
6822	#ifdef _GLIBCXX_USE_WCHAR_T
6823	_GLIBCXX_DEFAULT_ABI_TAG
6824	inline basic_string<wchar_t>
6825	operator""s(const wchar_t* __str, size_t __len)
6826	{ return basic_string<wchar_t>{__str, __len}; }
6827	#endif
6828
6829	#ifdef _GLIBCXX_USE_CHAR8_T
6830	_GLIBCXX_DEFAULT_ABI_TAG
6831	inline basic_string<char8_t>
6832	operator""s(const char8_t* __str, size_t __len)
6833	{ return basic_string<char8_t>{__str, __len}; }
6834	#endif
6835
6836	_GLIBCXX_DEFAULT_ABI_TAG
6837	inline basic_string<char16_t>
6838	operator""s(const char16_t* __str, size_t __len)
6839	{ return basic_string<char16_t>{__str, __len}; }
6840
6841	_GLIBCXX_DEFAULT_ABI_TAG
6842	inline basic_string<char32_t>
6843	operator""s(const char32_t* __str, size_t __len)
6844	{ return basic_string<char32_t>{__str, __len}; }
6845
6846	#pragma GCC diagnostic pop
6847	} // inline namespace string_literals
6848	} // inline namespace literals
6849
6850	#if __cplusplus >= 201703L
6851	namespace __detail::__variant
6852	{
6853	template<typename> struct _Never_valueless_alt; // see <variant>
6854
6855	// Provide the strong exception-safety guarantee when emplacing a
6856	// basic_string into a variant, but only if moving the string cannot throw.
6857	template<typename _Tp, typename _Traits, typename _Alloc>
6858	struct _Never_valueless_alt<std::basic_string<_Tp, _Traits, _Alloc>>
6859	: __and_<
6860	is_nothrow_move_constructible<std::basic_string<_Tp, _Traits, _Alloc>>,
6861	is_nothrow_move_assignable<std::basic_string<_Tp, _Traits, _Alloc>>
6862	>::type
6863	{ };
6864	} // namespace __detail::__variant
6865	#endif // C++17
6866	#endif // C++14
6867
6868	_GLIBCXX_END_NAMESPACE_VERSION
6869	} // namespace std
6870
6871	#endif // C++11
6872
6873	#endif /* _BASIC_STRING_H */
6874

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