libcxx/include/__cxx03/__algorithm/unwrap_range.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_UNWRAP_RANGE_H
  10 #define _LIBCPP___ALGORITHM_UNWRAP_RANGE_H
  11
  12 #include <__cxx03/__algorithm/unwrap_iter.h>
  13 #include <__cxx03/__concepts/constructible.h>
  14 #include <__cxx03/__config>
  15 #include <__cxx03/__iterator/concepts.h>
  16 #include <__cxx03/__iterator/next.h>
  17 #include <__cxx03/__utility/declval.h>
  18 #include <__cxx03/__utility/move.h>
  19 #include <__cxx03/__utility/pair.h>
  20
  21 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  22 #  pragma GCC system_header
  23 #endif
  24
  25 _LIBCPP_PUSH_MACROS
  26 #include <__cxx03/__undef_macros>
  27
  28 _LIBCPP_BEGIN_NAMESPACE_STD
  29
  30 // __unwrap_range and __rewrap_range are used to unwrap ranges which may have different iterator and sentinel types.
  31 // __unwrap_iter and __rewrap_iter don't work for this, because they assume that the iterator and sentinel have
  32 // the same type. __unwrap_range tries to get two iterators and then forward to __unwrap_iter.
  33
  34 #if _LIBCPP_STD_VER >= 20
  35 template <class _Iter, class _Sent>
  36 struct __unwrap_range_impl {
  37   _LIBCPP_HIDE_FROM_ABI static constexpr auto __unwrap(_Iter __first, _Sent __sent)
  38     requires random_access_iterator<_Iter> && sized_sentinel_for<_Sent, _Iter>
  39   {
  40     auto __last = ranges::next(__first, __sent);
  41     return pair{std::__unwrap_iter(std::move(__first)), std::__unwrap_iter(std::move(__last))};
  42   }
  43
  44   _LIBCPP_HIDE_FROM_ABI static constexpr auto __unwrap(_Iter __first, _Sent __last) {
  45     return pair{std::move(__first), std::move(__last)};
  46   }
  47
  48   _LIBCPP_HIDE_FROM_ABI static constexpr auto
  49   __rewrap(_Iter __orig_iter, decltype(std::__unwrap_iter(std::move(__orig_iter))) __iter)
  50     requires random_access_iterator<_Iter> && sized_sentinel_for<_Sent, _Iter>
  51   {
  52     return std::__rewrap_iter(std::move(__orig_iter), std::move(__iter));
  53   }
  54
  55   _LIBCPP_HIDE_FROM_ABI static constexpr auto __rewrap(const _Iter&, _Iter __iter)
  56     requires(!(random_access_iterator<_Iter> && sized_sentinel_for<_Sent, _Iter>))
  57   {
  58     return __iter;
  59   }
  60 };
  61
  62 template <class _Iter>
  63 struct __unwrap_range_impl<_Iter, _Iter> {
  64   _LIBCPP_HIDE_FROM_ABI static constexpr auto __unwrap(_Iter __first, _Iter __last) {
  65     return pair{std::__unwrap_iter(std::move(__first)), std::__unwrap_iter(std::move(__last))};
  66   }
  67
  68   _LIBCPP_HIDE_FROM_ABI static constexpr auto
  69   __rewrap(_Iter __orig_iter, decltype(std::__unwrap_iter(__orig_iter)) __iter) {
  70     return std::__rewrap_iter(std::move(__orig_iter), std::move(__iter));
  71   }
  72 };
  73
  74 template <class _Iter, class _Sent>
  75 _LIBCPP_HIDE_FROM_ABI constexpr auto __unwrap_range(_Iter __first, _Sent __last) {
  76   return __unwrap_range_impl<_Iter, _Sent>::__unwrap(std::move(__first), std::move(__last));
  77 }
  78
  79 template < class _Sent, class _Iter, class _Unwrapped>
  80 _LIBCPP_HIDE_FROM_ABI constexpr _Iter __rewrap_range(_Iter __orig_iter, _Unwrapped __iter) {
  81   return __unwrap_range_impl<_Iter, _Sent>::__rewrap(std::move(__orig_iter), std::move(__iter));
  82 }
  83 #else  // _LIBCPP_STD_VER >= 20
  84 template <class _Iter, class _Unwrapped = decltype(std::__unwrap_iter(std::declval<_Iter>()))>
  85 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR pair<_Unwrapped, _Unwrapped> __unwrap_range(_Iter __first, _Iter __last) {
  86   return std::make_pair(std::__unwrap_iter(std::move(__first)), std::__unwrap_iter(std::move(__last)));
  87 }
  88
  89 template <class _Iter, class _Unwrapped>
  90 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _Iter __rewrap_range(_Iter __orig_iter, _Unwrapped __iter) {
  91   return std::__rewrap_iter(std::move(__orig_iter), std::move(__iter));
  92 }
  93 #endif // _LIBCPP_STD_VER >= 20
  94
  95 _LIBCPP_END_NAMESPACE_STD
  96
  97 _LIBCPP_POP_MACROS
  98
  99 #endif // _LIBCPP___ALGORITHM_UNWRAP_RANGE_H