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258 lines
7.5 KiB
258 lines
7.5 KiB
// Stream iterators
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// Copyright (C) 2001-2021 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/** @file bits/stream_iterator.h
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* This is an internal header file, included by other library headers.
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* Do not attempt to use it directly. @headername{iterator}
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*/
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#ifndef _STREAM_ITERATOR_H
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#define _STREAM_ITERATOR_H 1
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#pragma GCC system_header
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#include <debug/debug.h>
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namespace std _GLIBCXX_VISIBILITY(default)
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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/**
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* @addtogroup iterators
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* @{
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*/
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/// Provides input iterator semantics for streams.
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template<typename _Tp, typename _CharT = char,
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typename _Traits = char_traits<_CharT>, typename _Dist = ptrdiff_t>
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class istream_iterator
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: public iterator<input_iterator_tag, _Tp, _Dist, const _Tp*, const _Tp&>
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{
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public:
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typedef _CharT char_type;
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typedef _Traits traits_type;
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typedef basic_istream<_CharT, _Traits> istream_type;
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private:
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istream_type* _M_stream;
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_Tp _M_value;
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// This bool becomes false at end-of-stream. It should be sufficient to
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// check _M_stream != nullptr instead, but historically we did not set
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// _M_stream to null when reaching the end, so we need to keep this flag.
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bool _M_ok;
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public:
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/// Construct end of input stream iterator.
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_GLIBCXX_CONSTEXPR istream_iterator()
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: _M_stream(0), _M_value(), _M_ok(false) {}
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/// Construct start of input stream iterator.
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istream_iterator(istream_type& __s)
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: _M_stream(std::__addressof(__s)), _M_ok(true)
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{ _M_read(); }
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istream_iterator(const istream_iterator& __obj)
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: _M_stream(__obj._M_stream), _M_value(__obj._M_value),
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_M_ok(__obj._M_ok)
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{ }
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#if __cplusplus > 201703L && __cpp_lib_concepts
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constexpr
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istream_iterator(default_sentinel_t)
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noexcept(is_nothrow_default_constructible_v<_Tp>)
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: istream_iterator() { }
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#endif
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#if __cplusplus >= 201103L
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istream_iterator& operator=(const istream_iterator&) = default;
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~istream_iterator() = default;
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#endif
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const _Tp&
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operator*() const
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{
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__glibcxx_requires_cond(_M_ok,
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_M_message(__gnu_debug::__msg_deref_istream)
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._M_iterator(*this));
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return _M_value;
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}
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const _Tp*
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operator->() const { return std::__addressof((operator*())); }
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istream_iterator&
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operator++()
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{
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__glibcxx_requires_cond(_M_ok,
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_M_message(__gnu_debug::__msg_inc_istream)
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._M_iterator(*this));
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_M_read();
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return *this;
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}
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istream_iterator
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operator++(int)
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{
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__glibcxx_requires_cond(_M_ok,
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_M_message(__gnu_debug::__msg_inc_istream)
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._M_iterator(*this));
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istream_iterator __tmp = *this;
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_M_read();
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return __tmp;
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}
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private:
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bool
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_M_equal(const istream_iterator& __x) const
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{
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// Ideally this would just return _M_stream == __x._M_stream,
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// but code compiled with old versions never sets _M_stream to null.
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return (_M_ok == __x._M_ok) && (!_M_ok || _M_stream == __x._M_stream);
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}
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void
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_M_read()
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{
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if (_M_stream && !(*_M_stream >> _M_value))
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{
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_M_stream = 0;
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_M_ok = false;
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}
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}
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/// Return true if the iterators refer to the same stream,
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/// or are both at end-of-stream.
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friend bool
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operator==(const istream_iterator& __x, const istream_iterator& __y)
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{ return __x._M_equal(__y); }
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/// Return true if the iterators refer to different streams,
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/// or if one is at end-of-stream and the other is not.
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friend bool
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operator!=(const istream_iterator& __x, const istream_iterator& __y)
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{ return !__x._M_equal(__y); }
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#if __cplusplus > 201703L && __cpp_lib_concepts
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friend bool
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operator==(const istream_iterator& __i, default_sentinel_t)
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{ return !__i._M_stream; }
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#endif
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};
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/**
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* @brief Provides output iterator semantics for streams.
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*
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* This class provides an iterator to write to an ostream. The type Tp is
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* the only type written by this iterator and there must be an
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* operator<<(Tp) defined.
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*
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* @tparam _Tp The type to write to the ostream.
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* @tparam _CharT The ostream char_type.
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* @tparam _Traits The ostream char_traits.
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*/
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template<typename _Tp, typename _CharT = char,
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typename _Traits = char_traits<_CharT> >
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class ostream_iterator
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: public iterator<output_iterator_tag, void, void, void, void>
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{
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public:
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///@{
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/// Public typedef
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#if __cplusplus > 201703L
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using difference_type = ptrdiff_t;
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#endif
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typedef _CharT char_type;
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typedef _Traits traits_type;
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typedef basic_ostream<_CharT, _Traits> ostream_type;
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///@}
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private:
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ostream_type* _M_stream;
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const _CharT* _M_string;
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public:
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#if __cplusplus > 201703L
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constexpr ostream_iterator() noexcept
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: _M_stream(nullptr), _M_string(nullptr) { }
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#endif
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/// Construct from an ostream.
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ostream_iterator(ostream_type& __s)
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: _M_stream(std::__addressof(__s)), _M_string(0) {}
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/**
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* Construct from an ostream.
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*
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* The delimiter string @a c is written to the stream after every Tp
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* written to the stream. The delimiter is not copied, and thus must
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* not be destroyed while this iterator is in use.
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*
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* @param __s Underlying ostream to write to.
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* @param __c CharT delimiter string to insert.
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*/
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ostream_iterator(ostream_type& __s, const _CharT* __c)
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: _M_stream(std::__addressof(__s)), _M_string(__c) { }
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/// Copy constructor.
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ostream_iterator(const ostream_iterator& __obj)
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: _M_stream(__obj._M_stream), _M_string(__obj._M_string) { }
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#if __cplusplus >= 201103L
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ostream_iterator& operator=(const ostream_iterator&) = default;
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#endif
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/// Writes @a value to underlying ostream using operator<<. If
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/// constructed with delimiter string, writes delimiter to ostream.
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ostream_iterator&
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operator=(const _Tp& __value)
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{
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__glibcxx_requires_cond(_M_stream != 0,
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_M_message(__gnu_debug::__msg_output_ostream)
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._M_iterator(*this));
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*_M_stream << __value;
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if (_M_string)
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*_M_stream << _M_string;
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return *this;
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}
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ostream_iterator&
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operator*()
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{ return *this; }
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ostream_iterator&
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operator++()
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{ return *this; }
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ostream_iterator&
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operator++(int)
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{ return *this; }
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};
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/// @} group iterators
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_GLIBCXX_END_NAMESPACE_VERSION
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} // namespace
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#endif
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