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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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