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- <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" />
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- <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>
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