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___FLAT_SET_UTILS_H
11#define _LIBCPP___FLAT_SET_UTILS_H
12
13#include <__config>
14#include <__iterator/iterator_traits.h>
15#include <__ranges/access.h>
16#include <__ranges/concepts.h>
17#include <__type_traits/container_traits.h>
18#include <__type_traits/decay.h>
19#include <__utility/exception_guard.h>
20#include <__utility/forward.h>
21#include <__utility/move.h>
22
23#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
24#  pragma GCC system_header
25#endif
26
27_LIBCPP_PUSH_MACROS
28#include <__undef_macros>
29
30#if _LIBCPP_STD_VER >= 23
31
32_LIBCPP_BEGIN_NAMESPACE_STD
33
34// These utilities are defined in a class instead of a namespace so that this class can be befriended more easily.
35struct __flat_set_utils {
36  // Emplace a key into a flat_{multi}set, at the exact position that
37  // __it point to, assuming that the key is not already present in the set.
38  // When an exception is thrown during the emplacement, the function will clear the set if the container does not
39  // have strong exception safety guarantee on emplacement.
40  template <class _Set, class _Iter, class _KeyArg>
41  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 static auto
42  __emplace_exact_pos(_Set& __set, _Iter&& __iter, _KeyArg&& __key) {
43    using _KeyContainer = typename decay_t<_Set>::container_type;
44    auto __on_failure   = std::__make_exception_guard([&]() noexcept {
45      if constexpr (!__container_traits<_KeyContainer>::__emplacement_has_strong_exception_safety_guarantee) {
46        __set.clear() /* noexcept */;
47      }
48    });
49    auto __key_it       = __set.__keys_.emplace(__iter.__base(), std::forward<_KeyArg>(__key));
50    __on_failure.__complete();
51    return typename decay_t<_Set>::iterator(std::move(__key_it));
52  }
53
54  template <class _Set, class _InputIterator>
55  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 static void
56  __append(_Set& __set, _InputIterator __first, _InputIterator __last) {
57    __set.__keys_.insert(__set.__keys_.end(), std::move(__first), std::move(__last));
58  }
59
60  template <class _Set, class _Range>
61  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 static void __append(_Set& __set, _Range&& __rng) {
62    if constexpr (requires { __set.__keys_.insert_range(__set.__keys_.end(), std::forward<_Range>(__rng)); }) {
63      // C++23 Sequence Container should have insert_range member function
64      // Note that not all Sequence Containers provide append_range.
65      __set.__keys_.insert_range(__set.__keys_.end(), std::forward<_Range>(__rng));
66    } else if constexpr (ranges::common_range<_Range> &&
67                         __has_input_iterator_category<ranges::iterator_t<_Range>>::value) {
68      __set.__keys_.insert(__set.__keys_.end(), ranges::begin(__rng), ranges::end(__rng));
69    } else {
70      for (auto&& __x : __rng) {
71        __set.__keys_.insert(__set.__keys_.end(), std::forward<decltype(__x)>(__x));
72      }
73    }
74  }
75};
76_LIBCPP_END_NAMESPACE_STD
77
78#endif // _LIBCPP_STD_VER >= 23
79
80_LIBCPP_POP_MACROS
81
82#endif // #define _LIBCPP___FLAT_SET_UTILS_H