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192 lines
13 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<meta name="generator" content="Docutils 0.7: http://docutils.sourceforge.net/" />
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<title>The MPL Reference Manual: Reversible Algorithm</title>
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</head>
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<body class="docframe refmanual">
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<table class="header"><tr class="header"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./inserter.html" class="navigation-link">Prev</a> <a href="./inserters.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./inserter.html" class="navigation-link">Back</a> Along</span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./algorithms-concepts.html" class="navigation-link">Up</a> <a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./refmanual_toc.html" class="navigation-link">Full TOC</a></span></td>
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<td class="header-group page-location"><a href="../refmanual.html" class="navigation-link">Front Page</a> / <a href="./algorithms.html" class="navigation-link">Algorithms</a> / <a href="./algorithms-concepts.html" class="navigation-link">Concepts</a> / <a href="./reversible-algorithm.html" class="navigation-link">Reversible Algorithm</a></td>
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</tr></table><div class="header-separator"></div>
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<div class="section" id="reversible-algorithm">
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<h1><a class="toc-backref" href="./algorithms-concepts.html#id1463">Reversible Algorithm</a></h1>
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<div class="section" id="id459">
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<h3><a class="subsection-title" href="#description" name="description">Description</a></h3>
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<p>A <a class="reference internal" href="./reversible-algorithm.html">Reversible Algorithm</a> is a member of a pair of
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transformation algorithms that iterate over their input sequence(s)
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in opposite directions. For each reversible
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algorithm <tt class="literal"><span class="pre">x</span></tt> there exists a <em>counterpart</em> algorithm <tt class="literal"><span class="pre">reverse_x</span></tt>,
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that exhibits the exact semantics of <tt class="literal"><span class="pre">x</span></tt> except that the elements
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of its input sequence argument(s) are processed in the reverse
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order.</p>
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</div>
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<div class="section" id="id460">
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<h3><a class="subsection-title" href="#expression-requirements" name="expression-requirements">Expression requirements</a></h3>
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<p>In the following table and subsequent specifications, <tt class="literal"><span class="pre">x</span></tt> is a placeholder token for the actual
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<a class="reference internal" href="./reversible-algorithm.html">Reversible Algorithm</a>'s name, <em>s</em><sub>1</sub>,<em>s</em><sub>2</sub>,...<em>s</em><sub>n</sub> are
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<a class="reference internal" href="./forward-sequence.html">Forward Sequence</a>s, and <tt class="literal"><span class="pre">in</span></tt> is an <a class="reference internal" href="./inserter.html">Inserter</a>.</p>
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<table border="1" class="docutils table">
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<colgroup>
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<col width="48%" />
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<col width="28%" />
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<col width="23%" />
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</colgroup>
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<thead valign="bottom">
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<tr><th class="head">Expression</th>
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<th class="head">Type</th>
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<th class="head">Complexity</th>
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</tr>
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</thead>
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<tbody valign="top">
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<tr><td><tt class="literal"><span class="pre">x<</span></tt><em>s</em><sub>1</sub>,<em>s</em><sub>2</sub>,...<em>s</em><sub>n</sub>, ...<tt class="literal"><span class="pre">>::type</span></tt></td>
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<td><a class="reference internal" href="./forward-sequence.html">Forward Sequence</a></td>
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<td>Unspecified.</td>
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</tr>
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<tr><td><tt class="literal"><span class="pre">x<</span></tt><em>s</em><sub>1</sub>,<em>s</em><sub>2</sub>,...<em>s</em><sub>n</sub>, ... <tt class="literal"><span class="pre">in>::type</span></tt></td>
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<td>Any type</td>
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<td>Unspecified.</td>
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</tr>
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<tr><td><tt class="literal"><span class="pre">reverse_x<</span></tt><em>s</em><sub>1</sub>,<em>s</em><sub>2</sub>,...<em>s</em><sub>n</sub>, ...<tt class="literal"><span class="pre">>::type</span></tt></td>
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<td><a class="reference internal" href="./forward-sequence.html">Forward Sequence</a></td>
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<td>Unspecified.</td>
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</tr>
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<tr><td><tt class="literal"><span class="pre">reverse_x<</span></tt><em>s</em><sub>1</sub>,<em>s</em><sub>2</sub>,...<em>s</em><sub>n</sub>, ... <tt class="literal"><span class="pre">in>::type</span></tt></td>
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<td>Any type</td>
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<td>Unspecified.</td>
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</tr>
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</tbody>
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</table>
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</div>
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<div class="section" id="id461">
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<h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3>
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<pre class="literal-block">
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typedef x<<em>s</em><sub>1</sub>,<em>s</em><sub>2</sub>,...<em>s</em><sub>n</sub>,...>::type t;
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</pre>
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<table class="docutils field-list" frame="void" rules="none">
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<col class="field-name" />
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<col class="field-body" />
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<tbody valign="top">
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<tr class="field"><th class="field-name">Precondition:</th><td class="field-body"><p class="first"><em>s</em><sub>1</sub> is an <a class="reference internal" href="./extensible-sequence.html">Extensible Sequence</a>.</p>
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</td>
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</tr>
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<tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first"><tt class="literal"><span class="pre">t</span></tt> is equivalent to</p>
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<pre class="literal-block">
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x<
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<em>s</em><sub>1</sub>,<em>s</em><sub>2</sub>,...<em>s</em><sub>n</sub>,...
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, <a href="./back-inserter.html" class="identifier">back_inserter</a>< <a href="./clear.html" class="identifier">clear</a><<em>s</em><sub>1</sub>>::type >
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>::type
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</pre>
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<p>if <tt class="literal"><span class="pre">has_push_back<</span></tt><em>s</em><sub>1</sub><tt class="literal"><span class="pre">>::value</span> <span class="pre">==</span> <span class="pre">true</span></tt> and</p>
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<pre class="literal-block">
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reverse_x<
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<em>s</em><sub>1</sub>,<em>s</em><sub>2</sub>,...<em>s</em><sub>n</sub>,...
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, <a href="./front-inserter.html" class="identifier">front_inserter</a>< <a href="./clear.html" class="identifier">clear</a><<em>s</em><sub>1</sub>>::type >
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>::type
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</pre>
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<p class="last">otherwise.</p>
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</td>
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</tr>
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</tbody>
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</table>
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<!-- .......................................................................... -->
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<pre class="literal-block">
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typedef x<<em>s</em><sub>1</sub>,<em>s</em><sub>2</sub>,...<em>s</em><sub>n</sub>,...in>::type t;
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</pre>
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<table class="docutils field-list" frame="void" rules="none">
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<col class="field-name" />
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<col class="field-body" />
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<tbody valign="top">
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<tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><tt class="literal"><span class="pre">t</span></tt> is the result of an <tt class="literal"><span class="pre">x</span></tt> invocation with arguments
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<em>s</em><sub>1</sub>,<em>s</em><sub>2</sub>,... <em>s</em><sub>n</sub>,...<tt class="literal"><span class="pre">in</span></tt>.</td>
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</tr>
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</tbody>
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</table>
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<!-- .......................................................................... -->
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<pre class="literal-block">
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typedef reverse_x<<em>s</em><sub>1</sub>,<em>s</em><sub>2</sub>,... <em>s</em><sub>n</sub>,... >::type t;
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</pre>
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<table class="docutils field-list" frame="void" rules="none">
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<col class="field-name" />
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<col class="field-body" />
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<tbody valign="top">
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<tr class="field"><th class="field-name">Precondition:</th><td class="field-body"><p class="first"><em>s</em><sub>1</sub> is an <a class="reference internal" href="./extensible-sequence.html">Extensible Sequence</a>.</p>
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</td>
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</tr>
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<tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first"><tt class="literal"><span class="pre">t</span></tt> is equivalent to</p>
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<pre class="literal-block">
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x<
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<em>s</em><sub>1</sub>,<em>s</em><sub>2</sub>,...<em>s</em><sub>n</sub>,...
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, <a href="./front-inserter.html" class="identifier">front_inserter</a>< <a href="./clear.html" class="identifier">clear</a><<em>s</em><sub>1</sub>>::type >
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>::type
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</pre>
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<p>if <tt class="literal"><span class="pre">has_push_front<</span></tt><em>s</em><sub>1</sub><tt class="literal"><span class="pre">>::value</span> <span class="pre">==</span> <span class="pre">true</span></tt> and</p>
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<pre class="literal-block">
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reverse_x<
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<em>s</em><sub>1</sub>,<em>s</em><sub>2</sub>,...<em>s</em><sub>n</sub>,...
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, <a href="./back-inserter.html" class="identifier">back_inserter</a>< <a href="./clear.html" class="identifier">clear</a><<em>s</em><sub>1</sub>>::type >
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>::type
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</pre>
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<p class="last">otherwise.</p>
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</td>
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</tr>
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</tbody>
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</table>
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<!-- .......................................................................... -->
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<pre class="literal-block">
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typedef reverse_x<<em>s</em><sub>1</sub>,<em>s</em><sub>2</sub>,...<em>s</em><sub>n</sub>,... in>::type t;
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</pre>
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<table class="docutils field-list" frame="void" rules="none">
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<col class="field-name" />
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<col class="field-body" />
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<tbody valign="top">
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<tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><tt class="literal"><span class="pre">t</span></tt> is the result of a <tt class="literal"><span class="pre">reverse_x</span></tt> invocation with arguments
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<em>s</em><sub>1</sub>,<em>s</em><sub>2</sub>,...<em>s</em><sub>n</sub>,...<tt class="literal"><span class="pre">in</span></tt>.</td>
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</tr>
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</tbody>
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</table>
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</div>
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<div class="section" id="id462">
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<h3><a class="subsection-title" href="#example" name="example">Example</a></h3>
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<pre class="literal-block">
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typedef <a href="./transform.html" class="identifier">transform</a><
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<a href="./range-c.html" class="identifier">range_c</a><int,0,10>
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, <a href="./plus.html" class="identifier">plus</a><<a href="./placeholders.html" class="identifier">_1</a>,<a href="./int.html" class="identifier">int_</a><7> >
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, <a href="./back-inserter.html" class="identifier">back_inserter</a>< vector0<> >
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>::type r1;
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typedef <a href="./transform.html" class="identifier">transform</a>< r1, <a href="./minus.html" class="identifier">minus</a><<a href="./placeholders.html" class="identifier">_1</a>,<a href="./int.html" class="identifier">int_</a><2> > >::type r2;
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typedef <a href="./reverse-transform.html" class="identifier">reverse_transform</a><
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r2
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, <a href="./minus.html" class="identifier">minus</a><<a href="./placeholders.html" class="identifier">_1</a>,5>
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, <a href="./front-inserter.html" class="identifier">front_inserter</a>< vector0<> >
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>::type r3;
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<a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( <a href="./equal.html" class="identifier">equal</a><r1, <a href="./range-c.html" class="identifier">range_c</a><int,7,17> > ));
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<a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( <a href="./equal.html" class="identifier">equal</a><r2, <a href="./range-c.html" class="identifier">range_c</a><int,5,15> > ));
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<a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( <a href="./equal.html" class="identifier">equal</a><r3, <a href="./range-c.html" class="identifier">range_c</a><int,0,10> > ));
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</pre>
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</div>
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<div class="section" id="id463">
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<h3><a class="subsection-title" href="#models" name="models">Models</a></h3>
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<ul class="simple">
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<li><a class="reference internal" href="./transform.html">transform</a></li>
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<li><a class="reference internal" href="./remove.html">remove</a></li>
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<li><a class="reference internal" href="./replace.html">replace</a></li>
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</ul>
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</div>
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<div class="section" id="id464">
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<h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3>
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<p><a class="reference internal" href="./transformation-algorithms.html">Transformation Algorithms</a>, <a class="reference internal" href="./inserter.html">Inserter</a></p>
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</div>
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</div>
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<table class="footer"><tr class="footer"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./inserter.html" class="navigation-link">Prev</a> <a href="./inserters.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./inserter.html" class="navigation-link">Back</a> Along</span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./algorithms-concepts.html" class="navigation-link">Up</a> <a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./refmanual_toc.html" class="navigation-link">Full TOC</a></span></td>
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<td><div class="copyright-footer"><div class="copyright">Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams</div>
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at <a class="reference external" href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)</div></td></tr></table></body>
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