integral-constant.html 9.3 KB

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  7. <title>The MPL Reference Manual: Integral Constant</title>
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  14. <div class="section" id="integral-constant">
  15. <h1><a class="toc-backref" href="./data-types-concepts.html#id1574">Integral Constant</a></h1>
  16. <div class="section" id="id1217">
  17. <h3><a class="subsection-title" href="#description" name="description">Description</a></h3>
  18. <p>An <a class="reference internal" href="./integral-constant.html">Integral Constant</a> is a holder class for a compile-time value of an
  19. integral type. Every <a class="reference internal" href="./integral-constant.html">Integral Constant</a> is also a nullary <a class="reference internal" href="./metafunction.html">Metafunction</a>,
  20. returning itself. An integral constant <em>object</em> is implicitly convertible to the
  21. corresponding run-time value of the wrapped integral type.</p>
  22. </div>
  23. <div class="section" id="id1218">
  24. <h3><a class="subsection-title" href="#expression-requirements" name="expression-requirements">Expression requirements</a></h3>
  25. <p>In the following table and subsequent specifications, <tt class="literal"><span class="pre">n</span></tt> is a model of <a class="reference internal" href="./integral-constant.html">Integral Constant</a>.</p>
  26. <table border="1" class="docutils table">
  27. <colgroup>
  28. <col width="35%" />
  29. <col width="39%" />
  30. <col width="27%" />
  31. </colgroup>
  32. <thead valign="bottom">
  33. <tr><th class="head">Expression</th>
  34. <th class="head">Type</th>
  35. <th class="head">Complexity</th>
  36. </tr>
  37. </thead>
  38. <tbody valign="top">
  39. <tr><td><tt class="literal"><span class="pre">n::tag</span></tt></td>
  40. <td><tt class="literal"><span class="pre">integral_c_tag</span></tt></td>
  41. <td>Constant time.</td>
  42. </tr>
  43. <tr><td><tt class="literal"><span class="pre">n::<a href="./value-type.html" class="identifier">value_type</a></span></tt></td>
  44. <td>An integral type</td>
  45. <td>Constant time.</td>
  46. </tr>
  47. <tr><td><tt class="literal"><span class="pre">n::value</span></tt></td>
  48. <td>An integral constant expression</td>
  49. <td>Constant time.</td>
  50. </tr>
  51. <tr><td><tt class="literal"><span class="pre">n::type</span></tt></td>
  52. <td><a class="reference internal" href="./integral-constant.html">Integral Constant</a></td>
  53. <td>Constant time.</td>
  54. </tr>
  55. <tr><td><tt class="literal"><span class="pre"><a href="./next.html" class="identifier">next</a>&lt;n&gt;::type</span></tt></td>
  56. <td><a class="reference internal" href="./integral-constant.html">Integral Constant</a></td>
  57. <td>Constant time.</td>
  58. </tr>
  59. <tr><td><tt class="literal"><span class="pre"><a href="./prior.html" class="identifier">prior</a>&lt;n&gt;::type</span></tt></td>
  60. <td><a class="reference internal" href="./integral-constant.html">Integral Constant</a></td>
  61. <td>Constant time.</td>
  62. </tr>
  63. <tr><td><tt class="literal"><span class="pre">n::<a href="./value-type.html" class="identifier">value_type</a></span> <span class="pre">const</span> <span class="pre">c</span> <span class="pre">=</span> <span class="pre">n()</span></tt></td>
  64. <td>&nbsp;</td>
  65. <td>Constant time.</td>
  66. </tr>
  67. </tbody>
  68. </table>
  69. </div>
  70. <div class="section" id="id1219">
  71. <h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3>
  72. <table border="1" class="docutils table">
  73. <colgroup>
  74. <col width="40%" />
  75. <col width="60%" />
  76. </colgroup>
  77. <thead valign="bottom">
  78. <tr><th class="head">Expression</th>
  79. <th class="head">Semantics</th>
  80. </tr>
  81. </thead>
  82. <tbody valign="top">
  83. <tr><td><tt class="literal"><span class="pre">n::tag</span></tt></td>
  84. <td><tt class="literal"><span class="pre">n</span></tt>'s tag type; <tt class="literal"><span class="pre">n::tag::value</span></tt> is <tt class="literal"><span class="pre">n</span></tt>'s
  85. <em>conversion rank</em>.</td>
  86. </tr>
  87. <tr><td><tt class="literal"><span class="pre">n::<a href="./value-type.html" class="identifier">value_type</a></span></tt></td>
  88. <td>A cv-unqualified type of <tt class="literal"><span class="pre">n::value</span></tt>.</td>
  89. </tr>
  90. <tr><td><tt class="literal"><span class="pre">n::value</span></tt></td>
  91. <td>The value of the wrapped integral constant.</td>
  92. </tr>
  93. <tr><td><tt class="literal"><span class="pre">n::type</span></tt></td>
  94. <td><tt class="literal"><span class="pre">is_same&lt;n::type,n&gt;::value</span> <span class="pre">==</span> <span class="pre">true</span></tt>.</td>
  95. </tr>
  96. <tr><td><tt class="literal"><span class="pre"><a href="./next.html" class="identifier">next</a>&lt;n&gt;::type</span></tt></td>
  97. <td>An <a class="reference internal" href="./integral-constant.html">Integral Constant</a> <tt class="literal"><span class="pre">c</span></tt> of type <tt class="literal"><span class="pre">n::<a href="./value-type.html" class="identifier">value_type</a></span></tt>
  98. such that <tt class="literal"><span class="pre">c::value</span> <span class="pre">==</span> <span class="pre">n::value</span> <span class="pre">+</span> <span class="pre">1</span></tt>.</td>
  99. </tr>
  100. <tr><td><tt class="literal"><span class="pre"><a href="./prior.html" class="identifier">prior</a>&lt;n&gt;::type</span></tt></td>
  101. <td>An <a class="reference internal" href="./integral-constant.html">Integral Constant</a> <tt class="literal"><span class="pre">c</span></tt> of type <tt class="literal"><span class="pre">n::<a href="./value-type.html" class="identifier">value_type</a></span></tt>
  102. such that <tt class="literal"><span class="pre">c::value</span> <span class="pre">==</span> <span class="pre">n::value</span> <span class="pre">-</span> <span class="pre">1</span></tt>.</td>
  103. </tr>
  104. <tr><td><tt class="literal"><span class="pre">n::<a href="./value-type.html" class="identifier">value_type</a></span> <span class="pre">const</span> <span class="pre">c</span> <span class="pre">=</span> <span class="pre">n()</span></tt></td>
  105. <td><tt class="literal"><span class="pre">c</span> <span class="pre">==</span> <span class="pre">n::value</span></tt>.</td>
  106. </tr>
  107. </tbody>
  108. </table>
  109. </div>
  110. <div class="section" id="id1220">
  111. <h3><a class="subsection-title" href="#models" name="models">Models</a></h3>
  112. <ul class="simple">
  113. <li><a class="reference internal" href="./bool.html">bool_</a></li>
  114. <li><a class="reference internal" href="./int.html">int_</a></li>
  115. <li><a class="reference internal" href="./long.html">long_</a></li>
  116. <li><a class="reference internal" href="./char.html">char_</a></li>
  117. <li><a class="reference internal" href="./integral-c.html">integral_c</a></li>
  118. </ul>
  119. </div>
  120. <div class="section" id="id1221">
  121. <h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3>
  122. <p><a class="reference internal" href="./data-types.html">Data Types</a>, <a class="reference internal" href="./integral-sequence-wrapper.html">Integral Sequence Wrapper</a>, <a class="reference internal" href="./integral-c.html">integral_c</a></p>
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  127. <td><div class="copyright-footer"><div class="copyright">Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams</div>
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