42 lines
1 KiB
C
42 lines
1 KiB
C
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// Copyright (c) 2013 GitHub, Inc. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef ATOM_COMMON_SWAP_OR_ASSIGN_H_
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#define ATOM_COMMON_SWAP_OR_ASSIGN_H_
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namespace internal {
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// Helper to detect whether value has specified method.
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template <typename T>
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class HasSwapMethod {
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typedef char one;
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typedef long two;
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template <typename C> static one test(char[sizeof(&C::swap)]) ;
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template <typename C> static two test(...);
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public:
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enum { value = sizeof(test<T>(0)) == sizeof(char) };
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};
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template<bool B, class T = void>
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struct enable_if {};
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template<class T>
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struct enable_if<true, T> { typedef T type; };
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template<typename T>
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typename enable_if<HasSwapMethod<T>::value>::type SwapOrAssign(
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T& v1, const T& v2) {
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v1.swap(const_cast<T&>(v2));
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}
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template<typename T>
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typename enable_if<!HasSwapMethod<T>::value>::type SwapOrAssign(
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T& v1, const T& v2) {
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v1 = v2;
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}
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} // namespace internal
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#endif // ATOM_COMMON_SWAP_OR_ASSIGN_H_
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