50 lines
1.2 KiB
C
50 lines
1.2 KiB
C
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/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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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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* http://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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*/
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#pragma once
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#include <type_traits>
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#include <folly/Traits.h>
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namespace folly {
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namespace detail {
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struct DefaultTag {};
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template <typename T>
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struct DefaultMake {
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struct Heap {
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std::unique_ptr<T> ptr{std::make_unique<T>()};
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/* implicit */ operator T&() {
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return *ptr;
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}
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};
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using is_returnable = StrictDisjunction<
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bool_constant<__cplusplus >= 201703ULL>,
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std::is_copy_constructible<T>,
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std::is_move_constructible<T>>;
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using type = std::conditional_t<is_returnable::value, T, Heap>;
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type operator()() const {
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return type();
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}
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};
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} // namespace detail
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} // namespace folly
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