1/*
2 * Copyright © 2018 Google, Inc.
3 *
4 * This is part of HarfBuzz, a text shaping library.
5 *
6 * Permission is hereby granted, without written agreement and without
7 * license or royalty fees, to use, copy, modify, and distribute this
8 * software and its documentation for any purpose, provided that the
9 * above copyright notice and the following two paragraphs appear in
10 * all copies of this software.
11 *
12 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
13 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
14 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
15 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
16 * DAMAGE.
17 *
18 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
19 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
20 * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
21 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
22 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
23 *
24 * Google Author(s): Behdad Esfahbod
25 */
26
27#ifndef HB_META_HH
28#define HB_META_HH
29
30#include "hb.hh"
31
32#include <memory>
33#include <type_traits>
34#include <utility>
35
36
37/*
38 * C++ template meta-programming & fundamentals used with them.
39 */
40
41/* Void! For when we need a expression-type of void. */
42struct hb_empty_t {};
43
44/* https://en.cppreference.com/w/cpp/types/void_t */
45template<typename... Ts> struct _hb_void_t { typedef void type; };
46template<typename... Ts> using hb_void_t = typename _hb_void_t<Ts...>::type;
47
48template<typename Head, typename... Ts> struct _hb_head_t { typedef Head type; };
49template<typename... Ts> using hb_head_t = typename _hb_head_t<Ts...>::type;
50
51template <typename T, T v> struct hb_integral_constant { static constexpr T value = v; };
52template <bool b> using hb_bool_constant = hb_integral_constant<bool, b>;
53using hb_true_type = hb_bool_constant<true>;
54using hb_false_type = hb_bool_constant<false>;
55
56/* Static-assert as expression. */
57template <bool cond> struct static_assert_expr;
58template <> struct static_assert_expr<true> : hb_false_type {};
59#define static_assert_expr(C) static_assert_expr<C>::value
60
61/* Basic type SFINAE. */
62
63template <bool B, typename T = void> struct hb_enable_if {};
64template <typename T> struct hb_enable_if<true, T> { typedef T type; };
65#define hb_enable_if(Cond) typename hb_enable_if<(Cond)>::type* = nullptr
66/* Concepts/Requires alias: */
67#define hb_requires(Cond) hb_enable_if((Cond))
68
69template <typename T, typename T2> struct hb_is_same : hb_false_type {};
70template <typename T> struct hb_is_same<T, T> : hb_true_type {};
71#define hb_is_same(T, T2) hb_is_same<T, T2>::value
72
73/* Function overloading SFINAE and priority. */
74
75#define HB_RETURN(Ret, E) -> hb_head_t<Ret, decltype ((E))> { return (E); }
76#define HB_AUTO_RETURN(E) -> decltype ((E)) { return (E); }
77#define HB_VOID_RETURN(E) -> hb_void_t<decltype ((E))> { (E); }
78
79template <unsigned Pri> struct hb_priority : hb_priority<Pri - 1> {};
80template <> struct hb_priority<0> {};
81#define hb_prioritize hb_priority<16> ()
82
83#define HB_FUNCOBJ(x) static_const x HB_UNUSED
84
85
86template <typename T> struct hb_type_identity_t { typedef T type; };
87template <typename T> using hb_type_identity = typename hb_type_identity_t<T>::type;
88
89template <typename T> static inline T hb_declval ();
90#define hb_declval(T) (hb_declval<T> ())
91
92template <typename T> struct hb_match_const : hb_type_identity_t<T>, hb_false_type {};
93template <typename T> struct hb_match_const<const T> : hb_type_identity_t<T>, hb_true_type {};
94template <typename T> using hb_remove_const = typename hb_match_const<T>::type;
95
96template <typename T> struct hb_match_reference : hb_type_identity_t<T>, hb_false_type {};
97template <typename T> struct hb_match_reference<T &> : hb_type_identity_t<T>, hb_true_type {};
98template <typename T> struct hb_match_reference<T &&> : hb_type_identity_t<T>, hb_true_type {};
99template <typename T> using hb_remove_reference = typename hb_match_reference<T>::type;
100template <typename T> auto _hb_try_add_lvalue_reference (hb_priority<1>) -> hb_type_identity<T&>;
101template <typename T> auto _hb_try_add_lvalue_reference (hb_priority<0>) -> hb_type_identity<T>;
102template <typename T> using hb_add_lvalue_reference = decltype (_hb_try_add_lvalue_reference<T> (hb_prioritize));
103template <typename T> auto _hb_try_add_rvalue_reference (hb_priority<1>) -> hb_type_identity<T&&>;
104template <typename T> auto _hb_try_add_rvalue_reference (hb_priority<0>) -> hb_type_identity<T>;
105template <typename T> using hb_add_rvalue_reference = decltype (_hb_try_add_rvalue_reference<T> (hb_prioritize));
106
107template <typename T> struct hb_match_pointer : hb_type_identity_t<T>, hb_false_type {};
108template <typename T> struct hb_match_pointer<T *> : hb_type_identity_t<T>, hb_true_type {};
109template <typename T> using hb_remove_pointer = typename hb_match_pointer<T>::type;
110template <typename T> auto _hb_try_add_pointer (hb_priority<1>) -> hb_type_identity<hb_remove_reference<T>*>;
111template <typename T> auto _hb_try_add_pointer (hb_priority<1>) -> hb_type_identity<T>;
112template <typename T> using hb_add_pointer = decltype (_hb_try_add_pointer<T> (hb_prioritize));
113
114
115template <typename T> using hb_decay = typename std::decay<T>::type;
116
117#define hb_is_convertible(From,To) std::is_convertible<From, To>::value
118
119template <typename From, typename To>
120using hb_is_cr_convertible = hb_bool_constant<
121 hb_is_same (hb_decay<From>, hb_decay<To>) &&
122 (!std::is_const<From>::value || std::is_const<To>::value) &&
123 (!std::is_reference<To>::value || std::is_const<To>::value || std::is_reference<To>::value)
124>;
125#define hb_is_cr_convertible(From,To) hb_is_cr_convertible<From, To>::value
126
127
128struct
129{
130 template <typename T> constexpr auto
131 operator () (T&& v) const HB_AUTO_RETURN (std::forward<T> (v))
132
133 template <typename T> constexpr auto
134 operator () (T *v) const HB_AUTO_RETURN (*v)
135
136 template <typename T> constexpr auto
137 operator () (const hb::shared_ptr<T>& v) const HB_AUTO_RETURN (*v)
138
139 template <typename T> constexpr auto
140 operator () (hb::shared_ptr<T>& v) const HB_AUTO_RETURN (*v)
141
142 template <typename T> constexpr auto
143 operator () (const hb::unique_ptr<T>& v) const HB_AUTO_RETURN (*v)
144
145 template <typename T> constexpr auto
146 operator () (hb::unique_ptr<T>& v) const HB_AUTO_RETURN (*v)
147}
148HB_FUNCOBJ (hb_deref);
149
150template <typename T>
151struct hb_reference_wrapper
152{
153 hb_reference_wrapper (T v) : v (v) {}
154 bool operator == (const hb_reference_wrapper& o) const { return v == o.v; }
155 bool operator != (const hb_reference_wrapper& o) const { return v != o.v; }
156 operator T& () { return v; }
157 T& get () { return v; }
158 T v;
159};
160template <typename T>
161struct hb_reference_wrapper<T&>
162{
163 hb_reference_wrapper (T& v) : v (std::addressof (v)) {}
164 bool operator == (const hb_reference_wrapper& o) const { return v == o.v; }
165 bool operator != (const hb_reference_wrapper& o) const { return v != o.v; }
166 operator T& () { return *v; }
167 T& get () { return *v; }
168 T* v;
169};
170
171
172/* Type traits */
173
174template <typename T> struct hb_int_min;
175template <> struct hb_int_min<char> : hb_integral_constant<char, CHAR_MIN> {};
176template <> struct hb_int_min<signed char> : hb_integral_constant<signed char, SCHAR_MIN> {};
177template <> struct hb_int_min<unsigned char> : hb_integral_constant<unsigned char, 0> {};
178template <> struct hb_int_min<signed short> : hb_integral_constant<signed short, SHRT_MIN> {};
179template <> struct hb_int_min<unsigned short> : hb_integral_constant<unsigned short, 0> {};
180template <> struct hb_int_min<signed int> : hb_integral_constant<signed int, INT_MIN> {};
181template <> struct hb_int_min<unsigned int> : hb_integral_constant<unsigned int, 0> {};
182template <> struct hb_int_min<signed long> : hb_integral_constant<signed long, LONG_MIN> {};
183template <> struct hb_int_min<unsigned long> : hb_integral_constant<unsigned long, 0> {};
184template <> struct hb_int_min<signed long long> : hb_integral_constant<signed long long, LLONG_MIN> {};
185template <> struct hb_int_min<unsigned long long> : hb_integral_constant<unsigned long long, 0> {};
186template <typename T> struct hb_int_min<T *> : hb_integral_constant<T *, nullptr> {};
187#define hb_int_min(T) hb_int_min<T>::value
188template <typename T> struct hb_int_max;
189template <> struct hb_int_max<char> : hb_integral_constant<char, CHAR_MAX> {};
190template <> struct hb_int_max<signed char> : hb_integral_constant<signed char, SCHAR_MAX> {};
191template <> struct hb_int_max<unsigned char> : hb_integral_constant<unsigned char, UCHAR_MAX> {};
192template <> struct hb_int_max<signed short> : hb_integral_constant<signed short, SHRT_MAX> {};
193template <> struct hb_int_max<unsigned short> : hb_integral_constant<unsigned short, USHRT_MAX> {};
194template <> struct hb_int_max<signed int> : hb_integral_constant<signed int, INT_MAX> {};
195template <> struct hb_int_max<unsigned int> : hb_integral_constant<unsigned int, UINT_MAX> {};
196template <> struct hb_int_max<signed long> : hb_integral_constant<signed long, LONG_MAX> {};
197template <> struct hb_int_max<unsigned long> : hb_integral_constant<unsigned long, ULONG_MAX> {};
198template <> struct hb_int_max<signed long long> : hb_integral_constant<signed long long, LLONG_MAX> {};
199template <> struct hb_int_max<unsigned long long> : hb_integral_constant<unsigned long long, ULLONG_MAX> {};
200#define hb_int_max(T) hb_int_max<T>::value
201
202#if defined(__GNUC__) && __GNUC__ < 5 && !defined(__clang__)
203#define hb_is_trivially_copyable(T) __has_trivial_copy(T)
204#define hb_is_trivially_copy_assignable(T) __has_trivial_assign(T)
205#define hb_is_trivially_constructible(T) __has_trivial_constructor(T)
206#define hb_is_trivially_copy_constructible(T) __has_trivial_copy_constructor(T)
207#define hb_is_trivially_destructible(T) __has_trivial_destructor(T)
208#else
209#define hb_is_trivially_copyable(T) std::is_trivially_copyable<T>::value
210#define hb_is_trivially_copy_assignable(T) std::is_trivially_copy_assignable<T>::value
211#define hb_is_trivially_constructible(T) std::is_trivially_constructible<T>::value
212#define hb_is_trivially_copy_constructible(T) std::is_trivially_copy_constructible<T>::value
213#define hb_is_trivially_destructible(T) std::is_trivially_destructible<T>::value
214#endif
215
216/* Class traits. */
217
218#define HB_DELETE_COPY_ASSIGN(TypeName) \
219 TypeName(const TypeName&) = delete; \
220 void operator=(const TypeName&) = delete
221#define HB_DELETE_CREATE_COPY_ASSIGN(TypeName) \
222 TypeName() = delete; \
223 TypeName(const TypeName&) = delete; \
224 void operator=(const TypeName&) = delete
225
226/* hb_unwrap_type (T)
227 * If T has no T::type, returns T. Otherwise calls itself on T::type recursively.
228 */
229
230template <typename T, typename>
231struct _hb_unwrap_type : hb_type_identity_t<T> {};
232template <typename T>
233struct _hb_unwrap_type<T, hb_void_t<typename T::type>> : _hb_unwrap_type<typename T::type, void> {};
234template <typename T>
235using hb_unwrap_type = _hb_unwrap_type<T, void>;
236#define hb_unwrap_type(T) typename hb_unwrap_type<T>::type
237
238#endif /* HB_META_HH */
239