1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
|
// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___FLAT_MAP_UTILS_H
#define _LIBCPP___FLAT_MAP_UTILS_H
#include <__config>
#include <__type_traits/container_traits.h>
#include <__utility/exception_guard.h>
#include <__utility/forward.h>
#include <__utility/move.h>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
#if _LIBCPP_STD_VER >= 23
_LIBCPP_BEGIN_NAMESPACE_STD
// These utilities are defined in a class instead of a namespace so that this class can be befriended more easily.
struct __flat_map_utils {
// Emplace a {key: value} into a flat_{multi}map, at the exact position that
// __it_key and __it_mapped point to, assuming that the key is not already present in the map.
// When an exception is thrown during the emplacement, the function will try its best to
// roll back the changes it made to the map. If it cannot roll back the changes, it will
// clear the map.
template <class _Map, class _IterK, class _IterM, class _KeyArg, class... _MArgs>
_LIBCPP_HIDE_FROM_ABI static typename _Map::iterator __emplace_exact_pos(
_Map& __map, _IterK&& __it_key, _IterM&& __it_mapped, _KeyArg&& __key, _MArgs&&... __mapped_args) {
auto __on_key_failed = std::__make_exception_guard([&]() noexcept {
using _KeyContainer = typename _Map::key_container_type;
if constexpr (__container_traits<_KeyContainer>::__emplacement_has_strong_exception_safety_guarantee) {
// Nothing to roll back!
} else {
// we need to clear both because we don't know the state of our keys anymore
__map.clear() /* noexcept */;
}
});
auto __key_it = __map.__containers_.keys.emplace(__it_key, std::forward<_KeyArg>(__key));
__on_key_failed.__complete();
auto __on_value_failed = std::__make_exception_guard([&]() noexcept {
using _MappedContainer = typename _Map::mapped_container_type;
if constexpr (!__container_traits<_MappedContainer>::__emplacement_has_strong_exception_safety_guarantee) {
// we need to clear both because we don't know the state of our values anymore
__map.clear() /* noexcept */;
} else {
// In this case, we know the values are just like before we attempted emplacement,
// and we also know that the keys have been emplaced successfully. Just roll back the keys.
# if _LIBCPP_HAS_EXCEPTIONS
try {
# endif // _LIBCPP_HAS_EXCEPTIONS
__map.__containers_.keys.erase(__key_it);
# if _LIBCPP_HAS_EXCEPTIONS
} catch (...) {
// Now things are funky for real. We're failing to rollback the keys.
// Just give up and clear the whole thing.
//
// Also, swallow the exception that happened during the rollback and let the
// original value-emplacement exception propagate normally.
__map.clear() /* noexcept */;
}
# endif // _LIBCPP_HAS_EXCEPTIONS
}
});
auto __mapped_it = __map.__containers_.values.emplace(__it_mapped, std::forward<_MArgs>(__mapped_args)...);
__on_value_failed.__complete();
return typename _Map::iterator(std::move(__key_it), std::move(__mapped_it));
}
// TODO: We could optimize this, see
// https://github.com/llvm/llvm-project/issues/108624
template <class _Map, class _InputIterator, class _Sentinel>
_LIBCPP_HIDE_FROM_ABI static typename _Map::size_type
__append(_Map& __map, _InputIterator __first, _Sentinel __last) {
typename _Map::size_type __num_appended = 0;
for (; __first != __last; ++__first) {
typename _Map::value_type __kv = *__first;
__map.__containers_.keys.insert(__map.__containers_.keys.end(), std::move(__kv.first));
__map.__containers_.values.insert(__map.__containers_.values.end(), std::move(__kv.second));
++__num_appended;
}
return __num_appended;
}
};
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP_STD_VER >= 23
_LIBCPP_POP_MACROS
#endif // #define _LIBCPP___FLAT_MAP_UTILS_H
|
