mirror of
https://github.com/jart/cosmopolitan.git
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141 lines
4.7 KiB
C++
141 lines
4.7 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___RANGES_ISTREAM_VIEW_H
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#define _LIBCPP___RANGES_ISTREAM_VIEW_H
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#include <__concepts/constructible.h>
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#include <__concepts/derived_from.h>
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#include <__concepts/movable.h>
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#include <__config>
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#include <__fwd/istream.h>
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#include <__fwd/string.h>
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#include <__iterator/default_sentinel.h>
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#include <__iterator/iterator_traits.h>
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#include <__memory/addressof.h>
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#include <__ranges/view_interface.h>
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#include <__type_traits/remove_cvref.h>
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#include <__utility/forward.h>
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#include <cstddef>
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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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#if _LIBCPP_STD_VER >= 20
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_LIBCPP_BEGIN_NAMESPACE_STD
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namespace ranges {
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template <class _Val, class _CharT, class _Traits>
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concept __stream_extractable = requires(basic_istream<_CharT, _Traits>& __is, _Val& __t) { __is >> __t; };
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template <movable _Val, class _CharT, class _Traits = char_traits<_CharT>>
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requires default_initializable<_Val> && __stream_extractable<_Val, _CharT, _Traits>
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class basic_istream_view : public view_interface<basic_istream_view<_Val, _CharT, _Traits>> {
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class __iterator;
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public:
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_LIBCPP_HIDE_FROM_ABI constexpr explicit basic_istream_view(basic_istream<_CharT, _Traits>& __stream)
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: __stream_(std::addressof(__stream)) {}
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_LIBCPP_HIDE_FROM_ABI constexpr auto begin() {
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*__stream_ >> __value_;
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return __iterator{*this};
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}
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_LIBCPP_HIDE_FROM_ABI constexpr default_sentinel_t end() const noexcept { return default_sentinel; }
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private:
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basic_istream<_CharT, _Traits>* __stream_;
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_LIBCPP_NO_UNIQUE_ADDRESS _Val __value_ = _Val();
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};
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template <movable _Val, class _CharT, class _Traits>
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requires default_initializable<_Val> && __stream_extractable<_Val, _CharT, _Traits>
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class basic_istream_view<_Val, _CharT, _Traits>::__iterator {
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public:
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using iterator_concept = input_iterator_tag;
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using difference_type = ptrdiff_t;
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using value_type = _Val;
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_LIBCPP_HIDE_FROM_ABI constexpr explicit __iterator(basic_istream_view<_Val, _CharT, _Traits>& __parent) noexcept
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: __parent_(std::addressof(__parent)) {}
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__iterator(const __iterator&) = delete;
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_LIBCPP_HIDE_FROM_ABI __iterator(__iterator&&) = default;
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__iterator& operator=(const __iterator&) = delete;
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_LIBCPP_HIDE_FROM_ABI __iterator& operator=(__iterator&&) = default;
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_LIBCPP_HIDE_FROM_ABI __iterator& operator++() {
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*__parent_->__stream_ >> __parent_->__value_;
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return *this;
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}
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_LIBCPP_HIDE_FROM_ABI void operator++(int) { ++*this; }
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_LIBCPP_HIDE_FROM_ABI _Val& operator*() const { return __parent_->__value_; }
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_LIBCPP_HIDE_FROM_ABI friend bool operator==(const __iterator& __x, default_sentinel_t) {
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return !*__x.__get_parent_stream();
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}
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private:
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basic_istream_view<_Val, _CharT, _Traits>* __parent_;
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_LIBCPP_HIDE_FROM_ABI constexpr basic_istream<_CharT, _Traits>* __get_parent_stream() const {
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return __parent_->__stream_;
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}
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};
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template <class _Val>
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using istream_view = basic_istream_view<_Val, char>;
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# ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
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template <class _Val>
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using wistream_view = basic_istream_view<_Val, wchar_t>;
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# endif
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namespace views {
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namespace __istream {
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// clang-format off
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template <class _Tp>
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struct __fn {
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template <class _Up, class _UnCVRef = remove_cvref_t<_Up>>
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requires derived_from<_UnCVRef, basic_istream<typename _UnCVRef::char_type,
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typename _UnCVRef::traits_type>>
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_LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Up&& __u) const
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noexcept(noexcept(basic_istream_view<_Tp, typename _UnCVRef::char_type,
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typename _UnCVRef::traits_type>(std::forward<_Up>(__u))))
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-> decltype( basic_istream_view<_Tp, typename _UnCVRef::char_type,
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typename _UnCVRef::traits_type>(std::forward<_Up>(__u)))
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{ return basic_istream_view<_Tp, typename _UnCVRef::char_type,
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typename _UnCVRef::traits_type>(std::forward<_Up>(__u));
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}
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};
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// clang-format on
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} // namespace __istream
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inline namespace __cpo {
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template <class _Tp>
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inline constexpr auto istream = __istream::__fn<_Tp>{};
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} // namespace __cpo
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} // namespace views
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} // namespace ranges
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP_STD_VER >= 20
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#endif // _LIBCPP___RANGES_ISTREAM_VIEW_H
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