1/*
2 * Copyright 2011-present Facebook, Inc.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17// @author Mark Rabkin (mrabkin@fb.com)
18// @author Andrei Alexandrescu (andrei.alexandrescu@fb.com)
19
20#pragma once
21
22#include <folly/Portability.h>
23#include <folly/hash/SpookyHashV2.h>
24#include <folly/lang/Exception.h>
25#include <folly/portability/Constexpr.h>
26#include <folly/portability/String.h>
27
28#include <algorithm>
29#include <array>
30#include <cassert>
31#include <climits>
32#include <cstddef>
33#include <cstring>
34#include <iosfwd>
35#include <iterator>
36#include <stdexcept>
37#include <string>
38#include <type_traits>
39
40#if FOLLY_HAS_STRING_VIEW
41#include <string_view> // @manual
42#endif
43
44#include <folly/CpuId.h>
45#include <folly/Likely.h>
46#include <folly/Traits.h>
47#include <folly/detail/RangeCommon.h>
48#include <folly/detail/RangeSse42.h>
49
50// Ignore shadowing warnings within this file, so includers can use -Wshadow.
51FOLLY_PUSH_WARNING
52FOLLY_GNU_DISABLE_WARNING("-Wshadow")
53
54namespace folly {
55
56/**
57 * Ubiquitous helper template for knowing what's a string.
58 */
59template <class T>
60struct IsSomeString : std::false_type {};
61
62template <typename Alloc>
63struct IsSomeString<std::basic_string<char, std::char_traits<char>, Alloc>>
64 : std::true_type {};
65
66template <class Iter>
67class Range;
68
69/**
70 * Finds the first occurrence of needle in haystack. The algorithm is on
71 * average faster than O(haystack.size() * needle.size()) but not as fast
72 * as Boyer-Moore. On the upside, it does not do any upfront
73 * preprocessing and does not allocate memory.
74 */
75template <
76 class Iter,
77 class Comp = std::equal_to<typename Range<Iter>::value_type>>
78inline size_t
79qfind(const Range<Iter>& haystack, const Range<Iter>& needle, Comp eq = Comp());
80
81/**
82 * Finds the first occurrence of needle in haystack. The result is the
83 * offset reported to the beginning of haystack, or string::npos if
84 * needle wasn't found.
85 */
86template <class Iter>
87size_t qfind(
88 const Range<Iter>& haystack,
89 const typename Range<Iter>::value_type& needle);
90
91/**
92 * Finds the last occurrence of needle in haystack. The result is the
93 * offset reported to the beginning of haystack, or string::npos if
94 * needle wasn't found.
95 */
96template <class Iter>
97size_t rfind(
98 const Range<Iter>& haystack,
99 const typename Range<Iter>::value_type& needle);
100
101/**
102 * Finds the first occurrence of any element of needle in
103 * haystack. The algorithm is O(haystack.size() * needle.size()).
104 */
105template <class Iter>
106inline size_t qfind_first_of(
107 const Range<Iter>& haystack,
108 const Range<Iter>& needle);
109
110/**
111 * Small internal helper - returns the value just before an iterator.
112 */
113namespace detail {
114
115/**
116 * For random-access iterators, the value before is simply i[-1].
117 */
118template <class Iter>
119typename std::enable_if<
120 std::is_same<
121 typename std::iterator_traits<Iter>::iterator_category,
122 std::random_access_iterator_tag>::value,
123 typename std::iterator_traits<Iter>::reference>::type
124value_before(Iter i) {
125 return i[-1];
126}
127
128/**
129 * For all other iterators, we need to use the decrement operator.
130 */
131template <class Iter>
132typename std::enable_if<
133 !std::is_same<
134 typename std::iterator_traits<Iter>::iterator_category,
135 std::random_access_iterator_tag>::value,
136 typename std::iterator_traits<Iter>::reference>::type
137value_before(Iter i) {
138 return *--i;
139}
140
141/*
142 * Use IsCharPointer<T>::type to enable const char* or char*.
143 * Use IsCharPointer<T>::const_type to enable only const char*.
144 */
145template <class T>
146struct IsCharPointer {};
147
148template <>
149struct IsCharPointer<char*> {
150 typedef int type;
151};
152
153template <>
154struct IsCharPointer<const char*> {
155 typedef int const_type;
156 typedef int type;
157};
158
159} // namespace detail
160
161/**
162 * Range abstraction keeping a pair of iterators. We couldn't use
163 * boost's similar range abstraction because we need an API identical
164 * with the former StringPiece class, which is used by a lot of other
165 * code. This abstraction does fulfill the needs of boost's
166 * range-oriented algorithms though.
167 *
168 * (Keep memory lifetime in mind when using this class, since it
169 * doesn't manage the data it refers to - just like an iterator
170 * wouldn't.)
171 */
172template <class Iter>
173class Range {
174 private:
175 template <typename Alloc>
176 using string = std::basic_string<char, std::char_traits<char>, Alloc>;
177
178 public:
179 typedef std::size_t size_type;
180 typedef Iter iterator;
181 typedef Iter const_iterator;
182 typedef typename std::remove_reference<
183 typename std::iterator_traits<Iter>::reference>::type value_type;
184 using difference_type = typename std::iterator_traits<Iter>::difference_type;
185 typedef typename std::iterator_traits<Iter>::reference reference;
186
187 /**
188 * For MutableStringPiece and MutableByteRange we define StringPiece
189 * and ByteRange as const_range_type (for everything else its just
190 * identity). We do that to enable operations such as find with
191 * args which are const.
192 */
193 typedef typename std::conditional<
194 std::is_same<Iter, char*>::value ||
195 std::is_same<Iter, unsigned char*>::value,
196 Range<const value_type*>,
197 Range<Iter>>::type const_range_type;
198
199 typedef std::char_traits<typename std::remove_const<value_type>::type>
200 traits_type;
201
202 static const size_type npos;
203
204 // Works for all iterators
205 constexpr Range() : b_(), e_() {}
206
207 constexpr Range(const Range&) = default;
208 constexpr Range(Range&&) = default;
209
210 public:
211 // Works for all iterators
212 constexpr Range(Iter start, Iter end) : b_(start), e_(end) {}
213
214 // Works only for random-access iterators
215 constexpr Range(Iter start, size_t size) : b_(start), e_(start + size) {}
216
217#if !__clang__ || __CLANG_PREREQ(3, 7) // Clang 3.6 crashes on this line
218 /* implicit */ Range(std::nullptr_t) = delete;
219#endif
220
221 constexpr /* implicit */ Range(Iter str)
222 : b_(str), e_(str + constexpr_strlen(str)) {
223 static_assert(
224 std::is_same<int, typename detail::IsCharPointer<Iter>::type>::value,
225 "This constructor is only available for character ranges");
226 }
227
228 template <
229 class Alloc,
230 class T = Iter,
231 typename detail::IsCharPointer<T>::const_type = 0>
232 /* implicit */ Range(const string<Alloc>& str)
233 : b_(str.data()), e_(b_ + str.size()) {}
234
235 template <
236 class Alloc,
237 class T = Iter,
238 typename detail::IsCharPointer<T>::const_type = 0>
239 Range(const string<Alloc>& str, typename string<Alloc>::size_type startFrom) {
240 if (UNLIKELY(startFrom > str.size())) {
241 throw_exception<std::out_of_range>("index out of range");
242 }
243 b_ = str.data() + startFrom;
244 e_ = str.data() + str.size();
245 }
246
247 template <
248 class Alloc,
249 class T = Iter,
250 typename detail::IsCharPointer<T>::const_type = 0>
251 Range(
252 const string<Alloc>& str,
253 typename string<Alloc>::size_type startFrom,
254 typename string<Alloc>::size_type size) {
255 if (UNLIKELY(startFrom > str.size())) {
256 throw_exception<std::out_of_range>("index out of range");
257 }
258 b_ = str.data() + startFrom;
259 if (str.size() - startFrom < size) {
260 e_ = str.data() + str.size();
261 } else {
262 e_ = b_ + size;
263 }
264 }
265
266 Range(const Range& other, size_type first, size_type length = npos)
267 : Range(other.subpiece(first, length)) {}
268
269 template <
270 class Container,
271 class = typename std::enable_if<
272 std::is_same<Iter, typename Container::const_pointer>::value>::type,
273 class = decltype(
274 Iter(std::declval<Container const&>().data()),
275 Iter(
276 std::declval<Container const&>().data() +
277 std::declval<Container const&>().size()))>
278 /* implicit */ constexpr Range(Container const& container)
279 : b_(container.data()), e_(b_ + container.size()) {}
280
281 template <
282 class Container,
283 class = typename std::enable_if<
284 std::is_same<Iter, typename Container::const_pointer>::value>::type,
285 class = decltype(
286 Iter(std::declval<Container const&>().data()),
287 Iter(
288 std::declval<Container const&>().data() +
289 std::declval<Container const&>().size()))>
290 Range(Container const& container, typename Container::size_type startFrom) {
291 auto const cdata = container.data();
292 auto const csize = container.size();
293 if (UNLIKELY(startFrom > csize)) {
294 throw_exception<std::out_of_range>("index out of range");
295 }
296 b_ = cdata + startFrom;
297 e_ = cdata + csize;
298 }
299
300 template <
301 class Container,
302 class = typename std::enable_if<
303 std::is_same<Iter, typename Container::const_pointer>::value>::type,
304 class = decltype(
305 Iter(std::declval<Container const&>().data()),
306 Iter(
307 std::declval<Container const&>().data() +
308 std::declval<Container const&>().size()))>
309 Range(
310 Container const& container,
311 typename Container::size_type startFrom,
312 typename Container::size_type size) {
313 auto const cdata = container.data();
314 auto const csize = container.size();
315 if (UNLIKELY(startFrom > csize)) {
316 throw_exception<std::out_of_range>("index out of range");
317 }
318 b_ = cdata + startFrom;
319 if (csize - startFrom < size) {
320 e_ = cdata + csize;
321 } else {
322 e_ = b_ + size;
323 }
324 }
325
326 // Allow implicit conversion from Range<const char*> (aka StringPiece) to
327 // Range<const unsigned char*> (aka ByteRange), as they're both frequently
328 // used to represent ranges of bytes. Allow explicit conversion in the other
329 // direction.
330 template <
331 class OtherIter,
332 typename std::enable_if<
333 (std::is_same<Iter, const unsigned char*>::value &&
334 (std::is_same<OtherIter, const char*>::value ||
335 std::is_same<OtherIter, char*>::value)),
336 int>::type = 0>
337 /* implicit */ Range(const Range<OtherIter>& other)
338 : b_(reinterpret_cast<const unsigned char*>(other.begin())),
339 e_(reinterpret_cast<const unsigned char*>(other.end())) {}
340
341 template <
342 class OtherIter,
343 typename std::enable_if<
344 (std::is_same<Iter, unsigned char*>::value &&
345 std::is_same<OtherIter, char*>::value),
346 int>::type = 0>
347 /* implicit */ Range(const Range<OtherIter>& other)
348 : b_(reinterpret_cast<unsigned char*>(other.begin())),
349 e_(reinterpret_cast<unsigned char*>(other.end())) {}
350
351 template <
352 class OtherIter,
353 typename std::enable_if<
354 (std::is_same<Iter, const char*>::value &&
355 (std::is_same<OtherIter, const unsigned char*>::value ||
356 std::is_same<OtherIter, unsigned char*>::value)),
357 int>::type = 0>
358 explicit Range(const Range<OtherIter>& other)
359 : b_(reinterpret_cast<const char*>(other.begin())),
360 e_(reinterpret_cast<const char*>(other.end())) {}
361
362 template <
363 class OtherIter,
364 typename std::enable_if<
365 (std::is_same<Iter, char*>::value &&
366 std::is_same<OtherIter, unsigned char*>::value),
367 int>::type = 0>
368 explicit Range(const Range<OtherIter>& other)
369 : b_(reinterpret_cast<char*>(other.begin())),
370 e_(reinterpret_cast<char*>(other.end())) {}
371
372 // Allow implicit conversion from Range<From> to Range<To> if From is
373 // implicitly convertible to To.
374 template <
375 class OtherIter,
376 typename std::enable_if<
377 (!std::is_same<Iter, OtherIter>::value &&
378 std::is_convertible<OtherIter, Iter>::value),
379 int>::type = 0>
380 constexpr /* implicit */ Range(const Range<OtherIter>& other)
381 : b_(other.begin()), e_(other.end()) {}
382
383 // Allow explicit conversion from Range<From> to Range<To> if From is
384 // explicitly convertible to To.
385 template <
386 class OtherIter,
387 typename std::enable_if<
388 (!std::is_same<Iter, OtherIter>::value &&
389 !std::is_convertible<OtherIter, Iter>::value &&
390 std::is_constructible<Iter, const OtherIter&>::value),
391 int>::type = 0>
392 constexpr explicit Range(const Range<OtherIter>& other)
393 : b_(other.begin()), e_(other.end()) {}
394
395 /**
396 * Allow explicit construction of Range() from a std::array of a
397 * convertible type.
398 *
399 * For instance, this allows constructing StringPiece from a
400 * std::array<char, N> or a std::array<const char, N>
401 */
402 template <
403 class T,
404 size_t N,
405 typename = typename std::enable_if<
406 std::is_convertible<const T*, Iter>::value>::type>
407 constexpr explicit Range(const std::array<T, N>& array)
408 : b_{array.empty() ? nullptr : &array.at(0)},
409 e_{array.empty() ? nullptr : &array.at(0) + N} {}
410 template <
411 class T,
412 size_t N,
413 typename =
414 typename std::enable_if<std::is_convertible<T*, Iter>::value>::type>
415 constexpr explicit Range(std::array<T, N>& array)
416 : b_{array.empty() ? nullptr : &array.at(0)},
417 e_{array.empty() ? nullptr : &array.at(0) + N} {}
418
419 Range& operator=(const Range& rhs) & = default;
420 Range& operator=(Range&& rhs) & = default;
421
422 template <
423 class Alloc,
424 class T = Iter,
425 typename detail::IsCharPointer<T>::const_type = 0>
426 Range& operator=(string<Alloc>&& rhs) = delete;
427
428 void clear() {
429 b_ = Iter();
430 e_ = Iter();
431 }
432
433 void assign(Iter start, Iter end) {
434 b_ = start;
435 e_ = end;
436 }
437
438 void reset(Iter start, size_type size) {
439 b_ = start;
440 e_ = start + size;
441 }
442
443 // Works only for Range<const char*>
444 template <typename Alloc>
445 void reset(const string<Alloc>& str) {
446 reset(str.data(), str.size());
447 }
448
449 constexpr size_type size() const {
450 // It would be nice to assert(b_ <= e_) here. This can be achieved even
451 // in a C++11 compatible constexpr function:
452 // http://ericniebler.com/2014/09/27/assert-and-constexpr-in-cxx11/
453 // Unfortunately current gcc versions have a bug causing it to reject
454 // this check in a constexpr function:
455 // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71448
456 return size_type(e_ - b_);
457 }
458 constexpr size_type walk_size() const {
459 return size_type(std::distance(b_, e_));
460 }
461 constexpr bool empty() const {
462 return b_ == e_;
463 }
464 constexpr Iter data() const {
465 return b_;
466 }
467 constexpr Iter start() const {
468 return b_;
469 }
470 constexpr Iter begin() const {
471 return b_;
472 }
473 constexpr Iter end() const {
474 return e_;
475 }
476 constexpr Iter cbegin() const {
477 return b_;
478 }
479 constexpr Iter cend() const {
480 return e_;
481 }
482 value_type& front() {
483 assert(b_ < e_);
484 return *b_;
485 }
486 value_type& back() {
487 assert(b_ < e_);
488 return detail::value_before(e_);
489 }
490 const value_type& front() const {
491 assert(b_ < e_);
492 return *b_;
493 }
494 const value_type& back() const {
495 assert(b_ < e_);
496 return detail::value_before(e_);
497 }
498
499 private:
500 // It would be nice to be able to implicit convert to any target type
501 // T for which either an (Iter, Iter) or (Iter, size_type) noexcept
502 // constructor was available, and explicitly convert to any target
503 // type for which those signatures were available but not noexcept.
504 // The problem is that this creates ambiguity when there is also a
505 // T constructor that takes a type U that is implicitly convertible
506 // from Range.
507 //
508 // To avoid ambiguity, we need to avoid having explicit operator T
509 // and implicit operator U coexist when T is constructible from U.
510 // U cannot be deduced when searching for operator T (and C++ won't
511 // perform an existential search for it), so we must limit the implicit
512 // target types to a finite set that we can enumerate.
513 //
514 // At the moment the set of implicit target types consists of just
515 // std::string_view (when it is available).
516#if FOLLY_HAS_STRING_VIEW
517 struct NotStringView {};
518 template <typename ValueType>
519 struct StringViewType
520 : std::conditional<
521 std::is_pod<std::remove_const_t<ValueType>>::value,
522 std::basic_string_view<std::remove_const_t<ValueType>>,
523 NotStringView> {};
524
525 template <typename Target>
526 struct IsConstructibleViaStringView
527 : Conjunction<
528 std::is_constructible<
529 _t<StringViewType<value_type>>,
530 Iter const&,
531 size_type>,
532 std::is_constructible<Target, _t<StringViewType<value_type>>>> {};
533#else
534 template <typename Target>
535 using IsConstructibleViaStringView = std::false_type;
536#endif
537
538 public:
539 /// explicit operator conversion to any compatible type
540 ///
541 /// A compatible type is one which is constructible with an iterator and a
542 /// size (preferred), or a pair of iterators (fallback), passed by const-ref.
543 ///
544 /// Participates in overload resolution precisely when the target type is
545 /// compatible. This allows std::is_constructible compile-time checks to work.
546 template <
547 typename Tgt,
548 std::enable_if_t<
549 std::is_constructible<Tgt, Iter const&, size_type>::value &&
550 !IsConstructibleViaStringView<Tgt>::value,
551 int> = 0>
552 constexpr explicit operator Tgt() const noexcept(
553 std::is_nothrow_constructible<Tgt, Iter const&, size_type>::value) {
554 return Tgt(b_, walk_size());
555 }
556 template <
557 typename Tgt,
558 std::enable_if_t<
559 !std::is_constructible<Tgt, Iter const&, size_type>::value &&
560 std::is_constructible<Tgt, Iter const&, Iter const&>::value &&
561 !IsConstructibleViaStringView<Tgt>::value,
562 int> = 0>
563 constexpr explicit operator Tgt() const noexcept(
564 std::is_nothrow_constructible<Tgt, Iter const&, Iter const&>::value) {
565 return Tgt(b_, e_);
566 }
567
568#if FOLLY_HAS_STRING_VIEW
569 /// implicit operator conversion to std::string_view
570 template <
571 typename Tgt,
572 typename ValueType = value_type,
573 std::enable_if_t<
574 StrictConjunction<
575 std::is_same<Tgt, _t<StringViewType<ValueType>>>,
576 std::is_constructible<
577 _t<StringViewType<ValueType>>,
578 Iter const&,
579 size_type>>::value,
580 int> = 0>
581 constexpr operator Tgt() const noexcept(
582 std::is_nothrow_constructible<Tgt, Iter const&, size_type>::value) {
583 return Tgt(b_, walk_size());
584 }
585#endif
586
587 /// explicit non-operator conversion to any compatible type
588 ///
589 /// A compatible type is one which is constructible with an iterator and a
590 /// size (preferred), or a pair of iterators (fallback), passed by const-ref.
591 ///
592 /// Participates in overload resolution precisely when the target type is
593 /// compatible. This allows is_invocable compile-time checks to work.
594 ///
595 /// Provided in addition to the explicit operator conversion to permit passing
596 /// additional arguments to the target type constructor. A canonical example
597 /// of an additional argument might be an allocator, where the target type is
598 /// some specialization of std::vector or std::basic_string in a context which
599 /// requires a non-default-constructed allocator.
600 template <typename Tgt, typename... Args>
601 constexpr std::enable_if_t<
602 std::is_constructible<Tgt, Iter const&, size_type>::value,
603 Tgt>
604 to(Args&&... args) const noexcept(
605 std::is_nothrow_constructible<Tgt, Iter const&, size_type, Args&&...>::
606 value) {
607 return Tgt(b_, walk_size(), static_cast<Args&&>(args)...);
608 }
609 template <typename Tgt, typename... Args>
610 constexpr std::enable_if_t<
611 !std::is_constructible<Tgt, Iter const&, size_type>::value &&
612 std::is_constructible<Tgt, Iter const&, Iter const&>::value,
613 Tgt>
614 to(Args&&... args) const noexcept(
615 std::is_nothrow_constructible<Tgt, Iter const&, Iter const&, Args&&...>::
616 value) {
617 return Tgt(b_, e_, static_cast<Args&&>(args)...);
618 }
619
620 // Works only for Range<const char*> and Range<char*>
621 std::string str() const {
622 return to<std::string>();
623 }
624 std::string toString() const {
625 return to<std::string>();
626 }
627
628 const_range_type castToConst() const {
629 return const_range_type(*this);
630 }
631
632 int compare(const const_range_type& o) const {
633 const size_type tsize = this->size();
634 const size_type osize = o.size();
635 const size_type msize = std::min(tsize, osize);
636 int r = traits_type::compare(data(), o.data(), msize);
637 if (r == 0 && tsize != osize) {
638 // We check the signed bit of the subtraction and bit shift it
639 // to produce either 0 or 2. The subtraction yields the
640 // comparison values of either -1 or 1.
641 r = (static_cast<int>((osize - tsize) >> (CHAR_BIT * sizeof(size_t) - 1))
642 << 1) -
643 1;
644 }
645 return r;
646 }
647
648 value_type& operator[](size_t i) {
649 assert(i < size());
650 return b_[i];
651 }
652
653 const value_type& operator[](size_t i) const {
654 assert(i < size());
655 return b_[i];
656 }
657
658 value_type& at(size_t i) {
659 if (i >= size()) {
660 throw_exception<std::out_of_range>("index out of range");
661 }
662 return b_[i];
663 }
664
665 const value_type& at(size_t i) const {
666 if (i >= size()) {
667 throw_exception<std::out_of_range>("index out of range");
668 }
669 return b_[i];
670 }
671
672 // Do NOT use this function, which was left behind for backwards
673 // compatibility. Use SpookyHashV2 instead -- it is faster, and produces
674 // a 64-bit hash, which means dramatically fewer collisions in large maps.
675 // (The above advice does not apply if you are targeting a 32-bit system.)
676 //
677 // Works only for Range<const char*> and Range<char*>
678 //
679 //
680 // ** WANT TO GET RID OF THIS LINT? **
681 //
682 // A) Use a better hash function (*cough*folly::Hash*cough*), but
683 // only if you don't serialize data in a format that depends on
684 // this formula (ie the writer and reader assume this exact hash
685 // function is used).
686 //
687 // B) If you have to use this exact function then make your own hasher
688 // object and copy the body over (see thrift example: D3972362).
689 // https://github.com/facebook/fbthrift/commit/f8ed502e24ab4a32a9d5f266580
690 [[deprecated(
691 "Replace with folly::Hash if the hash is not serialized")]] uint32_t
692 hash() const {
693 // Taken from fbi/nstring.h:
694 // Quick and dirty bernstein hash...fine for short ascii strings
695 uint32_t hash = 5381;
696 for (size_t ix = 0; ix < size(); ix++) {
697 hash = ((hash << 5) + hash) + b_[ix];
698 }
699 return hash;
700 }
701
702 void advance(size_type n) {
703 if (UNLIKELY(n > size())) {
704 throw_exception<std::out_of_range>("index out of range");
705 }
706 b_ += n;
707 }
708
709 void subtract(size_type n) {
710 if (UNLIKELY(n > size())) {
711 throw_exception<std::out_of_range>("index out of range");
712 }
713 e_ -= n;
714 }
715
716 Range subpiece(size_type first, size_type length = npos) const {
717 if (UNLIKELY(first > size())) {
718 throw_exception<std::out_of_range>("index out of range");
719 }
720
721 return Range(b_ + first, std::min(length, size() - first));
722 }
723
724 // unchecked versions
725 void uncheckedAdvance(size_type n) {
726 assert(n <= size());
727 b_ += n;
728 }
729
730 void uncheckedSubtract(size_type n) {
731 assert(n <= size());
732 e_ -= n;
733 }
734
735 Range uncheckedSubpiece(size_type first, size_type length = npos) const {
736 assert(first <= size());
737 return Range(b_ + first, std::min(length, size() - first));
738 }
739
740 void pop_front() {
741 assert(b_ < e_);
742 ++b_;
743 }
744
745 void pop_back() {
746 assert(b_ < e_);
747 --e_;
748 }
749
750 // string work-alike functions
751 size_type find(const_range_type str) const {
752 return qfind(castToConst(), str);
753 }
754
755 size_type find(const_range_type str, size_t pos) const {
756 if (pos > size()) {
757 return std::string::npos;
758 }
759 size_t ret = qfind(castToConst().subpiece(pos), str);
760 return ret == npos ? ret : ret + pos;
761 }
762
763 size_type find(Iter s, size_t pos, size_t n) const {
764 if (pos > size()) {
765 return std::string::npos;
766 }
767 auto forFinding = castToConst();
768 size_t ret = qfind(
769 pos ? forFinding.subpiece(pos) : forFinding, const_range_type(s, n));
770 return ret == npos ? ret : ret + pos;
771 }
772
773 // Works only for Range<(const) (unsigned) char*> which have Range(Iter) ctor
774 size_type find(const Iter s) const {
775 return qfind(castToConst(), const_range_type(s));
776 }
777
778 // Works only for Range<(const) (unsigned) char*> which have Range(Iter) ctor
779 size_type find(const Iter s, size_t pos) const {
780 if (pos > size()) {
781 return std::string::npos;
782 }
783 size_type ret = qfind(castToConst().subpiece(pos), const_range_type(s));
784 return ret == npos ? ret : ret + pos;
785 }
786
787 size_type find(value_type c) const {
788 return qfind(castToConst(), c);
789 }
790
791 size_type rfind(value_type c) const {
792 return folly::rfind(castToConst(), c);
793 }
794
795 size_type find(value_type c, size_t pos) const {
796 if (pos > size()) {
797 return std::string::npos;
798 }
799 size_type ret = qfind(castToConst().subpiece(pos), c);
800 return ret == npos ? ret : ret + pos;
801 }
802
803 size_type find_first_of(const_range_type needles) const {
804 return qfind_first_of(castToConst(), needles);
805 }
806
807 size_type find_first_of(const_range_type needles, size_t pos) const {
808 if (pos > size()) {
809 return std::string::npos;
810 }
811 size_type ret = qfind_first_of(castToConst().subpiece(pos), needles);
812 return ret == npos ? ret : ret + pos;
813 }
814
815 // Works only for Range<(const) (unsigned) char*> which have Range(Iter) ctor
816 size_type find_first_of(Iter needles) const {
817 return find_first_of(const_range_type(needles));
818 }
819
820 // Works only for Range<(const) (unsigned) char*> which have Range(Iter) ctor
821 size_type find_first_of(Iter needles, size_t pos) const {
822 return find_first_of(const_range_type(needles), pos);
823 }
824
825 size_type find_first_of(Iter needles, size_t pos, size_t n) const {
826 return find_first_of(const_range_type(needles, n), pos);
827 }
828
829 size_type find_first_of(value_type c) const {
830 return find(c);
831 }
832
833 size_type find_first_of(value_type c, size_t pos) const {
834 return find(c, pos);
835 }
836
837 /**
838 * Determine whether the range contains the given subrange or item.
839 *
840 * Note: Call find() directly if the index is needed.
841 */
842 bool contains(const const_range_type& other) const {
843 return find(other) != std::string::npos;
844 }
845
846 bool contains(const value_type& other) const {
847 return find(other) != std::string::npos;
848 }
849
850 void swap(Range& rhs) {
851 std::swap(b_, rhs.b_);
852 std::swap(e_, rhs.e_);
853 }
854
855 /**
856 * Does this Range start with another range?
857 */
858 bool startsWith(const const_range_type& other) const {
859 return size() >= other.size() &&
860 castToConst().subpiece(0, other.size()) == other;
861 }
862 bool startsWith(value_type c) const {
863 return !empty() && front() == c;
864 }
865
866 template <class Comp>
867 bool startsWith(const const_range_type& other, Comp&& eq) const {
868 if (size() < other.size()) {
869 return false;
870 }
871 auto const trunc = subpiece(0, other.size());
872 return std::equal(
873 trunc.begin(), trunc.end(), other.begin(), std::forward<Comp>(eq));
874 }
875
876 /**
877 * Does this Range end with another range?
878 */
879 bool endsWith(const const_range_type& other) const {
880 return size() >= other.size() &&
881 castToConst().subpiece(size() - other.size()) == other;
882 }
883 bool endsWith(value_type c) const {
884 return !empty() && back() == c;
885 }
886
887 template <class Comp>
888 bool endsWith(const const_range_type& other, Comp&& eq) const {
889 if (size() < other.size()) {
890 return false;
891 }
892 auto const trunc = subpiece(size() - other.size());
893 return std::equal(
894 trunc.begin(), trunc.end(), other.begin(), std::forward<Comp>(eq));
895 }
896
897 template <class Comp>
898 bool equals(const const_range_type& other, Comp&& eq) const {
899 return size() == other.size() &&
900 std::equal(begin(), end(), other.begin(), std::forward<Comp>(eq));
901 }
902
903 /**
904 * Remove the items in [b, e), as long as this subrange is at the beginning
905 * or end of the Range.
906 *
907 * Required for boost::algorithm::trim()
908 */
909 void erase(Iter b, Iter e) {
910 if (b == b_) {
911 b_ = e;
912 } else if (e == e_) {
913 e_ = b;
914 } else {
915 throw_exception<std::out_of_range>("index out of range");
916 }
917 }
918
919 /**
920 * Remove the given prefix and return true if the range starts with the given
921 * prefix; return false otherwise.
922 */
923 bool removePrefix(const const_range_type& prefix) {
924 return startsWith(prefix) && (b_ += prefix.size(), true);
925 }
926 bool removePrefix(value_type prefix) {
927 return startsWith(prefix) && (++b_, true);
928 }
929
930 /**
931 * Remove the given suffix and return true if the range ends with the given
932 * suffix; return false otherwise.
933 */
934 bool removeSuffix(const const_range_type& suffix) {
935 return endsWith(suffix) && (e_ -= suffix.size(), true);
936 }
937 bool removeSuffix(value_type suffix) {
938 return endsWith(suffix) && (--e_, true);
939 }
940
941 /**
942 * Replaces the content of the range, starting at position 'pos', with
943 * contents of 'replacement'. Entire 'replacement' must fit into the
944 * range. Returns false if 'replacements' does not fit. Example use:
945 *
946 * char in[] = "buffer";
947 * auto msp = MutablesStringPiece(input);
948 * EXPECT_TRUE(msp.replaceAt(2, "tt"));
949 * EXPECT_EQ(msp, "butter");
950 *
951 * // not enough space
952 * EXPECT_FALSE(msp.replace(msp.size() - 1, "rr"));
953 * EXPECT_EQ(msp, "butter"); // unchanged
954 */
955 bool replaceAt(size_t pos, const_range_type replacement) {
956 if (size() < pos + replacement.size()) {
957 return false;
958 }
959
960 std::copy(replacement.begin(), replacement.end(), begin() + pos);
961
962 return true;
963 }
964
965 /**
966 * Replaces all occurences of 'source' with 'dest'. Returns number
967 * of replacements made. Source and dest have to have the same
968 * length. Throws if the lengths are different. If 'source' is a
969 * pattern that is overlapping with itself, we perform sequential
970 * replacement: "aaaaaaa".replaceAll("aa", "ba") --> "bababaa"
971 *
972 * Example use:
973 *
974 * char in[] = "buffer";
975 * auto msp = MutablesStringPiece(input);
976 * EXPECT_EQ(msp.replaceAll("ff","tt"), 1);
977 * EXPECT_EQ(msp, "butter");
978 */
979 size_t replaceAll(const_range_type source, const_range_type dest) {
980 if (source.size() != dest.size()) {
981 throw_exception<std::invalid_argument>(
982 "replacement must have the same size as source");
983 }
984
985 if (dest.empty()) {
986 return 0;
987 }
988
989 size_t pos = 0;
990 size_t num_replaced = 0;
991 size_type found = std::string::npos;
992 while ((found = find(source, pos)) != std::string::npos) {
993 replaceAt(found, dest);
994 pos += source.size();
995 ++num_replaced;
996 }
997
998 return num_replaced;
999 }
1000
1001 /**
1002 * Splits this `Range` `[b, e)` in the position `i` dictated by the next
1003 * occurence of `delimiter`.
1004 *
1005 * Returns a new `Range` `[b, i)` and adjusts this range to start right after
1006 * the delimiter's position. This range will be empty if the delimiter is not
1007 * found. If called on an empty `Range`, both this and the returned `Range`
1008 * will be empty.
1009 *
1010 * Example:
1011 *
1012 * folly::StringPiece s("sample string for split_next");
1013 * auto p = s.split_step(' ');
1014 *
1015 * // prints "string for split_next"
1016 * cout << s << endl;
1017 *
1018 * // prints "sample"
1019 * cout << p << endl;
1020 *
1021 * Example 2:
1022 *
1023 * void tokenize(StringPiece s, char delimiter) {
1024 * while (!s.empty()) {
1025 * cout << s.split_step(delimiter);
1026 * }
1027 * }
1028 *
1029 * @author: Marcelo Juchem <marcelo@fb.com>
1030 */
1031 Range split_step(value_type delimiter) {
1032 auto i = std::find(b_, e_, delimiter);
1033 Range result(b_, i);
1034
1035 b_ = i == e_ ? e_ : std::next(i);
1036
1037 return result;
1038 }
1039
1040 Range split_step(Range delimiter) {
1041 auto i = find(delimiter);
1042 Range result(b_, i == std::string::npos ? size() : i);
1043
1044 b_ = result.end() == e_
1045 ? e_
1046 : std::next(
1047 result.end(),
1048 typename std::iterator_traits<Iter>::difference_type(
1049 delimiter.size()));
1050
1051 return result;
1052 }
1053
1054 /**
1055 * Convenience method that calls `split_step()` and passes the result to a
1056 * functor, returning whatever the functor does. Any additional arguments
1057 * `args` passed to this function are perfectly forwarded to the functor.
1058 *
1059 * Say you have a functor with this signature:
1060 *
1061 * Foo fn(Range r) { }
1062 *
1063 * `split_step()`'s return type will be `Foo`. It works just like:
1064 *
1065 * auto result = fn(myRange.split_step(' '));
1066 *
1067 * A functor returning `void` is also supported.
1068 *
1069 * Example:
1070 *
1071 * void do_some_parsing(folly::StringPiece s) {
1072 * auto version = s.split_step(' ', [&](folly::StringPiece x) {
1073 * if (x.empty()) {
1074 * throw std::invalid_argument("empty string");
1075 * }
1076 * return std::strtoull(x.begin(), x.end(), 16);
1077 * });
1078 *
1079 * // ...
1080 * }
1081 *
1082 * struct Foo {
1083 * void parse(folly::StringPiece s) {
1084 * s.split_step(' ', parse_field, bar, 10);
1085 * s.split_step('\t', parse_field, baz, 20);
1086 *
1087 * auto const kludge = [](folly::StringPiece x, int &out, int def) {
1088 * if (x == "null") {
1089 * out = 0;
1090 * } else {
1091 * parse_field(x, out, def);
1092 * }
1093 * };
1094 *
1095 * s.split_step('\t', kludge, gaz);
1096 * s.split_step(' ', kludge, foo);
1097 * }
1098 *
1099 * private:
1100 * int bar;
1101 * int baz;
1102 * int gaz;
1103 * int foo;
1104 *
1105 * static parse_field(folly::StringPiece s, int &out, int def) {
1106 * try {
1107 * out = folly::to<int>(s);
1108 * } catch (std::exception const &) {
1109 * value = def;
1110 * }
1111 * }
1112 * };
1113 *
1114 * @author: Marcelo Juchem <marcelo@fb.com>
1115 */
1116 template <typename TProcess, typename... Args>
1117 auto split_step(value_type delimiter, TProcess&& process, Args&&... args)
1118 -> decltype(process(std::declval<Range>(), std::forward<Args>(args)...)) {
1119 return process(split_step(delimiter), std::forward<Args>(args)...);
1120 }
1121
1122 template <typename TProcess, typename... Args>
1123 auto split_step(Range delimiter, TProcess&& process, Args&&... args)
1124 -> decltype(process(std::declval<Range>(), std::forward<Args>(args)...)) {
1125 return process(split_step(delimiter), std::forward<Args>(args)...);
1126 }
1127
1128 private:
1129 Iter b_, e_;
1130};
1131
1132template <class Iter>
1133const typename Range<Iter>::size_type Range<Iter>::npos = std::string::npos;
1134
1135template <class Iter>
1136void swap(Range<Iter>& lhs, Range<Iter>& rhs) {
1137 lhs.swap(rhs);
1138}
1139
1140/**
1141 * Create a range from two iterators, with type deduction.
1142 */
1143template <class Iter>
1144constexpr Range<Iter> range(Iter first, Iter last) {
1145 return Range<Iter>(first, last);
1146}
1147
1148/*
1149 * Creates a range to reference the contents of a contiguous-storage container.
1150 */
1151// Use pointers for types with '.data()' member
1152template <class Collection>
1153constexpr auto range(Collection& v) -> Range<decltype(v.data())> {
1154 return Range<decltype(v.data())>(v.data(), v.data() + v.size());
1155}
1156template <class Collection>
1157constexpr auto range(Collection const& v) -> Range<decltype(v.data())> {
1158 return Range<decltype(v.data())>(v.data(), v.data() + v.size());
1159}
1160template <class Collection>
1161constexpr auto crange(Collection const& v) -> Range<decltype(v.data())> {
1162 return Range<decltype(v.data())>(v.data(), v.data() + v.size());
1163}
1164
1165template <class T, size_t n>
1166constexpr Range<T*> range(T (&array)[n]) {
1167 return Range<T*>(array, array + n);
1168}
1169template <class T, size_t n>
1170constexpr Range<T const*> range(T const (&array)[n]) {
1171 return Range<T const*>(array, array + n);
1172}
1173template <class T, size_t n>
1174constexpr Range<T const*> crange(T const (&array)[n]) {
1175 return Range<T const*>(array, array + n);
1176}
1177
1178template <class T, size_t n>
1179constexpr Range<T*> range(std::array<T, n>& array) {
1180 return Range<T*>{array};
1181}
1182template <class T, size_t n>
1183constexpr Range<T const*> range(std::array<T, n> const& array) {
1184 return Range<T const*>{array};
1185}
1186template <class T, size_t n>
1187constexpr Range<T const*> crange(std::array<T, n> const& array) {
1188 return Range<T const*>{array};
1189}
1190
1191typedef Range<const char*> StringPiece;
1192typedef Range<char*> MutableStringPiece;
1193typedef Range<const unsigned char*> ByteRange;
1194typedef Range<unsigned char*> MutableByteRange;
1195
1196template <class C>
1197std::basic_ostream<C>& operator<<(
1198 std::basic_ostream<C>& os,
1199 Range<C const*> piece) {
1200 using StreamSize = decltype(os.width());
1201 os.write(piece.start(), static_cast<StreamSize>(piece.size()));
1202 return os;
1203}
1204
1205template <class C>
1206std::basic_ostream<C>& operator<<(std::basic_ostream<C>& os, Range<C*> piece) {
1207 using StreamSize = decltype(os.width());
1208 os.write(piece.start(), static_cast<StreamSize>(piece.size()));
1209 return os;
1210}
1211
1212/**
1213 * Templated comparison operators
1214 */
1215
1216template <class Iter>
1217inline bool operator==(const Range<Iter>& lhs, const Range<Iter>& rhs) {
1218 return lhs.size() == rhs.size() && lhs.compare(rhs) == 0;
1219}
1220
1221template <class Iter>
1222inline bool operator!=(const Range<Iter>& lhs, const Range<Iter>& rhs) {
1223 return !(operator==(lhs, rhs));
1224}
1225
1226template <class Iter>
1227inline bool operator<(const Range<Iter>& lhs, const Range<Iter>& rhs) {
1228 return lhs.compare(rhs) < 0;
1229}
1230
1231template <class Iter>
1232inline bool operator<=(const Range<Iter>& lhs, const Range<Iter>& rhs) {
1233 return lhs.compare(rhs) <= 0;
1234}
1235
1236template <class Iter>
1237inline bool operator>(const Range<Iter>& lhs, const Range<Iter>& rhs) {
1238 return lhs.compare(rhs) > 0;
1239}
1240
1241template <class Iter>
1242inline bool operator>=(const Range<Iter>& lhs, const Range<Iter>& rhs) {
1243 return lhs.compare(rhs) >= 0;
1244}
1245
1246/**
1247 * Specializations of comparison operators for StringPiece
1248 */
1249
1250namespace detail {
1251
1252template <class A, class B>
1253struct ComparableAsStringPiece {
1254 enum {
1255 value = (std::is_convertible<A, StringPiece>::value &&
1256 std::is_same<B, StringPiece>::value) ||
1257 (std::is_convertible<B, StringPiece>::value &&
1258 std::is_same<A, StringPiece>::value)
1259 };
1260};
1261
1262} // namespace detail
1263
1264/**
1265 * operator== through conversion for Range<const char*>
1266 */
1267template <class T, class U>
1268std::enable_if_t<detail::ComparableAsStringPiece<T, U>::value, bool> operator==(
1269 const T& lhs,
1270 const U& rhs) {
1271 return StringPiece(lhs) == StringPiece(rhs);
1272}
1273
1274/**
1275 * operator!= through conversion for Range<const char*>
1276 */
1277template <class T, class U>
1278std::enable_if_t<detail::ComparableAsStringPiece<T, U>::value, bool> operator!=(
1279 const T& lhs,
1280 const U& rhs) {
1281 return StringPiece(lhs) != StringPiece(rhs);
1282}
1283
1284/**
1285 * operator< through conversion for Range<const char*>
1286 */
1287template <class T, class U>
1288std::enable_if_t<detail::ComparableAsStringPiece<T, U>::value, bool> operator<(
1289 const T& lhs,
1290 const U& rhs) {
1291 return StringPiece(lhs) < StringPiece(rhs);
1292}
1293
1294/**
1295 * operator> through conversion for Range<const char*>
1296 */
1297template <class T, class U>
1298std::enable_if_t<detail::ComparableAsStringPiece<T, U>::value, bool> operator>(
1299 const T& lhs,
1300 const U& rhs) {
1301 return StringPiece(lhs) > StringPiece(rhs);
1302}
1303
1304/**
1305 * operator< through conversion for Range<const char*>
1306 */
1307template <class T, class U>
1308std::enable_if_t<detail::ComparableAsStringPiece<T, U>::value, bool> operator<=(
1309 const T& lhs,
1310 const U& rhs) {
1311 return StringPiece(lhs) <= StringPiece(rhs);
1312}
1313
1314/**
1315 * operator> through conversion for Range<const char*>
1316 */
1317template <class T, class U>
1318std::enable_if_t<detail::ComparableAsStringPiece<T, U>::value, bool> operator>=(
1319 const T& lhs,
1320 const U& rhs) {
1321 return StringPiece(lhs) >= StringPiece(rhs);
1322}
1323
1324/**
1325 * Finds substrings faster than brute force by borrowing from Boyer-Moore
1326 */
1327template <class Iter, class Comp>
1328size_t qfind(const Range<Iter>& haystack, const Range<Iter>& needle, Comp eq) {
1329 // Don't use std::search, use a Boyer-Moore-like trick by comparing
1330 // the last characters first
1331 auto const nsize = needle.size();
1332 if (haystack.size() < nsize) {
1333 return std::string::npos;
1334 }
1335 if (!nsize) {
1336 return 0;
1337 }
1338 auto const nsize_1 = nsize - 1;
1339 auto const lastNeedle = needle[nsize_1];
1340
1341 // Boyer-Moore skip value for the last char in the needle. Zero is
1342 // not a valid value; skip will be computed the first time it's
1343 // needed.
1344 std::string::size_type skip = 0;
1345
1346 auto i = haystack.begin();
1347 auto iEnd = haystack.end() - nsize_1;
1348
1349 while (i < iEnd) {
1350 // Boyer-Moore: match the last element in the needle
1351 while (!eq(i[nsize_1], lastNeedle)) {
1352 if (++i == iEnd) {
1353 // not found
1354 return std::string::npos;
1355 }
1356 }
1357 // Here we know that the last char matches
1358 // Continue in pedestrian mode
1359 for (size_t j = 0;;) {
1360 assert(j < nsize);
1361 if (!eq(i[j], needle[j])) {
1362 // Not found, we can skip
1363 // Compute the skip value lazily
1364 if (skip == 0) {
1365 skip = 1;
1366 while (skip <= nsize_1 && !eq(needle[nsize_1 - skip], lastNeedle)) {
1367 ++skip;
1368 }
1369 }
1370 i += skip;
1371 break;
1372 }
1373 // Check if done searching
1374 if (++j == nsize) {
1375 // Yay
1376 return size_t(i - haystack.begin());
1377 }
1378 }
1379 }
1380 return std::string::npos;
1381}
1382
1383namespace detail {
1384
1385inline size_t qfind_first_byte_of(
1386 const StringPiece haystack,
1387 const StringPiece needles) {
1388 static auto const qfind_first_byte_of_fn = folly::CpuId().sse42()
1389 ? qfind_first_byte_of_sse42
1390 : qfind_first_byte_of_nosse;
1391 return qfind_first_byte_of_fn(haystack, needles);
1392}
1393
1394} // namespace detail
1395
1396template <class Iter, class Comp>
1397size_t qfind_first_of(
1398 const Range<Iter>& haystack,
1399 const Range<Iter>& needles,
1400 Comp eq) {
1401 auto ret = std::find_first_of(
1402 haystack.begin(), haystack.end(), needles.begin(), needles.end(), eq);
1403 return ret == haystack.end() ? std::string::npos : ret - haystack.begin();
1404}
1405
1406struct AsciiCaseSensitive {
1407 bool operator()(char lhs, char rhs) const {
1408 return lhs == rhs;
1409 }
1410};
1411
1412/**
1413 * Check if two ascii characters are case insensitive equal.
1414 * The difference between the lower/upper case characters are the 6-th bit.
1415 * We also check they are alpha chars, in case of xor = 32.
1416 */
1417struct AsciiCaseInsensitive {
1418 bool operator()(char lhs, char rhs) const {
1419 char k = lhs ^ rhs;
1420 if (k == 0) {
1421 return true;
1422 }
1423 if (k != 32) {
1424 return false;
1425 }
1426 k = lhs | rhs;
1427 return (k >= 'a' && k <= 'z');
1428 }
1429};
1430
1431template <class Iter>
1432size_t qfind(
1433 const Range<Iter>& haystack,
1434 const typename Range<Iter>::value_type& needle) {
1435 auto pos = std::find(haystack.begin(), haystack.end(), needle);
1436 return pos == haystack.end() ? std::string::npos : pos - haystack.data();
1437}
1438
1439template <class Iter>
1440size_t rfind(
1441 const Range<Iter>& haystack,
1442 const typename Range<Iter>::value_type& needle) {
1443 for (auto i = haystack.size(); i-- > 0;) {
1444 if (haystack[i] == needle) {
1445 return i;
1446 }
1447 }
1448 return std::string::npos;
1449}
1450
1451// specialization for StringPiece
1452template <>
1453inline size_t qfind(const Range<const char*>& haystack, const char& needle) {
1454 // memchr expects a not-null pointer, early return if the range is empty.
1455 if (haystack.empty()) {
1456 return std::string::npos;
1457 }
1458 auto pos = static_cast<const char*>(
1459 ::memchr(haystack.data(), needle, haystack.size()));
1460 return pos == nullptr ? std::string::npos : pos - haystack.data();
1461}
1462
1463template <>
1464inline size_t rfind(const Range<const char*>& haystack, const char& needle) {
1465 // memchr expects a not-null pointer, early return if the range is empty.
1466 if (haystack.empty()) {
1467 return std::string::npos;
1468 }
1469 auto pos = static_cast<const char*>(
1470 ::memrchr(haystack.data(), needle, haystack.size()));
1471 return pos == nullptr ? std::string::npos : pos - haystack.data();
1472}
1473
1474// specialization for ByteRange
1475template <>
1476inline size_t qfind(
1477 const Range<const unsigned char*>& haystack,
1478 const unsigned char& needle) {
1479 // memchr expects a not-null pointer, early return if the range is empty.
1480 if (haystack.empty()) {
1481 return std::string::npos;
1482 }
1483 auto pos = static_cast<const unsigned char*>(
1484 ::memchr(haystack.data(), needle, haystack.size()));
1485 return pos == nullptr ? std::string::npos : pos - haystack.data();
1486}
1487
1488template <>
1489inline size_t rfind(
1490 const Range<const unsigned char*>& haystack,
1491 const unsigned char& needle) {
1492 // memchr expects a not-null pointer, early return if the range is empty.
1493 if (haystack.empty()) {
1494 return std::string::npos;
1495 }
1496 auto pos = static_cast<const unsigned char*>(
1497 ::memrchr(haystack.data(), needle, haystack.size()));
1498 return pos == nullptr ? std::string::npos : pos - haystack.data();
1499}
1500
1501template <class Iter>
1502size_t qfind_first_of(const Range<Iter>& haystack, const Range<Iter>& needles) {
1503 return qfind_first_of(haystack, needles, AsciiCaseSensitive());
1504}
1505
1506// specialization for StringPiece
1507template <>
1508inline size_t qfind_first_of(
1509 const Range<const char*>& haystack,
1510 const Range<const char*>& needles) {
1511 return detail::qfind_first_byte_of(haystack, needles);
1512}
1513
1514// specialization for ByteRange
1515template <>
1516inline size_t qfind_first_of(
1517 const Range<const unsigned char*>& haystack,
1518 const Range<const unsigned char*>& needles) {
1519 return detail::qfind_first_byte_of(
1520 StringPiece(haystack), StringPiece(needles));
1521}
1522
1523template <class Key, class Enable>
1524struct hasher;
1525
1526template <class T>
1527struct hasher<
1528 folly::Range<T*>,
1529 std::enable_if_t<std::is_integral<T>::value, void>> {
1530 using folly_is_avalanching = std::true_type;
1531
1532 size_t operator()(folly::Range<T*> r) const {
1533 // std::is_integral<T> is too restrictive, but is sufficient to
1534 // guarantee we can just hash all of the underlying bytes to get a
1535 // suitable hash of T. Something like absl::is_uniquely_represented<T>
1536 // would be better. std::is_pod is not enough, because POD types
1537 // can contain pointers and padding. Also, floating point numbers
1538 // may be == without being bit-identical.
1539 return hash::SpookyHashV2::Hash64(r.begin(), r.size() * sizeof(T), 0);
1540 }
1541};
1542
1543/**
1544 * _sp is a user-defined literal suffix to make an appropriate Range
1545 * specialization from a literal string.
1546 *
1547 * Modeled after C++17's `sv` suffix.
1548 */
1549inline namespace literals {
1550inline namespace string_piece_literals {
1551constexpr Range<char const*> operator"" _sp(
1552 char const* str,
1553 size_t len) noexcept {
1554 return Range<char const*>(str, len);
1555}
1556
1557constexpr Range<char16_t const*> operator"" _sp(
1558 char16_t const* str,
1559 size_t len) noexcept {
1560 return Range<char16_t const*>(str, len);
1561}
1562
1563constexpr Range<char32_t const*> operator"" _sp(
1564 char32_t const* str,
1565 size_t len) noexcept {
1566 return Range<char32_t const*>(str, len);
1567}
1568
1569constexpr Range<wchar_t const*> operator"" _sp(
1570 wchar_t const* str,
1571 size_t len) noexcept {
1572 return Range<wchar_t const*>(str, len);
1573}
1574} // namespace string_piece_literals
1575} // namespace literals
1576
1577} // namespace folly
1578
1579FOLLY_POP_WARNING
1580
1581FOLLY_ASSUME_FBVECTOR_COMPATIBLE_1(folly::Range)
1582