65 lines
1.8 KiB
C
65 lines
1.8 KiB
C
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/*
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* Copyright (c) 2021 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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// This implementation is borrowed from Chromium.
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#ifndef RTC_BASE_CONTAINERS_NOT_FN_H_
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#define RTC_BASE_CONTAINERS_NOT_FN_H_
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#include <type_traits>
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#include <utility>
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#include "rtc_base/containers/invoke.h"
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namespace webrtc {
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namespace not_fn_internal {
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template <typename F>
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struct NotFnImpl {
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F f;
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template <typename... Args>
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constexpr decltype(auto) operator()(Args&&... args) & noexcept {
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return !webrtc::invoke(f, std::forward<Args>(args)...);
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}
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template <typename... Args>
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constexpr decltype(auto) operator()(Args&&... args) const& noexcept {
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return !webrtc::invoke(f, std::forward<Args>(args)...);
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}
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template <typename... Args>
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constexpr decltype(auto) operator()(Args&&... args) && noexcept {
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return !webrtc::invoke(std::move(f), std::forward<Args>(args)...);
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}
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template <typename... Args>
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constexpr decltype(auto) operator()(Args&&... args) const&& noexcept {
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return !webrtc::invoke(std::move(f), std::forward<Args>(args)...);
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}
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};
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} // namespace not_fn_internal
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// Implementation of C++17's std::not_fn.
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//
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// Reference:
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// - https://en.cppreference.com/w/cpp/utility/functional/not_fn
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// - https://wg21.link/func.not.fn
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template <typename F>
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constexpr not_fn_internal::NotFnImpl<std::decay_t<F>> not_fn(F&& f) {
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return {std::forward<F>(f)};
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}
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} // namespace webrtc
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#endif // RTC_BASE_CONTAINERS_NOT_FN_H_
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