libcxx/include/__iterator/concepts.h

   1 // -*- C++ -*-
   2 //===----------------------------------------------------------------------===//
   3 //
   4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   5 // See https://llvm.org/LICENSE.txt for license information.
   6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #ifndef _LIBCPP___ITERATOR_CONCEPTS_H
  11 #define _LIBCPP___ITERATOR_CONCEPTS_H
  12
  13 #include <__concepts/arithmetic.h>
  14 #include <__concepts/assignable.h>
  15 #include <__concepts/common_reference_with.h>
  16 #include <__concepts/constructible.h>
  17 #include <__concepts/copyable.h>
  18 #include <__concepts/derived_from.h>
  19 #include <__concepts/equality_comparable.h>
  20 #include <__concepts/invocable.h>
  21 #include <__concepts/movable.h>
  22 #include <__concepts/predicate.h>
  23 #include <__concepts/regular.h>
  24 #include <__concepts/relation.h>
  25 #include <__concepts/same_as.h>
  26 #include <__concepts/semiregular.h>
  27 #include <__concepts/totally_ordered.h>
  28 #include <__config>
  29 #include <__functional/invoke.h>
  30 #include <__iterator/incrementable_traits.h>
  31 #include <__iterator/iter_move.h>
  32 #include <__iterator/iterator_traits.h>
  33 #include <__iterator/readable_traits.h>
  34 #include <__memory/pointer_traits.h>
  35 #include <__type_traits/add_pointer.h>
  36 #include <__type_traits/common_reference.h>
  37 #include <__type_traits/is_pointer.h>
  38 #include <__type_traits/is_reference.h>
  39 #include <__type_traits/remove_cv.h>
  40 #include <__type_traits/remove_cvref.h>
  41 #include <__utility/forward.h>
  42
  43 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  44 #  pragma GCC system_header
  45 #endif
  46
  47 _LIBCPP_BEGIN_NAMESPACE_STD
  48
  49 #if _LIBCPP_STD_VER >= 20
  50
  51 // [iterator.concept.readable]
  52 template <class _In>
  53 concept __indirectly_readable_impl =
  54     requires(const _In __i) {
  55       typename iter_value_t<_In>;
  56       typename iter_reference_t<_In>;
  57       typename iter_rvalue_reference_t<_In>;
  58       { *__i } -> same_as<iter_reference_t<_In>>;
  59       { ranges::iter_move(__i) } -> same_as<iter_rvalue_reference_t<_In>>;
  60     } && common_reference_with<iter_reference_t<_In>&&, iter_value_t<_In>&> &&
  61     common_reference_with<iter_reference_t<_In>&&, iter_rvalue_reference_t<_In>&&> &&
  62     common_reference_with<iter_rvalue_reference_t<_In>&&, const iter_value_t<_In>&>;
  63
  64 template <class _In>
  65 concept indirectly_readable = __indirectly_readable_impl<remove_cvref_t<_In>>;
  66
  67 template <indirectly_readable _Tp>
  68 using iter_common_reference_t = common_reference_t<iter_reference_t<_Tp>, iter_value_t<_Tp>&>;
  69
  70 // [iterator.concept.writable]
  71 template <class _Out, class _Tp>
  72 concept indirectly_writable = requires(_Out&& __o, _Tp&& __t) {
  73   *__o                                             = std::forward<_Tp>(__t); // not required to be equality-preserving
  74   *std::forward<_Out>(__o)                         = std::forward<_Tp>(__t); // not required to be equality-preserving
  75   const_cast<const iter_reference_t<_Out>&&>(*__o) = std::forward<_Tp>(__t); // not required to be equality-preserving
  76   const_cast<const iter_reference_t<_Out>&&>(*std::forward<_Out>(__o)) =
  77       std::forward<_Tp>(__t); // not required to be equality-preserving
  78 };
  79
  80 // [iterator.concept.winc]
  81 template <class _Tp>
  82 concept __integer_like = integral<_Tp> && !same_as<_Tp, bool>;
  83
  84 template <class _Tp>
  85 concept __signed_integer_like = signed_integral<_Tp>;
  86
  87 template <class _Ip>
  88 concept weakly_incrementable =
  89     // TODO: remove this once the clang bug is fixed (bugs.llvm.org/PR48173).
  90     !same_as<_Ip, bool> && // Currently, clang does not handle bool correctly.
  91     movable<_Ip> && requires(_Ip __i) {
  92       typename iter_difference_t<_Ip>;
  93       requires __signed_integer_like<iter_difference_t<_Ip>>;
  94       { ++__i } -> same_as<_Ip&>; // not required to be equality-preserving
  95       __i++;                      // not required to be equality-preserving
  96     };
  97
  98 // [iterator.concept.inc]
  99 template <class _Ip>
 100 concept incrementable = regular<_Ip> && weakly_incrementable<_Ip> && requires(_Ip __i) {
 101   { __i++ } -> same_as<_Ip>;
 102 };
 103
 104 // [iterator.concept.iterator]
 105 template <class _Ip>
 106 concept input_or_output_iterator = requires(_Ip __i) {
 107   { *__i } -> __can_reference;
 108 } && weakly_incrementable<_Ip>;
 109
 110 // [iterator.concept.sentinel]
 111 template <class _Sp, class _Ip>
 112 concept sentinel_for = semiregular<_Sp> && input_or_output_iterator<_Ip> && __weakly_equality_comparable_with<_Sp, _Ip>;
 113
 114 template <class, class>
 115 inline constexpr bool disable_sized_sentinel_for = false;
 116
 117 template <class _Sp, class _Ip>
 118 concept sized_sentinel_for =
 119     sentinel_for<_Sp, _Ip> && !disable_sized_sentinel_for<remove_cv_t<_Sp>, remove_cv_t<_Ip>> &&
 120     requires(const _Ip& __i, const _Sp& __s) {
 121       { __s - __i } -> same_as<iter_difference_t<_Ip>>;
 122       { __i - __s } -> same_as<iter_difference_t<_Ip>>;
 123     };
 124
 125 // [iterator.concept.input]
 126 template <class _Ip>
 127 concept input_iterator = input_or_output_iterator<_Ip> && indirectly_readable<_Ip> && requires {
 128   typename _ITER_CONCEPT<_Ip>;
 129 } && derived_from<_ITER_CONCEPT<_Ip>, input_iterator_tag>;
 130
 131 // [iterator.concept.output]
 132 template <class _Ip, class _Tp>
 133 concept output_iterator =
 134     input_or_output_iterator<_Ip> && indirectly_writable<_Ip, _Tp> && requires(_Ip __it, _Tp&& __t) {
 135       *__it++ = std::forward<_Tp>(__t); // not required to be equality-preserving
 136     };
 137
 138 // [iterator.concept.forward]
 139 template <class _Ip>
 140 concept forward_iterator =
 141     input_iterator<_Ip> && derived_from<_ITER_CONCEPT<_Ip>, forward_iterator_tag> && incrementable<_Ip> &&
 142     sentinel_for<_Ip, _Ip>;
 143
 144 // [iterator.concept.bidir]
 145 template <class _Ip>
 146 concept bidirectional_iterator =
 147     forward_iterator<_Ip> && derived_from<_ITER_CONCEPT<_Ip>, bidirectional_iterator_tag> && requires(_Ip __i) {
 148       { --__i } -> same_as<_Ip&>;
 149       { __i-- } -> same_as<_Ip>;
 150     };
 151
 152 template <class _Ip>
 153 concept random_access_iterator =
 154     bidirectional_iterator<_Ip> && derived_from<_ITER_CONCEPT<_Ip>, random_access_iterator_tag> &&
 155     totally_ordered<_Ip> && sized_sentinel_for<_Ip, _Ip> &&
 156     requires(_Ip __i, const _Ip __j, const iter_difference_t<_Ip> __n) {
 157       { __i += __n } -> same_as<_Ip&>;
 158       { __j + __n } -> same_as<_Ip>;
 159       { __n + __j } -> same_as<_Ip>;
 160       { __i -= __n } -> same_as<_Ip&>;
 161       { __j - __n } -> same_as<_Ip>;
 162       { __j[__n] } -> same_as<iter_reference_t<_Ip>>;
 163     };
 164
 165 template <class _Ip>
 166 concept contiguous_iterator =
 167     random_access_iterator<_Ip> && derived_from<_ITER_CONCEPT<_Ip>, contiguous_iterator_tag> &&
 168     is_lvalue_reference_v<iter_reference_t<_Ip>> && same_as<iter_value_t<_Ip>, remove_cvref_t<iter_reference_t<_Ip>>> &&
 169     requires(const _Ip& __i) {
 170       { std::to_address(__i) } -> same_as<add_pointer_t<iter_reference_t<_Ip>>>;
 171     };
 172
 173 template <class _Ip>
 174 concept __has_arrow = input_iterator<_Ip> && (is_pointer_v<_Ip> || requires(_Ip __i) { __i.operator->(); });
 175
 176 // [indirectcallable.indirectinvocable]
 177 template <class _Fp, class _It>
 178 concept indirectly_unary_invocable =
 179     indirectly_readable<_It> && copy_constructible<_Fp> && invocable<_Fp&, iter_value_t<_It>&> &&
 180     invocable<_Fp&, iter_reference_t<_It>> &&
 181     common_reference_with< invoke_result_t<_Fp&, iter_value_t<_It>&>, invoke_result_t<_Fp&, iter_reference_t<_It>>>;
 182
 183 template <class _Fp, class _It>
 184 concept indirectly_regular_unary_invocable =
 185     indirectly_readable<_It> && copy_constructible<_Fp> && regular_invocable<_Fp&, iter_value_t<_It>&> &&
 186     regular_invocable<_Fp&, iter_reference_t<_It>> &&
 187     common_reference_with< invoke_result_t<_Fp&, iter_value_t<_It>&>, invoke_result_t<_Fp&, iter_reference_t<_It>>>;
 188
 189 template <class _Fp, class _It>
 190 concept indirect_unary_predicate =
 191     indirectly_readable<_It> && copy_constructible<_Fp> && predicate<_Fp&, iter_value_t<_It>&> &&
 192     predicate<_Fp&, iter_reference_t<_It>>;
 193
 194 template <class _Fp, class _It1, class _It2>
 195 concept indirect_binary_predicate =
 196     indirectly_readable<_It1> && indirectly_readable<_It2> && copy_constructible<_Fp> &&
 197     predicate<_Fp&, iter_value_t<_It1>&, iter_value_t<_It2>&> &&
 198     predicate<_Fp&, iter_value_t<_It1>&, iter_reference_t<_It2>> &&
 199     predicate<_Fp&, iter_reference_t<_It1>, iter_value_t<_It2>&> &&
 200     predicate<_Fp&, iter_reference_t<_It1>, iter_reference_t<_It2>>;
 201
 202 template <class _Fp, class _It1, class _It2 = _It1>
 203 concept indirect_equivalence_relation =
 204     indirectly_readable<_It1> && indirectly_readable<_It2> && copy_constructible<_Fp> &&
 205     equivalence_relation<_Fp&, iter_value_t<_It1>&, iter_value_t<_It2>&> &&
 206     equivalence_relation<_Fp&, iter_value_t<_It1>&, iter_reference_t<_It2>> &&
 207     equivalence_relation<_Fp&, iter_reference_t<_It1>, iter_value_t<_It2>&> &&
 208     equivalence_relation<_Fp&, iter_reference_t<_It1>, iter_reference_t<_It2>>;
 209
 210 template <class _Fp, class _It1, class _It2 = _It1>
 211 concept indirect_strict_weak_order =
 212     indirectly_readable<_It1> && indirectly_readable<_It2> && copy_constructible<_Fp> &&
 213     strict_weak_order<_Fp&, iter_value_t<_It1>&, iter_value_t<_It2>&> &&
 214     strict_weak_order<_Fp&, iter_value_t<_It1>&, iter_reference_t<_It2>> &&
 215     strict_weak_order<_Fp&, iter_reference_t<_It1>, iter_value_t<_It2>&> &&
 216     strict_weak_order<_Fp&, iter_reference_t<_It1>, iter_reference_t<_It2>>;
 217
 218 template <class _Fp, class... _Its>
 219   requires(indirectly_readable<_Its> && ...) && invocable<_Fp, iter_reference_t<_Its>...>
 220 using indirect_result_t = invoke_result_t<_Fp, iter_reference_t<_Its>...>;
 221
 222 template <class _In, class _Out>
 223 concept indirectly_movable = indirectly_readable<_In> && indirectly_writable<_Out, iter_rvalue_reference_t<_In>>;
 224
 225 template <class _In, class _Out>
 226 concept indirectly_movable_storable =
 227     indirectly_movable<_In, _Out> && indirectly_writable<_Out, iter_value_t<_In>> && movable<iter_value_t<_In>> &&
 228     constructible_from<iter_value_t<_In>, iter_rvalue_reference_t<_In>> &&
 229     assignable_from<iter_value_t<_In>&, iter_rvalue_reference_t<_In>>;
 230
 231 template <class _In, class _Out>
 232 concept indirectly_copyable = indirectly_readable<_In> && indirectly_writable<_Out, iter_reference_t<_In>>;
 233
 234 template <class _In, class _Out>
 235 concept indirectly_copyable_storable =
 236     indirectly_copyable<_In, _Out> && indirectly_writable<_Out, iter_value_t<_In>&> &&
 237     indirectly_writable<_Out, const iter_value_t<_In>&> && indirectly_writable<_Out, iter_value_t<_In>&&> &&
 238     indirectly_writable<_Out, const iter_value_t<_In>&&> && copyable<iter_value_t<_In>> &&
 239     constructible_from<iter_value_t<_In>, iter_reference_t<_In>> &&
 240     assignable_from<iter_value_t<_In>&, iter_reference_t<_In>>;
 241
 242 // Note: indirectly_swappable is located in iter_swap.h to prevent a dependency cycle
 243 // (both iter_swap and indirectly_swappable require indirectly_readable).
 244
 245 #endif // _LIBCPP_STD_VER >= 20
 246
 247 template <class _Tp>
 248 using __has_random_access_iterator_category_or_concept
 249 #if _LIBCPP_STD_VER >= 20
 250     = integral_constant<bool, random_access_iterator<_Tp>>;
 251 #else  // _LIBCPP_STD_VER < 20
 252     = __has_random_access_iterator_category<_Tp>;
 253 #endif // _LIBCPP_STD_VER
 254
 255 _LIBCPP_END_NAMESPACE_STD
 256
 257 #endif // _LIBCPP___ITERATOR_CONCEPTS_H