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156ab87500
See: * https://discourse.llvm.org/t/rfc-freezing-c-03-headers-in-libc/77319 * https://discourse.llvm.org/t/rfc-project-hand-in-hand-llvm-libc-libc-code-sharing/77701 We're dropping support for C++03 for Zig due to the first change; it would be insane to ship 1018 duplicate header files just for this outdated use case. As a result of the second change, I had to bring in a subset of the headers from llvm-libc since libc++ now depends on these. Hopefully we can continue to get away with not copying the entirety of llvm-libc.
71 lines
2.8 KiB
C++
Vendored
71 lines
2.8 KiB
C++
Vendored
//===----------------------------------------------------------------------===//
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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___PSTL_DISPATCH_H
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#define _LIBCPP___PSTL_DISPATCH_H
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#include <__config>
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#include <__pstl/backend_fwd.h>
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#include <__type_traits/conditional.h>
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#include <__type_traits/enable_if.h>
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#include <__type_traits/integral_constant.h>
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#include <__type_traits/type_identity.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_PUSH_MACROS
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#include <__undef_macros>
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#if _LIBCPP_STD_VER >= 17
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_LIBCPP_BEGIN_NAMESPACE_STD
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namespace __pstl {
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template <template <class, class> class _Algorithm, class _Backend, class _ExecutionPolicy, class = void>
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constexpr bool __is_implemented_v = false;
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template <template <class, class> class _Algorithm, class _Backend, class _ExecutionPolicy>
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constexpr bool __is_implemented_v<_Algorithm,
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_Backend,
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_ExecutionPolicy,
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__enable_if_t<sizeof(_Algorithm<_Backend, _ExecutionPolicy>)>> = true;
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// Helpful to provide better error messages. This will show the algorithm and the execution policy
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// in the compiler diagnostic.
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template <template <class, class> class _Algorithm, class _ExecutionPolicy>
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constexpr bool __cant_find_backend_for = false;
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template <template <class, class> class _Algorithm, class _BackendConfiguration, class _ExecutionPolicy>
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struct __find_first_implemented;
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template <template <class, class> class _Algorithm, class _ExecutionPolicy>
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struct __find_first_implemented<_Algorithm, __backend_configuration<>, _ExecutionPolicy> {
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static_assert(__cant_find_backend_for<_Algorithm, _ExecutionPolicy>,
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"Could not find a PSTL backend for the given algorithm and execution policy");
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};
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template <template <class, class> class _Algorithm, class _B1, class... _Bn, class _ExecutionPolicy>
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struct __find_first_implemented<_Algorithm, __backend_configuration<_B1, _Bn...>, _ExecutionPolicy>
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: _If<__is_implemented_v<_Algorithm, _B1, _ExecutionPolicy>,
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__type_identity<_Algorithm<_B1, _ExecutionPolicy>>,
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__find_first_implemented<_Algorithm, __backend_configuration<_Bn...>, _ExecutionPolicy> > {};
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template <template <class, class> class _Algorithm, class _BackendConfiguration, class _ExecutionPolicy>
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using __dispatch _LIBCPP_NODEBUG =
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typename __find_first_implemented<_Algorithm, _BackendConfiguration, _ExecutionPolicy>::type;
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} // namespace __pstl
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP_STD_VER >= 17
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP___PSTL_DISPATCH_H
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