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| 24 | </div> | |
| 25 | <div class="section"> | |
| 26 | <div class="titlepage"><div><div><h2 class="title" style="clear: both"> | |
| 27 | <a name="boost_numericconversion.converter___function_object"></a><a class="link" href="converter___function_object.html" title="converter<> function object">converter<> | |
| 28 | function object</a> | |
| 29 | </h2></div></div></div> | |
| 30 | <div class="toc"><dl class="toc"> | |
| 31 | <dt><span class="section"><a href="converter___function_object.html#boost_numericconversion.converter___function_object.synopsis">Synopsis</a></span></dt> | |
| 32 | <dt><span class="section"><a href="converter___function_object.html#boost_numericconversion.converter___function_object.template_parameters">Template | |
| 33 | parameters</a></span></dt> | |
| 34 | <dt><span class="section"><a href="converter___function_object.html#boost_numericconversion.converter___function_object.member_functions">Member | |
| 35 | functions</a></span></dt> | |
| 36 | <dt><span class="section"><a href="converter___function_object.html#boost_numericconversion.converter___function_object.range_checking_logic">Range | |
| 37 | Checking Logic</a></span></dt> | |
| 38 | <dt><span class="section"><a href="converter___function_object.html#boost_numericconversion.converter___function_object.examples">Examples</a></span></dt> | |
| 39 | </dl></div> | |
| 40 | <div class="section"> | |
| 41 | <div class="titlepage"><div><div><h3 class="title"> | |
| 42 | <a name="boost_numericconversion.converter___function_object.synopsis"></a><a class="link" href="converter___function_object.html#boost_numericconversion.converter___function_object.synopsis" title="Synopsis">Synopsis</a> | |
| 43 | </h3></div></div></div> | |
| 44 | <pre class="programlisting"><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> | |
| 45 | ||
| 46 | ||
| 47 | <span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> | |
| 48 | <span class="keyword">class</span> <span class="identifier">S</span><span class="special">,</span> | |
| 49 | <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> | |
| 50 | <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> | |
| 51 | <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> | |
| 52 | <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> | |
| 53 | <span class="keyword">class</span> <span class="identifier">UserRangeChecker</span> <span class="special">=</span> <span class="identifier">UseInternalRangeChecker</span> | |
| 54 | <span class="special">></span> | |
| 55 | <span class="keyword">struct</span> <span class="identifier">converter</span> | |
| 56 | <span class="special">{</span> | |
| 57 | <span class="keyword">typedef</span> <span class="identifier">Traits</span> <span class="identifier">traits</span> <span class="special">;</span> | |
| 58 | ||
| 59 | <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> | |
| 60 | <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> | |
| 61 | <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> | |
| 62 | ||
| 63 | <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> | |
| 64 | ||
| 65 | <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> | |
| 66 | ||
| 67 | <span class="comment">// Internal member functions:</span> | |
| 68 | ||
| 69 | <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> | |
| 70 | <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> | |
| 71 | <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> | |
| 72 | <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> | |
| 73 | ||
| 74 | <span class="special">}</span> <span class="special">;</span> | |
| 75 | ||
| 76 | <span class="special">}</span> <span class="special">}</span> <span class="comment">// namespace numeric, boost</span> | |
| 77 | </pre> | |
| 78 | <p> | |
| 79 | <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> | |
| 80 | is a <a href="http://www.sgi.com/tech/stl/UnaryFunction.html" target="_top">Unary Function | |
| 81 | Object</a> encapsulating the code to perform a numeric conversion with | |
| 82 | the direction and properties specified by the Traits template parameter. | |
| 83 | It can optionally take some <a class="link" href="numeric_converter_policy_classes.html" title="Numeric Converter Policy Classes">policies</a> | |
| 84 | which can be used to customize its behavior. The <code class="computeroutput"><span class="identifier">Traits</span></code> | |
| 85 | parameter is not a policy but the parameter that defines the conversion. | |
| 86 | </p> | |
| 87 | </div> | |
| 88 | <div class="section"> | |
| 89 | <div class="titlepage"><div><div><h3 class="title"> | |
| 90 | <a name="boost_numericconversion.converter___function_object.template_parameters"></a><a class="link" href="converter___function_object.html#boost_numericconversion.converter___function_object.template_parameters" title="Template parameters">Template | |
| 91 | parameters</a> | |
| 92 | </h3></div></div></div> | |
| 93 | <div class="informaltable"><table class="table"> | |
| 94 | <colgroup> | |
| 95 | <col> | |
| 96 | <col> | |
| 97 | </colgroup> | |
| 98 | <thead><tr> | |
| 99 | <th> | |
| 100 | </th> | |
| 101 | <th> | |
| 102 | </th> | |
| 103 | </tr></thead> | |
| 104 | <tbody> | |
| 105 | <tr> | |
| 106 | <td> | |
| 107 | <p> | |
| 108 | <code class="computeroutput"><span class="identifier">T</span></code> | |
| 109 | </p> | |
| 110 | </td> | |
| 111 | <td> | |
| 112 | <p> | |
| 113 | The <a class="link" href="definitions.html#boost_numericconversion.definitions.numeric_types" title="Numeric Types">Numeric | |
| 114 | Type</a> which is the <span class="emphasis"><em>Target</em></span> of the conversion. | |
| 115 | </p> | |
| 116 | </td> | |
| 117 | </tr> | |
| 118 | <tr> | |
| 119 | <td> | |
| 120 | <p> | |
| 121 | <code class="computeroutput"><span class="identifier">S</span></code> | |
| 122 | </p> | |
| 123 | </td> | |
| 124 | <td> | |
| 125 | <p> | |
| 126 | The <a class="link" href="definitions.html#boost_numericconversion.definitions.numeric_types" title="Numeric Types">Numeric | |
| 127 | Type</a> which is the <span class="emphasis"><em>Source</em></span> of the conversion. | |
| 128 | </p> | |
| 129 | </td> | |
| 130 | </tr> | |
| 131 | <tr> | |
| 132 | <td> | |
| 133 | <p> | |
| 134 | <code class="computeroutput"><span class="identifier">Traits</span></code> | |
| 135 | </p> | |
| 136 | </td> | |
| 137 | <td> | |
| 138 | <p> | |
| 139 | This must be a conversion traits class with the interface of <a class="link" href="conversion_traits___traits_class.html" title="conversion_traits<> traits class"><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> | |
| 140 | </p> | |
| 141 | </td> | |
| 142 | </tr> | |
| 143 | <tr> | |
| 144 | <td> | |
| 145 | <p> | |
| 146 | <code class="computeroutput"><span class="identifier">OverflowHandler</span></code> | |
| 147 | </p> | |
| 148 | </td> | |
| 149 | <td> | |
| 150 | <p> | |
| 151 | <span class="bold"><strong>Stateless Policy</strong></span> called to administrate | |
| 152 | the result of the range checking. | |
| 153 | </p> | |
| 154 | <p> | |
| 155 | It is a <span class="bold"><strong>Function Object</strong></span> which | |
| 156 | receives 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> | |
| 157 | static member function exposed by the converter. | |
| 158 | </p> | |
| 159 | </td> | |
| 160 | </tr> | |
| 161 | <tr> | |
| 162 | <td> | |
| 163 | <p> | |
| 164 | <code class="computeroutput"><span class="identifier">Float2IntRounder</span></code> | |
| 165 | </p> | |
| 166 | </td> | |
| 167 | <td> | |
| 168 | <p> | |
| 169 | <span class="bold"><strong>Stateless Policy</strong></span> which specifies | |
| 170 | the rounding mode used for float to integral conversions. | |
| 171 | </p> | |
| 172 | <p> | |
| 173 | It supplies the <code class="computeroutput"><span class="identifier">nearbyint</span><span class="special">()</span></code> static member function exposed | |
| 174 | by the converter. | |
| 175 | </p> | |
| 176 | </td> | |
| 177 | </tr> | |
| 178 | <tr> | |
| 179 | <td> | |
| 180 | <p> | |
| 181 | <code class="computeroutput"><span class="identifier">RawConverter</span></code> | |
| 182 | </p> | |
| 183 | </td> | |
| 184 | <td> | |
| 185 | <p> | |
| 186 | <span class="bold"><strong>Stateless Policy</strong></span> which is used | |
| 187 | to perform the actual conversion. | |
| 188 | </p> | |
| 189 | <p> | |
| 190 | It supplies the <code class="computeroutput"><span class="identifier">low_level_convert</span><span class="special">()</span></code> static member function exposed | |
| 191 | by the converter. | |
| 192 | </p> | |
| 193 | </td> | |
| 194 | </tr> | |
| 195 | <tr> | |
| 196 | <td> | |
| 197 | <p> | |
| 198 | <code class="computeroutput"><span class="identifier">UserRangeChecker</span></code> | |
| 199 | </p> | |
| 200 | </td> | |
| 201 | <td> | |
| 202 | <p> | |
| 203 | <span class="emphasis"><em>Special and Optional</em></span> <span class="bold"><strong>Stateless | |
| 204 | Policy</strong></span> which can be used to override the internal range | |
| 205 | checking logic. | |
| 206 | </p> | |
| 207 | <p> | |
| 208 | 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 | |
| 209 | by the converter. | |
| 210 | </p> | |
| 211 | </td> | |
| 212 | </tr> | |
| 213 | </tbody> | |
| 214 | </table></div> | |
| 215 | </div> | |
| 216 | <div class="section"> | |
| 217 | <div class="titlepage"><div><div><h3 class="title"> | |
| 218 | <a name="boost_numericconversion.converter___function_object.member_functions"></a><a class="link" href="converter___function_object.html#boost_numericconversion.converter___function_object.member_functions" title="Member functions">Member | |
| 219 | functions</a> | |
| 220 | </h3></div></div></div> | |
| 221 | <div class="blockquote"><blockquote class="blockquote"><p> | |
| 222 | <code class="computeroutput"><span class="keyword">static</span> <span class="identifier">result_type</span> | |
| 223 | <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> | |
| 224 | <span class="special">)</span> <span class="special">;</span> <span class="comment">// throw</span> </code> | |
| 225 | </p></blockquote></div> | |
| 226 | <p> | |
| 227 | This static member function converts an rvalue of type <code class="computeroutput"><span class="identifier">source_type</span></code> | |
| 228 | to an rvalue of type <code class="computeroutput"><span class="identifier">target_type</span></code>. | |
| 229 | </p> | |
| 230 | <p> | |
| 231 | If the conversion requires it, it performs a range checking before the conversion | |
| 232 | and passes the result of the check to the overflow handler policy (the default | |
| 233 | policy throws an exception if out-of-range is detected) | |
| 234 | </p> | |
| 235 | <p> | |
| 236 | The implementation of this function is actually built from the policies and | |
| 237 | is basically as follows: | |
| 238 | </p> | |
| 239 | <pre class="programlisting"><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> | |
| 240 | <span class="special">{</span> | |
| 241 | <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</span> | |
| 242 | <span class="comment">// (which also calls the OverflowHandler policy)</span> | |
| 243 | <span class="comment">// or externally supplied by the UserRangeChecker policy.</span> | |
| 244 | ||
| 245 | <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.</span> | |
| 246 | <span class="comment">// NOTE: This is actually called only for float to int conversions.</span> | |
| 247 | ||
| 248 | <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.</span> | |
| 249 | <span class="special">}</span> | |
| 250 | </pre> | |
| 251 | <p> | |
| 252 | <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> | |
| 253 | </p> | |
| 254 | <p> | |
| 255 | <span class="inlinemediaobject"><img src="../images/space.png" alt="space"></span> | |
| 256 | </p> | |
| 257 | <div class="blockquote"><blockquote class="blockquote"><p> | |
| 258 | <code class="computeroutput"><span class="keyword">static</span> <span class="identifier">range_check_result</span> | |
| 259 | <span class="identifier">numeric_converter</span><span class="special"><>::</span><span class="identifier">out_of_range</span> <span class="special">(</span> | |
| 260 | <span class="identifier">argument_type</span> <span class="identifier">s</span> | |
| 261 | <span class="special">)</span> <span class="special">;</span></code> | |
| 262 | </p></blockquote></div> | |
| 263 | <p> | |
| 264 | This <a class="link" href="converter___function_object.html#numeric_conversion_converter_internal">internal</a> | |
| 265 | static member function determines if the value <code class="computeroutput"><span class="identifier">s</span></code> | |
| 266 | can be represented by the target type without overflow. | |
| 267 | </p> | |
| 268 | <p> | |
| 269 | It does not determine if the conversion is <span class="emphasis"><em>exact</em></span>; that | |
| 270 | is, it does not detect <span class="emphasis"><em>inexact</em></span> conversions, only <span class="emphasis"><em>out-of-range</em></span> | |
| 271 | conversions (see the <a class="link" href="definitions.html#boost_numericconversion.definitions.exact__correctly_rounded_and_out_of_range_representations" title="Exact, Correctly Rounded and Out-Of-Range Representations">Definitions</a> | |
| 272 | for further details). | |
| 273 | </p> | |
| 274 | <p> | |
| 275 | The return value is of enum type <a class="link" href="numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.enum_range_check_result" title="enum 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> | |
| 276 | </p> | |
| 277 | <p> | |
| 278 | The actual code for the range checking logic is optimized for the combined | |
| 279 | properties of the source and target types. For example, a non-subranged conversion | |
| 280 | (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> | |
| 281 | returns <code class="computeroutput"><span class="identifier">cInRange</span></code> directly. | |
| 282 | See the following <a class="link" href="converter___function_object.html#boost_numericconversion.converter___function_object.range_checking_logic" title="Range Checking Logic">table</a> | |
| 283 | for more details. | |
| 284 | </p> | |
| 285 | <p> | |
| 286 | If the user supplied a <a class="link" href="numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_userrangechecker" title="Policy UserRangeChecker">UserRangeChecker</a> | |
| 287 | policy, is this policy which implements this function, so the implementation | |
| 288 | is user defined, although it is expected to perform the same conceptual check | |
| 289 | and return the appropriate result. | |
| 290 | </p> | |
| 291 | <p> | |
| 292 | <span class="inlinemediaobject"><img src="../images/space.png" alt="space"></span> | |
| 293 | </p> | |
| 294 | <div class="blockquote"><blockquote class="blockquote"><p> | |
| 295 | <code class="computeroutput"><span class="keyword">static</span> <span class="keyword">void</span> | |
| 296 | <span class="identifier">numeric_converter</span><span class="special"><>::</span><span class="identifier">validate_range</span> <span class="special">(</span> | |
| 297 | <span class="identifier">argument_type</span> <span class="identifier">s</span> | |
| 298 | <span class="special">)</span> <span class="special">;</span> <span class="comment">// no throw</span> </code> | |
| 299 | </p></blockquote></div> | |
| 300 | <p> | |
| 301 | This <a class="link" href="converter___function_object.html#numeric_conversion_converter_internal">internal</a> | |
| 302 | static member function calls out_of_range(s), and passes the result to the | |
| 303 | <a class="link" href="numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_overflowhandler" title="Policy OverflowHandler">OverflowHandler</a> | |
| 304 | policy class. | |
| 305 | </p> | |
| 306 | <p> | |
| 307 | For those Target/Source combinations which don't require range checking, | |
| 308 | this is an empty inline function. | |
| 309 | </p> | |
| 310 | <p> | |
| 311 | If the user supplied a <a class="link" href="numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_userrangechecker" title="Policy UserRangeChecker">UserRangeChecker</a> | |
| 312 | policy, is this policy which implements this function, so the implementation | |
| 313 | is user defined, although it is expected to perform the same action as the | |
| 314 | default. In particular, it is expected to pass the result of the check to | |
| 315 | the overflow handler. | |
| 316 | </p> | |
| 317 | <p> | |
| 318 | <span class="inlinemediaobject"><img src="../images/space.png" alt="space"></span> | |
| 319 | </p> | |
| 320 | <div class="blockquote"><blockquote class="blockquote"><p> | |
| 321 | <code class="computeroutput"><span class="keyword">static</span> <span class="identifier">result_type</span> | |
| 322 | <span class="identifier">numeric_converter</span><span class="special"><>::</span><span class="identifier">low_level_convert</span> <span class="special">(</span> | |
| 323 | <span class="identifier">argument_type</span> <span class="identifier">s</span> | |
| 324 | <span class="special">)</span> <span class="special">;</span></code> | |
| 325 | </p></blockquote></div> | |
| 326 | <p> | |
| 327 | This <a class="link" href="converter___function_object.html#numeric_conversion_converter_internal">internal</a> | |
| 328 | static member function performs the actual conversion. | |
| 329 | </p> | |
| 330 | <p> | |
| 331 | This function is externally supplied by the <a class="link" href="numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_rawconverter" title="Policy RawConverter">RawConverter</a> | |
| 332 | policy class. | |
| 333 | </p> | |
| 334 | <p> | |
| 335 | <span class="inlinemediaobject"><img src="../images/space.png" alt="space"></span> | |
| 336 | </p> | |
| 337 | <div class="blockquote"><blockquote class="blockquote"><p> | |
| 338 | <code class="computeroutput"><span class="keyword">static</span> <span class="identifier">source_type</span> | |
| 339 | <span class="identifier">converter</span><span class="special"><>::</span><span class="identifier">nearbyint</span> <span class="special">(</span> | |
| 340 | <span class="identifier">argument_type</span> <span class="identifier">s</span> | |
| 341 | <span class="special">)</span> <span class="special">;</span></code> | |
| 342 | </p></blockquote></div> | |
| 343 | <p> | |
| 344 | This <a class="link" href="converter___function_object.html#numeric_conversion_converter_internal">internal</a> | |
| 345 | static member function, which is <span class="underline">only used</span> | |
| 346 | for <code class="computeroutput"><span class="keyword">float</span></code> to <code class="computeroutput"><span class="keyword">int</span></code> | |
| 347 | 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 | |
| 348 | rounding direction. | |
| 349 | </p> | |
| 350 | <p> | |
| 351 | This function is externally supplied by the <a class="link" href="numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_float2introunder" title="Policy Float2IntRounder">Float2IntRounder</a> | |
| 352 | policy class which encapsulates the specific rounding mode. | |
| 353 | </p> | |
| 354 | <p> | |
| 355 | <span class="inlinemediaobject"><img src="../images/space.png" alt="space"></span> | |
| 356 | </p> | |
| 357 | <a name="numeric_conversion_converter_internal"></a><h5> | |
| 358 | <a name="boost_numericconversion.converter___function_object.member_functions.h0"></a> | |
| 359 | <span class="phrase"><a name="boost_numericconversion.converter___function_object.member_functions.internal_member_functions"></a></span><a class="link" href="converter___function_object.html#boost_numericconversion.converter___function_object.member_functions.internal_member_functions">Internal | |
| 360 | Member Functions</a> | |
| 361 | </h5> | |
| 362 | <p> | |
| 363 | These static member functions build the actual conversion code used by <code class="computeroutput"><span class="identifier">convert</span><span class="special">()</span></code>. | |
| 364 | 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 | |
| 365 | called separately for specific needs. | |
| 366 | </p> | |
| 367 | </div> | |
| 368 | <div class="section"> | |
| 369 | <div class="titlepage"><div><div><h3 class="title"> | |
| 370 | <a name="boost_numericconversion.converter___function_object.range_checking_logic"></a><a class="link" href="converter___function_object.html#boost_numericconversion.converter___function_object.range_checking_logic" title="Range Checking Logic">Range | |
| 371 | Checking Logic</a> | |
| 372 | </h3></div></div></div> | |
| 373 | <p> | |
| 374 | The following table summarizes the internal range checking logic performed | |
| 375 | for each combination of the properties of Source and Target. | |
| 376 | </p> | |
| 377 | <p> | |
| 378 | LowestT/HighestT denotes the highest and lowest values of the Target type, | |
| 379 | respectively. | |
| 380 | </p> | |
| 381 | <p> | |
| 382 | <code class="computeroutput"><span class="identifier">S</span><span class="special">(</span><span class="identifier">n</span><span class="special">)</span></code> is short | |
| 383 | 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). | |
| 384 | </p> | |
| 385 | <p> | |
| 386 | <code class="computeroutput"><span class="identifier">NONE</span></code> indicates that for this | |
| 387 | case there is no range checking. | |
| 388 | </p> | |
| 389 | <pre class="programlisting"><code class="literal"> | |
| 390 | int_to_int |--> sig_to_sig |--> subranged |--> ( s >= S(LowestT) ) && ( s <= S(HighestT) ) | |
| 391 | | |--> not subranged |--> NONE | |
| 392 | | | |
| 393 | |--> unsig_to_unsig |--> subranged |--> ( s >= S(LowestT) ) && ( s <= S(HighestT) ) | |
| 394 | | |--> not subranged |--> NONE | |
| 395 | | | |
| 396 | |--> sig_to_unsig |--> pos subranged |--> ( s >= S(0) ) && ( s <= S(HighestT) ) | |
| 397 | | |--> not pos subranged |--> ( s >= S(0) ) | |
| 398 | | | |
| 399 | |--> unsig_to_sig |--> subranged |--> ( s <= S(HighestT) ) | |
| 400 | | |--> not subranged |--> NONE | |
| 401 | </code> | |
| 402 | <code class="literal"> | |
| 403 | int_to_float |--> NONE | |
| 404 | </code> | |
| 405 | <code class="literal"> | |
| 406 | float_to_int |--> round_to_zero |--> ( s > S(LowestT)-S(1) ) && ( s < S(HighestT)+S(1) ) | |
| 407 | |--> round_to_even_nearest |--> ( s >= S(LowestT)-S(0.5) ) && ( s < S(HighestT)+S(0.5) ) | |
| 408 | |--> round_to_infinity |--> ( s > S(LowestT)-S(1) ) && ( s <= S(HighestT) ) | |
| 409 | |--> round_to_neg_infinity |--> ( s >= S(LowestT) ) && ( s < S(HighestT)+S(1) ) | |
| 410 | </code> | |
| 411 | <code class="literal"> | |
| 412 | float_to_float |--> subranged |--> ( s >= S(LowestT) ) && ( s <= S(HighestT) ) | |
| 413 | |--> not subranged |--> NONE | |
| 414 | </code> | |
| 415 | </pre> | |
| 416 | </div> | |
| 417 | <div class="section"> | |
| 418 | <div class="titlepage"><div><div><h3 class="title"> | |
| 419 | <a name="boost_numericconversion.converter___function_object.examples"></a><a class="link" href="converter___function_object.html#boost_numericconversion.converter___function_object.examples" title="Examples">Examples</a> | |
| 420 | </h3></div></div></div> | |
| 421 | <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">cassert</span><span class="special">></span> | |
| 422 | <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> | |
| 423 | ||
| 424 | <span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span> <span class="special">{</span> | |
| 425 | ||
| 426 | <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> | |
| 427 | ||
| 428 | <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> | |
| 429 | <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> | |
| 430 | ||
| 431 | <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> | |
| 432 | <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> | |
| 433 | ||
| 434 | <span class="keyword">try</span> | |
| 435 | <span class="special">{</span> | |
| 436 | <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> | |
| 437 | <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> | |
| 438 | <span class="special">}</span> | |
| 439 | <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> | |
| 440 | <span class="special">{</span> | |
| 441 | <span class="special">}</span> | |
| 442 | ||
| 443 | <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span> | |
| 444 | <span class="special">}</span> | |
| 445 | </pre> | |
| 446 | </div> | |
| 447 | </div> | |
| 448 | <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> | |
| 449 | <td align="left"></td> | |
| 450 | <td align="right"><div class="copyright-footer">Copyright © 2004-2007 Fernando | |
| 451 | Luis Cacciola Carballal<p> | |
| 452 | Distributed under the Boost Software License, Version 1.0. (See accompanying | |
| 453 | 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>) | |
| 454 | </p> | |
| 455 | </div></td> | |
| 456 | </tr></table> | |
| 457 | <hr> | |
| 458 | <div class="spirit-nav"> | |
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