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