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def50f701f
fixes https://github.com/llvm/llvm-project/issues/105190 --------- Co-authored-by: Hui Xie <huixie@Mac.broadband> Co-authored-by: Hui Xie <huixie@Huis-MacBook-Pro.local>
104 lines
4.3 KiB
C++
104 lines
4.3 KiB
C++
// -*- C++ -*-
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//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___FLAT_MAP_UTILS_H
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#define _LIBCPP___FLAT_MAP_UTILS_H
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#include <__config>
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#include <__type_traits/container_traits.h>
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#include <__utility/exception_guard.h>
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#include <__utility/forward.h>
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#include <__utility/move.h>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_PUSH_MACROS
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#include <__undef_macros>
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#if _LIBCPP_STD_VER >= 23
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_LIBCPP_BEGIN_NAMESPACE_STD
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// These utilities are defined in a class instead of a namespace so that this class can be befriended more easily.
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struct __flat_map_utils {
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// Emplace a {key: value} into a flat_{multi}map, at the exact position that
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// __it_key and __it_mapped point to, assuming that the key is not already present in the map.
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// When an exception is thrown during the emplacement, the function will try its best to
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// roll back the changes it made to the map. If it cannot roll back the changes, it will
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// clear the map.
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template <class _Map, class _IterK, class _IterM, class _KeyArg, class... _MArgs>
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_LIBCPP_HIDE_FROM_ABI static typename _Map::iterator __emplace_exact_pos(
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_Map& __map, _IterK&& __it_key, _IterM&& __it_mapped, _KeyArg&& __key, _MArgs&&... __mapped_args) {
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auto __on_key_failed = std::__make_exception_guard([&]() noexcept {
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using _KeyContainer = typename _Map::key_container_type;
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if constexpr (__container_traits<_KeyContainer>::__emplacement_has_strong_exception_safety_guarantee) {
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// Nothing to roll back!
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} else {
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// we need to clear both because we don't know the state of our keys anymore
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__map.clear() /* noexcept */;
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}
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});
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auto __key_it = __map.__containers_.keys.emplace(__it_key, std::forward<_KeyArg>(__key));
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__on_key_failed.__complete();
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auto __on_value_failed = std::__make_exception_guard([&]() noexcept {
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using _MappedContainer = typename _Map::mapped_container_type;
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if constexpr (!__container_traits<_MappedContainer>::__emplacement_has_strong_exception_safety_guarantee) {
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// we need to clear both because we don't know the state of our values anymore
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__map.clear() /* noexcept */;
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} else {
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// In this case, we know the values are just like before we attempted emplacement,
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// and we also know that the keys have been emplaced successfully. Just roll back the keys.
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# if _LIBCPP_HAS_EXCEPTIONS
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try {
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# endif // _LIBCPP_HAS_EXCEPTIONS
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__map.__containers_.keys.erase(__key_it);
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# if _LIBCPP_HAS_EXCEPTIONS
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} catch (...) {
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// Now things are funky for real. We're failing to rollback the keys.
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// Just give up and clear the whole thing.
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//
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// Also, swallow the exception that happened during the rollback and let the
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// original value-emplacement exception propagate normally.
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__map.clear() /* noexcept */;
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}
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# endif // _LIBCPP_HAS_EXCEPTIONS
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}
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});
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auto __mapped_it = __map.__containers_.values.emplace(__it_mapped, std::forward<_MArgs>(__mapped_args)...);
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__on_value_failed.__complete();
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return typename _Map::iterator(std::move(__key_it), std::move(__mapped_it));
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}
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// TODO: We could optimize this, see
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// https://github.com/llvm/llvm-project/issues/108624
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template <class _Map, class _InputIterator, class _Sentinel>
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_LIBCPP_HIDE_FROM_ABI static typename _Map::size_type
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__append(_Map& __map, _InputIterator __first, _Sentinel __last) {
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typename _Map::size_type __num_appended = 0;
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for (; __first != __last; ++__first) {
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typename _Map::value_type __kv = *__first;
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__map.__containers_.keys.insert(__map.__containers_.keys.end(), std::move(__kv.first));
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__map.__containers_.values.insert(__map.__containers_.values.end(), std::move(__kv.second));
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++__num_appended;
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}
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return __num_appended;
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}
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};
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP_STD_VER >= 23
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_LIBCPP_POP_MACROS
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#endif // #define _LIBCPP___FLAT_MAP_UTILS_H
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