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function object</title>
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<link rel="start" href="../index.html" title="Chapter 1. Boost.NumericConversion">
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<div class="section" lang="en">
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<div class="titlepage"><div><div><h2 class="title" style="clear: both">
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<a name="boost_numericconversion.converter___function_object"></a><a href="converter___function_object.html" title="converter<>
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function object">converter<>
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function object</a>
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</h2></div></div></div>
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<div class="toc"><dl>
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<dt><span class="section"><a href="converter___function_object.html#boost_numericconversion.converter___function_object.synopsis">Synopsis</a></span></dt>
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<dt><span class="section"><a href="converter___function_object.html#boost_numericconversion.converter___function_object.template_parameters">Template
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parameters</a></span></dt>
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<dt><span class="section"><a href="converter___function_object.html#boost_numericconversion.converter___function_object.member_functions">Member
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functions</a></span></dt>
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<dt><span class="section"><a href="converter___function_object.html#boost_numericconversion.converter___function_object.range_checking_logic">Range
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Checking Logic</a></span></dt>
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<dt><span class="section"><a href="converter___function_object.html#boost_numericconversion.converter___function_object.examples">Examples</a></span></dt>
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</dl></div>
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<div class="section" lang="en">
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<div class="titlepage"><div><div><h3 class="title">
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<a name="boost_numericconversion.converter___function_object.synopsis"></a><a href="converter___function_object.html#boost_numericconversion.converter___function_object.synopsis" title="Synopsis">Synopsis</a>
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</h3></div></div></div>
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<pre class="programlisting">
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<span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span> <span class="keyword">namespace</span> <span class="identifier">numeric</span> <span class="special">{</span>
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<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span>
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<span class="keyword">class</span> <span class="identifier">S</span><span class="special">,</span>
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<span class="keyword">class</span> <span class="identifier">Traits</span><span class="special">,</span> <span class="special">=</span> <span class="identifier">conversion_traits</span><span class="special"><</span><span class="identifier">T</span><span class="special">,</span><span class="identifier">S</span><span class="special">></span>
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<span class="keyword">class</span> <span class="identifier">OverflowHandler</span> <span class="special">=</span> <span class="identifier">def_overflow_handler</span><span class="special">,</span>
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<span class="keyword">class</span> <span class="identifier">Float2IntRounder</span> <span class="special">=</span> <span class="identifier">Trunc</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">Traits</span><span class="special">::</span><span class="identifier">source_type</span> <span class="special">>,</span>
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<span class="keyword">class</span> <span class="identifier">RawConverter</span> <span class="special">=</span> <span class="identifier">raw_converter</span><span class="special"><</span><span class="identifier">Traits</span><span class="special">>,</span>
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<span class="keyword">class</span> <span class="identifier">UserRangeChecker</span> <span class="special">=</span> <span class="identifier">UseInternalRangeChecker</span>
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<span class="special">></span>
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<span class="keyword">struct</span> <span class="identifier">converter</span>
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<span class="special">{</span>
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<span class="keyword">typedef</span> <span class="identifier">Traits</span> <span class="identifier">traits</span> <span class="special">;</span>
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<span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">Traits</span><span class="special">::</span><span class="identifier">source_type</span> <span class="identifier">source_type</span> <span class="special">;</span>
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<span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">Traits</span><span class="special">::</span><span class="identifier">argument_type</span> <span class="identifier">argument_type</span> <span class="special">;</span>
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<span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">Traits</span><span class="special">::</span><span class="identifier">result_type</span> <span class="identifier">result_type</span> <span class="special">;</span>
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<span class="keyword">static</span> <span class="identifier">result_type</span> <span class="identifier">convert</span> <span class="special">(</span> <span class="identifier">argument_type</span> <span class="identifier">s</span> <span class="special">)</span> <span class="special">;</span>
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<span class="identifier">result_type</span> <span class="keyword">operator</span><span class="special">()</span> <span class="special">(</span> <span class="identifier">argument_type</span> <span class="identifier">s</span> <span class="special">)</span> <span class="keyword">const</span> <span class="special">;</span>
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<span class="comment">// Internal member functions:
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</span>
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<span class="keyword">static</span> <span class="identifier">range_check_result</span> <span class="identifier">out_of_range</span> <span class="special">(</span> <span class="identifier">argument_type</span> <span class="identifier">s</span> <span class="special">)</span> <span class="special">;</span>
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<span class="keyword">static</span> <span class="keyword">void</span> <span class="identifier">validate_range</span> <span class="special">(</span> <span class="identifier">argument_type</span> <span class="identifier">s</span> <span class="special">)</span> <span class="special">;</span>
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<span class="keyword">static</span> <span class="identifier">result_type</span> <span class="identifier">low_level_convert</span> <span class="special">(</span> <span class="identifier">argument_type</span> <span class="identifier">s</span> <span class="special">)</span> <span class="special">;</span>
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<span class="keyword">static</span> <span class="identifier">source_type</span> <span class="identifier">nearbyint</span> <span class="special">(</span> <span class="identifier">argument_type</span> <span class="identifier">s</span> <span class="special">)</span> <span class="special">;</span>
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<span class="special">}</span> <span class="special">;</span>
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<span class="special">}</span> <span class="special">}</span> <span class="comment">// namespace numeric, boost
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</span></pre>
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<p>
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<code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">numeric</span><span class="special">::</span><span class="identifier">converter</span><span class="special"><></span></code>
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is a <a href="http://www.sgi.com/tech/stl/UnaryFunction.html" target="_top">Unary Function
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Object</a> encapsulating the code to perform a numeric conversion with
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the direction and properties specified by the Traits template parameter.
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It can optionally take some <a href="../index.html#numeric_coversion_converter_policies">policies</a>
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which can be used to customize its behavior. The <code class="computeroutput"><span class="identifier">Traits</span></code>
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parameter is not a policy but the parameter that defines the conversion.
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</p>
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</div>
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<div class="section" lang="en">
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<div class="titlepage"><div><div><h3 class="title">
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<a name="boost_numericconversion.converter___function_object.template_parameters"></a><a href="converter___function_object.html#boost_numericconversion.converter___function_object.template_parameters" title="Template
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parameters">Template
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parameters</a>
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</h3></div></div></div>
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<div class="informaltable"><table class="table">
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<colgroup>
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<col>
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<col>
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</colgroup>
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<thead><tr>
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<th>
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<p>
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</p>
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</th>
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<th>
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<p>
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</p>
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</th>
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</tr></thead>
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<tbody>
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<tr>
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<td>
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<p>
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<code class="computeroutput"><span class="identifier">T</span></code>
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</p>
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</td>
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<td>
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<p>
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The <a href="definitions.html#numeric_conversion_definitions_numeric_types">Numeric
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Type</a> which is the <span class="emphasis"><em>Target</em></span> of the conversion.
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<code class="computeroutput"><span class="identifier">S</span></code>
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</p>
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</td>
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<td>
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<p>
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The <a href="definitions.html#numeric_conversion_definitions_numeric_types">Numeric
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Type</a> which is the <span class="emphasis"><em>Source</em></span> of the conversion.
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<code class="computeroutput"><span class="identifier">Traits</span></code>
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</p>
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</td>
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<td>
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<p>
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This must be a conversion traits class with the interface of <a href="../index.html#numeric_conversion_traits"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">numeric</span><span class="special">::</span><span class="identifier">conversion_traits</span></code></a>
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<code class="computeroutput"><span class="identifier">OverflowHandler</span></code>
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||
</p>
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||
</td>
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<td>
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<p>
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<span class="bold"><strong>Stateless Policy</strong></span> called to administrate
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the result of the range checking.
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</p>
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<p>
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It is a <span class="bold"><strong>Function Object</strong></span> which receives
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the result of <code class="computeroutput"><span class="identifier">out_of_range</span><span class="special">()</span></code> and is called inside the <code class="computeroutput"><span class="identifier">validate_range</span><span class="special">()</span></code>
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||
static member function exposed by the converter.
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||
</p>
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</td>
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||
</tr>
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<tr>
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<td>
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<p>
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||
<code class="computeroutput"><span class="identifier">Float2IntRounder</span></code>
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||
</p>
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||
</td>
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||
<td>
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||
<p>
|
||
<span class="bold"><strong>Stateless Policy</strong></span> which specifies
|
||
the rounding mode used for float to integral conversions.
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||
</p>
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||
<p>
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||
It supplies the <code class="computeroutput"><span class="identifier">nearbyint</span><span class="special">()</span></code> static member function exposed
|
||
by the converter.
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||
</p>
|
||
</td>
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||
</tr>
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<tr>
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||
<td>
|
||
<p>
|
||
<code class="computeroutput"><span class="identifier">RawConverter</span></code>
|
||
</p>
|
||
</td>
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||
<td>
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||
<p>
|
||
<span class="bold"><strong>Stateless Policy</strong></span> which is used to
|
||
perform the actual conversion.
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||
</p>
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||
<p>
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||
It supplies the <code class="computeroutput"><span class="identifier">low_level_convert</span><span class="special">()</span></code> static member function exposed
|
||
by the converter.
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||
</p>
|
||
</td>
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||
</tr>
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||
<tr>
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||
<td>
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||
<p>
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||
<code class="computeroutput"><span class="identifier">UserRangeChecker</span></code>
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||
</p>
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||
</td>
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<td>
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<p>
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<span class="emphasis"><em>Special and Optional</em></span> <span class="bold"><strong>Stateless
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||
Policy</strong></span> which can be used to override the internal range
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||
checking logic.
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</p>
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<p>
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If given, supplies alternative code for the <code class="computeroutput"><span class="identifier">out_of_range</span><span class="special">()</span></code> and <code class="computeroutput"><span class="identifier">validate_range</span><span class="special">()</span></code> static member functions exposed
|
||
by the converter.
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</p>
|
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</td>
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</tr>
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||
</tbody>
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||
</table></div>
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</div>
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||
<div class="section" lang="en">
|
||
<div class="titlepage"><div><div><h3 class="title">
|
||
<a name="boost_numericconversion.converter___function_object.member_functions"></a><a href="converter___function_object.html#boost_numericconversion.converter___function_object.member_functions" title="Member
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||
functions">Member
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||
functions</a>
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</h3></div></div></div>
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<div class="blockquote"><blockquote class="blockquote">
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<p>
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||
</p>
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<p>
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<code class="computeroutput"><span class="keyword">static</span> <span class="identifier">result_type</span>
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<span class="identifier">converter</span><span class="special"><>::</span><span class="identifier">convert</span> <span class="special">(</span>
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<span class="identifier">argument_type</span> <span class="identifier">s</span>
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<span class="special">)</span> <span class="special">;</span>
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<span class="comment">// throw </span></code>
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</p>
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<p>
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</p>
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</blockquote></div>
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<p>
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This static member function converts an rvalue of type <code class="computeroutput"><span class="identifier">source_type</span></code>
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to an rvalue of type <code class="computeroutput"><span class="identifier">target_type</span></code>.
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</p>
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<p>
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If the conversion requires it, it performs a range checking before the conversion
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and passes the result of the check to the overflow handler policy (the default
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policy throws an exception if out-of-range is detected)
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</p>
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<p>
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The implementation of this function is actually built from the policies and
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is basically as follows:
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</p>
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<pre class="programlisting">
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||
<span class="identifier">result_type</span> <span class="identifier">converter</span><span class="special"><>::</span><span class="identifier">convert</span> <span class="special">(</span> <span class="identifier">argument_type</span> <span class="identifier">s</span> <span class="special">)</span>
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<span class="special">{</span>
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<span class="identifier">validate_range</span><span class="special">(</span><span class="identifier">s</span><span class="special">);</span> <span class="comment">// Implemented by the internal range checking logic
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</span> <span class="comment">// (which also calls the OverflowHandler policy)
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</span> <span class="comment">// or externally supplied by the UserRangeChecker policy.
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</span>
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<span class="identifier">s</span> <span class="special">=</span> <span class="identifier">nearbyint</span><span class="special">(</span><span class="identifier">s</span><span class="special">);</span> <span class="comment">// Externally supplied by the Float2IntRounder policy.
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</span> <span class="comment">// NOTE: This is actually called only for float to int conversions.
|
||
</span>
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||
<span class="keyword">return</span> <span class="identifier">low_level_convert</span><span class="special">(</span><span class="identifier">s</span><span class="special">);</span> <span class="comment">// Externally supplied by the RawConverter policy.
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</span><span class="special">}</span>
|
||
</pre>
|
||
<p>
|
||
<code class="computeroutput"><span class="identifier">converter</span><span class="special"><>::</span><span class="keyword">operator</span><span class="special">()</span> <span class="keyword">const</span></code> just calls <code class="computeroutput"><span class="identifier">convert</span><span class="special">()</span></code>
|
||
</p>
|
||
<p>
|
||
<span class="inlinemediaobject"><img src="../images/space.png" alt="space"></span>
|
||
</p>
|
||
<div class="blockquote"><blockquote class="blockquote">
|
||
<p>
|
||
</p>
|
||
<p>
|
||
<code class="computeroutput"><span class="keyword">static</span> <span class="identifier">range_check_result</span>
|
||
<span class="identifier">numeric_converter</span><span class="special"><>::</span><span class="identifier">out_of_range</span> <span class="special">(</span>
|
||
<span class="identifier">argument_type</span> <span class="identifier">s</span>
|
||
<span class="special">)</span> <span class="special">;</span></code>
|
||
</p>
|
||
<p>
|
||
</p>
|
||
</blockquote></div>
|
||
<p>
|
||
This <a href="converter___function_object.html#numeric_conversion_converter_internal">internal</a>
|
||
static member function determines if the value <code class="computeroutput"><span class="identifier">s</span></code>
|
||
can be represented by the target type without overflow.
|
||
</p>
|
||
<p>
|
||
It does not determine if the conversion is <span class="emphasis"><em>exact</em></span>; that
|
||
is, it does not detect <span class="emphasis"><em>inexact</em></span> conversions, only <span class="emphasis"><em>out-of-range</em></span>
|
||
conversions (see the <a href="definitions.html#numeric_conversion_definitions_roundoff">Definitions</a>
|
||
for further details).
|
||
</p>
|
||
<p>
|
||
The return value is of enum type <a href="numeric_converter_policy_classes.html#numeric_conversion_converter_policies_range_check_result"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">numeric</span><span class="special">::</span><span class="identifier">range_check_result</span></code></a>
|
||
</p>
|
||
<p>
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||
The actual code for the range checking logic is optimized for the combined
|
||
properties of the source and target types. For example, a non-subranged conversion
|
||
(i.e: <code class="computeroutput"><span class="keyword">int</span></code>-><code class="computeroutput"><span class="keyword">float</span></code>), requires no range checking, so <code class="computeroutput"><span class="identifier">out_of_range</span><span class="special">()</span></code>
|
||
returns <code class="computeroutput"><span class="identifier">cInRange</span></code> directly.
|
||
See the following <a href="converter___function_object.html#numeric_conversion_converter_range_checking_logic">table</a>
|
||
for more details.
|
||
</p>
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||
<p>
|
||
If the user supplied a <a href="numeric_converter_policy_classes.html#numeric_conversion_policy_user_range_checker">UserRangeChecker</a>
|
||
policy, is this policy which implements this function, so the implementation
|
||
is user defined, although it is expected to perform the same conceptual check
|
||
and return the appropriate result.
|
||
</p>
|
||
<p>
|
||
<span class="inlinemediaobject"><img src="../images/space.png" alt="space"></span>
|
||
</p>
|
||
<div class="blockquote"><blockquote class="blockquote">
|
||
<p>
|
||
</p>
|
||
<p>
|
||
<code class="computeroutput"><span class="keyword">static</span> <span class="keyword">void</span>
|
||
<span class="identifier">numeric_converter</span><span class="special"><>::</span><span class="identifier">validate_range</span> <span class="special">(</span>
|
||
<span class="identifier">argument_type</span> <span class="identifier">s</span>
|
||
<span class="special">)</span> <span class="special">;</span>
|
||
<span class="comment">// no throw </span></code>
|
||
</p>
|
||
<p>
|
||
</p>
|
||
</blockquote></div>
|
||
<p>
|
||
This <a href="converter___function_object.html#numeric_conversion_converter_internal">internal</a>
|
||
static member function calls out_of_range(s), and passes the result to the
|
||
<a href="numeric_converter_policy_classes.html#numeric_conversion_policy_overflow_handler">OverflowHandler</a>
|
||
policy class.
|
||
</p>
|
||
<p>
|
||
For those Target/Source combinations which don't require range checking,
|
||
this is an empty inline function.
|
||
</p>
|
||
<p>
|
||
If the user supplied a <a href="numeric_converter_policy_classes.html#numeric_conversion_policy_user_range_checker">UserRangeChecker</a>
|
||
policy, is this policy which implements this function, so the implementation
|
||
is user defined, although it is expected to perform the same action as the
|
||
default. In particular, it is expected to pass the result of the check to
|
||
the overflow handler.
|
||
</p>
|
||
<p>
|
||
<span class="inlinemediaobject"><img src="../images/space.png" alt="space"></span>
|
||
</p>
|
||
<div class="blockquote"><blockquote class="blockquote">
|
||
<p>
|
||
</p>
|
||
<p>
|
||
<code class="computeroutput"><span class="keyword">static</span> <span class="identifier">result_type</span>
|
||
<span class="identifier">numeric_converter</span><span class="special"><>::</span><span class="identifier">low_level_convert</span> <span class="special">(</span>
|
||
<span class="identifier">argument_type</span> <span class="identifier">s</span>
|
||
<span class="special">)</span> <span class="special">;</span></code>
|
||
</p>
|
||
<p>
|
||
</p>
|
||
</blockquote></div>
|
||
<p>
|
||
This <a href="converter___function_object.html#numeric_conversion_converter_internal">internal</a>
|
||
static member function performs the actual conversion.
|
||
</p>
|
||
<p>
|
||
This function is externally supplied by the <a href="numeric_converter_policy_classes.html#numeric_conversion_policy_raw_converter">RawConverter</a>
|
||
policy class.
|
||
</p>
|
||
<p>
|
||
<span class="inlinemediaobject"><img src="../images/space.png" alt="space"></span>
|
||
</p>
|
||
<div class="blockquote"><blockquote class="blockquote">
|
||
<p>
|
||
</p>
|
||
<p>
|
||
<code class="computeroutput"><span class="keyword">static</span> <span class="identifier">source_type</span>
|
||
<span class="identifier">converter</span><span class="special"><>::</span><span class="identifier">nearbyint</span> <span class="special">(</span>
|
||
<span class="identifier">argument_type</span> <span class="identifier">s</span>
|
||
<span class="special">)</span> <span class="special">;</span></code>
|
||
</p>
|
||
<p>
|
||
</p>
|
||
</blockquote></div>
|
||
<p>
|
||
This <a href="converter___function_object.html#numeric_conversion_converter_internal">internal</a>
|
||
static member function, which is <span class="underline">only used</span>
|
||
for <code class="computeroutput"><span class="keyword">float</span></code> to <code class="computeroutput"><span class="keyword">int</span></code>
|
||
conversions, returns an <span class="emphasis"><em>integer</em></span> value of <span class="emphasis"><em><span class="underline">floating-point type</span></em></span> according to some
|
||
rounding direction.
|
||
</p>
|
||
<p>
|
||
This function is externally supplied by the <a href="numeric_converter_policy_classes.html#numeric_conversion_policy_float_to_int_rounder">Float2IntRounder</a>
|
||
policy class which encapsulates the specific rounding mode.
|
||
</p>
|
||
<p>
|
||
<span class="inlinemediaobject"><img src="../images/space.png" alt="space"></span>
|
||
</p>
|
||
<a name="numeric_conversion_converter_internal"></a><p>
|
||
</p>
|
||
<a name="boost_numericconversion.converter___function_object.member_functions.internal_member_functions"></a><h5>
|
||
<a name="id2624118"></a>
|
||
<a href="converter___function_object.html#boost_numericconversion.converter___function_object.member_functions.internal_member_functions">Internal
|
||
Member Functions</a>
|
||
</h5>
|
||
<p>
|
||
These static member functions build the actual conversion code used by <code class="computeroutput"><span class="identifier">convert</span><span class="special">()</span></code>.
|
||
The user does not have to call these if calling <code class="computeroutput"><span class="identifier">convert</span><span class="special">()</span></code>, since <code class="computeroutput"><span class="identifier">convert</span><span class="special">()</span></code> calls them infernally, but they can be
|
||
called separately for specific needs.
|
||
</p>
|
||
</div>
|
||
<a name="numeric_conversion_converter_range_checking_logic"></a><p>
|
||
</p>
|
||
<div class="section" lang="en">
|
||
<div class="titlepage"><div><div><h3 class="title">
|
||
<a name="boost_numericconversion.converter___function_object.range_checking_logic"></a><a href="converter___function_object.html#boost_numericconversion.converter___function_object.range_checking_logic" title="Range
|
||
Checking Logic">Range
|
||
Checking Logic</a>
|
||
</h3></div></div></div>
|
||
<p>
|
||
The following table summarizes the internal range checking logic performed
|
||
for each combination of the properties of Source and Target.
|
||
</p>
|
||
<p>
|
||
LowestT/HighestT denotes the highest and lowest values of the Target type,
|
||
respectively.
|
||
</p>
|
||
<p>
|
||
<code class="computeroutput"><span class="identifier">S</span><span class="special">(</span><span class="identifier">n</span><span class="special">)</span></code> is short
|
||
for <code class="computeroutput"><span class="keyword">static_cast</span><span class="special"><</span><span class="identifier">S</span><span class="special">>(</span><span class="identifier">n</span><span class="special">)</span></code> (<code class="computeroutput"><span class="identifier">S</span></code> denotes the Source type).
|
||
</p>
|
||
<p>
|
||
<code class="computeroutput"><span class="identifier">NONE</span></code> indicates that for this
|
||
case there is no range checking.
|
||
</p>
|
||
<pre class="programlisting"><code class="literal">
|
||
int_to_int |--> sig_to_sig |--> subranged |--> ( s >= S(LowestT) ) && ( s <= S(HighestT) )
|
||
| |--> not subranged |--> NONE
|
||
|
|
||
|--> unsig_to_unsig |--> subranged |--> ( s >= S(LowestT) ) && ( s <= S(HighestT) )
|
||
| |--> not subranged |--> NONE
|
||
|
|
||
|--> sig_to_unsig |--> pos subranged |--> ( s >= S(0) ) && ( s <= S(HighestT) )
|
||
| |--> not pos subranged |--> ( s >= S(0) )
|
||
|
|
||
|--> unsig_to_sig |--> subranged |--> ( s <= S(HighestT) )
|
||
| |--> not subranged |--> NONE
|
||
</code>
|
||
<code class="literal">
|
||
int_to_float |--> NONE
|
||
</code>
|
||
<code class="literal">
|
||
float_to_int |--> round_to_zero |--> ( s > S(LowestT)-S(1) ) && ( s < S(HighestT)+S(1) )
|
||
|--> round_to_even_nearest |--> ( s >= S(LowestT)-S(0.5) ) && ( s < S(HighestT)+S(0.5) )
|
||
|--> round_to_infinity |--> ( s > S(LowestT)-S(1) ) && ( s <= S(HighestT) )
|
||
|--> round_to_neg_infinity |--> ( s >= S(LowestT) ) && ( s < S(HighestT)+S(1) )
|
||
</code>
|
||
<code class="literal">
|
||
float_to_float |--> subranged |--> ( s >= S(LowestT) ) && ( s <= S(HighestT) )
|
||
|--> not subranged |--> NONE
|
||
</code>
|
||
</pre>
|
||
</div>
|
||
<div class="section" lang="en">
|
||
<div class="titlepage"><div><div><h3 class="title">
|
||
<a name="boost_numericconversion.converter___function_object.examples"></a><a href="converter___function_object.html#boost_numericconversion.converter___function_object.examples" title="Examples">Examples</a>
|
||
</h3></div></div></div>
|
||
<pre class="programlisting">
|
||
<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">cassert</span><span class="special">></span>
|
||
<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">numeric</span><span class="special">/</span><span class="identifier">conversion</span><span class="special">/</span><span class="identifier">converter</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span>
|
||
|
||
<span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span> <span class="special">{</span>
|
||
|
||
<span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">numeric</span><span class="special">::</span><span class="identifier">converter</span><span class="special"><</span><span class="keyword">int</span><span class="special">,</span><span class="keyword">double</span><span class="special">></span> <span class="identifier">Double2Int</span> <span class="special">;</span>
|
||
|
||
<span class="keyword">int</span> <span class="identifier">x</span> <span class="special">=</span> <span class="identifier">Double2Int</span><span class="special">::</span><span class="identifier">convert</span><span class="special">(</span><span class="number">2.0</span><span class="special">);</span>
|
||
<span class="identifier">assert</span> <span class="special">(</span> <span class="identifier">x</span> <span class="special">==</span> <span class="number">2</span> <span class="special">);</span>
|
||
|
||
<span class="keyword">int</span> <span class="identifier">y</span> <span class="special">=</span> <span class="identifier">Double2Int</span><span class="special">()(</span><span class="number">3.14</span><span class="special">);</span> <span class="comment">// As a function object.
|
||
</span> <span class="identifier">assert</span> <span class="special">(</span> <span class="identifier">y</span> <span class="special">==</span> <span class="number">3</span> <span class="special">)</span> <span class="special">;</span> <span class="comment">// The default rounding is trunc.
|
||
</span>
|
||
<span class="keyword">try</span>
|
||
<span class="special">{</span>
|
||
<span class="keyword">double</span> <span class="identifier">m</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">numeric</span><span class="special">::</span><span class="identifier">bounds</span><span class="special"><</span><span class="keyword">double</span><span class="special">>::</span><span class="identifier">highest</span><span class="special">();</span>
|
||
<span class="keyword">int</span> <span class="identifier">z</span> <span class="special">=</span> <span class="identifier">Double2Int</span><span class="special">::</span><span class="identifier">convert</span><span class="special">(</span><span class="identifier">m</span><span class="special">);</span> <span class="comment">// By default throws positive_overflow()
|
||
</span> <span class="special">}</span>
|
||
<span class="keyword">catch</span> <span class="special">(</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">numeric</span><span class="special">::</span><span class="identifier">positive_overflow</span> <span class="keyword">const</span><span class="special">&</span> <span class="special">)</span>
|
||
<span class="special">{</span>
|
||
<span class="special">}</span>
|
||
|
||
<span class="keyword">return</span> <span class="number">0</span><span class="special">;</span>
|
||
<span class="special">}</span>
|
||
</pre>
|
||
</div>
|
||
</div>
|
||
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
|
||
<td align="left"></td>
|
||
<td align="right"><div class="copyright-footer">Copyright © 2004 -2007 Fernando Luis Cacciola Carballal<p>
|
||
Distributed under the Boost Software License, Version 1.0. (See accompanying
|
||
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
|
||
</p>
|
||
</div></td>
|
||
</tr></table>
|
||
<hr>
|
||
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|
||
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