fc8dc48020
git-subtree-dir: third_party/abseil_cpp git-subtree-mainline:ffb2ae54begit-subtree-split:768eb2ca28
95 lines
3.6 KiB
C++
95 lines
3.6 KiB
C++
// Copyright 2018 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Implementation details for `absl::bind_front()`.
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#ifndef ABSL_FUNCTIONAL_INTERNAL_FRONT_BINDER_H_
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#define ABSL_FUNCTIONAL_INTERNAL_FRONT_BINDER_H_
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#include <cstddef>
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#include <type_traits>
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#include <utility>
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#include "absl/base/internal/invoke.h"
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#include "absl/container/internal/compressed_tuple.h"
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#include "absl/meta/type_traits.h"
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#include "absl/utility/utility.h"
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namespace absl {
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ABSL_NAMESPACE_BEGIN
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namespace functional_internal {
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// Invoke the method, expanding the tuple of bound arguments.
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template <class R, class Tuple, size_t... Idx, class... Args>
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R Apply(Tuple&& bound, absl::index_sequence<Idx...>, Args&&... free) {
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return base_internal::Invoke(
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absl::forward<Tuple>(bound).template get<Idx>()...,
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absl::forward<Args>(free)...);
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}
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template <class F, class... BoundArgs>
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class FrontBinder {
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using BoundArgsT = absl::container_internal::CompressedTuple<F, BoundArgs...>;
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using Idx = absl::make_index_sequence<sizeof...(BoundArgs) + 1>;
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BoundArgsT bound_args_;
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public:
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template <class... Ts>
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constexpr explicit FrontBinder(absl::in_place_t, Ts&&... ts)
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: bound_args_(absl::forward<Ts>(ts)...) {}
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template <class... FreeArgs,
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class R = base_internal::InvokeT<F&, BoundArgs&..., FreeArgs&&...>>
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R operator()(FreeArgs&&... free_args) & {
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return functional_internal::Apply<R>(bound_args_, Idx(),
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absl::forward<FreeArgs>(free_args)...);
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}
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template <class... FreeArgs,
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class R = base_internal::InvokeT<const F&, const BoundArgs&...,
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FreeArgs&&...>>
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R operator()(FreeArgs&&... free_args) const& {
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return functional_internal::Apply<R>(bound_args_, Idx(),
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absl::forward<FreeArgs>(free_args)...);
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}
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template <class... FreeArgs, class R = base_internal::InvokeT<
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F&&, BoundArgs&&..., FreeArgs&&...>>
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R operator()(FreeArgs&&... free_args) && {
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// This overload is called when *this is an rvalue. If some of the bound
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// arguments are stored by value or rvalue reference, we move them.
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return functional_internal::Apply<R>(absl::move(bound_args_), Idx(),
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absl::forward<FreeArgs>(free_args)...);
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}
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template <class... FreeArgs,
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class R = base_internal::InvokeT<const F&&, const BoundArgs&&...,
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FreeArgs&&...>>
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R operator()(FreeArgs&&... free_args) const&& {
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// This overload is called when *this is an rvalue. If some of the bound
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// arguments are stored by value or rvalue reference, we move them.
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return functional_internal::Apply<R>(absl::move(bound_args_), Idx(),
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absl::forward<FreeArgs>(free_args)...);
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}
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};
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template <class F, class... BoundArgs>
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using bind_front_t = FrontBinder<decay_t<F>, absl::decay_t<BoundArgs>...>;
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} // namespace functional_internal
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ABSL_NAMESPACE_END
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} // namespace absl
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#endif // ABSL_FUNCTIONAL_INTERNAL_FRONT_BINDER_H_
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