libstdc++-v3/include/experimental/iterator

// <experimental/iterator> -*- C++ -*-

// Copyright (C) 2015-2026 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/** @file experimental/iterator
 *  This is a TS C++ Library header.
 *  @ingroup libfund-ts
 */

//
// N4336 Working Draft, C++ Extensions for Library Fundamentals, Version 2
//

#ifndef _GLIBCXX_EXPERIMENTAL_ITERATOR
#define _GLIBCXX_EXPERIMENTAL_ITERATOR 1

#ifdef _GLIBCXX_SYSHDR
#pragma GCC system_header
#endif

#include <bits/requires_hosted.h> // experimental is currently omitted

#if __cplusplus >= 201402L

#include <iterator>
#include <iosfwd>
#include <experimental/type_traits>

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

namespace experimental
{
inline namespace fundamentals_v2
{
#define __cpp_lib_experimental_ostream_joiner 201411

  /// Output iterator that inserts a delimiter between elements.
  template<typename _DelimT, typename _CharT = char,
	   typename _Traits = char_traits<_CharT>>
  class ostream_joiner
  {
  public:
    typedef _CharT				char_type;
    typedef _Traits				traits_type;
    typedef basic_ostream<_CharT, _Traits>	ostream_type;
    typedef output_iterator_tag			iterator_category;
    typedef void				value_type;
    typedef void				difference_type;
    typedef void				pointer;
    typedef void				reference;

    ostream_joiner(ostream_type& __os, const _DelimT& __delimiter)
    noexcept(is_nothrow_copy_constructible_v<_DelimT>)
    : _M_out(std::__addressof(__os)), _M_delim(__delimiter)
    { }

    ostream_joiner(ostream_type& __os, _DelimT&& __delimiter)
    noexcept(is_nothrow_move_constructible_v<_DelimT>)
    : _M_out(std::__addressof(__os)), _M_delim(std::move(__delimiter))
    { }

    template<typename _Tp>
      ostream_joiner&
      operator=(const _Tp& __value)
      {
	if (!_M_first)
	  *_M_out << _M_delim;
	_M_first = false;
	*_M_out << __value;
	return *this;
      }

    ostream_joiner& operator*() noexcept { return *this; }
    ostream_joiner& operator++() noexcept { return *this; }
    ostream_joiner& operator++(int) noexcept { return *this; }

  private:
    ostream_type* _M_out;
    _DelimT _M_delim;
    bool _M_first = true;
  };

  /// Object generator for ostream_joiner.
  template<typename _CharT, typename _Traits, typename _DelimT>
    inline ostream_joiner<decay_t<_DelimT>, _CharT, _Traits>
    make_ostream_joiner(basic_ostream<_CharT, _Traits>& __os,
			_DelimT&& __delimiter)
    { return { __os, std::forward<_DelimT>(__delimiter) }; }
} // namespace fundamentals_v2
} // namespace experimental

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std

#endif // __cplusplus <= 201103L

#endif // _GLIBCXX_EXPERIMENTAL_ITERATOR