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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.numeric_converter_policy_classes"></a><a class="link" href="numeric_converter_policy_classes.html" title="Numeric Converter Policy Classes">Numeric | |
28 | Converter Policy Classes</a> | |
29 | </h2></div></div></div> | |
30 | <div class="toc"><dl class="toc"> | |
31 | <dt><span class="section"><a href="numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.enum_range_check_result">enum | |
32 | range_check_result</a></span></dt> | |
33 | <dt><span class="section"><a href="numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_overflowhandler">Policy | |
34 | OverflowHandler</a></span></dt> | |
35 | <dt><span class="section"><a href="numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_float2introunder">Policy | |
36 | Float2IntRounder</a></span></dt> | |
37 | <dt><span class="section"><a href="numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_rawconverter">Policy | |
38 | RawConverter</a></span></dt> | |
39 | <dt><span class="section"><a href="numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_userrangechecker">Policy | |
40 | UserRangeChecker</a></span></dt> | |
41 | </dl></div> | |
42 | <div class="section"> | |
43 | <div class="titlepage"><div><div><h3 class="title"> | |
44 | <a name="boost_numericconversion.numeric_converter_policy_classes.enum_range_check_result"></a><a class="link" href="numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.enum_range_check_result" title="enum range_check_result">enum | |
45 | range_check_result</a> | |
46 | </h3></div></div></div> | |
47 | <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> | |
48 | ||
49 | <span class="keyword">enum</span> <span class="identifier">range_check_result</span> | |
50 | <span class="special">{</span> | |
51 | <span class="identifier">cInRange</span> <span class="special">,</span> | |
52 | <span class="identifier">cNegOverflow</span> <span class="special">,</span> | |
53 | <span class="identifier">cPosOverflow</span> | |
54 | <span class="special">}</span> <span class="special">;</span> | |
55 | ||
56 | <span class="special">}</span> <span class="special">}</span> | |
57 | </pre> | |
58 | <p> | |
59 | Defines the values returned by <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><span class="identifier">out_of_range</span><span class="special">()</span></code> | |
60 | </p> | |
61 | </div> | |
62 | <div class="section"> | |
63 | <div class="titlepage"><div><div><h3 class="title"> | |
64 | <a name="boost_numericconversion.numeric_converter_policy_classes.policy_overflowhandler"></a><a class="link" href="numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_overflowhandler" title="Policy OverflowHandler">Policy | |
65 | OverflowHandler</a> | |
66 | </h3></div></div></div> | |
67 | <p> | |
68 | This <span class="emphasis"><em>stateless</em></span> non-template policy class must be a | |
69 | <span class="emphasis"><em>function object</em></span> and is called to administrate the result | |
70 | of the range checking. It can throw an exception if overflow has been detected | |
71 | by the range checking as indicated by its argument. If it throws, is is recommended | |
72 | that it be <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">bad_cast</span></code> or derived. | |
73 | </p> | |
74 | <p> | |
75 | It must have the following interface (it does not has to be a template class): | |
76 | </p> | |
77 | <pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">YourOverflowHandlerPolicy</span> | |
78 | <span class="special">{</span> | |
79 | <span class="keyword">void</span> <span class="keyword">operator</span><span class="special">()</span> <span class="special">(</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">range_check_result</span> <span class="special">)</span> <span class="special">;</span> <span class="comment">// throw bad_cast or derived</span> | |
80 | <span class="special">}</span> <span class="special">;</span> | |
81 | </pre> | |
82 | <p> | |
83 | It is called with the result of the converter's <code class="computeroutput"><span class="identifier">out_of_range</span><span class="special">()</span></code> inside <code class="computeroutput"><span class="identifier">validate_range</span><span class="special">()</span></code>. | |
84 | </p> | |
85 | <p> | |
86 | These are the two overflow handler classes provided by the library: | |
87 | </p> | |
88 | <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> | |
89 | ||
90 | <span class="keyword">struct</span> <span class="identifier">def_overflow_handler</span> | |
91 | <span class="special">{</span> | |
92 | <span class="keyword">void</span> <span class="keyword">operator</span><span class="special">()</span> <span class="special">(</span> <span class="identifier">range_check_result</span> <span class="identifier">r</span> <span class="special">)</span> <span class="comment">// throw bad_numeric_conversion derived</span> | |
93 | <span class="special">{</span> | |
94 | <span class="keyword">if</span> <span class="special">(</span> <span class="identifier">r</span> <span class="special">==</span> <span class="identifier">cNegOverflow</span> <span class="special">)</span> | |
95 | <span class="keyword">throw</span> <span class="identifier">negative_overflow</span><span class="special">()</span> <span class="special">;</span> | |
96 | <span class="keyword">else</span> <span class="keyword">if</span> <span class="special">(</span> <span class="identifier">r</span> <span class="special">==</span> <span class="identifier">cPosOverflow</span> <span class="special">)</span> | |
97 | <span class="keyword">throw</span> <span class="identifier">positive_overflow</span><span class="special">()</span> <span class="special">;</span> | |
98 | <span class="special">}</span> | |
99 | <span class="special">}</span> <span class="special">;</span> | |
100 | ||
101 | <span class="keyword">struct</span> <span class="identifier">silent_overflow_handler</span> | |
102 | <span class="special">{</span> | |
103 | <span class="keyword">void</span> <span class="keyword">operator</span><span class="special">()</span> <span class="special">(</span> <span class="identifier">range_check_result</span> <span class="special">)</span> <span class="comment">// no-throw</span> | |
104 | <span class="special">{}</span> | |
105 | <span class="special">}</span> <span class="special">;</span> | |
106 | ||
107 | <span class="special">}</span> <span class="special">}</span> | |
108 | </pre> | |
109 | <p> | |
110 | And these are the Exception Classes thrown by the default overflow handler | |
111 | <a class="link" href="numeric_converter_policy_classes.html#numeric_conversion_policy_overflow_handler_important_note">(see | |
112 | IMPORTANT note)</a> | |
113 | </p> | |
114 | <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> | |
115 | ||
116 | <a name="numeric_conversion_bad_numeric_cast"></a> | |
117 | <span class="keyword">class</span> <span class="identifier">bad_numeric_cast</span> <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">bad_cast</span> | |
118 | <span class="special">{</span> | |
119 | <span class="keyword">public</span><span class="special">:</span> | |
120 | <span class="keyword">virtual</span> <span class="keyword">const</span> <span class="keyword">char</span> <span class="special">*</span><span class="identifier">what</span><span class="special">()</span> <span class="keyword">const</span> <span class="comment">// throw()</span> | |
121 | <span class="special">{</span> | |
122 | <span class="keyword">return</span> <span class="string">"bad numeric conversion: overflow"</span><span class="special">;</span> | |
123 | <span class="special">}</span> | |
124 | ||
125 | <span class="special">};</span> | |
126 | ||
127 | <a name="numeric_conversion_negative_overflow"></a> | |
128 | <span class="keyword">class</span> <span class="identifier">negative_overflow</span> <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">bad_numeric_cast</span> | |
129 | <span class="special">{</span> | |
130 | <span class="keyword">public</span><span class="special">:</span> | |
131 | <span class="keyword">virtual</span> <span class="keyword">const</span> <span class="keyword">char</span> <span class="special">*</span><span class="identifier">what</span><span class="special">()</span> <span class="keyword">const</span> <span class="comment">// throw()</span> | |
132 | <span class="special">{</span> | |
133 | <span class="keyword">return</span> <span class="string">"bad numeric conversion: negative overflow"</span><span class="special">;</span> | |
134 | <span class="special">}</span> | |
135 | <span class="special">};</span> | |
136 | ||
137 | <a name="numeric_conversion_possitive_overflow"></a> | |
138 | <span class="keyword">class</span> <span class="identifier">positive_overflow</span> <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">bad_numeric_cast</span> | |
139 | <span class="special">{</span> | |
140 | <span class="keyword">public</span><span class="special">:</span> | |
141 | <span class="keyword">virtual</span> <span class="keyword">const</span> <span class="keyword">char</span> <span class="special">*</span><span class="identifier">what</span><span class="special">()</span> <span class="keyword">const</span> <span class="comment">// throw()</span> | |
142 | <span class="special">{</span> | |
143 | <span class="keyword">return</span> <span class="string">"bad numeric conversion: positive overflow"</span><span class="special">;</span> | |
144 | <span class="special">}</span> | |
145 | <span class="special">};</span> | |
146 | ||
147 | ||
148 | <span class="special">}</span> <span class="special">}</span> | |
149 | </pre> | |
150 | <a name="numeric_conversion_policy_overflow_handler_important_note"></a><div class="important"><table border="0" summary="Important"> | |
151 | <tr> | |
152 | <td rowspan="2" align="center" valign="top" width="25"><img alt="[Important]" src="../../../../../../doc/src/images/important.png"></td> | |
153 | <th align="left">Important</th> | |
154 | </tr> | |
155 | <tr><td align="left" valign="top"><p> | |
156 | <span class="bold"><strong>RELEASE NOTE for 1.33</strong></span> Previous to boost | |
157 | version 1.33, the exception class <code class="computeroutput"><span class="identifier">bad_numeric_cast</span></code> | |
158 | was named <code class="computeroutput"><span class="identifier">bad_numeric_conversion</span></code>. | |
159 | However, in 1.33, the old function <code class="computeroutput"><span class="identifier">numeric_cast</span><span class="special"><></span></code> from <code class="computeroutput"><span class="identifier">boost</span><span class="special">/</span><span class="identifier">cast</span><span class="special">.</span><span class="identifier">hpp</span></code> | |
160 | was completly replaced by the new <code class="computeroutput"><span class="identifier">numeric_cast</span><span class="special"><></span></code> in <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</span><span class="special">/</span><span class="identifier">cast</span><span class="special">.</span><span class="identifier">hpp</span></code> | |
161 | (and <code class="computeroutput"><span class="identifier">boost</span><span class="special">/</span><span class="identifier">cast</span><span class="special">.</span><span class="identifier">hpp</span></code> is including <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</span><span class="special">/</span><span class="identifier">cast</span><span class="special">.</span><span class="identifier">hpp</span></code> | |
162 | now). That old function which existed in boost for quite some time used | |
163 | the <code class="computeroutput"><span class="identifier">bad_numeric_cast</span></code> as | |
164 | its exception type so I decided to avoid backward compatibility problems | |
165 | by adopting it (guessing that the user base for the old code is wider than | |
166 | for the new code). | |
167 | </p></td></tr> | |
168 | </table></div> | |
169 | </div> | |
170 | <div class="section"> | |
171 | <div class="titlepage"><div><div><h3 class="title"> | |
172 | <a name="boost_numericconversion.numeric_converter_policy_classes.policy_float2introunder"></a><a class="link" href="numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_float2introunder" title="Policy Float2IntRounder">Policy | |
173 | Float2IntRounder</a> | |
174 | </h3></div></div></div> | |
175 | <p> | |
176 | This <span class="emphasis"><em>stateless</em></span> template policy class specifies the rounding | |
177 | mode used for <span class="underline">float to integral</span> conversions. | |
178 | It supplies the <code class="computeroutput"><span class="identifier">nearbyint</span><span class="special">()</span></code> static member function exposed by the converter, | |
179 | which means that it <span class="underline">publicly inherits from this | |
180 | policy</span>. | |
181 | </p> | |
182 | <p> | |
183 | The policy must have the following interface: | |
184 | </p> | |
185 | <pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">S</span><span class="special">></span> | |
186 | <span class="keyword">struct</span> <span class="identifier">YourFloat2IntRounderPolicy</span> | |
187 | <span class="special">{</span> | |
188 | <span class="keyword">typedef</span> <span class="identifier">S</span> <span class="identifier">source_type</span> <span class="special">;</span> | |
189 | <span class="keyword">typedef</span> <span class="special">{</span><span class="identifier">S</span> <span class="keyword">or</span> <span class="identifier">S</span> <span class="keyword">const</span><span class="special">&}</span> <span class="identifier">argument_type</span> <span class="special">;</span> | |
190 | ||
191 | <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> <span class="special">...</span> <span class="special">}</span> | |
192 | ||
193 | <span class="keyword">typedef</span> <span class="identifier">mpl</span><span class="special">::</span><span class="identifier">integral_c</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">float_round_style</span><span class="special">,</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">round_</span><span class="special">...></span> <span class="identifier">round_style</span> <span class="special">;</span> | |
194 | ||
195 | <span class="special">}</span> <span class="special">;</span> | |
196 | </pre> | |
197 | <p> | |
198 | These are the rounder classes provided by the library (only the specific | |
199 | parts are shown, see the general policy form above) | |
200 | </p> | |
201 | <div class="note"><table border="0" summary="Note"> | |
202 | <tr> | |
203 | <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../../doc/src/images/note.png"></td> | |
204 | <th align="left">Note</th> | |
205 | </tr> | |
206 | <tr><td align="left" valign="top"><p> | |
207 | These classes are not intended to be general purpose rounding functions | |
208 | but specific policies for <code class="computeroutput"><span class="identifier">converter</span><span class="special"><></span></code>. This is why they are not function | |
209 | objects. | |
210 | </p></td></tr> | |
211 | </table></div> | |
212 | <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> | |
213 | ||
214 | ||
215 | <span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">S</span><span class="special">></span> | |
216 | <span class="keyword">struct</span> <span class="identifier">Trunc</span> | |
217 | <span class="special">{</span> | |
218 | <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> | |
219 | <span class="special">{</span> | |
220 | <span class="keyword">using</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">floor</span> <span class="special">;</span> | |
221 | <span class="keyword">using</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">ceil</span> <span class="special">;</span> | |
222 | ||
223 | <span class="keyword">return</span> <span class="identifier">s</span> <span class="special">>=</span> <span class="keyword">static_cast</span><span class="special"><</span><span class="identifier">S</span><span class="special">>(</span><span class="number">0</span><span class="special">)</span> <span class="special">?</span> <span class="identifier">floor</span><span class="special">(</span><span class="identifier">s</span><span class="special">)</span> <span class="special">:</span> <span class="identifier">ceil</span><span class="special">(</span><span class="identifier">s</span><span class="special">)</span> <span class="special">;</span> | |
224 | <span class="special">}</span> | |
225 | ||
226 | <span class="keyword">typedef</span> <span class="identifier">mpl</span><span class="special">::</span><span class="identifier">integral_c</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">float_round_style</span><span class="special">,</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">round_toward_zero</span><span class="special">></span> <span class="identifier">round_style</span> <span class="special">;</span> | |
227 | <span class="special">}</span> <span class="special">;</span> | |
228 | ||
229 | ||
230 | <span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">S</span><span class="special">></span> | |
231 | <span class="keyword">struct</span> <span class="identifier">RoundEven</span> | |
232 | <span class="special">{</span> | |
233 | <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> | |
234 | <span class="special">{</span> | |
235 | <span class="keyword">return</span> <span class="identifier">impl</span><span class="special">-</span><span class="identifier">defined</span><span class="special">-</span><span class="identifier">value</span> <span class="special">;</span> | |
236 | <span class="special">}</span> | |
237 | ||
238 | <span class="keyword">typedef</span> <span class="identifier">mpl</span><span class="special">::</span><span class="identifier">integral_c</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">float_round_style</span><span class="special">,</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">round_to_nearest</span><span class="special">></span> <span class="identifier">round_style</span> <span class="special">;</span> | |
239 | <span class="special">}</span> <span class="special">;</span> | |
240 | ||
241 | ||
242 | <span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">S</span><span class="special">></span> | |
243 | <span class="keyword">struct</span> <span class="identifier">Ceil</span> | |
244 | <span class="special">{</span> | |
245 | <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> | |
246 | <span class="special">{</span> | |
247 | <span class="keyword">using</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">ceil</span> <span class="special">;</span> | |
248 | <span class="keyword">return</span> <span class="identifier">ceil</span><span class="special">(</span><span class="identifier">s</span><span class="special">)</span> <span class="special">;</span> | |
249 | <span class="special">}</span> | |
250 | ||
251 | <span class="keyword">typedef</span> <span class="identifier">mpl</span><span class="special">::</span><span class="identifier">integral_c</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">float_round_style</span><span class="special">,</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">round_toward_infinity</span><span class="special">></span> <span class="identifier">round_style</span> <span class="special">;</span> | |
252 | <span class="special">}</span> <span class="special">;</span> | |
253 | ||
254 | ||
255 | <span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">S</span><span class="special">></span> | |
256 | <span class="keyword">struct</span> <span class="identifier">Floor</span> | |
257 | <span class="special">{</span> | |
258 | <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> | |
259 | <span class="special">{</span> | |
260 | <span class="keyword">using</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">floor</span> <span class="special">;</span> | |
261 | <span class="keyword">return</span> <span class="identifier">floor</span><span class="special">(</span><span class="identifier">s</span><span class="special">)</span> <span class="special">;</span> | |
262 | <span class="special">}</span> | |
263 | <span class="keyword">typedef</span> <span class="identifier">mpl</span><span class="special">::</span><span class="identifier">integral_c</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">float_round_style</span><span class="special">,</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">round_toward_neg_infinity</span><span class="special">></span> <span class="identifier">round_style</span> <span class="special">;</span> | |
264 | <span class="special">}</span> <span class="special">;</span> | |
265 | ||
266 | <span class="special">}</span> <span class="special">}</span> <span class="comment">// namespace numeric, namespace boost</span> | |
267 | </pre> | |
268 | <h5> | |
269 | <a name="boost_numericconversion.numeric_converter_policy_classes.policy_float2introunder.h0"></a> | |
270 | <span class="phrase"><a name="boost_numericconversion.numeric_converter_policy_classes.policy_float2introunder.math_functions_used_by_the_rounder_policies"></a></span><a class="link" href="numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_float2introunder.math_functions_used_by_the_rounder_policies">Math | |
271 | Functions used by the rounder policies</a> | |
272 | </h5> | |
273 | <p> | |
274 | The rounder policies supplied by this header use math functions <code class="computeroutput"><span class="identifier">floor</span><span class="special">()</span></code> | |
275 | and <code class="computeroutput"><span class="identifier">ceil</span><span class="special">()</span></code>. | |
276 | The standard versions of these functions are introduced in context by a using | |
277 | directive, so in normal conditions, the standard functions will be used. | |
278 | </p> | |
279 | <p> | |
280 | However, if there are other visible corresponding overloads an ambiguity | |
281 | could arise. In this case, the user can supply her own rounder policy which | |
282 | could, for instance, use a fully qualified call. | |
283 | </p> | |
284 | <p> | |
285 | This technique allows the default rounder policies to be used directly with | |
286 | user defined types. The user only requires that suitable overloads of <code class="computeroutput"><span class="identifier">floor</span><span class="special">()</span></code> | |
287 | and <code class="computeroutput"><span class="identifier">ceil</span><span class="special">()</span></code> | |
288 | be visible. See also <a class="link" href="type_requirements_and_user_defined_types_support.html" title="Type Requirements and User-defined-types support">User | |
289 | Defined Numeric Types</a> support. | |
290 | </p> | |
291 | </div> | |
292 | <div class="section"> | |
293 | <div class="titlepage"><div><div><h3 class="title"> | |
294 | <a name="boost_numericconversion.numeric_converter_policy_classes.policy_rawconverter"></a><a class="link" href="numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_rawconverter" title="Policy RawConverter">Policy | |
295 | RawConverter</a> | |
296 | </h3></div></div></div> | |
297 | <p> | |
298 | This <span class="emphasis"><em>stateless</em></span> template policy class is used to perform | |
299 | the actual conversion from Source to Target. It supplies the <code class="computeroutput"><span class="identifier">low_level_convert</span><span class="special">()</span></code> | |
300 | static member function exposed by the converter, which means that it publicly | |
301 | inherits from this policy. | |
302 | </p> | |
303 | <p> | |
304 | The policy must have the following interface: | |
305 | </p> | |
306 | <pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">Traits</span><span class="special">></span> | |
307 | <span class="keyword">struct</span> <span class="identifier">YourRawConverterPolicy</span> | |
308 | <span class="special">{</span> | |
309 | <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> | |
310 | <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> | |
311 | ||
312 | <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> <span class="keyword">return</span> <span class="special"><</span><span class="identifier">impl</span> <span class="identifier">defined</span><span class="special">></span> <span class="special">;</span> <span class="special">}</span> | |
313 | <span class="special">}</span> <span class="special">;</span> | |
314 | </pre> | |
315 | <p> | |
316 | This policy is mostly provided as a hook for user defined types which don't | |
317 | support <code class="computeroutput"><span class="keyword">static_cast</span><span class="special"><></span></code> | |
318 | conversions to some types | |
319 | </p> | |
320 | <p> | |
321 | This is the only raw converter policy class provided by the library: | |
322 | </p> | |
323 | <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> | |
324 | ||
325 | <span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">Traits</span><span class="special">></span> | |
326 | <span class="keyword">struct</span> <span class="identifier">raw_numeric_converter</span> | |
327 | <span class="special">{</span> | |
328 | <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> | |
329 | <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> | |
330 | ||
331 | <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> | |
332 | <span class="special">{</span> | |
333 | <span class="keyword">return</span> <span class="keyword">static_cast</span><span class="special"><</span><span class="identifier">result_type</span><span class="special">>(</span><span class="identifier">s</span><span class="special">)</span> <span class="special">;</span> | |
334 | <span class="special">}</span> | |
335 | <span class="special">}</span> <span class="special">;</span> | |
336 | ||
337 | <span class="special">}</span> <span class="special">}</span> | |
338 | </pre> | |
339 | </div> | |
340 | <div class="section"> | |
341 | <div class="titlepage"><div><div><h3 class="title"> | |
342 | <a name="boost_numericconversion.numeric_converter_policy_classes.policy_userrangechecker"></a><a class="link" href="numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_userrangechecker" title="Policy UserRangeChecker">Policy | |
343 | UserRangeChecker</a> | |
344 | </h3></div></div></div> | |
345 | <p> | |
346 | This <span class="emphasis"><em>stateless</em></span> template policy class is used <span class="underline">only if supplied</span> to <span class="bold"><strong>override</strong></span> | |
347 | the internal range checking logic. | |
348 | </p> | |
349 | <p> | |
350 | It supplies the <code class="computeroutput"><span class="identifier">validate_range</span><span class="special">()</span></code> static member function exposed by the converter, | |
351 | which means that it publicly inherits from this policy. | |
352 | </p> | |
353 | <p> | |
354 | The policy must have the following interface: | |
355 | </p> | |
356 | <pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">Traits</span><span class="special">></span> | |
357 | <span class="keyword">struct</span> <span class="identifier">YourRangeCheckerPolicy</span> | |
358 | <span class="special">{</span> | |
359 | <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> | |
360 | ||
361 | <span class="comment">// Determines if the value 's' fits in the range of the Target type.</span> | |
362 | <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> | |
363 | ||
364 | <span class="comment">// Checks whether the value 's' is out_of_range()</span> | |
365 | <span class="comment">// and passes the result of the check to the OverflowHandler policy.</span> | |
366 | <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> | |
367 | <span class="special">{</span> | |
368 | <span class="identifier">OverflowHandler</span><span class="special">()(</span> <span class="identifier">out_of_range</span><span class="special">(</span><span class="identifier">s</span><span class="special">)</span> <span class="special">)</span> <span class="special">;</span> | |
369 | <span class="special">}</span> | |
370 | <span class="special">}</span> <span class="special">;</span> | |
371 | </pre> | |
372 | <p> | |
373 | This policy is <span class="bold"><strong>only</strong></span> provided as a hook for | |
374 | user defined types which require range checking (which is disabled by default | |
375 | when a UDT is involved). The library provides a class: <code class="computeroutput"><span class="identifier">UseInternalRangeChecker</span><span class="special">{}</span></code>; which is a <span class="emphasis"><em>fake</em></span> | |
376 | <code class="computeroutput"><span class="identifier">RangeChecker</span></code> policy used | |
377 | to signal the converter to use its internal range checking implementation. | |
378 | </p> | |
379 | </div> | |
380 | </div> | |
381 | <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> | |
382 | <td align="left"></td> | |
383 | <td align="right"><div class="copyright-footer">Copyright © 2004-2007 Fernando | |
384 | Luis Cacciola Carballal<p> | |
385 | Distributed under the Boost Software License, Version 1.0. (See accompanying | |
386 | 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>) | |
387 | </p> | |
388 | </div></td> | |
389 | </tr></table> | |
390 | <hr> | |
391 | <div class="spirit-nav"> | |
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