libcxx/include/__algorithm/ranges_transform.h

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef _LIBCPP___ALGORITHM_RANGES_TRANSFORM_H
  10 #define _LIBCPP___ALGORITHM_RANGES_TRANSFORM_H
  11
  12 #include <__algorithm/in_in_out_result.h>
  13 #include <__algorithm/in_out_result.h>
  14 #include <__concepts/constructible.h>
  15 #include <__config>
  16 #include <__functional/identity.h>
  17 #include <__functional/invoke.h>
  18 #include <__iterator/concepts.h>
  19 #include <__iterator/projected.h>
  20 #include <__ranges/access.h>
  21 #include <__ranges/concepts.h>
  22 #include <__ranges/dangling.h>
  23 #include <__utility/move.h>
  24
  25 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  26 #  pragma GCC system_header
  27 #endif
  28
  29 #if _LIBCPP_STD_VER >= 20
  30
  31 _LIBCPP_BEGIN_NAMESPACE_STD
  32
  33 namespace ranges {
  34
  35 template <class _Ip, class _Op>
  36 using unary_transform_result = in_out_result<_Ip, _Op>;
  37
  38 template <class _I1, class _I2, class _O1>
  39 using binary_transform_result = in_in_out_result<_I1, _I2, _O1>;
  40
  41 namespace __transform {
  42 struct __fn {
  43 private:
  44   template <class _InIter, class _Sent, class _OutIter, class _Func, class _Proj>
  45   _LIBCPP_HIDE_FROM_ABI static constexpr unary_transform_result<_InIter, _OutIter>
  46   __unary(_InIter __first, _Sent __last, _OutIter __result, _Func& __operation, _Proj& __projection) {
  47     while (__first != __last) {
  48       *__result = std::invoke(__operation, std::invoke(__projection, *__first));
  49       ++__first;
  50       ++__result;
  51     }
  52
  53     return {std::move(__first), std::move(__result)};
  54   }
  55
  56   template <class _InIter1,
  57             class _Sent1,
  58             class _InIter2,
  59             class _Sent2,
  60             class _OutIter,
  61             class _Func,
  62             class _Proj1,
  63             class _Proj2>
  64   _LIBCPP_HIDE_FROM_ABI static constexpr binary_transform_result<_InIter1, _InIter2, _OutIter>
  65   __binary(_InIter1 __first1,
  66            _Sent1 __last1,
  67            _InIter2 __first2,
  68            _Sent2 __last2,
  69            _OutIter __result,
  70            _Func& __binary_operation,
  71            _Proj1& __projection1,
  72            _Proj2& __projection2) {
  73     while (__first1 != __last1 && __first2 != __last2) {
  74       *__result =
  75           std::invoke(__binary_operation, std::invoke(__projection1, *__first1), std::invoke(__projection2, *__first2));
  76       ++__first1;
  77       ++__first2;
  78       ++__result;
  79     }
  80     return {std::move(__first1), std::move(__first2), std::move(__result)};
  81   }
  82
  83 public:
  84   template <input_iterator _InIter,
  85             sentinel_for<_InIter> _Sent,
  86             weakly_incrementable _OutIter,
  87             copy_constructible _Func,
  88             class _Proj = identity>
  89     requires indirectly_writable<_OutIter, indirect_result_t<_Func&, projected<_InIter, _Proj>>>
  90   _LIBCPP_HIDE_FROM_ABI constexpr unary_transform_result<_InIter, _OutIter>
  91   operator()(_InIter __first, _Sent __last, _OutIter __result, _Func __operation, _Proj __proj = {}) const {
  92     return __unary(std::move(__first), std::move(__last), std::move(__result), __operation, __proj);
  93   }
  94
  95   template <input_range _Range, weakly_incrementable _OutIter, copy_constructible _Func, class _Proj = identity>
  96     requires indirectly_writable<_OutIter, indirect_result_t<_Func, projected<iterator_t<_Range>, _Proj>>>
  97   _LIBCPP_HIDE_FROM_ABI constexpr unary_transform_result<borrowed_iterator_t<_Range>, _OutIter>
  98   operator()(_Range&& __range, _OutIter __result, _Func __operation, _Proj __projection = {}) const {
  99     return __unary(ranges::begin(__range), ranges::end(__range), std::move(__result), __operation, __projection);
 100   }
 101
 102   template <input_iterator _InIter1,
 103             sentinel_for<_InIter1> _Sent1,
 104             input_iterator _InIter2,
 105             sentinel_for<_InIter2> _Sent2,
 106             weakly_incrementable _OutIter,
 107             copy_constructible _Func,
 108             class _Proj1 = identity,
 109             class _Proj2 = identity>
 110     requires indirectly_writable<_OutIter,
 111                                  indirect_result_t<_Func&, projected<_InIter1, _Proj1>, projected<_InIter2, _Proj2>>>
 112   _LIBCPP_HIDE_FROM_ABI constexpr binary_transform_result<_InIter1, _InIter2, _OutIter> operator()(
 113       _InIter1 __first1,
 114       _Sent1 __last1,
 115       _InIter2 __first2,
 116       _Sent2 __last2,
 117       _OutIter __result,
 118       _Func __binary_operation,
 119       _Proj1 __projection1 = {},
 120       _Proj2 __projection2 = {}) const {
 121     return __binary(
 122         std::move(__first1),
 123         std::move(__last1),
 124         std::move(__first2),
 125         std::move(__last2),
 126         std::move(__result),
 127         __binary_operation,
 128         __projection1,
 129         __projection2);
 130   }
 131
 132   template <input_range _Range1,
 133             input_range _Range2,
 134             weakly_incrementable _OutIter,
 135             copy_constructible _Func,
 136             class _Proj1 = identity,
 137             class _Proj2 = identity>
 138     requires indirectly_writable<
 139         _OutIter,
 140         indirect_result_t<_Func&, projected<iterator_t<_Range1>, _Proj1>, projected<iterator_t<_Range2>, _Proj2>>>
 141   _LIBCPP_HIDE_FROM_ABI constexpr binary_transform_result<borrowed_iterator_t<_Range1>,
 142                                                           borrowed_iterator_t<_Range2>,
 143                                                           _OutIter>
 144   operator()(_Range1&& __range1,
 145              _Range2&& __range2,
 146              _OutIter __result,
 147              _Func __binary_operation,
 148              _Proj1 __projection1 = {},
 149              _Proj2 __projection2 = {}) const {
 150     return __binary(
 151         ranges::begin(__range1),
 152         ranges::end(__range1),
 153         ranges::begin(__range2),
 154         ranges::end(__range2),
 155         std::move(__result),
 156         __binary_operation,
 157         __projection1,
 158         __projection2);
 159   }
 160 };
 161 } // namespace __transform
 162
 163 inline namespace __cpo {
 164 inline constexpr auto transform = __transform::__fn{};
 165 } // namespace __cpo
 166 } // namespace ranges
 167
 168 _LIBCPP_END_NAMESPACE_STD
 169
 170 #endif // _LIBCPP_STD_VER >= 20
 171
 172 #endif // _LIBCPP___ALGORITHM_RANGES_TRANSFORM_H