// Copyright 2021 The Chromium Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #ifndef BASE_CONTAINERS_CXX20_ERASE_FORWARD_LIST_H_ #define BASE_CONTAINERS_CXX20_ERASE_FORWARD_LIST_H_ #include #include namespace base { // Erase/EraseIf are based on C++20's uniform container erasure API: // - https://eel.is/c++draft/libraryindex#:erase // - https://eel.is/c++draft/libraryindex#:erase_if // They provide a generic way to erase elements from a container. // The functions here implement these for the standard containers until those // functions are available in the C++ standard. // Note: there is no std::erase for standard associative containers so we don't // have it either. template size_t EraseIf(std::forward_list& container, Predicate pred) { // Note: std::forward_list does not have a size() API, thus we need to use the // O(n) std::distance work-around. However, given that EraseIf is O(n) // already, this should not make a big difference. size_t old_size = std::distance(container.begin(), container.end()); container.remove_if(pred); return old_size - std::distance(container.begin(), container.end()); } template size_t Erase(std::forward_list& container, const Value& value) { // Unlike std::forward_list::remove, this function template accepts // heterogeneous types and does not force a conversion to the container's // value type before invoking the == operator. return EraseIf(container, [&](const T& cur) { return cur == value; }); } } // namespace base #endif // BASE_CONTAINERS_CXX20_ERASE_FORWARD_LIST_H_