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1 /********************************************************************************
2 * Copyright (C) 2008-2010, International Business Machines Corporation and
3 * others. All Rights Reserved.
4 *******************************************************************************
5 *
6 * File DTITVFMT.H
7 *
8 *******************************************************************************
9 */
10 
11 #ifndef __DTITVFMT_H__
12 #define __DTITVFMT_H__
13 
14 
15 #include "unicode/utypes.h"
16 
17 /**
18  * \file
19  * \brief C++ API: Format and parse date interval in a language-independent manner.
20  */
21 
22 #if !UCONFIG_NO_FORMATTING
23 
24 #include "unicode/ucal.h"
25 #include "unicode/smpdtfmt.h"
26 #include "unicode/dtintrv.h"
27 #include "unicode/dtitvinf.h"
28 #include "unicode/dtptngen.h"
29 
30 U_NAMESPACE_BEGIN
31 
32 
33 
34 /**
35  * DateIntervalFormat is a class for formatting and parsing date
36  * intervals in a language-independent manner.
37  * Only formatting is supported, parsing is not supported.
38  *
39  * <P>
40  * Date interval means from one date to another date,
41  * for example, from "Jan 11, 2008" to "Jan 18, 2008".
42  * We introduced class DateInterval to represent it.
43  * DateInterval is a pair of UDate, which is
44  * the standard milliseconds since 24:00 GMT, Jan 1, 1970.
45  *
46  * <P>
47  * DateIntervalFormat formats a DateInterval into
48  * text as compactly as possible.
49  * For example, the date interval format from "Jan 11, 2008" to "Jan 18,. 2008"
50  * is "Jan 11-18, 2008" for English.
51  * And it parses text into DateInterval,
52  * although initially, parsing is not supported.
53  *
54  * <P>
55  * There is no structural information in date time patterns.
56  * For any punctuations and string literals inside a date time pattern,
57  * we do not know whether it is just a separator, or a prefix, or a suffix.
58  * Without such information, so, it is difficult to generate a sub-pattern
59  * (or super-pattern) by algorithm.
60  * So, formatting a DateInterval is pattern-driven. It is very
61  * similar to formatting in SimpleDateFormat.
62  * We introduce class DateIntervalInfo to save date interval
63  * patterns, similar to date time pattern in SimpleDateFormat.
64  *
65  * <P>
66  * Logically, the interval patterns are mappings
67  * from (skeleton, the_largest_different_calendar_field)
68  * to (date_interval_pattern).
69  *
70  * <P>
71  * A skeleton
72  * <ol>
73  * <li>
74  * only keeps the field pattern letter and ignores all other parts
75  * in a pattern, such as space, punctuations, and string literals.
76  * </li>
77  * <li>
78  * hides the order of fields.
79  * </li>
80  * <li>
81  * might hide a field's pattern letter length.
82  * </li>
83  * </ol>
84  *
85  * For those non-digit calendar fields, the pattern letter length is
86  * important, such as MMM, MMMM, and MMMMM; EEE and EEEE,
87  * and the field's pattern letter length is honored.
88  *
89  * For the digit calendar fields,  such as M or MM, d or dd, yy or yyyy,
90  * the field pattern length is ignored and the best match, which is defined
91  * in date time patterns, will be returned without honor the field pattern
92  * letter length in skeleton.
93  *
94  * <P>
95  * The calendar fields we support for interval formatting are:
96  * year, month, date, day-of-week, am-pm, hour, hour-of-day, and minute.
97  * Those calendar fields can be defined in the following order:
98  * year >  month > date > hour (in day) >  minute
99  *
100  * The largest different calendar fields between 2 calendars is the
101  * first different calendar field in above order.
102  *
103  * For example: the largest different calendar fields between "Jan 10, 2007"
104  * and "Feb 20, 2008" is year.
105  *
106  * <P>
107  * For other calendar fields, the compact interval formatting is not
108  * supported. And the interval format will be fall back to fall-back
109  * patterns, which is mostly "{date0} - {date1}".
110  *
111  * <P>
112  * There is a set of pre-defined static skeleton strings.
113  * There are pre-defined interval patterns for those pre-defined skeletons
114  * in locales' resource files.
115  * For example, for a skeleton UDAT_YEAR_ABBR_MONTH_DAY, which is  &quot;yMMMd&quot;,
116  * in  en_US, if the largest different calendar field between date1 and date2
117  * is &quot;year&quot;, the date interval pattern  is &quot;MMM d, yyyy - MMM d, yyyy&quot;,
118  * such as &quot;Jan 10, 2007 - Jan 10, 2008&quot;.
119  * If the largest different calendar field between date1 and date2 is &quot;month&quot;,
120  * the date interval pattern is &quot;MMM d - MMM d, yyyy&quot;,
121  * such as &quot;Jan 10 - Feb 10, 2007&quot;.
122  * If the largest different calendar field between date1 and date2 is &quot;day&quot;,
123  * the date interval pattern is &quot;MMM d-d, yyyy&quot;, such as &quot;Jan 10-20, 2007&quot;.
124  *
125  * For date skeleton, the interval patterns when year, or month, or date is
126  * different are defined in resource files.
127  * For time skeleton, the interval patterns when am/pm, or hour, or minute is
128  * different are defined in resource files.
129  *
130  * <P>
131  * If a skeleton is not found in a locale's DateIntervalInfo, which means
132  * the interval patterns for the skeleton is not defined in resource file,
133  * the interval pattern will falls back to the interval "fallback" pattern
134  * defined in resource file.
135  * If the interval "fallback" pattern is not defined, the default fall-back
136  * is "{date0} - {data1}".
137  *
138  * <P>
139  * For the combination of date and time,
140  * The rule to generate interval patterns are:
141  * <ol>
142  * <li>
143  *    when the year, month, or day differs, falls back to fall-back
144  *    interval pattern, which mostly is the concatenate the two original
145  *    expressions with a separator between,
146  *    For example, interval pattern from "Jan 10, 2007 10:10 am"
147  *    to "Jan 11, 2007 10:10am" is
148  *    "Jan 10, 2007 10:10 am - Jan 11, 2007 10:10am"
149  * </li>
150  * <li>
151  *    otherwise, present the date followed by the range expression
152  *    for the time.
153  *    For example, interval pattern from "Jan 10, 2007 10:10 am"
154  *    to "Jan 10, 2007 11:10am" is "Jan 10, 2007 10:10 am - 11:10am"
155  * </li>
156  * </ol>
157  *
158  *
159  * <P>
160  * If two dates are the same, the interval pattern is the single date pattern.
161  * For example, interval pattern from "Jan 10, 2007" to "Jan 10, 2007" is
162  * "Jan 10, 2007".
163  *
164  * Or if the presenting fields between 2 dates have the exact same values,
165  * the interval pattern is the  single date pattern.
166  * For example, if user only requests year and month,
167  * the interval pattern from "Jan 10, 2007" to "Jan 20, 2007" is "Jan 2007".
168  *
169  * <P>
170  * DateIntervalFormat needs the following information for correct
171  * formatting: time zone, calendar type, pattern, date format symbols,
172  * and date interval patterns.
173  * It can be instantiated in 2 ways:
174  * <ol>
175  * <li>
176  *    create an instance using default or given locale plus given skeleton.
177  *    Users are encouraged to created date interval formatter this way and
178  *    to use the pre-defined skeleton macros, such as
179  *    UDAT_YEAR_NUM_MONTH, which consists the calendar fields and
180  *    the format style.
181  * </li>
182  * <li>
183  *    create an instance using default or given locale plus given skeleton
184  *    plus a given DateIntervalInfo.
185  *    This factory method is for powerful users who want to provide their own
186  *    interval patterns.
187  *    Locale provides the timezone, calendar, and format symbols information.
188  *    Local plus skeleton provides full pattern information.
189  *    DateIntervalInfo provides the date interval patterns.
190  * </li>
191  * </ol>
192  *
193  * <P>
194  * For the calendar field pattern letter, such as G, y, M, d, a, h, H, m, s etc.
195  * DateIntervalFormat uses the same syntax as that of
196  * DateTime format.
197  *
198  * <P>
199  * Code Sample: general usage
200  * <pre>
201  * \code
202  *   // the date interval object which the DateIntervalFormat formats on
203  *   // and parses into
204  *   DateInterval*  dtInterval = new DateInterval(1000*3600*24, 1000*3600*24*2);
205  *   UErrorCode status = U_ZERO_ERROR;
206  *   DateIntervalFormat* dtIntervalFmt = DateIntervalFormat::createInstance(
207  *                           UDAT_YEAR_MONTH_DAY,
208  *                           Locale("en", "GB", ""), status);
209  *   UnicodeUnicodeString dateIntervalString;
210  *   FieldPosition pos = 0;
211  *   // formatting
212  *   dtIntervalFmt->format(dtInterval, dateIntervalUnicodeString, pos, status);
213  *   delete dtIntervalFmt;
214  * \endcode
215  * </pre>
216  */
217 
218 class U_I18N_API DateIntervalFormat : public Format {
219 public:
220 
221     /**
222      * Construct a DateIntervalFormat from skeleton and  the default locale.
223      *
224      * This is a convenient override of
225      * createInstance(const UnicodeString& skeleton, const Locale& locale,
226      *                UErrorCode&)
227      * with the value of locale as default locale.
228      *
229      * @param skeleton  the skeleton on which interval format based.
230      * @param status    output param set to success/failure code on exit
231      * @return          a date time interval formatter which the caller owns.
232      * @stable ICU 4.0
233      */
234     static DateIntervalFormat* U_EXPORT2 createInstance(
235                                                const UnicodeString& skeleton,
236                                                UErrorCode& status);
237 
238     /**
239      * Construct a DateIntervalFormat from skeleton and a given locale.
240      * <P>
241      * In this factory method,
242      * the date interval pattern information is load from resource files.
243      * Users are encouraged to created date interval formatter this way and
244      * to use the pre-defined skeleton macros.
245      *
246      * <P>
247      * There are pre-defined skeletons (defined in udate.h) having predefined
248      * interval patterns in resource files.
249      * Users are encouraged to use those macros.
250      * For example:
251      * DateIntervalFormat::createInstance(UDAT_MONTH_DAY, status)
252      *
253      * The given Locale provides the interval patterns.
254      * For example, for en_GB, if skeleton is UDAT_YEAR_ABBR_MONTH_WEEKDAY_DAY,
255      * which is "yMMMEEEd",
256      * the interval patterns defined in resource file to above skeleton are:
257      * "EEE, d MMM, yyyy - EEE, d MMM, yyyy" for year differs,
258      * "EEE, d MMM - EEE, d MMM, yyyy" for month differs,
259      * "EEE, d - EEE, d MMM, yyyy" for day differs,
260      * @param skeleton  the skeleton on which interval format based.
261      * @param locale    the given locale
262      * @param status    output param set to success/failure code on exit
263      * @return          a date time interval formatter which the caller owns.
264      * @stable ICU 4.0
265      */
266 
267     static DateIntervalFormat* U_EXPORT2 createInstance(
268                                                const UnicodeString& skeleton,
269                                                const Locale& locale,
270                                                UErrorCode& status);
271 
272     /**
273      * Construct a DateIntervalFormat from skeleton
274      *  DateIntervalInfo, and default locale.
275      *
276      * This is a convenient override of
277      * createInstance(const UnicodeString& skeleton, const Locale& locale,
278      *                const DateIntervalInfo& dtitvinf, UErrorCode&)
279      * with the locale value as default locale.
280      *
281      * @param skeleton  the skeleton on which interval format based.
282      * @param dtitvinf  the DateIntervalInfo object.
283      * @param status    output param set to success/failure code on exit
284      * @return          a date time interval formatter which the caller owns.
285      * @stable ICU 4.0
286      */
287     static DateIntervalFormat* U_EXPORT2 createInstance(
288                                               const UnicodeString& skeleton,
289                                               const DateIntervalInfo& dtitvinf,
290                                               UErrorCode& status);
291 
292     /**
293      * Construct a DateIntervalFormat from skeleton
294      * a DateIntervalInfo, and the given locale.
295      *
296      * <P>
297      * In this factory method, user provides its own date interval pattern
298      * information, instead of using those pre-defined data in resource file.
299      * This factory method is for powerful users who want to provide their own
300      * interval patterns.
301      * <P>
302      * There are pre-defined skeletons (defined in udate.h) having predefined
303      * interval patterns in resource files.
304      * Users are encouraged to use those macros.
305      * For example:
306      * DateIntervalFormat::createInstance(UDAT_MONTH_DAY, status)
307      *
308      * The DateIntervalInfo provides the interval patterns.
309      * and the DateIntervalInfo ownership remains to the caller.
310      *
311      * User are encouraged to set default interval pattern in DateIntervalInfo
312      * as well, if they want to set other interval patterns ( instead of
313      * reading the interval patterns from resource files).
314      * When the corresponding interval pattern for a largest calendar different
315      * field is not found ( if user not set it ), interval format fallback to
316      * the default interval pattern.
317      * If user does not provide default interval pattern, it fallback to
318      * "{date0} - {date1}"
319      *
320      * @param skeleton  the skeleton on which interval format based.
321      * @param locale    the given locale
322      * @param dtitvinf  the DateIntervalInfo object.
323      * @param status    output param set to success/failure code on exit
324      * @return          a date time interval formatter which the caller owns.
325      * @stable ICU 4.0
326      */
327     static DateIntervalFormat* U_EXPORT2 createInstance(
328                                               const UnicodeString& skeleton,
329                                               const Locale& locale,
330                                               const DateIntervalInfo& dtitvinf,
331                                               UErrorCode& status);
332 
333     /**
334      * Destructor.
335      * @stable ICU 4.0
336      */
337     virtual ~DateIntervalFormat();
338 
339     /**
340      * Clone this Format object polymorphically. The caller owns the result and
341      * should delete it when done.
342      * @return    A copy of the object.
343      * @stable ICU 4.0
344      */
345     virtual Format* clone(void) const;
346 
347     /**
348      * Return true if the given Format objects are semantically equal. Objects
349      * of different subclasses are considered unequal.
350      * @param other    the object to be compared with.
351      * @return         true if the given Format objects are semantically equal.
352      * @stable ICU 4.0
353      */
354     virtual UBool operator==(const Format& other) const;
355 
356     /**
357      * Return true if the given Format objects are not semantically equal.
358      * Objects of different subclasses are considered unequal.
359      * @param other the object to be compared with.
360      * @return      true if the given Format objects are not semantically equal.
361      * @stable ICU 4.0
362      */
363     UBool operator!=(const Format& other) const;
364 
365 
366     using Format::format;
367 
368     /**
369      * Format an object to produce a string. This method handles Formattable
370      * objects with a DateInterval type.
371      * If a the Formattable object type is not a DateInterval,
372      * then it returns a failing UErrorCode.
373      *
374      * @param obj               The object to format.
375      *                          Must be a DateInterval.
376      * @param appendTo          Output parameter to receive result.
377      *                          Result is appended to existing contents.
378      * @param fieldPosition     On input: an alignment field, if desired.
379      *                          On output: the offsets of the alignment field.
380      * @param status            Output param filled with success/failure status.
381      * @return                  Reference to 'appendTo' parameter.
382      * @stable ICU 4.0
383      */
384     virtual UnicodeString& format(const Formattable& obj,
385                                   UnicodeString& appendTo,
386                                   FieldPosition& fieldPosition,
387                                   UErrorCode& status) const ;
388 
389 
390 
391     /**
392      * Format a DateInterval to produce a string.
393      *
394      * @param dtInterval        DateInterval to be formatted.
395      * @param appendTo          Output parameter to receive result.
396      *                          Result is appended to existing contents.
397      * @param fieldPosition     On input: an alignment field, if desired.
398      *                          On output: the offsets of the alignment field.
399      * @param status            Output param filled with success/failure status.
400      * @return                  Reference to 'appendTo' parameter.
401      * @stable ICU 4.0
402      */
403     UnicodeString& format(const DateInterval* dtInterval,
404                           UnicodeString& appendTo,
405                           FieldPosition& fieldPosition,
406                           UErrorCode& status) const ;
407 
408 
409     /**
410      * Format 2 Calendars to produce a string.
411      *
412      * Note: "fromCalendar" and "toCalendar" are not const,
413      * since calendar is not const in  SimpleDateFormat::format(Calendar&),
414      *
415      * @param fromCalendar      calendar set to the from date in date interval
416      *                          to be formatted into date interval string
417      * @param toCalendar        calendar set to the to date in date interval
418      *                          to be formatted into date interval string
419      * @param appendTo          Output parameter to receive result.
420      *                          Result is appended to existing contents.
421      * @param fieldPosition     On input: an alignment field, if desired.
422      *                          On output: the offsets of the alignment field.
423      * @param status            Output param filled with success/failure status.
424      *                          Caller needs to make sure it is SUCCESS
425      *                          at the function entrance
426      * @return                  Reference to 'appendTo' parameter.
427      * @stable ICU 4.0
428      */
429     UnicodeString& format(Calendar& fromCalendar,
430                           Calendar& toCalendar,
431                           UnicodeString& appendTo,
432                           FieldPosition& fieldPosition,
433                           UErrorCode& status) const ;
434 
435     /**
436      * Date interval parsing is not supported. Please do not use.
437      * <P>
438      * This method should handle parsing of
439      * date time interval strings into Formattable objects with
440      * DateInterval type, which is a pair of UDate.
441      * <P>
442      * Before calling, set parse_pos.index to the offset you want to start
443      * parsing at in the source. After calling, parse_pos.index is the end of
444      * the text you parsed. If error occurs, index is unchanged.
445      * <P>
446      * When parsing, leading whitespace is discarded (with a successful parse),
447      * while trailing whitespace is left as is.
448      * <P>
449      * See Format::parseObject() for more.
450      *
451      * @param source    The string to be parsed into an object.
452      * @param result    Formattable to be set to the parse result.
453      *                  If parse fails, return contents are undefined.
454      * @param parse_pos The position to start parsing at. Since no parsing
455      *                  is supported, upon return this param is unchanged.
456      * @return          A newly created Formattable* object, or NULL
457      *                  on failure.  The caller owns this and should
458      *                  delete it when done.
459      * @internal ICU 4.0
460      */
461     virtual void parseObject(const UnicodeString& source,
462                              Formattable& result,
463                              ParsePosition& parse_pos) const;
464 
465 
466     /**
467      * Gets the date time interval patterns.
468      * @return the date time interval patterns associated with
469      * this date interval formatter.
470      * @stable ICU 4.0
471      */
472     const DateIntervalInfo* getDateIntervalInfo(void) const;
473 
474 
475     /**
476      * Set the date time interval patterns.
477      * @param newIntervalPatterns   the given interval patterns to copy.
478      * @param status          output param set to success/failure code on exit
479      * @stable ICU 4.0
480      */
481     void setDateIntervalInfo(const DateIntervalInfo& newIntervalPatterns,
482                              UErrorCode& status);
483 
484 
485     /**
486      * Gets the date formatter
487      * @return the date formatter associated with this date interval formatter.
488      * @stable ICU 4.0
489      */
490     const DateFormat* getDateFormat(void) const;
491 
492     /**
493      * Return the class ID for this class. This is useful only for comparing to
494      * a return value from getDynamicClassID(). For example:
495      * <pre>
496      * .   Base* polymorphic_pointer = createPolymorphicObject();
497      * .   if (polymorphic_pointer->getDynamicClassID() ==
498      * .       erived::getStaticClassID()) ...
499      * </pre>
500      * @return          The class ID for all objects of this class.
501      * @stable ICU 4.0
502      */
503     static UClassID U_EXPORT2 getStaticClassID(void);
504 
505     /**
506      * Returns a unique class ID POLYMORPHICALLY. Pure virtual override. This
507      * method is to implement a simple version of RTTI, since not all C++
508      * compilers support genuine RTTI. Polymorphic operator==() and clone()
509      * methods call this method.
510      *
511      * @return          The class ID for this object. All objects of a
512      *                  given class have the same class ID.  Objects of
513      *                  other classes have different class IDs.
514      * @stable ICU 4.0
515      */
516     virtual UClassID getDynamicClassID(void) const;
517 
518 protected:
519 
520     /**
521      * Copy constructor.
522      * @stable ICU 4.0
523      */
524     DateIntervalFormat(const DateIntervalFormat&);
525 
526     /**
527      * Assignment operator.
528      * @stable ICU 4.0
529      */
530     DateIntervalFormat& operator=(const DateIntervalFormat&);
531 
532 private:
533 
534     /*
535      * This is for ICU internal use only. Please do not use.
536      * Save the interval pattern information.
537      * Interval pattern consists of 2 single date patterns and the separator.
538      * For example, interval pattern "MMM d - MMM d, yyyy" consists
539      * a single date pattern "MMM d", another single date pattern "MMM d, yyyy",
540      * and a separator "-".
541      * The pattern is divided into 2 parts. For above example,
542      * the first part is "MMM d - ", and the second part is "MMM d, yyyy".
543      * Also, the first date appears in an interval pattern could be
544      * the earlier date or the later date.
545      * And such information is saved in the interval pattern as well.
546      * @internal ICU 4.0
547      */
548     struct PatternInfo {
549         UnicodeString firstPart;
550         UnicodeString secondPart;
551         /**
552          * Whether the first date in interval pattern is later date or not.
553          * Fallback format set the default ordering.
554          * And for a particular interval pattern, the order can be
555          * overriden by prefixing the interval pattern with "latestFirst:" or
556          * "earliestFirst:"
557          * For example, given 2 date, Jan 10, 2007 to Feb 10, 2007.
558          * if the fallback format is "{0} - {1}",
559          * and the pattern is "d MMM - d MMM yyyy", the interval format is
560          * "10 Jan - 10 Feb, 2007".
561          * If the pattern is "latestFirst:d MMM - d MMM yyyy",
562          * the interval format is "10 Feb - 10 Jan, 2007"
563          */
564         UBool         laterDateFirst;
565     };
566 
567 
568     /**
569      * default constructor
570      * @internal ICU 4.0
571      */
572     DateIntervalFormat();
573 
574     /**
575      * Construct a DateIntervalFormat from DateFormat,
576      * a DateIntervalInfo, and skeleton.
577      * DateFormat provides the timezone, calendar,
578      * full pattern, and date format symbols information.
579      * It should be a SimpleDateFormat object which
580      * has a pattern in it.
581      * the DateIntervalInfo provides the interval patterns.
582      *
583      * Note: the DateIntervalFormat takes ownership of both
584      * DateFormat and DateIntervalInfo objects.
585      * Caller should not delete them.
586      *
587      * @param locale    the locale of this date interval formatter.
588      * @param dtitvinf  the DateIntervalInfo object to be adopted.
589      * @param skeleton  the skeleton of the date formatter
590      * @param status    output param set to success/failure code on exit
591      * @internal ICU 4.0
592      */
593     DateIntervalFormat(const Locale& locale, DateIntervalInfo* dtItvInfo,
594                        const UnicodeString* skeleton, UErrorCode& status);
595 
596 
597     /**
598      * Construct a DateIntervalFormat from DateFormat
599      * and a DateIntervalInfo.
600      *
601      * It is a wrapper of the constructor.
602      *
603      * @param locale    the locale of this date interval formatter.
604      * @param dtitvinf  the DateIntervalInfo object to be adopted.
605      * @param skeleton  the skeleton of this formatter.
606      * @param status    Output param set to success/failure code.
607      * @return          a date time interval formatter which the caller owns.
608      * @internal ICU 4.0
609      */
610     static DateIntervalFormat* U_EXPORT2 create(const Locale& locale,
611                                                 DateIntervalInfo* dtitvinf,
612                                                 const UnicodeString* skeleton,
613                                                 UErrorCode& status);
614 
615     /**
616      * Create a simple date/time formatter from skeleton, given locale,
617      * and date time pattern generator.
618      *
619      * @param skeleton  the skeleton on which date format based.
620      * @param locale    the given locale.
621      * @param dtpng     the date time pattern generator.
622      * @param status    Output param to be set to success/failure code.
623      *                  If it is failure, the returned date formatter will
624      *                  be NULL.
625      * @return          a simple date formatter which the caller owns.
626      * @internal ICU 4.0
627      */
628     static SimpleDateFormat* U_EXPORT2 createSDFPatternInstance(
629                                         const UnicodeString& skeleton,
630                                         const Locale& locale,
631                                         DateTimePatternGenerator* dtpng,
632                                         UErrorCode& status);
633 
634 
635     /**
636      *  Below are for generating interval patterns local to the formatter
637      */
638 
639 
640     /**
641      * Format 2 Calendars using fall-back interval pattern
642      *
643      * The full pattern used in this fall-back format is the
644      * full pattern of the date formatter.
645      *
646      * @param fromCalendar      calendar set to the from date in date interval
647      *                          to be formatted into date interval string
648      * @param toCalendar        calendar set to the to date in date interval
649      *                          to be formatted into date interval string
650      * @param appendTo          Output parameter to receive result.
651      *                          Result is appended to existing contents.
652      * @param pos               On input: an alignment field, if desired.
653      *                          On output: the offsets of the alignment field.
654      * @param status            output param set to success/failure code on exit
655      * @return                  Reference to 'appendTo' parameter.
656      * @internal ICU 4.0
657      */
658     UnicodeString& fallbackFormat(Calendar& fromCalendar,
659                                   Calendar& toCalendar,
660                                   UnicodeString& appendTo,
661                                   FieldPosition& pos,
662                                   UErrorCode& status) const;
663 
664 
665 
666     /**
667      * Initialize interval patterns locale to this formatter
668      *
669      * This code is a bit complicated since
670      * 1. the interval patterns saved in resource bundle files are interval
671      *    patterns based on date or time only.
672      *    It does not have interval patterns based on both date and time.
673      *    Interval patterns on both date and time are algorithm generated.
674      *
675      *    For example, it has interval patterns on skeleton "dMy" and "hm",
676      *    but it does not have interval patterns on skeleton "dMyhm".
677      *
678      *    The rule to generate interval patterns for both date and time skeleton are
679      *    1) when the year, month, or day differs, concatenate the two original
680      *    expressions with a separator between,
681      *    For example, interval pattern from "Jan 10, 2007 10:10 am"
682      *    to "Jan 11, 2007 10:10am" is
683      *    "Jan 10, 2007 10:10 am - Jan 11, 2007 10:10am"
684      *
685      *    2) otherwise, present the date followed by the range expression
686      *    for the time.
687      *    For example, interval pattern from "Jan 10, 2007 10:10 am"
688      *    to "Jan 10, 2007 11:10am" is
689      *    "Jan 10, 2007 10:10 am - 11:10am"
690      *
691      * 2. even a pattern does not request a certain calendar field,
692      *    the interval pattern needs to include such field if such fields are
693      *    different between 2 dates.
694      *    For example, a pattern/skeleton is "hm", but the interval pattern
695      *    includes year, month, and date when year, month, and date differs.
696      *
697      *
698      * @param status    output param set to success/failure code on exit
699      * @internal ICU 4.0
700      */
701     void initializePattern(UErrorCode& status);
702 
703 
704 
705     /**
706      * Set fall back interval pattern given a calendar field,
707      * a skeleton, and a date time pattern generator.
708      * @param field      the largest different calendar field
709      * @param skeleton   a skeleton
710      * @param status     output param set to success/failure code on exit
711      * @internal ICU 4.0
712      */
713     void setFallbackPattern(UCalendarDateFields field,
714                             const UnicodeString& skeleton,
715                             UErrorCode& status);
716 
717 
718 
719     /**
720      * get separated date and time skeleton from a combined skeleton.
721      *
722      * The difference between date skeleton and normalizedDateSkeleton are:
723      * 1. both 'y' and 'd' are appeared only once in normalizeDateSkeleton
724      * 2. 'E' and 'EE' are normalized into 'EEE'
725      * 3. 'MM' is normalized into 'M'
726      *
727      ** the difference between time skeleton and normalizedTimeSkeleton are:
728      * 1. both 'H' and 'h' are normalized as 'h' in normalized time skeleton,
729      * 2. 'a' is omitted in normalized time skeleton.
730      * 3. there is only one appearance for 'h', 'm','v', 'z' in normalized time
731      *    skeleton
732      *
733      *
734      *  @param skeleton               given combined skeleton.
735      *  @param date                   Output parameter for date only skeleton.
736      *  @param normalizedDate         Output parameter for normalized date only
737      *
738      *  @param time                   Output parameter for time only skeleton.
739      *  @param normalizedTime         Output parameter for normalized time only
740      *                                skeleton.
741      *
742      * @internal ICU 4.0
743      */
744     static void  U_EXPORT2 getDateTimeSkeleton(const UnicodeString& skeleton,
745                                     UnicodeString& date,
746                                     UnicodeString& normalizedDate,
747                                     UnicodeString& time,
748                                     UnicodeString& normalizedTime);
749 
750 
751 
752     /**
753      * Generate date or time interval pattern from resource,
754      * and set them into the interval pattern locale to this formatter.
755      *
756      * It needs to handle the following:
757      * 1. need to adjust field width.
758      *    For example, the interval patterns saved in DateIntervalInfo
759      *    includes "dMMMy", but not "dMMMMy".
760      *    Need to get interval patterns for dMMMMy from dMMMy.
761      *    Another example, the interval patterns saved in DateIntervalInfo
762      *    includes "hmv", but not "hmz".
763      *    Need to get interval patterns for "hmz' from 'hmv'
764      *
765      * 2. there might be no pattern for 'y' differ for skeleton "Md",
766      *    in order to get interval patterns for 'y' differ,
767      *    need to look for it from skeleton 'yMd'
768      *
769      * @param dateSkeleton   normalized date skeleton
770      * @param timeSkeleton   normalized time skeleton
771      * @return               whether the resource is found for the skeleton.
772      *                       TRUE if interval pattern found for the skeleton,
773      *                       FALSE otherwise.
774      * @internal ICU 4.0
775      */
776     UBool setSeparateDateTimePtn(const UnicodeString& dateSkeleton,
777                                  const UnicodeString& timeSkeleton);
778 
779 
780 
781 
782     /**
783      * Generate interval pattern from existing resource
784      *
785      * It not only save the interval patterns,
786      * but also return the extended skeleton and its best match skeleton.
787      *
788      * @param field           largest different calendar field
789      * @param skeleton        skeleton
790      * @param bestSkeleton    the best match skeleton which has interval pattern
791      *                        defined in resource
792      * @param differenceInfo  the difference between skeleton and best skeleton
793      *         0 means the best matched skeleton is the same as input skeleton
794      *         1 means the fields are the same, but field width are different
795      *         2 means the only difference between fields are v/z,
796      *        -1 means there are other fields difference
797      *
798      * @param extendedSkeleton      extended skeleton
799      * @param extendedBestSkeleton  extended best match skeleton
800      * @return                      whether the interval pattern is found
801      *                              through extending skeleton or not.
802      *                              TRUE if interval pattern is found by
803      *                              extending skeleton, FALSE otherwise.
804      * @internal ICU 4.0
805      */
806     UBool setIntervalPattern(UCalendarDateFields field,
807                              const UnicodeString* skeleton,
808                              const UnicodeString* bestSkeleton,
809                              int8_t differenceInfo,
810                              UnicodeString* extendedSkeleton = NULL,
811                              UnicodeString* extendedBestSkeleton = NULL);
812 
813     /**
814      * Adjust field width in best match interval pattern to match
815      * the field width in input skeleton.
816      *
817      * TODO (xji) make a general solution
818      * The adjusting rule can be:
819      * 1. always adjust
820      * 2. never adjust
821      * 3. default adjust, which means adjust according to the following rules
822      * 3.1 always adjust string, such as MMM and MMMM
823      * 3.2 never adjust between string and numeric, such as MM and MMM
824      * 3.3 always adjust year
825      * 3.4 do not adjust 'd', 'h', or 'm' if h presents
826      * 3.5 do not adjust 'M' if it is numeric(?)
827      *
828      * Since date interval format is well-formed format,
829      * date and time skeletons are normalized previously,
830      * till this stage, the adjust here is only "adjust strings, such as MMM
831      * and MMMM, EEE and EEEE.
832      *
833      * @param inputSkeleton            the input skeleton
834      * @param bestMatchSkeleton        the best match skeleton
835      * @param bestMatchIntervalpattern the best match interval pattern
836      * @param differenceInfo           the difference between 2 skeletons
837      *                                 1 means only field width differs
838      *                                 2 means v/z exchange
839      * @param adjustedIntervalPattern  adjusted interval pattern
840      * @internal ICU 4.0
841      */
842     static void U_EXPORT2 adjustFieldWidth(
843                             const UnicodeString& inputSkeleton,
844                             const UnicodeString& bestMatchSkeleton,
845                             const UnicodeString& bestMatchIntervalPattern,
846                             int8_t differenceInfo,
847                             UnicodeString& adjustedIntervalPattern);
848 
849     /**
850      * Concat a single date pattern with a time interval pattern,
851      * set it into the intervalPatterns, while field is time field.
852      * This is used to handle time interval patterns on skeleton with
853      * both time and date. Present the date followed by
854      * the range expression for the time.
855      * @param format         date and time format
856      * @param formatLen      format string length
857      * @param datePattern    date pattern
858      * @param field          time calendar field: AM_PM, HOUR, MINUTE
859      * @param status         output param set to success/failure code on exit
860      * @internal ICU 4.0
861      */
862     void concatSingleDate2TimeInterval(const UChar* format,
863                                        int32_t formatLen,
864                                        const UnicodeString& datePattern,
865                                        UCalendarDateFields field,
866                                        UErrorCode& status);
867 
868     /**
869      * check whether a calendar field present in a skeleton.
870      * @param field      calendar field need to check
871      * @param skeleton   given skeleton on which to check the calendar field
872      * @return           true if field present in a skeleton.
873      * @internal ICU 4.0
874      */
875     static UBool U_EXPORT2 fieldExistsInSkeleton(UCalendarDateFields field,
876                                                  const UnicodeString& skeleton);
877 
878 
879     /**
880      * Split interval patterns into 2 part.
881      * @param intervalPattern  interval pattern
882      * @return the index in interval pattern which split the pattern into 2 part
883      * @internal ICU 4.0
884      */
885     static int32_t  U_EXPORT2 splitPatternInto2Part(const UnicodeString& intervalPattern);
886 
887 
888     /**
889      * Break interval patterns as 2 part and save them into pattern info.
890      * @param field            calendar field
891      * @param intervalPattern  interval pattern
892      * @internal ICU 4.0
893      */
894     void setIntervalPattern(UCalendarDateFields field,
895                             const UnicodeString& intervalPattern);
896 
897 
898     /**
899      * Break interval patterns as 2 part and save them into pattern info.
900      * @param field            calendar field
901      * @param intervalPattern  interval pattern
902      * @param laterDateFirst   whether later date appear first in interval pattern
903      * @internal ICU 4.0
904      */
905     void setIntervalPattern(UCalendarDateFields field,
906                             const UnicodeString& intervalPattern,
907                             UBool laterDateFirst);
908 
909 
910     /**
911      * Set pattern information.
912      *
913      * @param field            calendar field
914      * @param firstPart        the first part in interval pattern
915      * @param secondPart       the second part in interval pattern
916      * @param laterDateFirst   whether the first date in intervalPattern
917      *                         is earlier date or later date
918      * @internal ICU 4.0
919      */
920     void setPatternInfo(UCalendarDateFields field,
921                         const UnicodeString* firstPart,
922                         const UnicodeString* secondpart,
923                         UBool laterDateFirst);
924 
925 
926     // from calendar field to pattern letter
927     static const UChar fgCalendarFieldToPatternLetter[];
928 
929 
930     /**
931      * The interval patterns for this locale.
932      */
933     DateIntervalInfo*     fInfo;
934 
935     /**
936      * The DateFormat object used to format single pattern
937      */
938     SimpleDateFormat*     fDateFormat;
939 
940     /**
941      * The 2 calendars with the from and to date.
942      * could re-use the calendar in fDateFormat,
943      * but keeping 2 calendars make it clear and clean.
944      */
945     Calendar* fFromCalendar;
946     Calendar* fToCalendar;
947 
948     /**
949      * Date time pattern generator
950      */
951     DateTimePatternGenerator* fDtpng;
952 
953     /**
954      * Following are interval information relavent (locale) to this formatter.
955      */
956     UnicodeString fSkeleton;
957     PatternInfo fIntervalPatterns[DateIntervalInfo::kIPI_MAX_INDEX];
958 };
959 
960 inline UBool
961 DateIntervalFormat::operator!=(const Format& other) const  {
962     return !operator==(other);
963 }
964 
965 U_NAMESPACE_END
966 
967 #endif /* #if !UCONFIG_NO_FORMATTING */
968 
969 #endif // _DTITVFMT_H__
970 //eof
971