75 lines
2.9 KiB
C++
75 lines
2.9 KiB
C++
//===----------------------------------------------------------------------===//
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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___CXX03___ALGORITHM_MAKE_PROJECTED_H
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#define _LIBCPP___CXX03___ALGORITHM_MAKE_PROJECTED_H
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#include <__cxx03/__config>
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#include <__cxx03/__functional/identity.h>
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#include <__cxx03/__type_traits/decay.h>
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#include <__cxx03/__type_traits/enable_if.h>
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#include <__cxx03/__type_traits/integral_constant.h>
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#include <__cxx03/__type_traits/invoke.h>
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#include <__cxx03/__type_traits/is_member_pointer.h>
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#include <__cxx03/__type_traits/is_same.h>
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#include <__cxx03/__utility/declval.h>
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#include <__cxx03/__utility/forward.h>
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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_BEGIN_NAMESPACE_STD
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template <class _Pred, class _Proj>
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struct _ProjectedPred {
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_Pred& __pred; // Can be a unary or a binary predicate.
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_Proj& __proj;
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_LIBCPP_HIDE_FROM_ABI _ProjectedPred(_Pred& __pred_arg, _Proj& __proj_arg) : __pred(__pred_arg), __proj(__proj_arg) {}
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template <class _Tp>
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typename __invoke_of<_Pred&, decltype(std::__invoke(std::declval<_Proj&>(), std::declval<_Tp>()))>::type
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_LIBCPP_HIDE_FROM_ABI
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operator()(_Tp&& __v) const {
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return std::__invoke(__pred, std::__invoke(__proj, std::forward<_Tp>(__v)));
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}
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template <class _T1, class _T2>
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typename __invoke_of<_Pred&,
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decltype(std::__invoke(std::declval<_Proj&>(), std::declval<_T1>())),
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decltype(std::__invoke(std::declval<_Proj&>(), std::declval<_T2>()))>::type _LIBCPP_HIDE_FROM_ABI
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operator()(_T1&& __lhs, _T2&& __rhs) const {
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return std::__invoke(
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__pred, std::__invoke(__proj, std::forward<_T1>(__lhs)), std::__invoke(__proj, std::forward<_T2>(__rhs)));
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}
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};
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template <
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class _Pred,
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class _Proj,
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__enable_if_t<!(!is_member_pointer<__decay_t<_Pred> >::value && __is_identity<__decay_t<_Proj> >::value), int> = 0>
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_LIBCPP_HIDE_FROM_ABI _ProjectedPred<_Pred, _Proj> __make_projected(_Pred& __pred, _Proj& __proj) {
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return _ProjectedPred<_Pred, _Proj>(__pred, __proj);
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}
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// Avoid creating the functor and just use the pristine comparator -- for certain algorithms, this would enable
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// optimizations that rely on the type of the comparator. Additionally, this results in less layers of indirection in
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// the call stack when the comparator is invoked, even in an unoptimized build.
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template <
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class _Pred,
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class _Proj,
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__enable_if_t<!is_member_pointer<__decay_t<_Pred> >::value && __is_identity<__decay_t<_Proj> >::value, int> = 0>
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_LIBCPP_HIDE_FROM_ABI _Pred& __make_projected(_Pred& __pred, _Proj&) {
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return __pred;
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}
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___CXX03___ALGORITHM_MAKE_PROJECTED_H
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