advance.html 9.6 KB

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  7. <title>The MPL Reference Manual: advance</title>
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  12. <td class="header-group page-location"><a href="../refmanual.html" class="navigation-link">Front Page</a> / <a href="./iterators.html" class="navigation-link">Iterators</a> / <a href="./iterator-metafunctions.html" class="navigation-link">Iterator Metafunctions</a> / <a href="./advance.html" class="navigation-link">advance</a></td>
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  14. <div class="section" id="advance">
  15. <h1><a class="toc-backref" href="./iterator-metafunctions.html#id1454">advance</a></h1>
  16. <div class="section" id="id403">
  17. <h3><a class="subsection-title" href="#synopsis" name="synopsis">Synopsis</a></h3>
  18. <pre class="literal-block">
  19. template&lt;
  20. typename Iterator
  21. , typename N
  22. &gt;
  23. struct <a href="./advance.html" class="identifier">advance</a>
  24. {
  25. typedef <em>unspecified</em> type;
  26. };
  27. </pre>
  28. </div>
  29. <div class="section" id="id404">
  30. <h3><a class="subsection-title" href="#description" name="description">Description</a></h3>
  31. <p>Moves <tt class="literal"><span class="pre">Iterator</span></tt> by the distance <tt class="literal"><span class="pre">N</span></tt>. For <a class="reference internal" href="./bidirectional-iterator.html">bidirectional</a> and
  32. <a class="reference internal" href="./random-access-iterator.html">random access</a> iterators, the distance may be negative.</p>
  33. </div>
  34. <div class="section" id="id405">
  35. <h3><a class="subsection-title" href="#header" name="header">Header</a></h3>
  36. <pre class="literal-block">
  37. #include &lt;<a href="../../../../boost/mpl/advance.hpp" class="header">boost/mpl/advance.hpp</a>&gt;
  38. </pre>
  39. </div>
  40. <div class="section" id="id406">
  41. <h3><a class="subsection-title" href="#parameters" name="parameters">Parameters</a></h3>
  42. <table border="1" class="docutils table">
  43. <colgroup>
  44. <col width="19%" />
  45. <col width="35%" />
  46. <col width="45%" />
  47. </colgroup>
  48. <thead valign="bottom">
  49. <tr><th class="head">Parameter</th>
  50. <th class="head">Requirement</th>
  51. <th class="head">Description</th>
  52. </tr>
  53. </thead>
  54. <tbody valign="top">
  55. <tr><td><tt class="literal"><span class="pre">Iterator</span></tt></td>
  56. <td><a class="reference internal" href="./forward-iterator.html">Forward Iterator</a></td>
  57. <td>An iterator to advance.</td>
  58. </tr>
  59. <tr><td><tt class="literal"><span class="pre">N</span></tt></td>
  60. <td><a class="reference internal" href="./integral-constant.html">Integral Constant</a></td>
  61. <td>A distance.</td>
  62. </tr>
  63. </tbody>
  64. </table>
  65. </div>
  66. <div class="section" id="id407">
  67. <h3><a class="subsection-title" href="#model-of" name="model-of">Model Of</a></h3>
  68. <p><a class="reference internal" href="./tag-dispatched-metafunction.html">Tag Dispatched Metafunction</a></p>
  69. </div>
  70. <div class="section" id="id408">
  71. <h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3>
  72. <p>For a <a class="reference internal" href="./forward-iterator.html">Forward Iterator</a> <tt class="literal"><span class="pre">iter</span></tt> and arbitrary <a class="reference internal" href="./integral-constant.html">Integral Constant</a> <tt class="literal"><span class="pre">n</span></tt>:</p>
  73. <pre class="literal-block">
  74. typedef <a href="./advance.html" class="identifier">advance</a>&lt;iter,n&gt;::type j;
  75. </pre>
  76. <table class="docutils field-list" frame="void" rules="none">
  77. <col class="field-name" />
  78. <col class="field-body" />
  79. <tbody valign="top">
  80. <tr class="field"><th class="field-name">Return type:</th><td class="field-body"><p class="first"><a class="reference internal" href="./forward-iterator.html">Forward Iterator</a>.</p>
  81. </td>
  82. </tr>
  83. <tr class="field"><th class="field-name">Precondition:</th><td class="field-body"><p class="first">If <tt class="literal"><span class="pre">Iterator</span></tt> is a <a class="reference internal" href="./forward-iterator.html">Forward Iterator</a>, <tt class="literal"><span class="pre">n::value</span></tt> must be nonnegative.</p>
  84. </td>
  85. </tr>
  86. <tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first">Equivalent to:</p>
  87. <pre class="literal-block">
  88. typedef iter i0;
  89. typedef <a href="./next.html" class="identifier">next</a>&lt;i0&gt;::type i1;
  90. <em>...</em>
  91. typedef <a href="./next.html" class="identifier">next</a>&lt;i<em>n-1</em>&gt;::type j;
  92. </pre>
  93. <p>if <tt class="literal"><span class="pre">n::value</span> <span class="pre">&gt;</span> <span class="pre">0</span></tt>, and</p>
  94. <pre class="literal-block">
  95. typedef iter i0;
  96. typedef <a href="./prior.html" class="identifier">prior</a>&lt;i0&gt;::type i1;
  97. <em>...</em>
  98. typedef <a href="./prior.html" class="identifier">prior</a>&lt;i<em>n-1</em>&gt;::type j;
  99. </pre>
  100. <p>otherwise.</p>
  101. </td>
  102. </tr>
  103. <tr class="field"><th class="field-name">Postcondition:</th><td class="field-body"><p class="first last"><tt class="literal"><span class="pre">j</span></tt> is dereferenceable or past-the-end;
  104. <tt class="literal"><span class="pre"><a href="./distance.html" class="identifier">distance</a>&lt;iter,j&gt;::value</span> <span class="pre">==</span> <span class="pre">n::value</span></tt> if <tt class="literal"><span class="pre">n::value</span> <span class="pre">&gt;</span> <span class="pre">0</span></tt>, and
  105. <tt class="literal"><span class="pre"><a href="./distance.html" class="identifier">distance</a>&lt;j,iter&gt;::value</span> <span class="pre">==</span> <span class="pre">n::value</span></tt> otherwise.</p>
  106. </td>
  107. </tr>
  108. </tbody>
  109. </table>
  110. </div>
  111. <div class="section" id="id409">
  112. <h3><a class="subsection-title" href="#complexity" name="complexity">Complexity</a></h3>
  113. <p>Amortized constant time if <tt class="literal"><span class="pre">iter</span></tt> is a model of
  114. <a class="reference internal" href="./random-access-iterator.html">Random Access Iterator</a>, otherwise linear time.</p>
  115. </div>
  116. <div class="section" id="id410">
  117. <h3><a class="subsection-title" href="#example" name="example">Example</a></h3>
  118. <pre class="literal-block">
  119. typedef <a href="./range-c.html" class="identifier">range_c</a>&lt;int,0,10&gt; numbers;
  120. typedef <a href="./begin.html" class="identifier">begin</a>&lt;numbers&gt;::type first;
  121. typedef <a href="./end.html" class="identifier">end</a>&lt;numbers&gt;::type last;
  122. typedef <a href="./advance.html" class="identifier">advance</a>&lt;first,<a href="./int.html" class="identifier">int_</a>&lt;10&gt; &gt;::type i1;
  123. typedef <a href="./advance.html" class="identifier">advance</a>&lt;last,<a href="./int.html" class="identifier">int_</a>&lt;-10&gt; &gt;::type i2;
  124. <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( boost::is_same&lt;i1,last&gt; ));
  125. <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( boost::is_same&lt;i2,first&gt; ));
  126. </pre>
  127. </div>
  128. <div class="section" id="id411">
  129. <h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3>
  130. <p><a class="reference internal" href="./iterators.html">Iterators</a>, <a class="reference internal" href="./tag-dispatched-metafunction.html">Tag Dispatched Metafunction</a>, <a class="reference internal" href="./distance.html">distance</a>, <a class="reference internal" href="./next.html">next</a></p>
  131. <!-- Iterators/Iterator Metafunctions//distance |20 -->
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  136. <td><div class="copyright-footer"><div class="copyright">Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams</div>
  137. Distributed under the Boost Software License, Version 1.0. (See accompanying
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