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1 // © 2016 and later: Unicode, Inc. and others.
2 // License & terms of use: http://www.unicode.org/copyright.html
3 /*
4 *******************************************************************************
5 * Copyright (C) 2007-2014, International Business Machines Corporation and
6 * others. All Rights Reserved.
7 *******************************************************************************
8 *
9 
10 * File PLURFMT.H
11 ********************************************************************************
12 */
13 
14 #ifndef PLURFMT
15 #define PLURFMT
16 
17 #include "unicode/utypes.h"
18 
19 #if U_SHOW_CPLUSPLUS_API
20 
21 /**
22  * \file
23  * \brief C++ API: PluralFormat object
24  */
25 
26 #if !UCONFIG_NO_FORMATTING
27 
28 #include "unicode/messagepattern.h"
29 #include "unicode/numfmt.h"
30 #include "unicode/plurrule.h"
31 
32 U_NAMESPACE_BEGIN
33 
34 class Hashtable;
35 class NFRule;
36 
37 /**
38  * <p>
39  * <code>PluralFormat</code> supports the creation of internationalized
40  * messages with plural inflection. It is based on <i>plural
41  * selection</i>, i.e. the caller specifies messages for each
42  * plural case that can appear in the user's language and the
43  * <code>PluralFormat</code> selects the appropriate message based on
44  * the number.
45  * </p>
46  * <h4>The Problem of Plural Forms in Internationalized Messages</h4>
47  * <p>
48  * Different languages have different ways to inflect
49  * plurals. Creating internationalized messages that include plural
50  * forms is only feasible when the framework is able to handle plural
51  * forms of <i>all</i> languages correctly. <code>ChoiceFormat</code>
52  * doesn't handle this well, because it attaches a number interval to
53  * each message and selects the message whose interval contains a
54  * given number. This can only handle a finite number of
55  * intervals. But in some languages, like Polish, one plural case
56  * applies to infinitely many intervals (e.g., the plural case applies to
57  * numbers ending with 2, 3, or 4 except those ending with 12, 13, or
58  * 14). Thus <code>ChoiceFormat</code> is not adequate.
59  * </p><p>
60  * <code>PluralFormat</code> deals with this by breaking the problem
61  * into two parts:
62  * <ul>
63  * <li>It uses <code>PluralRules</code> that can define more complex
64  *     conditions for a plural case than just a single interval. These plural
65  *     rules define both what plural cases exist in a language, and to
66  *     which numbers these cases apply.
67  * <li>It provides predefined plural rules for many languages. Thus, the programmer
68  *     need not worry about the plural cases of a language and
69  *     does not have to define the plural cases; they can simply
70  *     use the predefined keywords. The whole plural formatting of messages can
71  *     be done using localized patterns from resource bundles. For predefined plural
72  *     rules, see the CLDR <i>Language Plural Rules</i> page at
73  *    http://unicode.org/repos/cldr-tmp/trunk/diff/supplemental/language_plural_rules.html
74  * </ul>
75  * </p>
76  * <h4>Usage of <code>PluralFormat</code></h4>
77  * <p>Note: Typically, plural formatting is done via <code>MessageFormat</code>
78  * with a <code>plural</code> argument type,
79  * rather than using a stand-alone <code>PluralFormat</code>.
80  * </p><p>
81  * This discussion assumes that you use <code>PluralFormat</code> with
82  * a predefined set of plural rules. You can create one using one of
83  * the constructors that takes a <code>locale</code> object. To
84  * specify the message pattern, you can either pass it to the
85  * constructor or set it explicitly using the
86  * <code>applyPattern()</code> method. The <code>format()</code>
87  * method takes a number object and selects the message of the
88  * matching plural case. This message will be returned.
89  * </p>
90  * <h5>Patterns and Their Interpretation</h5>
91  * <p>
92  * The pattern text defines the message output for each plural case of the
93  * specified locale. Syntax:
94  * <pre>
95  * pluralStyle = [offsetValue] (selector '{' message '}')+
96  * offsetValue = "offset:" number
97  * selector = explicitValue | keyword
98  * explicitValue = '=' number  // adjacent, no white space in between
99  * keyword = [^[[:Pattern_Syntax:][:Pattern_White_Space:]]]+
100  * message: see {@link MessageFormat}
101  * </pre>
102  * Pattern_White_Space between syntax elements is ignored, except
103  * between the {curly braces} and their sub-message,
104  * and between the '=' and the number of an explicitValue.
105  *
106  * </p><p>
107  * There are 6 predefined casekeyword in CLDR/ICU - 'zero', 'one', 'two', 'few', 'many' and
108  * 'other'. You always have to define a message text for the default plural case
109  * <code>other</code> which is contained in every rule set.
110  * If you do not specify a message text for a particular plural case, the
111  * message text of the plural case <code>other</code> gets assigned to this
112  * plural case.
113  * </p><p>
114  * When formatting, the input number is first matched against the explicitValue clauses.
115  * If there is no exact-number match, then a keyword is selected by calling
116  * the <code>PluralRules</code> with the input number <em>minus the offset</em>.
117  * (The offset defaults to 0 if it is omitted from the pattern string.)
118  * If there is no clause with that keyword, then the "other" clauses is returned.
119  * </p><p>
120  * An unquoted pound sign (<code>#</code>) in the selected sub-message
121  * itself (i.e., outside of arguments nested in the sub-message)
122  * is replaced by the input number minus the offset.
123  * The number-minus-offset value is formatted using a
124  * <code>NumberFormat</code> for the <code>PluralFormat</code>'s locale. If you
125  * need special number formatting, you have to use a <code>MessageFormat</code>
126  * and explicitly specify a <code>NumberFormat</code> argument.
127  * <strong>Note:</strong> That argument is formatting without subtracting the offset!
128  * If you need a custom format and have a non-zero offset, then you need to pass the
129  * number-minus-offset value as a separate parameter.
130  * </p>
131  * For a usage example, see the {@link MessageFormat} class documentation.
132  *
133  * <h4>Defining Custom Plural Rules</h4>
134  * <p>If you need to use <code>PluralFormat</code> with custom rules, you can
135  * create a <code>PluralRules</code> object and pass it to
136  * <code>PluralFormat</code>'s constructor. If you also specify a locale in this
137  * constructor, this locale will be used to format the number in the message
138  * texts.
139  * </p><p>
140  * For more information about <code>PluralRules</code>, see
141  * {@link PluralRules}.
142  * </p>
143  *
144  * ported from Java
145  * @stable ICU 4.0
146  */
147 
148 class U_I18N_API PluralFormat : public Format {
149 public:
150 
151     /**
152      * Creates a new cardinal-number <code>PluralFormat</code> for the default locale.
153      * This locale will be used to get the set of plural rules and for standard
154      * number formatting.
155      * @param status  output param set to success/failure code on exit, which
156      *                must not indicate a failure before the function call.
157      * @stable ICU 4.0
158      */
159     PluralFormat(UErrorCode& status);
160 
161     /**
162      * Creates a new cardinal-number <code>PluralFormat</code> for a given locale.
163      * @param locale the <code>PluralFormat</code> will be configured with
164      *               rules for this locale. This locale will also be used for
165      *               standard number formatting.
166      * @param status output param set to success/failure code on exit, which
167      *               must not indicate a failure before the function call.
168      * @stable ICU 4.0
169      */
170     PluralFormat(const Locale& locale, UErrorCode& status);
171 
172     /**
173      * Creates a new <code>PluralFormat</code> for a given set of rules.
174      * The standard number formatting will be done using the default locale.
175      * @param rules   defines the behavior of the <code>PluralFormat</code>
176      *                object.
177      * @param status  output param set to success/failure code on exit, which
178      *                must not indicate a failure before the function call.
179      * @stable ICU 4.0
180      */
181     PluralFormat(const PluralRules& rules, UErrorCode& status);
182 
183     /**
184      * Creates a new <code>PluralFormat</code> for a given set of rules.
185      * The standard number formatting will be done using the given locale.
186      * @param locale  the default number formatting will be done using this
187      *                locale.
188      * @param rules   defines the behavior of the <code>PluralFormat</code>
189      *                object.
190      * @param status  output param set to success/failure code on exit, which
191      *                must not indicate a failure before the function call.
192      * @stable ICU 4.0
193 	 * <p>
194 	 * <h4>Sample code</h4>
195 	 * \snippet samples/plurfmtsample/plurfmtsample.cpp PluralFormatExample1
196 	 * \snippet samples/plurfmtsample/plurfmtsample.cpp PluralFormatExample
197 	 * <p>
198      */
199     PluralFormat(const Locale& locale, const PluralRules& rules, UErrorCode& status);
200 
201     /**
202      * Creates a new <code>PluralFormat</code> for the plural type.
203      * The standard number formatting will be done using the given locale.
204      * @param locale  the default number formatting will be done using this
205      *                locale.
206      * @param type    The plural type (e.g., cardinal or ordinal).
207      * @param status  output param set to success/failure code on exit, which
208      *                must not indicate a failure before the function call.
209      * @stable ICU 50
210      */
211     PluralFormat(const Locale& locale, UPluralType type, UErrorCode& status);
212 
213     /**
214      * Creates a new cardinal-number <code>PluralFormat</code> for a given pattern string.
215      * The default locale will be used to get the set of plural rules and for
216      * standard number formatting.
217      * @param  pattern the pattern for this <code>PluralFormat</code>.
218      *                 errors are returned to status if the pattern is invalid.
219      * @param status   output param set to success/failure code on exit, which
220      *                 must not indicate a failure before the function call.
221      * @stable ICU 4.0
222      */
223     PluralFormat(const UnicodeString& pattern, UErrorCode& status);
224 
225     /**
226      * Creates a new cardinal-number <code>PluralFormat</code> for a given pattern string and
227      * locale.
228      * The locale will be used to get the set of plural rules and for
229      * standard number formatting.
230      * @param locale   the <code>PluralFormat</code> will be configured with
231      *                 rules for this locale. This locale will also be used for
232      *                 standard number formatting.
233      * @param pattern  the pattern for this <code>PluralFormat</code>.
234      *                 errors are returned to status if the pattern is invalid.
235      * @param status   output param set to success/failure code on exit, which
236      *                 must not indicate a failure before the function call.
237      * @stable ICU 4.0
238      */
239     PluralFormat(const Locale& locale, const UnicodeString& pattern, UErrorCode& status);
240 
241     /**
242      * Creates a new <code>PluralFormat</code> for a given set of rules, a
243      * pattern and a locale.
244      * @param rules    defines the behavior of the <code>PluralFormat</code>
245      *                 object.
246      * @param pattern  the pattern for this <code>PluralFormat</code>.
247      *                 errors are returned to status if the pattern is invalid.
248      * @param status   output param set to success/failure code on exit, which
249      *                 must not indicate a failure before the function call.
250      * @stable ICU 4.0
251      */
252     PluralFormat(const PluralRules& rules,
253                  const UnicodeString& pattern,
254                  UErrorCode& status);
255 
256     /**
257      * Creates a new <code>PluralFormat</code> for a given set of rules, a
258      * pattern and a locale.
259      * @param locale  the <code>PluralFormat</code> will be configured with
260      *                rules for this locale. This locale will also be used for
261      *                standard number formatting.
262      * @param rules   defines the behavior of the <code>PluralFormat</code>
263      *                object.
264      * @param pattern the pattern for this <code>PluralFormat</code>.
265      *                errors are returned to status if the pattern is invalid.
266      * @param status  output param set to success/failure code on exit, which
267      *                must not indicate a failure before the function call.
268      * @stable ICU 4.0
269      */
270     PluralFormat(const Locale& locale,
271                  const PluralRules& rules,
272                  const UnicodeString& pattern,
273                  UErrorCode& status);
274 
275     /**
276      * Creates a new <code>PluralFormat</code> for a plural type, a
277      * pattern and a locale.
278      * @param locale  the <code>PluralFormat</code> will be configured with
279      *                rules for this locale. This locale will also be used for
280      *                standard number formatting.
281      * @param type    The plural type (e.g., cardinal or ordinal).
282      * @param pattern the pattern for this <code>PluralFormat</code>.
283      *                errors are returned to status if the pattern is invalid.
284      * @param status  output param set to success/failure code on exit, which
285      *                must not indicate a failure before the function call.
286      * @stable ICU 50
287      */
288     PluralFormat(const Locale& locale,
289                  UPluralType type,
290                  const UnicodeString& pattern,
291                  UErrorCode& status);
292 
293     /**
294       * copy constructor.
295       * @stable ICU 4.0
296       */
297     PluralFormat(const PluralFormat& other);
298 
299     /**
300      * Destructor.
301      * @stable ICU 4.0
302      */
303     virtual ~PluralFormat();
304 
305     /**
306      * Sets the pattern used by this plural format.
307      * The method parses the pattern and creates a map of format strings
308      * for the plural rules.
309      * Patterns and their interpretation are specified in the class description.
310      *
311      * @param pattern the pattern for this plural format
312      *                errors are returned to status if the pattern is invalid.
313      * @param status  output param set to success/failure code on exit, which
314      *                must not indicate a failure before the function call.
315      * @stable ICU 4.0
316      */
317     void applyPattern(const UnicodeString& pattern, UErrorCode& status);
318 
319 
320     using Format::format;
321 
322     /**
323      * Formats a plural message for a given number.
324      *
325      * @param number  a number for which the plural message should be formatted
326      *                for. If no pattern has been applied to this
327      *                <code>PluralFormat</code> object yet, the formatted number
328      *                will be returned.
329      * @param status  output param set to success/failure code on exit, which
330      *                must not indicate a failure before the function call.
331      * @return        the string containing the formatted plural message.
332      * @stable ICU 4.0
333      */
334     UnicodeString format(int32_t number, UErrorCode& status) const;
335 
336     /**
337      * Formats a plural message for a given number.
338      *
339      * @param number  a number for which the plural message should be formatted
340      *                for. If no pattern has been applied to this
341      *                PluralFormat object yet, the formatted number
342      *                will be returned.
343      * @param status  output param set to success or failure code on exit, which
344      *                must not indicate a failure before the function call.
345      * @return        the string containing the formatted plural message.
346      * @stable ICU 4.0
347      */
348     UnicodeString format(double number, UErrorCode& status) const;
349 
350     /**
351      * Formats a plural message for a given number.
352      *
353      * @param number   a number for which the plural message should be formatted
354      *                 for. If no pattern has been applied to this
355      *                 <code>PluralFormat</code> object yet, the formatted number
356      *                 will be returned.
357      * @param appendTo output parameter to receive result.
358      *                 result is appended to existing contents.
359      * @param pos      On input: an alignment field, if desired.
360      *                 On output: the offsets of the alignment field.
361      * @param status   output param set to success/failure code on exit, which
362      *                 must not indicate a failure before the function call.
363      * @return         the string containing the formatted plural message.
364      * @stable ICU 4.0
365      */
366     UnicodeString& format(int32_t number,
367                           UnicodeString& appendTo,
368                           FieldPosition& pos,
369                           UErrorCode& status) const;
370 
371     /**
372      * Formats a plural message for a given number.
373      *
374      * @param number   a number for which the plural message should be formatted
375      *                 for. If no pattern has been applied to this
376      *                 PluralFormat object yet, the formatted number
377      *                 will be returned.
378      * @param appendTo output parameter to receive result.
379      *                 result is appended to existing contents.
380      * @param pos      On input: an alignment field, if desired.
381      *                 On output: the offsets of the alignment field.
382      * @param status   output param set to success/failure code on exit, which
383      *                 must not indicate a failure before the function call.
384      * @return         the string containing the formatted plural message.
385      * @stable ICU 4.0
386      */
387     UnicodeString& format(double number,
388                           UnicodeString& appendTo,
389                           FieldPosition& pos,
390                           UErrorCode& status) const;
391 
392 #ifndef U_HIDE_DEPRECATED_API
393     /**
394      * Sets the locale used by this <code>PluraFormat</code> object.
395      * Note: Calling this method resets this <code>PluraFormat</code> object,
396      *     i.e., a pattern that was applied previously will be removed,
397      *     and the NumberFormat is set to the default number format for
398      *     the locale.  The resulting format behaves the same as one
399      *     constructed from {@link #PluralFormat(const Locale& locale, UPluralType type, UErrorCode& status)}
400      *     with UPLURAL_TYPE_CARDINAL.
401      * @param locale  the <code>locale</code> to use to configure the formatter.
402      * @param status  output param set to success/failure code on exit, which
403      *                must not indicate a failure before the function call.
404      * @deprecated ICU 50 This method clears the pattern and might create
405      *             a different kind of PluralRules instance;
406      *             use one of the constructors to create a new instance instead.
407      */
408     void setLocale(const Locale& locale, UErrorCode& status);
409 #endif  /* U_HIDE_DEPRECATED_API */
410 
411     /**
412       * Sets the number format used by this formatter.  You only need to
413       * call this if you want a different number format than the default
414       * formatter for the locale.
415       * @param format  the number format to use.
416       * @param status  output param set to success/failure code on exit, which
417       *                must not indicate a failure before the function call.
418       * @stable ICU 4.0
419       */
420     void setNumberFormat(const NumberFormat* format, UErrorCode& status);
421 
422     /**
423        * Assignment operator
424        *
425        * @param other    the PluralFormat object to copy from.
426        * @stable ICU 4.0
427        */
428     PluralFormat& operator=(const PluralFormat& other);
429 
430     /**
431       * Return true if another object is semantically equal to this one.
432       *
433       * @param other    the PluralFormat object to be compared with.
434       * @return         true if other is semantically equal to this.
435       * @stable ICU 4.0
436       */
437     virtual UBool operator==(const Format& other) const;
438 
439     /**
440      * Return true if another object is semantically unequal to this one.
441      *
442      * @param other    the PluralFormat object to be compared with.
443      * @return         true if other is semantically unequal to this.
444      * @stable ICU 4.0
445      */
446     virtual UBool operator!=(const Format& other) const;
447 
448     /**
449      * Clones this Format object polymorphically.  The caller owns the
450      * result and should delete it when done.
451      * @stable ICU 4.0
452      */
453     virtual PluralFormat* clone() const;
454 
455    /**
456     * Formats a plural message for a number taken from a Formattable object.
457     *
458     * @param obj       The object containing a number for which the
459     *                  plural message should be formatted.
460     *                  The object must be of a numeric type.
461     * @param appendTo  output parameter to receive result.
462     *                  Result is appended to existing contents.
463     * @param pos       On input: an alignment field, if desired.
464     *                  On output: the offsets of the alignment field.
465     * @param status    output param filled with success/failure status.
466     * @return          Reference to 'appendTo' parameter.
467     * @stable ICU 4.0
468     */
469    UnicodeString& format(const Formattable& obj,
470                          UnicodeString& appendTo,
471                          FieldPosition& pos,
472                          UErrorCode& status) const;
473 
474    /**
475     * Returns the pattern from applyPattern() or constructor().
476     *
477     * @param  appendTo  output parameter to receive result.
478      *                  Result is appended to existing contents.
479     * @return the UnicodeString with inserted pattern.
480     * @stable ICU 4.0
481     */
482    UnicodeString& toPattern(UnicodeString& appendTo);
483 
484    /**
485     * This method is not yet supported by <code>PluralFormat</code>.
486     * <P>
487     * Before calling, set parse_pos.index to the offset you want to start
488     * parsing at in the source. After calling, parse_pos.index is the end of
489     * the text you parsed. If error occurs, index is unchanged.
490     * <P>
491     * When parsing, leading whitespace is discarded (with a successful parse),
492     * while trailing whitespace is left as is.
493     * <P>
494     * See Format::parseObject() for more.
495     *
496     * @param source    The string to be parsed into an object.
497     * @param result    Formattable to be set to the parse result.
498     *                  If parse fails, return contents are undefined.
499     * @param parse_pos The position to start parsing at. Upon return
500     *                  this param is set to the position after the
501     *                  last character successfully parsed. If the
502     *                  source is not parsed successfully, this param
503     *                  will remain unchanged.
504     * @stable ICU 4.0
505     */
506    virtual void parseObject(const UnicodeString& source,
507                             Formattable& result,
508                             ParsePosition& parse_pos) const;
509 
510     /**
511      * ICU "poor man's RTTI", returns a UClassID for this class.
512      *
513      * @stable ICU 4.0
514      *
515      */
516     static UClassID U_EXPORT2 getStaticClassID(void);
517 
518     /**
519      * ICU "poor man's RTTI", returns a UClassID for the actual class.
520      *
521      * @stable ICU 4.0
522      */
523      virtual UClassID getDynamicClassID() const;
524 
525 private:
526      /**
527       * @internal (private)
528       */
529     class U_I18N_API PluralSelector : public UMemory {
530       public:
531         virtual ~PluralSelector();
532         /**
533          * Given a number, returns the appropriate PluralFormat keyword.
534          *
535          * @param context worker object for the selector.
536          * @param number The number to be plural-formatted.
537          * @param ec Error code.
538          * @return The selected PluralFormat keyword.
539          * @internal (private)
540          */
541         virtual UnicodeString select(void *context, double number, UErrorCode& ec) const = 0;
542     };
543 
544     class U_I18N_API PluralSelectorAdapter : public PluralSelector {
545       public:
PluralSelectorAdapter()546         PluralSelectorAdapter() : pluralRules(NULL) {
547         }
548 
549         virtual ~PluralSelectorAdapter();
550 
551         virtual UnicodeString select(void *context, double number, UErrorCode& /*ec*/) const;
552 
553         void reset();
554 
555         PluralRules* pluralRules;
556     };
557 
558     Locale  locale;
559     MessagePattern msgPattern;
560     NumberFormat*  numberFormat;
561     double offset;
562     PluralSelectorAdapter pluralRulesWrapper;
563 
564     PluralFormat();   // default constructor not implemented
565     void init(const PluralRules* rules, UPluralType type, UErrorCode& status);
566     /**
567      * Copies dynamically allocated values (pointer fields).
568      * Others are copied using their copy constructors and assignment operators.
569      */
570     void copyObjects(const PluralFormat& other);
571 
572     UnicodeString& format(const Formattable& numberObject, double number,
573                           UnicodeString& appendTo,
574                           FieldPosition& pos,
575                           UErrorCode& status) const;
576 
577     /**
578      * Finds the PluralFormat sub-message for the given number, or the "other" sub-message.
579      * @param pattern A MessagePattern.
580      * @param partIndex the index of the first PluralFormat argument style part.
581      * @param selector the PluralSelector for mapping the number (minus offset) to a keyword.
582      * @param context worker object for the selector.
583      * @param number a number to be matched to one of the PluralFormat argument's explicit values,
584      *        or mapped via the PluralSelector.
585      * @param ec ICU error code.
586      * @return the sub-message start part index.
587      */
588     static int32_t findSubMessage(
589          const MessagePattern& pattern, int32_t partIndex,
590          const PluralSelector& selector, void *context, double number, UErrorCode& ec); /**< @internal */
591 
592     void parseType(const UnicodeString& source, const NFRule *rbnfLenientScanner,
593         Formattable& result, FieldPosition& pos) const;
594 
595     friend class MessageFormat;
596     friend class NFRule;
597 };
598 
599 U_NAMESPACE_END
600 
601 #endif /* #if !UCONFIG_NO_FORMATTING */
602 
603 #endif /* U_SHOW_CPLUSPLUS_API */
604 
605 #endif // _PLURFMT
606 //eof
607