<?xml version="1.0" encoding="utf-8" ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta name="generator" content="Docutils 0.5: http://docutils.sourceforge.net/" /> <title>Function Output Iterator</title> <meta name="author" content="David Abrahams, Jeremy Siek, Thomas Witt" /> <meta name="organization" content="Boost Consulting, Indiana University Open Systems Lab, University of Hanover Institute for Transport Railway Operation and Construction" /> <meta name="date" content="2006-09-11" /> <meta name="copyright" content="Copyright David Abrahams, Jeremy Siek, and Thomas Witt 2003." /> <link rel="stylesheet" href="../../../rst.css" type="text/css" /> </head> <body> <div class="document" id="function-output-iterator"> <h1 class="title">Function Output Iterator</h1> <table class="docinfo" frame="void" rules="none"> <col class="docinfo-name" /> <col class="docinfo-content" /> <tbody valign="top"> <tr><th class="docinfo-name">Author:</th> <td>David Abrahams, Jeremy Siek, Thomas Witt</td></tr> <tr><th class="docinfo-name">Contact:</th> <td><a class="first reference external" href="mailto:dave@boost-consulting.com">dave@boost-consulting.com</a>, <a class="reference external" href="mailto:jsiek@osl.iu.edu">jsiek@osl.iu.edu</a>, <a class="last reference external" href="mailto:witt@ive.uni-hannover.de">witt@ive.uni-hannover.de</a></td></tr> <tr><th class="docinfo-name">Organization:</th> <td><a class="first reference external" href="http://www.boost-consulting.com">Boost Consulting</a>, Indiana University <a class="reference external" href="http://www.osl.iu.edu">Open Systems Lab</a>, University of Hanover <a class="last reference external" href="http://www.ive.uni-hannover.de">Institute for Transport Railway Operation and Construction</a></td></tr> <tr><th class="docinfo-name">Date:</th> <td>2006-09-11</td></tr> <tr><th class="docinfo-name">Copyright:</th> <td>Copyright David Abrahams, Jeremy Siek, and Thomas Witt 2003.</td></tr> </tbody> </table> <!-- Distributed under the Boost --> <!-- Software License, Version 1.0. (See accompanying --> <!-- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) --> <table class="docutils field-list" frame="void" rules="none"> <col class="field-name" /> <col class="field-body" /> <tbody valign="top"> <tr class="field"><th class="field-name">abstract:</th><td class="field-body"><!-- Copyright David Abrahams 2006. Distributed under the Boost --> <!-- Software License, Version 1.0. (See accompanying --> <!-- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) --> The function output iterator adaptor makes it easier to create custom output iterators. The adaptor takes a unary function and creates a model of Output Iterator. Each item assigned to the output iterator is passed as an argument to the unary function. The motivation for this iterator is that creating a conforming output iterator is non-trivial, particularly because the proper implementation usually requires a proxy object.</td> </tr> </tbody> </table> <div class="contents topic" id="table-of-contents"> <p class="topic-title first">Table of Contents</p> <ul class="simple"> <li><a class="reference internal" href="#header" id="id1">Header</a></li> <li><a class="reference internal" href="#function-output-iterator-requirements" id="id2"><tt class="docutils literal"><span class="pre">function_output_iterator</span></tt> requirements</a></li> <li><a class="reference internal" href="#function-output-iterator-models" id="id3"><tt class="docutils literal"><span class="pre">function_output_iterator</span></tt> models</a></li> <li><a class="reference internal" href="#function-output-iterator-operations" id="id4"><tt class="docutils literal"><span class="pre">function_output_iterator</span></tt> operations</a></li> <li><a class="reference internal" href="#example" id="id5">Example</a></li> </ul> </div> <!-- Copyright David Abrahams 2006. Distributed under the Boost --> <!-- Software License, Version 1.0. (See accompanying --> <!-- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) --> <div class="section" id="header"> <h1><a class="toc-backref" href="#id1">Header</a></h1> <pre class="literal-block"> #include <boost/function_output_iterator.hpp> </pre> <pre class="literal-block"> template <class UnaryFunction> class function_output_iterator { public: typedef std::output_iterator_tag iterator_category; typedef void value_type; typedef void difference_type; typedef void pointer; typedef void reference; explicit function_output_iterator(); explicit function_output_iterator(const UnaryFunction& f); /* see below */ operator*(); function_output_iterator& operator++(); function_output_iterator& operator++(int); private: UnaryFunction m_f; // exposition only }; </pre> </div> <div class="section" id="function-output-iterator-requirements"> <h1><a class="toc-backref" href="#id2"><tt class="docutils literal"><span class="pre">function_output_iterator</span></tt> requirements</a></h1> <p><tt class="docutils literal"><span class="pre">UnaryFunction</span></tt> must be Assignable and Copy Constructible.</p> </div> <div class="section" id="function-output-iterator-models"> <h1><a class="toc-backref" href="#id3"><tt class="docutils literal"><span class="pre">function_output_iterator</span></tt> models</a></h1> <p><tt class="docutils literal"><span class="pre">function_output_iterator</span></tt> is a model of the Writable and Incrementable Iterator concepts.</p> </div> <div class="section" id="function-output-iterator-operations"> <h1><a class="toc-backref" href="#id4"><tt class="docutils literal"><span class="pre">function_output_iterator</span></tt> operations</a></h1> <p><tt class="docutils literal"><span class="pre">explicit</span> <span class="pre">function_output_iterator(const</span> <span class="pre">UnaryFunction&</span> <span class="pre">f</span> <span class="pre">=</span> <span class="pre">UnaryFunction());</span></tt></p> <table class="docutils field-list" frame="void" rules="none"> <col class="field-name" /> <col class="field-body" /> <tbody valign="top"> <tr class="field"><th class="field-name">Effects:</th><td class="field-body">Constructs an instance of <tt class="docutils literal"><span class="pre">function_output_iterator</span></tt> with <tt class="docutils literal"><span class="pre">m_f</span></tt> constructed from <tt class="docutils literal"><span class="pre">f</span></tt>.</td> </tr> </tbody> </table> <p><tt class="docutils literal"><span class="pre">operator*();</span></tt></p> <table class="docutils field-list" frame="void" rules="none"> <col class="field-name" /> <col class="field-body" /> <tbody valign="top"> <tr class="field"><th class="field-name">Returns:</th><td class="field-body">An object <tt class="docutils literal"><span class="pre">r</span></tt> of unspecified type such that <tt class="docutils literal"><span class="pre">r</span> <span class="pre">=</span> <span class="pre">t</span></tt> is equivalent to <tt class="docutils literal"><span class="pre">m_f(t)</span></tt> for all <tt class="docutils literal"><span class="pre">t</span></tt>.</td> </tr> </tbody> </table> <p><tt class="docutils literal"><span class="pre">function_output_iterator&</span> <span class="pre">operator++();</span></tt></p> <table class="docutils field-list" frame="void" rules="none"> <col class="field-name" /> <col class="field-body" /> <tbody valign="top"> <tr class="field"><th class="field-name">Returns:</th><td class="field-body"><tt class="docutils literal"><span class="pre">*this</span></tt></td> </tr> </tbody> </table> <p><tt class="docutils literal"><span class="pre">function_output_iterator&</span> <span class="pre">operator++(int);</span></tt></p> <table class="docutils field-list" frame="void" rules="none"> <col class="field-name" /> <col class="field-body" /> <tbody valign="top"> <tr class="field"><th class="field-name">Returns:</th><td class="field-body"><tt class="docutils literal"><span class="pre">*this</span></tt></td> </tr> </tbody> </table> <!-- Copyright David Abrahams 2006. Distributed under the Boost --> <!-- Software License, Version 1.0. (See accompanying --> <!-- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) --> </div> <div class="section" id="example"> <h1><a class="toc-backref" href="#id5">Example</a></h1> <pre class="literal-block"> struct string_appender { string_appender(std::string& s) : m_str(&s) {} void operator()(const std::string& x) const { *m_str += x; } std::string* m_str; }; int main(int, char*[]) { std::vector<std::string> x; x.push_back("hello"); x.push_back(" "); x.push_back("world"); x.push_back("!"); std::string s = ""; std::copy(x.begin(), x.end(), boost::make_function_output_iterator(string_appender(s))); std::cout << s << std::endl; return 0; } </pre> </div> </div> <div class="footer"> <hr class="footer" /> <a class="reference external" href="function_output_iterator.rst">View document source</a>. 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