forked from OSchip/llvm-project
Implement an _is_allocator type trait for use in deduction guides.
llvm-svn: 322306
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@ -5597,6 +5597,16 @@ struct __temp_value {
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};
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#endif
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#if _LIBCPP_STD_VER > 14
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template<typename _Alloc, typename = void>
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struct __is_allocator : false_type {};
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template<typename _Alloc>
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struct __is_allocator<_Alloc,
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void_t<typename _Alloc::value_type, decltype(_VSTD::declval<_Alloc&>().allocate(size_t{}))>>
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: true_type {};
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#endif
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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@ -0,0 +1,41 @@
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//===----------------------------------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is dual licensed under the MIT and the University of Illinois Open
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// Source Licenses. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// <memory>
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// UNSUPPORTED: c++98, c++03, c++11, c++14
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// template<typename _Alloc>
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// struct __is_allocator;
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// Is either true_type or false_type depending on if A is an allocator.
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#include <memory>
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#include <string>
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#include "test_macros.h"
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#include "min_allocator.h"
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#include "test_allocator.h"
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template <typename T>
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void test_allocators()
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{
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static_assert( std::__is_allocator<std::allocator<T>>::value, "" );
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static_assert( std::__is_allocator<test_allocator<T>>::value, "" );
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static_assert( std::__is_allocator<min_allocator<T>>::value, "" );
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}
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int main()
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{
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// test_allocators<void>();
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test_allocators<char>();
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test_allocators<int>();
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test_allocators<std::string>();
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}
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