1<?xml version="1.0" encoding="utf-8" ?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> 4<head> 5<meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 6<meta name="generator" content="Docutils 0.5: http://docutils.sourceforge.net/" /> 7<title>Function Output Iterator</title> 8<meta name="author" content="David Abrahams, Jeremy Siek, Thomas Witt" /> 9<meta name="organization" content="Boost Consulting, Indiana University Open Systems Lab, University of Hanover Institute for Transport Railway Operation and Construction" /> 10<meta name="date" content="2006-09-11" /> 11<meta name="copyright" content="Copyright David Abrahams, Jeremy Siek, and Thomas Witt 2003." /> 12<link rel="stylesheet" href="../../../rst.css" type="text/css" /> 13</head> 14<body> 15<div class="document" id="function-output-iterator"> 16<h1 class="title">Function Output Iterator</h1> 17<table class="docinfo" frame="void" rules="none"> 18<col class="docinfo-name" /> 19<col class="docinfo-content" /> 20<tbody valign="top"> 21<tr><th class="docinfo-name">Author:</th> 22<td>David Abrahams, Jeremy Siek, Thomas Witt</td></tr> 23<tr><th class="docinfo-name">Contact:</th> 24<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> 25<tr><th class="docinfo-name">Organization:</th> 26<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 27Lab</a>, University of Hanover <a class="last reference external" href="http://www.ive.uni-hannover.de">Institute for Transport 28Railway Operation and Construction</a></td></tr> 29<tr><th class="docinfo-name">Date:</th> 30<td>2006-09-11</td></tr> 31<tr><th class="docinfo-name">Copyright:</th> 32<td>Copyright David Abrahams, Jeremy Siek, and Thomas Witt 2003.</td></tr> 33</tbody> 34</table> 35<!-- Distributed under the Boost --> 36<!-- Software License, Version 1.0. (See accompanying --> 37<!-- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) --> 38<table class="docutils field-list" frame="void" rules="none"> 39<col class="field-name" /> 40<col class="field-body" /> 41<tbody valign="top"> 42<tr class="field"><th class="field-name">abstract:</th><td class="field-body"><!-- Copyright David Abrahams 2006. Distributed under the Boost --> 43<!-- Software License, Version 1.0. (See accompanying --> 44<!-- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) --> 45The function output iterator adaptor makes it easier to create custom 46output iterators. The adaptor takes a unary function and creates a 47model of Output Iterator. Each item assigned to the output iterator is 48passed as an argument to the unary function. The motivation for this 49iterator is that creating a conforming output iterator is non-trivial, 50particularly because the proper implementation usually requires a 51proxy object.</td> 52</tr> 53</tbody> 54</table> 55<div class="contents topic" id="table-of-contents"> 56<p class="topic-title first">Table of Contents</p> 57<ul class="simple"> 58<li><a class="reference internal" href="#header" id="id1">Header</a></li> 59<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> 60<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> 61<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> 62<li><a class="reference internal" href="#example" id="id5">Example</a></li> 63</ul> 64</div> 65<!-- Copyright David Abrahams 2006. Distributed under the Boost --> 66<!-- Software License, Version 1.0. (See accompanying --> 67<!-- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) --> 68<div class="section" id="header"> 69<h1><a class="toc-backref" href="#id1">Header</a></h1> 70<pre class="literal-block"> 71#include <boost/function_output_iterator.hpp> 72</pre> 73<pre class="literal-block"> 74template <class UnaryFunction> 75class function_output_iterator { 76public: 77 typedef std::output_iterator_tag iterator_category; 78 typedef void value_type; 79 typedef void difference_type; 80 typedef void pointer; 81 typedef void reference; 82 83 explicit function_output_iterator(); 84 85 explicit function_output_iterator(const UnaryFunction& f); 86 87 /* see below */ operator*(); 88 function_output_iterator& operator++(); 89 function_output_iterator& operator++(int); 90private: 91 UnaryFunction m_f; // exposition only 92}; 93</pre> 94</div> 95<div class="section" id="function-output-iterator-requirements"> 96<h1><a class="toc-backref" href="#id2"><tt class="docutils literal"><span class="pre">function_output_iterator</span></tt> requirements</a></h1> 97<p><tt class="docutils literal"><span class="pre">UnaryFunction</span></tt> must be Assignable and Copy Constructible.</p> 98</div> 99<div class="section" id="function-output-iterator-models"> 100<h1><a class="toc-backref" href="#id3"><tt class="docutils literal"><span class="pre">function_output_iterator</span></tt> models</a></h1> 101<p><tt class="docutils literal"><span class="pre">function_output_iterator</span></tt> is a model of the Writable and 102Incrementable Iterator concepts.</p> 103</div> 104<div class="section" id="function-output-iterator-operations"> 105<h1><a class="toc-backref" href="#id4"><tt class="docutils literal"><span class="pre">function_output_iterator</span></tt> operations</a></h1> 106<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> 107<table class="docutils field-list" frame="void" rules="none"> 108<col class="field-name" /> 109<col class="field-body" /> 110<tbody valign="top"> 111<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> 112with <tt class="docutils literal"><span class="pre">m_f</span></tt> constructed from <tt class="docutils literal"><span class="pre">f</span></tt>.</td> 113</tr> 114</tbody> 115</table> 116<p><tt class="docutils literal"><span class="pre">operator*();</span></tt></p> 117<table class="docutils field-list" frame="void" rules="none"> 118<col class="field-name" /> 119<col class="field-body" /> 120<tbody valign="top"> 121<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> 122is 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> 123</tr> 124</tbody> 125</table> 126<p><tt class="docutils literal"><span class="pre">function_output_iterator&</span> <span class="pre">operator++();</span></tt></p> 127<table class="docutils field-list" frame="void" rules="none"> 128<col class="field-name" /> 129<col class="field-body" /> 130<tbody valign="top"> 131<tr class="field"><th class="field-name">Returns:</th><td class="field-body"><tt class="docutils literal"><span class="pre">*this</span></tt></td> 132</tr> 133</tbody> 134</table> 135<p><tt class="docutils literal"><span class="pre">function_output_iterator&</span> <span class="pre">operator++(int);</span></tt></p> 136<table class="docutils field-list" frame="void" rules="none"> 137<col class="field-name" /> 138<col class="field-body" /> 139<tbody valign="top"> 140<tr class="field"><th class="field-name">Returns:</th><td class="field-body"><tt class="docutils literal"><span class="pre">*this</span></tt></td> 141</tr> 142</tbody> 143</table> 144<!-- Copyright David Abrahams 2006. Distributed under the Boost --> 145<!-- Software License, Version 1.0. (See accompanying --> 146<!-- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) --> 147</div> 148<div class="section" id="example"> 149<h1><a class="toc-backref" href="#id5">Example</a></h1> 150<pre class="literal-block"> 151struct string_appender 152{ 153 string_appender(std::string& s) 154 : m_str(&s) 155 {} 156 157 void operator()(const std::string& x) const 158 { 159 *m_str += x; 160 } 161 162 std::string* m_str; 163}; 164 165int main(int, char*[]) 166{ 167 std::vector<std::string> x; 168 x.push_back("hello"); 169 x.push_back(" "); 170 x.push_back("world"); 171 x.push_back("!"); 172 173 std::string s = ""; 174 std::copy(x.begin(), x.end(), 175 boost::make_function_output_iterator(string_appender(s))); 176 177 std::cout << s << std::endl; 178 179 return 0; 180} 181</pre> 182</div> 183</div> 184<div class="footer"> 185<hr class="footer" /> 186<a class="reference external" href="function_output_iterator.rst">View document source</a>. 187Generated by <a class="reference external" href="http://docutils.sourceforge.net/">Docutils</a> from <a class="reference external" href="http://docutils.sourceforge.net/rst.html">reStructuredText</a> source. 188 189</div> 190</body> 191</html> 192