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intl/icu/source/i18n/unicode/plurrule.h

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1 /*
2 *******************************************************************************
3 * Copyright (C) 2008-2013, International Business Machines Corporation and
4 * others. All Rights Reserved.
5 *******************************************************************************
6 *
7 *
8 * File PLURRULE.H
9 *
10 * Modification History:*
11 * Date Name Description
12 *
13 ********************************************************************************
14 */
15
16 #ifndef PLURRULE
17 #define PLURRULE
18
19 #include "unicode/utypes.h"
20
21 /**
22 * \file
23 * \brief C++ API: PluralRules object
24 */
25
26 #if !UCONFIG_NO_FORMATTING
27
28 #include "unicode/format.h"
29 #include "unicode/upluralrules.h"
30
31 /**
32 * Value returned by PluralRules::getUniqueKeywordValue() when there is no
33 * unique value to return.
34 * @stable ICU 4.8
35 */
36 #define UPLRULES_NO_UNIQUE_VALUE ((double)-0.00123456777)
37
38 U_NAMESPACE_BEGIN
39
40 class Hashtable;
41 class FixedDecimal;
42 class RuleChain;
43 class PluralRuleParser;
44 class PluralKeywordEnumeration;
45 class AndConstraint;
46
47 /**
48 * Defines rules for mapping non-negative numeric values onto a small set of
49 * keywords. Rules are constructed from a text description, consisting
50 * of a series of keywords and conditions. The {@link #select} method
51 * examines each condition in order and returns the keyword for the
52 * first condition that matches the number. If none match,
53 * default rule(other) is returned.
54 *
55 * For more information, details, and tips for writing rules, see the
56 * LDML spec, C.11 Language Plural Rules:
57 * http://www.unicode.org/draft/reports/tr35/tr35.html#Language_Plural_Rules
58 *
59 * Examples:<pre>
60 * "one: n is 1; few: n in 2..4"</pre>
61 * This defines two rules, for 'one' and 'few'. The condition for
62 * 'one' is "n is 1" which means that the number must be equal to
63 * 1 for this condition to pass. The condition for 'few' is
64 * "n in 2..4" which means that the number must be between 2 and
65 * 4 inclusive for this condition to pass. All other numbers
66 * are assigned the keyword "other" by the default rule.
67 * </p><pre>
68 * "zero: n is 0; one: n is 1; zero: n mod 100 in 1..19"</pre>
69 * This illustrates that the same keyword can be defined multiple times.
70 * Each rule is examined in order, and the first keyword whose condition
71 * passes is the one returned. Also notes that a modulus is applied
72 * to n in the last rule. Thus its condition holds for 119, 219, 319...
73 * </p><pre>
74 * "one: n is 1; few: n mod 10 in 2..4 and n mod 100 not in 12..14"</pre>
75 * This illustrates conjunction and negation. The condition for 'few'
76 * has two parts, both of which must be met: "n mod 10 in 2..4" and
77 * "n mod 100 not in 12..14". The first part applies a modulus to n
78 * before the test as in the previous example. The second part applies
79 * a different modulus and also uses negation, thus it matches all
80 * numbers _not_ in 12, 13, 14, 112, 113, 114, 212, 213, 214...
81 * </p>
82 * <p>
83 * Syntax:<pre>
84 * \code
85 * rules = rule (';' rule)*
86 * rule = keyword ':' condition
87 * keyword = <identifier>
88 * condition = and_condition ('or' and_condition)*
89 * and_condition = relation ('and' relation)*
90 * relation = is_relation | in_relation | within_relation | 'n' <EOL>
91 * is_relation = expr 'is' ('not')? value
92 * in_relation = expr ('not')? 'in' range_list
93 * within_relation = expr ('not')? 'within' range
94 * expr = ('n' | 'i' | 'f' | 'v' | 'j') ('mod' value)?
95 * range_list = (range | value) (',' range_list)*
96 * value = digit+ ('.' digit+)?
97 * digit = 0|1|2|3|4|5|6|7|8|9
98 * range = value'..'value
99 * \endcode
100 * </pre></p>
101 * <p>
102 * <p>
103 * The i, f, and v values are defined as follows:
104 * </p>
105 * <ul>
106 * <li>i to be the integer digits.</li>
107 * <li>f to be the visible fractional digits, as an integer.</li>
108 * <li>v to be the number of visible fraction digits.</li>
109 * <li>j is defined to only match integers. That is j is 3 fails if v != 0 (eg for 3.1 or 3.0).</li>
110 * </ul>
111 * <p>
112 * Examples are in the following table:
113 * </p>
114 * <table border='1' style="border-collapse:collapse">
115 * <tbody>
116 * <tr>
117 * <th>n</th>
118 * <th>i</th>
119 * <th>f</th>
120 * <th>v</th>
121 * </tr>
122 * <tr>
123 * <td>1.0</td>
124 * <td>1</td>
125 * <td align="right">0</td>
126 * <td>1</td>
127 * </tr>
128 * <tr>
129 * <td>1.00</td>
130 * <td>1</td>
131 * <td align="right">0</td>
132 * <td>2</td>
133 * </tr>
134 * <tr>
135 * <td>1.3</td>
136 * <td>1</td>
137 * <td align="right">3</td>
138 * <td>1</td>
139 * </tr>
140 * <tr>
141 * <td>1.03</td>
142 * <td>1</td>
143 * <td align="right">3</td>
144 * <td>2</td>
145 * </tr>
146 * <tr>
147 * <td>1.23</td>
148 * <td>1</td>
149 * <td align="right">23</td>
150 * <td>2</td>
151 * </tr>
152 * </tbody>
153 * </table>
154 * <p>
155 * The difference between 'in' and 'within' is that 'in' only includes integers in the specified range, while 'within'
156 * includes all values. Using 'within' with a range_list consisting entirely of values is the same as using 'in' (it's
157 * not an error).
158 * </p>
159
160 * An "identifier" is a sequence of characters that do not have the
161 * Unicode Pattern_Syntax or Pattern_White_Space properties.
162 * <p>
163 * The difference between 'in' and 'within' is that 'in' only includes
164 * integers in the specified range, while 'within' includes all values.
165 * Using 'within' with a range_list consisting entirely of values is the
166 * same as using 'in' (it's not an error).
167 *</p>
168 * <p>
169 * Keywords
170 * could be defined by users or from ICU locale data. There are 6
171 * predefined values in ICU - 'zero', 'one', 'two', 'few', 'many' and
172 * 'other'. Callers need to check the value of keyword returned by
173 * {@link #select} method.
174 * </p>
175 *
176 * Examples:<pre>
177 * UnicodeString keyword = pl->select(number);
178 * if (keyword== UnicodeString("one") {
179 * ...
180 * }
181 * else if ( ... )
182 * </pre>
183 * <strong>Note:</strong><br>
184 * <p>
185 * ICU defines plural rules for many locales based on CLDR <i>Language Plural Rules</i>.
186 * For these predefined rules, see CLDR page at
187 * http://unicode.org/repos/cldr-tmp/trunk/diff/supplemental/language_plural_rules.html
188 * </p>
189 */
190 class U_I18N_API PluralRules : public UObject {
191 public:
192
193 /**
194 * Constructor.
195 * @param status Output param set to success/failure code on exit, which
196 * must not indicate a failure before the function call.
197 *
198 * @stable ICU 4.0
199 */
200 PluralRules(UErrorCode& status);
201
202 /**
203 * Copy constructor.
204 * @stable ICU 4.0
205 */
206 PluralRules(const PluralRules& other);
207
208 /**
209 * Destructor.
210 * @stable ICU 4.0
211 */
212 virtual ~PluralRules();
213
214 /**
215 * Clone
216 * @stable ICU 4.0
217 */
218 PluralRules* clone() const;
219
220 /**
221 * Assignment operator.
222 * @stable ICU 4.0
223 */
224 PluralRules& operator=(const PluralRules&);
225
226 /**
227 * Creates a PluralRules from a description if it is parsable, otherwise
228 * returns NULL.
229 *
230 * @param description rule description
231 * @param status Output param set to success/failure code on exit, which
232 * must not indicate a failure before the function call.
233 * @return new PluralRules pointer. NULL if there is an error.
234 * @stable ICU 4.0
235 */
236 static PluralRules* U_EXPORT2 createRules(const UnicodeString& description,
237 UErrorCode& status);
238
239 /**
240 * The default rules that accept any number.
241 *
242 * @param status Output param set to success/failure code on exit, which
243 * must not indicate a failure before the function call.
244 * @return new PluralRules pointer. NULL if there is an error.
245 * @stable ICU 4.0
246 */
247 static PluralRules* U_EXPORT2 createDefaultRules(UErrorCode& status);
248
249 /**
250 * Provides access to the predefined cardinal-number <code>PluralRules</code> for a given
251 * locale.
252 * Same as forLocale(locale, UPLURAL_TYPE_CARDINAL, status).
253 *
254 * @param locale The locale for which a <code>PluralRules</code> object is
255 * returned.
256 * @param status Output param set to success/failure code on exit, which
257 * must not indicate a failure before the function call.
258 * @return The predefined <code>PluralRules</code> object pointer for
259 * this locale. If there's no predefined rules for this locale,
260 * the rules for the closest parent in the locale hierarchy
261 * that has one will be returned. The final fallback always
262 * returns the default 'other' rules.
263 * @stable ICU 4.0
264 */
265 static PluralRules* U_EXPORT2 forLocale(const Locale& locale, UErrorCode& status);
266
267 /**
268 * Provides access to the predefined <code>PluralRules</code> for a given
269 * locale and the plural type.
270 *
271 * @param locale The locale for which a <code>PluralRules</code> object is
272 * returned.
273 * @param type The plural type (e.g., cardinal or ordinal).
274 * @param status Output param set to success/failure code on exit, which
275 * must not indicate a failure before the function call.
276 * @return The predefined <code>PluralRules</code> object pointer for
277 * this locale. If there's no predefined rules for this locale,
278 * the rules for the closest parent in the locale hierarchy
279 * that has one will be returned. The final fallback always
280 * returns the default 'other' rules.
281 * @stable ICU 50
282 */
283 static PluralRules* U_EXPORT2 forLocale(const Locale& locale, UPluralType type, UErrorCode& status);
284
285 #ifndef U_HIDE_INTERNAL_API
286 /**
287 * Return a StringEnumeration over the locales for which there is plurals data.
288 * @return a StringEnumeration over the locales available.
289 * @internal
290 */
291 static StringEnumeration* U_EXPORT2 getAvailableLocales(UErrorCode &status);
292
293 /**
294 * Returns whether or not there are overrides.
295 * @param locale the locale to check.
296 * @return
297 * @internal
298 */
299 static UBool hasOverride(const Locale &locale);
300 #endif /* U_HIDE_INTERNAL_API */
301
302 /**
303 * Given a number, returns the keyword of the first rule that applies to
304 * the number. This function can be used with isKeyword* functions to
305 * determine the keyword for default plural rules.
306 *
307 * @param number The number for which the rule has to be determined.
308 * @return The keyword of the selected rule.
309 * @stable ICU 4.0
310 */
311 UnicodeString select(int32_t number) const;
312
313 /**
314 * Given a number, returns the keyword of the first rule that applies to
315 * the number. This function can be used with isKeyword* functions to
316 * determine the keyword for default plural rules.
317 *
318 * @param number The number for which the rule has to be determined.
319 * @return The keyword of the selected rule.
320 * @stable ICU 4.0
321 */
322 UnicodeString select(double number) const;
323
324 #ifndef U_HIDE_INTERNAL_API
325 /**
326 * @internal
327 */
328 UnicodeString select(const FixedDecimal &number) const;
329 #endif /* U_HIDE_INTERNAL_API */
330
331 /**
332 * Returns a list of all rule keywords used in this <code>PluralRules</code>
333 * object. The rule 'other' is always present by default.
334 *
335 * @param status Output param set to success/failure code on exit, which
336 * must not indicate a failure before the function call.
337 * @return StringEnumeration with the keywords.
338 * The caller must delete the object.
339 * @stable ICU 4.0
340 */
341 StringEnumeration* getKeywords(UErrorCode& status) const;
342
343 /**
344 * Returns a unique value for this keyword if it exists, else the constant
345 * UPLRULES_NO_UNIQUE_VALUE.
346 *
347 * @param keyword The keyword.
348 * @return The unique value that generates the keyword, or
349 * UPLRULES_NO_UNIQUE_VALUE if the keyword is undefined or there is no
350 * unique value that generates this keyword.
351 * @stable ICU 4.8
352 */
353 double getUniqueKeywordValue(const UnicodeString& keyword);
354
355 /**
356 * Returns all the values for which select() would return the keyword. If
357 * the keyword is unknown, returns no values, but this is not an error. If
358 * the number of values is unlimited, returns no values and -1 as the
359 * count.
360 *
361 * The number of returned values is typically small.
362 *
363 * @param keyword The keyword.
364 * @param dest Array into which to put the returned values. May
365 * be NULL if destCapacity is 0.
366 * @param destCapacity The capacity of the array, must be at least 0.
367 * @param status The error code.
368 * @return The count of values available, or -1. This count
369 * can be larger than destCapacity, but no more than
370 * destCapacity values will be written.
371 * @stable ICU 4.8
372 */
373 int32_t getAllKeywordValues(const UnicodeString &keyword,
374 double *dest, int32_t destCapacity,
375 UErrorCode& status);
376
377 /**
378 * Returns sample values for which select() would return the keyword. If
379 * the keyword is unknown, returns no values, but this is not an error.
380 *
381 * The number of returned values is typically small.
382 *
383 * @param keyword The keyword.
384 * @param dest Array into which to put the returned values. May
385 * be NULL if destCapacity is 0.
386 * @param destCapacity The capacity of the array, must be at least 0.
387 * @param status The error code.
388 * @return The count of values written.
389 * If more than destCapacity samples are available, then
390 * only destCapacity are written, and destCapacity is returned as the count,
391 * rather than setting a U_BUFFER_OVERFLOW_ERROR.
392 * (The actual number of keyword values could be unlimited.)
393 * @stable ICU 4.8
394 */
395 int32_t getSamples(const UnicodeString &keyword,
396 double *dest, int32_t destCapacity,
397 UErrorCode& status);
398
399 /**
400 * Returns TRUE if the given keyword is defined in this
401 * <code>PluralRules</code> object.
402 *
403 * @param keyword the input keyword.
404 * @return TRUE if the input keyword is defined.
405 * Otherwise, return FALSE.
406 * @stable ICU 4.0
407 */
408 UBool isKeyword(const UnicodeString& keyword) const;
409
410
411 /**
412 * Returns keyword for default plural form.
413 *
414 * @return keyword for default plural form.
415 * @stable ICU 4.0
416 */
417 UnicodeString getKeywordOther() const;
418
419 #ifndef U_HIDE_INTERNAL_API
420 /**
421 *
422 * @internal
423 */
424 UnicodeString getRules() const;
425 #endif /* U_HIDE_INTERNAL_API */
426
427 /**
428 * Compares the equality of two PluralRules objects.
429 *
430 * @param other The other PluralRules object to be compared with.
431 * @return True if the given PluralRules is the same as this
432 * PluralRules; false otherwise.
433 * @stable ICU 4.0
434 */
435 virtual UBool operator==(const PluralRules& other) const;
436
437 /**
438 * Compares the inequality of two PluralRules objects.
439 *
440 * @param other The PluralRules object to be compared with.
441 * @return True if the given PluralRules is not the same as this
442 * PluralRules; false otherwise.
443 * @stable ICU 4.0
444 */
445 UBool operator!=(const PluralRules& other) const {return !operator==(other);}
446
447
448 /**
449 * ICU "poor man's RTTI", returns a UClassID for this class.
450 *
451 * @stable ICU 4.0
452 *
453 */
454 static UClassID U_EXPORT2 getStaticClassID(void);
455
456 /**
457 * ICU "poor man's RTTI", returns a UClassID for the actual class.
458 *
459 * @stable ICU 4.0
460 */
461 virtual UClassID getDynamicClassID() const;
462
463
464 private:
465 RuleChain *mRules;
466
467 PluralRules(); // default constructor not implemented
468 void parseDescription(const UnicodeString& ruleData, UErrorCode &status);
469 int32_t getNumberValue(const UnicodeString& token) const;
470 UnicodeString getRuleFromResource(const Locale& locale, UPluralType type, UErrorCode& status);
471 RuleChain *rulesForKeyword(const UnicodeString &keyword) const;
472
473 friend class PluralRuleParser;
474 };
475
476 U_NAMESPACE_END
477
478 #endif /* #if !UCONFIG_NO_FORMATTING */
479
480 #endif // _PLURRULE
481 //eof

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