57 lines
1.7 KiB
C++
57 lines
1.7 KiB
C++
// -*- C++ -*-
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//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___ITERATOR_FUNCTION_LIKE_H
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#define _LIBCPP___ITERATOR_FUNCTION_LIKE_H
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#include <__config>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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#pragma GCC system_header
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#endif
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_LIBCPP_PUSH_MACROS
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#include <__undef_macros>
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_LIBCPP_BEGIN_NAMESPACE_STD
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#if !defined(_LIBCPP_HAS_NO_RANGES)
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namespace ranges {
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// Per [range.iter.ops.general] and [algorithms.requirements], functions in namespace std::ranges
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// can't be found by ADL and inhibit ADL when found by unqualified lookup. The easiest way to
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// facilitate this is to use function objects.
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//
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// Since these are still standard library functions, we use `__function_like` to eliminate most of
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// the properties that function objects get by default (e.g. semiregularity, addressability), to
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// limit the surface area of the unintended public interface, so as to curb the effect of Hyrum's
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// law.
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struct __function_like {
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__function_like() = delete;
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__function_like(__function_like const&) = delete;
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__function_like& operator=(__function_like const&) = delete;
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void operator&() const = delete;
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struct __tag { };
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protected:
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constexpr explicit __function_like(__tag) noexcept {}
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~__function_like() = default;
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};
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} // namespace ranges
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#endif // !defined(_LIBCPP_HAS_NO_RANGES)
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP___ITERATOR_FUNCTION_LIKE_H
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