boost_mpl/doc/refmanual/integral-constant.html

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<div class="section" id="integral-constant">
<h1><a class="toc-backref" href="./data-types-concepts.html#id1574">Integral Constant</a></h1>
<div class="section" id="id1217">
<h3><a class="subsection-title" href="#description" name="description">Description</a></h3>
<p>An <a class="reference internal" href="./integral-constant.html">Integral Constant</a> is a holder class for a compile-time value of an
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>,
returning itself. An integral constant <em>object</em> is implicitly convertible to the
corresponding run-time value of the wrapped integral type.</p>
</div>
<div class="section" id="id1218">
<h3><a class="subsection-title" href="#expression-requirements" name="expression-requirements">Expression requirements</a></h3>
<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>
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<tr><th class="head">Expression</th>
<th class="head">Type</th>
<th class="head">Complexity</th>
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<tr><td><tt class="literal"><span class="pre">n::tag</span></tt></td>
<td><tt class="literal"><span class="pre">integral_c_tag</span></tt></td>
<td>Constant time.</td>
</tr>
<tr><td><tt class="literal"><span class="pre">n::<a href="./value-type.html" class="identifier">value_type</a></span></tt></td>
<td>An integral type</td>
<td>Constant time.</td>
</tr>
<tr><td><tt class="literal"><span class="pre">n::value</span></tt></td>
<td>An integral constant expression</td>
<td>Constant time.</td>
</tr>
<tr><td><tt class="literal"><span class="pre">n::type</span></tt></td>
<td><a class="reference internal" href="./integral-constant.html">Integral Constant</a></td>
<td>Constant time.</td>
</tr>
<tr><td><tt class="literal"><span class="pre"><a href="./next.html" class="identifier">next</a>&lt;n&gt;::type</span></tt></td>
<td><a class="reference internal" href="./integral-constant.html">Integral Constant</a></td>
<td>Constant time.</td>
</tr>
<tr><td><tt class="literal"><span class="pre"><a href="./prior.html" class="identifier">prior</a>&lt;n&gt;::type</span></tt></td>
<td><a class="reference internal" href="./integral-constant.html">Integral Constant</a></td>
<td>Constant time.</td>
</tr>
<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>
<td>&nbsp;</td>
<td>Constant time.</td>
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</table>
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<div class="section" id="id1219">
<h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3>
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<col width="60%" />
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<tr><th class="head">Expression</th>
<th class="head">Semantics</th>
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<tr><td><tt class="literal"><span class="pre">n::tag</span></tt></td>
<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
<em>conversion rank</em>.</td>
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<tr><td><tt class="literal"><span class="pre">n::<a href="./value-type.html" class="identifier">value_type</a></span></tt></td>
<td>A cv-unqualified type of <tt class="literal"><span class="pre">n::value</span></tt>.</td>
</tr>
<tr><td><tt class="literal"><span class="pre">n::value</span></tt></td>
<td>The value of the wrapped integral constant.</td>
</tr>
<tr><td><tt class="literal"><span class="pre">n::type</span></tt></td>
<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>
</tr>
<tr><td><tt class="literal"><span class="pre"><a href="./next.html" class="identifier">next</a>&lt;n&gt;::type</span></tt></td>
<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>
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>
</tr>
<tr><td><tt class="literal"><span class="pre"><a href="./prior.html" class="identifier">prior</a>&lt;n&gt;::type</span></tt></td>
<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>
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>
</tr>
<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>
<td><tt class="literal"><span class="pre">c</span> <span class="pre">==</span> <span class="pre">n::value</span></tt>.</td>
</tr>
</tbody>
</table>
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<div class="section" id="id1220">
<h3><a class="subsection-title" href="#models" name="models">Models</a></h3>
<ul class="simple">
<li><a class="reference internal" href="./bool.html">bool_</a></li>
<li><a class="reference internal" href="./int.html">int_</a></li>
<li><a class="reference internal" href="./long.html">long_</a></li>
<li><a class="reference internal" href="./char.html">char_</a></li>
<li><a class="reference internal" href="./integral-c.html">integral_c</a></li>
</ul>
</div>
<div class="section" id="id1221">
<h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3>
<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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