| <?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>Reverse 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="reverse-iterator"> |
| <h1 class="title">Reverse 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 reverse iterator adaptor iterates through the adapted iterator |
| range in the opposite direction.</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="#reverse-iterator-synopsis" id="id2"><tt class="docutils literal"><span class="pre">reverse_iterator</span></tt> synopsis</a></li> |
| <li><a class="reference internal" href="#reverse-iterator-requirements" id="id3"><tt class="docutils literal"><span class="pre">reverse_iterator</span></tt> requirements</a></li> |
| <li><a class="reference internal" href="#reverse-iterator-models" id="id4"><tt class="docutils literal"><span class="pre">reverse_iterator</span></tt> models</a></li> |
| <li><a class="reference internal" href="#reverse-iterator-operations" id="id5"><tt class="docutils literal"><span class="pre">reverse_iterator</span></tt> operations</a></li> |
| <li><a class="reference internal" href="#example" id="id6">Example</a></li> |
| </ul> |
| </div> |
| <div class="section" id="reverse-iterator-synopsis"> |
| <h1><a class="toc-backref" href="#id2"><tt class="docutils literal"><span class="pre">reverse_iterator</span></tt> synopsis</a></h1> |
| <!-- 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) --> |
| <pre class="literal-block"> |
| template <class Iterator> |
| class reverse_iterator |
| { |
| public: |
| typedef iterator_traits<Iterator>::value_type value_type; |
| typedef iterator_traits<Iterator>::reference reference; |
| typedef iterator_traits<Iterator>::pointer pointer; |
| typedef iterator_traits<Iterator>::difference_type difference_type; |
| typedef /* see below */ iterator_category; |
| |
| reverse_iterator() {} |
| explicit reverse_iterator(Iterator x) ; |
| |
| template<class OtherIterator> |
| reverse_iterator( |
| reverse_iterator<OtherIterator> const& r |
| , typename enable_if_convertible<OtherIterator, Iterator>::type* = 0 // exposition |
| ); |
| Iterator const& base() const; |
| reference operator*() const; |
| reverse_iterator& operator++(); |
| reverse_iterator& operator--(); |
| private: |
| Iterator m_iterator; // exposition |
| }; |
| </pre> |
| <p>If <tt class="docutils literal"><span class="pre">Iterator</span></tt> models Random Access Traversal Iterator and Readable |
| Lvalue Iterator, then <tt class="docutils literal"><span class="pre">iterator_category</span></tt> is convertible to |
| <tt class="docutils literal"><span class="pre">random_access_iterator_tag</span></tt>. Otherwise, if |
| <tt class="docutils literal"><span class="pre">Iterator</span></tt> models Bidirectional Traversal Iterator and Readable |
| Lvalue Iterator, then <tt class="docutils literal"><span class="pre">iterator_category</span></tt> is convertible to |
| <tt class="docutils literal"><span class="pre">bidirectional_iterator_tag</span></tt>. Otherwise, <tt class="docutils literal"><span class="pre">iterator_category</span></tt> is |
| convertible to <tt class="docutils literal"><span class="pre">input_iterator_tag</span></tt>.</p> |
| </div> |
| <div class="section" id="reverse-iterator-requirements"> |
| <h1><a class="toc-backref" href="#id3"><tt class="docutils literal"><span class="pre">reverse_iterator</span></tt> requirements</a></h1> |
| <p><tt class="docutils literal"><span class="pre">Iterator</span></tt> must be a model of Bidirectional Traversal Iterator. The |
| type <tt class="docutils literal"><span class="pre">iterator_traits<Iterator>::reference</span></tt> must be the type of |
| <tt class="docutils literal"><span class="pre">*i</span></tt>, where <tt class="docutils literal"><span class="pre">i</span></tt> is an object of type <tt class="docutils literal"><span class="pre">Iterator</span></tt>.</p> |
| </div> |
| <div class="section" id="reverse-iterator-models"> |
| <h1><a class="toc-backref" href="#id4"><tt class="docutils literal"><span class="pre">reverse_iterator</span></tt> models</a></h1> |
| <p>A specialization of <tt class="docutils literal"><span class="pre">reverse_iterator</span></tt> models the same iterator |
| traversal and iterator access concepts modeled by its <tt class="docutils literal"><span class="pre">Iterator</span></tt> |
| argument. In addition, it may model old iterator concepts |
| specified in the following table:</p> |
| <table border="1" class="docutils"> |
| <colgroup> |
| <col width="53%" /> |
| <col width="47%" /> |
| </colgroup> |
| <thead valign="bottom"> |
| <tr><th class="head">If <tt class="docutils literal"><span class="pre">I</span></tt> models</th> |
| <th class="head">then <tt class="docutils literal"><span class="pre">reverse_iterator<I></span></tt> models</th> |
| </tr> |
| </thead> |
| <tbody valign="top"> |
| <tr><td>Readable Lvalue Iterator, |
| Bidirectional Traversal Iterator</td> |
| <td>Bidirectional Iterator</td> |
| </tr> |
| <tr><td>Writable Lvalue Iterator, |
| Bidirectional Traversal Iterator</td> |
| <td>Mutable Bidirectional Iterator</td> |
| </tr> |
| <tr><td>Readable Lvalue Iterator, |
| Random Access Traversal Iterator</td> |
| <td>Random Access Iterator</td> |
| </tr> |
| <tr><td>Writable Lvalue Iterator, |
| Random Access Traversal Iterator</td> |
| <td>Mutable Random Access Iterator</td> |
| </tr> |
| </tbody> |
| </table> |
| <p><tt class="docutils literal"><span class="pre">reverse_iterator<X></span></tt> is interoperable with |
| <tt class="docutils literal"><span class="pre">reverse_iterator<Y></span></tt> if and only if <tt class="docutils literal"><span class="pre">X</span></tt> is interoperable with |
| <tt class="docutils literal"><span class="pre">Y</span></tt>.</p> |
| </div> |
| <div class="section" id="reverse-iterator-operations"> |
| <h1><a class="toc-backref" href="#id5"><tt class="docutils literal"><span class="pre">reverse_iterator</span></tt> operations</a></h1> |
| <p>In addition to the operations required by the concepts modeled by |
| <tt class="docutils literal"><span class="pre">reverse_iterator</span></tt>, <tt class="docutils literal"><span class="pre">reverse_iterator</span></tt> provides the following |
| operations.</p> |
| <p><tt class="docutils literal"><span class="pre">reverse_iterator();</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">Requires:</th><td class="field-body"><tt class="docutils literal"><span class="pre">Iterator</span></tt> must be Default Constructible.</td> |
| </tr> |
| <tr class="field"><th class="field-name">Effects:</th><td class="field-body">Constructs an instance of <tt class="docutils literal"><span class="pre">reverse_iterator</span></tt> with <tt class="docutils literal"><span class="pre">m_iterator</span></tt> |
| default constructed.</td> |
| </tr> |
| </tbody> |
| </table> |
| <p><tt class="docutils literal"><span class="pre">explicit</span> <span class="pre">reverse_iterator(Iterator</span> <span class="pre">x);</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">reverse_iterator</span></tt> with |
| <tt class="docutils literal"><span class="pre">m_iterator</span></tt> copy constructed from <tt class="docutils literal"><span class="pre">x</span></tt>.</td> |
| </tr> |
| </tbody> |
| </table> |
| <pre class="literal-block"> |
| template<class OtherIterator> |
| reverse_iterator( |
| reverse_iterator<OtherIterator> const& r |
| , typename enable_if_convertible<OtherIterator, Iterator>::type* = 0 // exposition |
| ); |
| </pre> |
| <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">Requires:</th><td class="field-body"><tt class="docutils literal"><span class="pre">OtherIterator</span></tt> is implicitly convertible to <tt class="docutils literal"><span class="pre">Iterator</span></tt>.</td> |
| </tr> |
| <tr class="field"><th class="field-name">Effects:</th><td class="field-body">Constructs instance of <tt class="docutils literal"><span class="pre">reverse_iterator</span></tt> whose |
| <tt class="docutils literal"><span class="pre">m_iterator</span></tt> subobject is constructed from <tt class="docutils literal"><span class="pre">y.base()</span></tt>.</td> |
| </tr> |
| </tbody> |
| </table> |
| <p><tt class="docutils literal"><span class="pre">Iterator</span> <span class="pre">const&</span> <span class="pre">base()</span> <span class="pre">const;</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">m_iterator</span></tt></td> |
| </tr> |
| </tbody> |
| </table> |
| <p><tt class="docutils literal"><span class="pre">reference</span> <span class="pre">operator*()</span> <span class="pre">const;</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"></td> |
| </tr> |
| </tbody> |
| </table> |
| <pre class="literal-block"> |
| Iterator tmp = m_iterator; |
| return *--tmp; |
| </pre> |
| <p><tt class="docutils literal"><span class="pre">reverse_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">Effects:</th><td class="field-body"><tt class="docutils literal"><span class="pre">--m_iterator</span></tt></td> |
| </tr> |
| <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">reverse_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">Effects:</th><td class="field-body"><tt class="docutils literal"><span class="pre">++m_iterator</span></tt></td> |
| </tr> |
| <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) --> |
| <pre class="literal-block"> |
| template <class BidirectionalIterator> |
| reverse_iterator<BidirectionalIterator>n |
| make_reverse_iterator(BidirectionalIterator x); |
| </pre> |
| <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 instance of <tt class="docutils literal"><span class="pre">reverse_iterator<BidirectionalIterator></span></tt> |
| with a <tt class="docutils literal"><span class="pre">current</span></tt> constructed from <tt class="docutils literal"><span class="pre">x</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="#id6">Example</a></h1> |
| <p>The following example prints an array of characters in reverse order |
| using <tt class="docutils literal"><span class="pre">reverse_iterator</span></tt>.</p> |
| <pre class="literal-block"> |
| char letters_[] = "hello world!"; |
| const int N = sizeof(letters_)/sizeof(char) - 1; |
| typedef char* base_iterator; |
| base_iterator letters(letters_); |
| std::cout << "original sequence of letters:\t\t\t" << letters_ << std::endl; |
| |
| boost::reverse_iterator<base_iterator> |
| reverse_letters_first(letters + N), |
| reverse_letters_last(letters); |
| |
| std::cout << "sequence in reverse order:\t\t\t"; |
| std::copy(reverse_letters_first, reverse_letters_last, |
| std::ostream_iterator<char>(std::cout)); |
| std::cout << std::endl; |
| |
| std::cout << "sequence in double-reversed (normal) order:\t"; |
| std::copy(boost::make_reverse_iterator(reverse_letters_last), |
| boost::make_reverse_iterator(reverse_letters_first), |
| std::ostream_iterator<char>(std::cout)); |
| std::cout << std::endl; |
| </pre> |
| <p>The output is:</p> |
| <pre class="literal-block"> |
| original sequence of letters: hello world! |
| sequence in reverse order: !dlrow olleh |
| sequence in double-reversed (normal) order: hello world! |
| </pre> |
| <p>The source code for this example can be found <a class="reference external" href="../example/reverse_iterator_example.cpp">here</a>.</p> |
| </div> |
| </div> |
| <div class="footer"> |
| <hr class="footer" /> |
| <a class="reference external" href="reverse_iterator.rst">View document source</a>. |
| Generated 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. |
| |
| </div> |
| </body> |
| </html> |