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124 lines
2.9 KiB
C++
124 lines
2.9 KiB
C++
/// \file
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// Range v3 library
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//
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// Copyright Eric Niebler 2013-present
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//
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// Use, modification and distribution is subject to the
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// Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//
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// Project home: https://github.com/ericniebler/range-v3
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//
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#ifndef RANGES_V3_VIEW_ISTREAM_HPP
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#define RANGES_V3_VIEW_ISTREAM_HPP
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#include <istream>
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#include <range/v3/range_fwd.hpp>
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#include <range/v3/iterator/default_sentinel.hpp>
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#include <range/v3/utility/semiregular_box.hpp>
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#include <range/v3/utility/static_const.hpp>
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#include <range/v3/view/facade.hpp>
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#include <range/v3/detail/prologue.hpp>
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namespace ranges
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{
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/// \addtogroup group-views
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/// @{
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template<typename Val>
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struct istream_view : view_facade<istream_view<Val>, unknown>
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{
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private:
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friend range_access;
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std::istream * sin_;
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semiregular_box_t<Val> obj_;
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struct cursor
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{
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private:
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friend range_access;
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using single_pass = std::true_type;
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istream_view * rng_ = nullptr;
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public:
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cursor() = default;
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explicit cursor(istream_view * rng)
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: rng_(rng)
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{}
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void next()
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{
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rng_->next();
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}
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Val & read() const noexcept
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{
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return rng_->cached();
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}
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bool equal(default_sentinel_t) const
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{
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return !rng_->sin_;
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}
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bool equal(cursor that) const
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{
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return !rng_->sin_ == !that.rng_->sin_;
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}
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};
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void next()
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{
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if(!(*sin_ >> cached()))
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sin_ = nullptr;
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}
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cursor begin_cursor()
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{
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return cursor{this};
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}
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public:
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istream_view() = default;
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explicit istream_view(std::istream & sin)
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: sin_(&sin)
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, obj_{}
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{
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next(); // prime the pump
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}
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Val & cached() noexcept
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{
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return obj_;
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}
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};
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/// \cond
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template<typename Val>
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using istream_range RANGES_DEPRECATED(
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"istream_range<T> has been renamed to istream_view<T>") = istream_view<Val>;
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/// \endcond
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/// \cond
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namespace _istream_
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{
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/// \endcond
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template(typename Val)(
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requires copy_constructible<Val> AND default_constructible<Val>)
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inline istream_view<Val> istream(std::istream & sin)
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{
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return istream_view<Val>{sin};
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}
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/// \cond
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} // namespace _istream_
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using namespace _istream_;
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/// \endcond
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namespace cpp20
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{
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template<typename Val>
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using basic_istream_view = ::ranges::istream_view<Val>;
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} // namespace cpp20
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/// @}
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} // namespace ranges
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#include <range/v3/detail/epilogue.hpp>
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#endif
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