Check in the pristine copy of ICU 4.6...

icu46/source/i18n/unicode/dtitvfmt.h

+/********************************************************************************
+* Copyright (C) 2008-2010, International Business Machines Corporation and
+* others. All Rights Reserved.
+*******************************************************************************
+*
+* File DTITVFMT.H
+*
+*******************************************************************************
+*/
+
+#ifndef __DTITVFMT_H__
+#define __DTITVFMT_H__
+
+
+#include "unicode/utypes.h"
+
+/**
+ * \file
+ * \brief C++ API: Format and parse date interval in a language-independent manner.
+ */
+
+#if !UCONFIG_NO_FORMATTING
+
+#include "unicode/ucal.h"
+#include "unicode/smpdtfmt.h"
+#include "unicode/dtintrv.h"
+#include "unicode/dtitvinf.h"
+#include "unicode/dtptngen.h"
+
+U_NAMESPACE_BEGIN
+
+
+
+/**
+ * DateIntervalFormat is a class for formatting and parsing date
+ * intervals in a language-independent manner.
+ * Only formatting is supported, parsing is not supported.
+ *
+ * <P>
+ * Date interval means from one date to another date,
+ * for example, from "Jan 11, 2008" to "Jan 18, 2008".
+ * We introduced class DateInterval to represent it.
+ * DateInterval is a pair of UDate, which is
+ * the standard milliseconds since 24:00 GMT, Jan 1, 1970.
+ *
+ * <P>
+ * DateIntervalFormat formats a DateInterval into
+ * text as compactly as possible.
+ * For example, the date interval format from "Jan 11, 2008" to "Jan 18,. 2008"
+ * is "Jan 11-18, 2008" for English.
+ * And it parses text into DateInterval,
+ * although initially, parsing is not supported.
+ *
+ * <P>
+ * There is no structural information in date time patterns.
+ * For any punctuations and string literals inside a date time pattern,
+ * we do not know whether it is just a separator, or a prefix, or a suffix.
+ * Without such information, so, it is difficult to generate a sub-pattern
+ * (or super-pattern) by algorithm.
+ * So, formatting a DateInterval is pattern-driven. It is very
+ * similar to formatting in SimpleDateFormat.
+ * We introduce class DateIntervalInfo to save date interval
+ * patterns, similar to date time pattern in SimpleDateFormat.
+ *
+ * <P>
+ * Logically, the interval patterns are mappings
+ * from (skeleton, the_largest_different_calendar_field)
+ * to (date_interval_pattern).
+ *
+ * <P>
+ * A skeleton
+ * <ol>
+ * <li>
+ * only keeps the field pattern letter and ignores all other parts
+ * in a pattern, such as space, punctuations, and string literals.
+ * </li>
+ * <li>
+ * hides the order of fields.
+ * </li>
+ * <li>
+ * might hide a field's pattern letter length.
+ * </li>
+ * </ol>
+ *
+ * For those non-digit calendar fields, the pattern letter length is
+ * important, such as MMM, MMMM, and MMMMM; EEE and EEEE,
+ * and the field's pattern letter length is honored.
+ *
+ * For the digit calendar fields,  such as M or MM, d or dd, yy or yyyy,
+ * the field pattern length is ignored and the best match, which is defined
+ * in date time patterns, will be returned without honor the field pattern
+ * letter length in skeleton.
+ *
+ * <P>
+ * The calendar fields we support for interval formatting are:
+ * year, month, date, day-of-week, am-pm, hour, hour-of-day, and minute.
+ * Those calendar fields can be defined in the following order:
+ * year >  month > date > hour (in day) >  minute
+ *
+ * The largest different calendar fields between 2 calendars is the
+ * first different calendar field in above order.
+ *
+ * For example: the largest different calendar fields between "Jan 10, 2007"
+ * and "Feb 20, 2008" is year.
+ *
+ * <P>
+ * For other calendar fields, the compact interval formatting is not
+ * supported. And the interval format will be fall back to fall-back
+ * patterns, which is mostly "{date0} - {date1}".
+ *
+ * <P>
+ * There is a set of pre-defined static skeleton strings.
+ * There are pre-defined interval patterns for those pre-defined skeletons
+ * in locales' resource files.
+ * For example, for a skeleton UDAT_YEAR_ABBR_MONTH_DAY, which is  &quot;yMMMd&quot;,
+ * in  en_US, if the largest different calendar field between date1 and date2
+ * is &quot;year&quot;, the date interval pattern  is &quot;MMM d, yyyy - MMM d, yyyy&quot;,
+ * such as &quot;Jan 10, 2007 - Jan 10, 2008&quot;.
+ * If the largest different calendar field between date1 and date2 is &quot;month&quot;,
+ * the date interval pattern is &quot;MMM d - MMM d, yyyy&quot;,
+ * such as &quot;Jan 10 - Feb 10, 2007&quot;.
+ * If the largest different calendar field between date1 and date2 is &quot;day&quot;,
+ * the date interval pattern is &quot;MMM d-d, yyyy&quot;, such as &quot;Jan 10-20, 2007&quot;.
+ *
+ * For date skeleton, the interval patterns when year, or month, or date is
+ * different are defined in resource files.
+ * For time skeleton, the interval patterns when am/pm, or hour, or minute is
+ * different are defined in resource files.
+ *
+ * <P>
+ * If a skeleton is not found in a locale's DateIntervalInfo, which means
+ * the interval patterns for the skeleton is not defined in resource file,
+ * the interval pattern will falls back to the interval "fallback" pattern
+ * defined in resource file.
+ * If the interval "fallback" pattern is not defined, the default fall-back
+ * is "{date0} - {data1}".
+ *
+ * <P>
+ * For the combination of date and time,
+ * The rule to generate interval patterns are:
+ * <ol>
+ * <li>
+ *    when the year, month, or day differs, falls back to fall-back
+ *    interval pattern, which mostly is the concatenate the two original
+ *    expressions with a separator between,
+ *    For example, interval pattern from "Jan 10, 2007 10:10 am"
+ *    to "Jan 11, 2007 10:10am" is
+ *    "Jan 10, 2007 10:10 am - Jan 11, 2007 10:10am"
+ * </li>
+ * <li>
+ *    otherwise, present the date followed by the range expression
+ *    for the time.
+ *    For example, interval pattern from "Jan 10, 2007 10:10 am"
+ *    to "Jan 10, 2007 11:10am" is "Jan 10, 2007 10:10 am - 11:10am"
+ * </li>
+ * </ol>
+ *
+ *
+ * <P>
+ * If two dates are the same, the interval pattern is the single date pattern.
+ * For example, interval pattern from "Jan 10, 2007" to "Jan 10, 2007" is
+ * "Jan 10, 2007".
+ *
+ * Or if the presenting fields between 2 dates have the exact same values,
+ * the interval pattern is the  single date pattern.
+ * For example, if user only requests year and month,
+ * the interval pattern from "Jan 10, 2007" to "Jan 20, 2007" is "Jan 2007".
+ *
+ * <P>
+ * DateIntervalFormat needs the following information for correct
+ * formatting: time zone, calendar type, pattern, date format symbols,
+ * and date interval patterns.
+ * It can be instantiated in 2 ways:
+ * <ol>
+ * <li>
+ *    create an instance using default or given locale plus given skeleton.
+ *    Users are encouraged to created date interval formatter this way and
+ *    to use the pre-defined skeleton macros, such as
+ *    UDAT_YEAR_NUM_MONTH, which consists the calendar fields and
+ *    the format style.
+ * </li>
+ * <li>
+ *    create an instance using default or given locale plus given skeleton
+ *    plus a given DateIntervalInfo.
+ *    This factory method is for powerful users who want to provide their own
+ *    interval patterns.
+ *    Locale provides the timezone, calendar, and format symbols information.
+ *    Local plus skeleton provides full pattern information.
+ *    DateIntervalInfo provides the date interval patterns.
+ * </li>
+ * </ol>
+ *
+ * <P>
+ * For the calendar field pattern letter, such as G, y, M, d, a, h, H, m, s etc.
+ * DateIntervalFormat uses the same syntax as that of
+ * DateTime format.
+ *
+ * <P>
+ * Code Sample: general usage
+ * <pre>
+ * \code
+ *   // the date interval object which the DateIntervalFormat formats on
+ *   // and parses into
+ *   DateInterval*  dtInterval = new DateInterval(1000*3600*24, 1000*3600*24*2);
+ *   UErrorCode status = U_ZERO_ERROR;
+ *   DateIntervalFormat* dtIntervalFmt = DateIntervalFormat::createInstance(
+ *                           UDAT_YEAR_MONTH_DAY,
+ *                           Locale("en", "GB", ""), status);
+ *   UnicodeUnicodeString dateIntervalString;
+ *   FieldPosition pos = 0;
+ *   // formatting
+ *   dtIntervalFmt->format(dtInterval, dateIntervalUnicodeString, pos, status);
+ *   delete dtIntervalFmt;
+ * \endcode
+ * </pre>
+ */
+
+class U_I18N_API DateIntervalFormat : public Format {
+public:
+
+    /**
+     * Construct a DateIntervalFormat from skeleton and  the default locale.
+     *
+     * This is a convenient override of
+     * createInstance(const UnicodeString& skeleton, const Locale& locale,
+     *                UErrorCode&)
+     * with the value of locale as default locale.
+     *
+     * @param skeleton  the skeleton on which interval format based.
+     * @param status    output param set to success/failure code on exit
+     * @return          a date time interval formatter which the caller owns.
+     * @stable ICU 4.0
+     */
+    static DateIntervalFormat* U_EXPORT2 createInstance(
+                                               const UnicodeString& skeleton,
+                                               UErrorCode& status);
+
+    /**
+     * Construct a DateIntervalFormat from skeleton and a given locale.
+     * <P>
+     * In this factory method,
+     * the date interval pattern information is load from resource files.
+     * Users are encouraged to created date interval formatter this way and
+     * to use the pre-defined skeleton macros.
+     *
+     * <P>
+     * There are pre-defined skeletons (defined in udate.h) having predefined
+     * interval patterns in resource files.
+     * Users are encouraged to use those macros.
+     * For example:
+     * DateIntervalFormat::createInstance(UDAT_MONTH_DAY, status)
+     *
+     * The given Locale provides the interval patterns.
+     * For example, for en_GB, if skeleton is UDAT_YEAR_ABBR_MONTH_WEEKDAY_DAY,
+     * which is "yMMMEEEd",
+     * the interval patterns defined in resource file to above skeleton are:
+     * "EEE, d MMM, yyyy - EEE, d MMM, yyyy" for year differs,
+     * "EEE, d MMM - EEE, d MMM, yyyy" for month differs,
+     * "EEE, d - EEE, d MMM, yyyy" for day differs,
+     * @param skeleton  the skeleton on which interval format based.
+     * @param locale    the given locale
+     * @param status    output param set to success/failure code on exit
+     * @return          a date time interval formatter which the caller owns.
+     * @stable ICU 4.0
+     */
+
+    static DateIntervalFormat* U_EXPORT2 createInstance(
+                                               const UnicodeString& skeleton,
+                                               const Locale& locale,
+                                               UErrorCode& status);
+
+    /**
+     * Construct a DateIntervalFormat from skeleton
+     *  DateIntervalInfo, and default locale.
+     *
+     * This is a convenient override of
+     * createInstance(const UnicodeString& skeleton, const Locale& locale,
+     *                const DateIntervalInfo& dtitvinf, UErrorCode&)
+     * with the locale value as default locale.
+     *
+     * @param skeleton  the skeleton on which interval format based.
+     * @param dtitvinf  the DateIntervalInfo object.
+     * @param status    output param set to success/failure code on exit
+     * @return          a date time interval formatter which the caller owns.
+     * @stable ICU 4.0
+     */
+    static DateIntervalFormat* U_EXPORT2 createInstance(
+                                              const UnicodeString& skeleton,
+                                              const DateIntervalInfo& dtitvinf,
+                                              UErrorCode& status);
+
+    /**
+     * Construct a DateIntervalFormat from skeleton
+     * a DateIntervalInfo, and the given locale.
+     *
+     * <P>
+     * In this factory method, user provides its own date interval pattern
+     * information, instead of using those pre-defined data in resource file.
+     * This factory method is for powerful users who want to provide their own
+     * interval patterns.
+     * <P>
+     * There are pre-defined skeletons (defined in udate.h) having predefined
+     * interval patterns in resource files.
+     * Users are encouraged to use those macros.
+     * For example:
+     * DateIntervalFormat::createInstance(UDAT_MONTH_DAY, status)
+     *
+     * The DateIntervalInfo provides the interval patterns.
+     * and the DateIntervalInfo ownership remains to the caller.
+     *
+     * User are encouraged to set default interval pattern in DateIntervalInfo
+     * as well, if they want to set other interval patterns ( instead of
+     * reading the interval patterns from resource files).
+     * When the corresponding interval pattern for a largest calendar different
+     * field is not found ( if user not set it ), interval format fallback to
+     * the default interval pattern.
+     * If user does not provide default interval pattern, it fallback to
+     * "{date0} - {date1}"
+     *
+     * @param skeleton  the skeleton on which interval format based.
+     * @param locale    the given locale
+     * @param dtitvinf  the DateIntervalInfo object.
+     * @param status    output param set to success/failure code on exit
+     * @return          a date time interval formatter which the caller owns.
+     * @stable ICU 4.0
+     */
+    static DateIntervalFormat* U_EXPORT2 createInstance(
+                                              const UnicodeString& skeleton,
+                                              const Locale& locale,
+                                              const DateIntervalInfo& dtitvinf,
+                                              UErrorCode& status);
+
+    /**
+     * Destructor.
+     * @stable ICU 4.0
+     */
+    virtual ~DateIntervalFormat();
+
+    /**
+     * Clone this Format object polymorphically. The caller owns the result and
+     * should delete it when done.
+     * @return    A copy of the object.
+     * @stable ICU 4.0
+     */
+    virtual Format* clone(void) const;
+
+    /**
+     * Return true if the given Format objects are semantically equal. Objects
+     * of different subclasses are considered unequal.
+     * @param other    the object to be compared with.
+     * @return         true if the given Format objects are semantically equal.
+     * @stable ICU 4.0
+     */
+    virtual UBool operator==(const Format& other) const;
+
+    /**
+     * Return true if the given Format objects are not semantically equal.
+     * Objects of different subclasses are considered unequal.
+     * @param other the object to be compared with.
+     * @return      true if the given Format objects are not semantically equal.
+     * @stable ICU 4.0
+     */
+    UBool operator!=(const Format& other) const;
+
+
+    using Format::format;
+
+    /**
+     * Format an object to produce a string. This method handles Formattable
+     * objects with a DateInterval type.
+     * If a the Formattable object type is not a DateInterval,
+     * then it returns a failing UErrorCode.
+     *
+     * @param obj               The object to format.
+     *                          Must be a DateInterval.
+     * @param appendTo          Output parameter to receive result.
+     *                          Result is appended to existing contents.
+     * @param fieldPosition     On input: an alignment field, if desired.
+     *                          On output: the offsets of the alignment field.
+     * @param status            Output param filled with success/failure status.
+     * @return                  Reference to 'appendTo' parameter.
+     * @stable ICU 4.0
+     */
+    virtual UnicodeString& format(const Formattable& obj,
+                                  UnicodeString& appendTo,
+                                  FieldPosition& fieldPosition,
+                                  UErrorCode& status) const ;
+
+
+
+    /**
+     * Format a DateInterval to produce a string.
+     *
+     * @param dtInterval        DateInterval to be formatted.
+     * @param appendTo          Output parameter to receive result.
+     *                          Result is appended to existing contents.
+     * @param fieldPosition     On input: an alignment field, if desired.
+     *                          On output: the offsets of the alignment field.
+     * @param status            Output param filled with success/failure status.
+     * @return                  Reference to 'appendTo' parameter.
+     * @stable ICU 4.0
+     */
+    UnicodeString& format(const DateInterval* dtInterval,
+                          UnicodeString& appendTo,
+                          FieldPosition& fieldPosition,
+                          UErrorCode& status) const ;
+
+
+    /**
+     * Format 2 Calendars to produce a string.
+     *
+     * Note: "fromCalendar" and "toCalendar" are not const,
+     * since calendar is not const in  SimpleDateFormat::format(Calendar&),
+     *
+     * @param fromCalendar      calendar set to the from date in date interval
+     *                          to be formatted into date interval string
+     * @param toCalendar        calendar set to the to date in date interval
+     *                          to be formatted into date interval string
+     * @param appendTo          Output parameter to receive result.
+     *                          Result is appended to existing contents.
+     * @param fieldPosition     On input: an alignment field, if desired.
+     *                          On output: the offsets of the alignment field.
+     * @param status            Output param filled with success/failure status.
+     *                          Caller needs to make sure it is SUCCESS
+     *                          at the function entrance
+     * @return                  Reference to 'appendTo' parameter.
+     * @stable ICU 4.0
+     */
+    UnicodeString& format(Calendar& fromCalendar,
+                          Calendar& toCalendar,
+                          UnicodeString& appendTo,
+                          FieldPosition& fieldPosition,
+                          UErrorCode& status) const ;
+
+    /**
+     * Date interval parsing is not supported. Please do not use.
+     * <P>
+     * This method should handle parsing of
+     * date time interval strings into Formattable objects with
+     * DateInterval type, which is a pair of UDate.
+     * <P>
+     * Before calling, set parse_pos.index to the offset you want to start
+     * parsing at in the source. After calling, parse_pos.index is the end of
+     * the text you parsed. If error occurs, index is unchanged.
+     * <P>
+     * When parsing, leading whitespace is discarded (with a successful parse),
+     * while trailing whitespace is left as is.
+     * <P>
+     * See Format::parseObject() for more.
+     *
+     * @param source    The string to be parsed into an object.
+     * @param result    Formattable to be set to the parse result.
+     *                  If parse fails, return contents are undefined.
+     * @param parse_pos The position to start parsing at. Since no parsing
+     *                  is supported, upon return this param is unchanged.
+     * @return          A newly created Formattable* object, or NULL
+     *                  on failure.  The caller owns this and should
+     *                  delete it when done.
+     * @internal ICU 4.0
+     */
+    virtual void parseObject(const UnicodeString& source,
+                             Formattable& result,
+                             ParsePosition& parse_pos) const;
+
+
+    /**
+     * Gets the date time interval patterns.
+     * @return the date time interval patterns associated with
+     * this date interval formatter.
+     * @stable ICU 4.0
+     */
+    const DateIntervalInfo* getDateIntervalInfo(void) const;
+
+
+    /**
+     * Set the date time interval patterns.
+     * @param newIntervalPatterns   the given interval patterns to copy.
+     * @param status          output param set to success/failure code on exit
+     * @stable ICU 4.0
+     */
+    void setDateIntervalInfo(const DateIntervalInfo& newIntervalPatterns,
+                             UErrorCode& status);
+
+
+    /**
+     * Gets the date formatter
+     * @return the date formatter associated with this date interval formatter.
+     * @stable ICU 4.0
+     */
+    const DateFormat* getDateFormat(void) const;
+
+    /**
+     * Return the class ID for this class. This is useful only for comparing to
+     * a return value from getDynamicClassID(). For example:
+     * <pre>
+     * .   Base* polymorphic_pointer = createPolymorphicObject();
+     * .   if (polymorphic_pointer->getDynamicClassID() ==
+     * .       erived::getStaticClassID()) ...
+     * </pre>
+     * @return          The class ID for all objects of this class.
+     * @stable ICU 4.0
+     */
+    static UClassID U_EXPORT2 getStaticClassID(void);
+
+    /**
+     * Returns a unique class ID POLYMORPHICALLY. Pure virtual override. This
+     * method is to implement a simple version of RTTI, since not all C++
+     * compilers support genuine RTTI. Polymorphic operator==() and clone()
+     * methods call this method.
+     *
+     * @return          The class ID for this object. All objects of a
+     *                  given class have the same class ID.  Objects of
+     *                  other classes have different class IDs.
+     * @stable ICU 4.0
+     */
+    virtual UClassID getDynamicClassID(void) const;
+
+protected:
+
+    /**
+     * Copy constructor.
+     * @stable ICU 4.0
+     */
+    DateIntervalFormat(const DateIntervalFormat&);
+
+    /**
+     * Assignment operator.
+     * @stable ICU 4.0
+     */
+    DateIntervalFormat& operator=(const DateIntervalFormat&);
+
+private:
+
+    /*
+     * This is for ICU internal use only. Please do not use.
+     * Save the interval pattern information.
+     * Interval pattern consists of 2 single date patterns and the separator.
+     * For example, interval pattern "MMM d - MMM d, yyyy" consists
+     * a single date pattern "MMM d", another single date pattern "MMM d, yyyy",
+     * and a separator "-".
+     * The pattern is divided into 2 parts. For above example,
+     * the first part is "MMM d - ", and the second part is "MMM d, yyyy".
+     * Also, the first date appears in an interval pattern could be
+     * the earlier date or the later date.
+     * And such information is saved in the interval pattern as well.
+     * @internal ICU 4.0
+     */
+    struct PatternInfo {
+        UnicodeString firstPart;
+        UnicodeString secondPart;
+        /**
+         * Whether the first date in interval pattern is later date or not.
+         * Fallback format set the default ordering.
+         * And for a particular interval pattern, the order can be
+         * overriden by prefixing the interval pattern with "latestFirst:" or
+         * "earliestFirst:"
+         * For example, given 2 date, Jan 10, 2007 to Feb 10, 2007.
+         * if the fallback format is "{0} - {1}",
+         * and the pattern is "d MMM - d MMM yyyy", the interval format is
+         * "10 Jan - 10 Feb, 2007".
+         * If the pattern is "latestFirst:d MMM - d MMM yyyy",
+         * the interval format is "10 Feb - 10 Jan, 2007"
+         */
+        UBool         laterDateFirst;
+    };
+
+
+    /**
+     * default constructor
+     * @internal ICU 4.0
+     */
+    DateIntervalFormat();
+
+    /**
+     * Construct a DateIntervalFormat from DateFormat,
+     * a DateIntervalInfo, and skeleton.
+     * DateFormat provides the timezone, calendar,
+     * full pattern, and date format symbols information.
+     * It should be a SimpleDateFormat object which
+     * has a pattern in it.
+     * the DateIntervalInfo provides the interval patterns.
+     *
+     * Note: the DateIntervalFormat takes ownership of both
+     * DateFormat and DateIntervalInfo objects.
+     * Caller should not delete them.
+     *
+     * @param locale    the locale of this date interval formatter.
+     * @param dtitvinf  the DateIntervalInfo object to be adopted.
+     * @param skeleton  the skeleton of the date formatter
+     * @param status    output param set to success/failure code on exit
+     * @internal ICU 4.0
+     */
+    DateIntervalFormat(const Locale& locale, DateIntervalInfo* dtItvInfo,
+                       const UnicodeString* skeleton, UErrorCode& status);
+
+
+    /**
+     * Construct a DateIntervalFormat from DateFormat
+     * and a DateIntervalInfo.
+     *
+     * It is a wrapper of the constructor.
+     *
+     * @param locale    the locale of this date interval formatter.
+     * @param dtitvinf  the DateIntervalInfo object to be adopted.
+     * @param skeleton  the skeleton of this formatter.
+     * @param status    Output param set to success/failure code.
+     * @return          a date time interval formatter which the caller owns.
+     * @internal ICU 4.0
+     */
+    static DateIntervalFormat* U_EXPORT2 create(const Locale& locale,
+                                                DateIntervalInfo* dtitvinf,
+                                                const UnicodeString* skeleton,
+                                                UErrorCode& status);
+
+    /**
+     * Create a simple date/time formatter from skeleton, given locale,
+     * and date time pattern generator.
+     *
+     * @param skeleton  the skeleton on which date format based.
+     * @param locale    the given locale.
+     * @param dtpng     the date time pattern generator.
+     * @param status    Output param to be set to success/failure code.
+     *                  If it is failure, the returned date formatter will
+     *                  be NULL.
+     * @return          a simple date formatter which the caller owns.
+     * @internal ICU 4.0
+     */
+    static SimpleDateFormat* U_EXPORT2 createSDFPatternInstance(
+                                        const UnicodeString& skeleton,
+                                        const Locale& locale,
+                                        DateTimePatternGenerator* dtpng,
+                                        UErrorCode& status);
+
+
+    /**
+     *  Below are for generating interval patterns local to the formatter
+     */
+
+
+    /**
+     * Format 2 Calendars using fall-back interval pattern
+     *
+     * The full pattern used in this fall-back format is the
+     * full pattern of the date formatter.
+     *
+     * @param fromCalendar      calendar set to the from date in date interval
+     *                          to be formatted into date interval string
+     * @param toCalendar        calendar set to the to date in date interval
+     *                          to be formatted into date interval string
+     * @param appendTo          Output parameter to receive result.
+     *                          Result is appended to existing contents.
+     * @param pos               On input: an alignment field, if desired.
+     *                          On output: the offsets of the alignment field.
+     * @param status            output param set to success/failure code on exit
+     * @return                  Reference to 'appendTo' parameter.
+     * @internal ICU 4.0
+     */
+    UnicodeString& fallbackFormat(Calendar& fromCalendar,
+                                  Calendar& toCalendar,
+                                  UnicodeString& appendTo,
+                                  FieldPosition& pos,
+                                  UErrorCode& status) const;
+
+
+
+    /**
+     * Initialize interval patterns locale to this formatter
+     *
+     * This code is a bit complicated since
+     * 1. the interval patterns saved in resource bundle files are interval
+     *    patterns based on date or time only.
+     *    It does not have interval patterns based on both date and time.
+     *    Interval patterns on both date and time are algorithm generated.
+     *
+     *    For example, it has interval patterns on skeleton "dMy" and "hm",
+     *    but it does not have interval patterns on skeleton "dMyhm".
+     *
+     *    The rule to generate interval patterns for both date and time skeleton are
+     *    1) when the year, month, or day differs, concatenate the two original
+     *    expressions with a separator between,
+     *    For example, interval pattern from "Jan 10, 2007 10:10 am"
+     *    to "Jan 11, 2007 10:10am" is
+     *    "Jan 10, 2007 10:10 am - Jan 11, 2007 10:10am"
+     *
+     *    2) otherwise, present the date followed by the range expression
+     *    for the time.
+     *    For example, interval pattern from "Jan 10, 2007 10:10 am"
+     *    to "Jan 10, 2007 11:10am" is
+     *    "Jan 10, 2007 10:10 am - 11:10am"
+     *
+     * 2. even a pattern does not request a certain calendar field,
+     *    the interval pattern needs to include such field if such fields are
+     *    different between 2 dates.
+     *    For example, a pattern/skeleton is "hm", but the interval pattern
+     *    includes year, month, and date when year, month, and date differs.
+     *
+     *
+     * @param status    output param set to success/failure code on exit
+     * @internal ICU 4.0
+     */
+    void initializePattern(UErrorCode& status);
+
+
+
+    /**
+     * Set fall back interval pattern given a calendar field,
+     * a skeleton, and a date time pattern generator.
+     * @param field      the largest different calendar field
+     * @param skeleton   a skeleton
+     * @param status     output param set to success/failure code on exit
+     * @internal ICU 4.0
+     */
+    void setFallbackPattern(UCalendarDateFields field,
+                            const UnicodeString& skeleton,
+                            UErrorCode& status);
+
+
+
+    /**
+     * get separated date and time skeleton from a combined skeleton.
+     *
+     * The difference between date skeleton and normalizedDateSkeleton are:
+     * 1. both 'y' and 'd' are appeared only once in normalizeDateSkeleton
+     * 2. 'E' and 'EE' are normalized into 'EEE'
+     * 3. 'MM' is normalized into 'M'
+     *
+     ** the difference between time skeleton and normalizedTimeSkeleton are:
+     * 1. both 'H' and 'h' are normalized as 'h' in normalized time skeleton,
+     * 2. 'a' is omitted in normalized time skeleton.
+     * 3. there is only one appearance for 'h', 'm','v', 'z' in normalized time
+     *    skeleton
+     *
+     *
+     *  @param skeleton               given combined skeleton.
+     *  @param date                   Output parameter for date only skeleton.
+     *  @param normalizedDate         Output parameter for normalized date only
+     *
+     *  @param time                   Output parameter for time only skeleton.
+     *  @param normalizedTime         Output parameter for normalized time only
+     *                                skeleton.
+     *
+     * @internal ICU 4.0
+     */
+    static void  U_EXPORT2 getDateTimeSkeleton(const UnicodeString& skeleton,
+                                    UnicodeString& date,
+                                    UnicodeString& normalizedDate,
+                                    UnicodeString& time,
+                                    UnicodeString& normalizedTime);
+
+
+
+    /**
+     * Generate date or time interval pattern from resource,
+     * and set them into the interval pattern locale to this formatter.
+     *
+     * It needs to handle the following:
+     * 1. need to adjust field width.
+     *    For example, the interval patterns saved in DateIntervalInfo
+     *    includes "dMMMy", but not "dMMMMy".
+     *    Need to get interval patterns for dMMMMy from dMMMy.
+     *    Another example, the interval patterns saved in DateIntervalInfo
+     *    includes "hmv", but not "hmz".
+     *    Need to get interval patterns for "hmz' from 'hmv'
+     *
+     * 2. there might be no pattern for 'y' differ for skeleton "Md",
+     *    in order to get interval patterns for 'y' differ,
+     *    need to look for it from skeleton 'yMd'
+     *
+     * @param dateSkeleton   normalized date skeleton
+     * @param timeSkeleton   normalized time skeleton
+     * @return               whether the resource is found for the skeleton.
+     *                       TRUE if interval pattern found for the skeleton,
+     *                       FALSE otherwise.
+     * @internal ICU 4.0
+     */
+    UBool setSeparateDateTimePtn(const UnicodeString& dateSkeleton,
+                                 const UnicodeString& timeSkeleton);
+
+
+
+
+    /**
+     * Generate interval pattern from existing resource
+     *
+     * It not only save the interval patterns,
+     * but also return the extended skeleton and its best match skeleton.
+     *
+     * @param field           largest different calendar field
+     * @param skeleton        skeleton
+     * @param bestSkeleton    the best match skeleton which has interval pattern
+     *                        defined in resource
+     * @param differenceInfo  the difference between skeleton and best skeleton
+     *         0 means the best matched skeleton is the same as input skeleton
+     *         1 means the fields are the same, but field width are different
+     *         2 means the only difference between fields are v/z,
+     *        -1 means there are other fields difference
+     *
+     * @param extendedSkeleton      extended skeleton
+     * @param extendedBestSkeleton  extended best match skeleton
+     * @return                      whether the interval pattern is found
+     *                              through extending skeleton or not.
+     *                              TRUE if interval pattern is found by
+     *                              extending skeleton, FALSE otherwise.
+     * @internal ICU 4.0
+     */
+    UBool setIntervalPattern(UCalendarDateFields field,
+                             const UnicodeString* skeleton,
+                             const UnicodeString* bestSkeleton,
+                             int8_t differenceInfo,
+                             UnicodeString* extendedSkeleton = NULL,
+                             UnicodeString* extendedBestSkeleton = NULL);
+
+    /**
+     * Adjust field width in best match interval pattern to match
+     * the field width in input skeleton.
+     *
+     * TODO (xji) make a general solution
+     * The adjusting rule can be:
+     * 1. always adjust
+     * 2. never adjust
+     * 3. default adjust, which means adjust according to the following rules
+     * 3.1 always adjust string, such as MMM and MMMM
+     * 3.2 never adjust between string and numeric, such as MM and MMM
+     * 3.3 always adjust year
+     * 3.4 do not adjust 'd', 'h', or 'm' if h presents
+     * 3.5 do not adjust 'M' if it is numeric(?)
+     *
+     * Since date interval format is well-formed format,
+     * date and time skeletons are normalized previously,
+     * till this stage, the adjust here is only "adjust strings, such as MMM
+     * and MMMM, EEE and EEEE.
+     *
+     * @param inputSkeleton            the input skeleton
+     * @param bestMatchSkeleton        the best match skeleton
+     * @param bestMatchIntervalpattern the best match interval pattern
+     * @param differenceInfo           the difference between 2 skeletons
+     *                                 1 means only field width differs
+     *                                 2 means v/z exchange
+     * @param adjustedIntervalPattern  adjusted interval pattern
+     * @internal ICU 4.0
+     */
+    static void U_EXPORT2 adjustFieldWidth(
+                            const UnicodeString& inputSkeleton,
+                            const UnicodeString& bestMatchSkeleton,
+                            const UnicodeString& bestMatchIntervalPattern,
+                            int8_t differenceInfo,
+                            UnicodeString& adjustedIntervalPattern);
+
+    /**
+     * Concat a single date pattern with a time interval pattern,
+     * set it into the intervalPatterns, while field is time field.
+     * This is used to handle time interval patterns on skeleton with
+     * both time and date. Present the date followed by
+     * the range expression for the time.
+     * @param format         date and time format
+     * @param formatLen      format string length
+     * @param datePattern    date pattern
+     * @param field          time calendar field: AM_PM, HOUR, MINUTE
+     * @param status         output param set to success/failure code on exit
+     * @internal ICU 4.0
+     */
+    void concatSingleDate2TimeInterval(const UChar* format,
+                                       int32_t formatLen,
+                                       const UnicodeString& datePattern,
+                                       UCalendarDateFields field,
+                                       UErrorCode& status);
+
+    /**
+     * check whether a calendar field present in a skeleton.
+     * @param field      calendar field need to check
+     * @param skeleton   given skeleton on which to check the calendar field
+     * @return           true if field present in a skeleton.
+     * @internal ICU 4.0
+     */
+    static UBool U_EXPORT2 fieldExistsInSkeleton(UCalendarDateFields field,
+                                                 const UnicodeString& skeleton);
+
+
+    /**
+     * Split interval patterns into 2 part.
+     * @param intervalPattern  interval pattern
+     * @return the index in interval pattern which split the pattern into 2 part
+     * @internal ICU 4.0
+     */
+    static int32_t  U_EXPORT2 splitPatternInto2Part(const UnicodeString& intervalPattern);
+
+
+    /**
+     * Break interval patterns as 2 part and save them into pattern info.
+     * @param field            calendar field
+     * @param intervalPattern  interval pattern
+     * @internal ICU 4.0
+     */
+    void setIntervalPattern(UCalendarDateFields field,
+                            const UnicodeString& intervalPattern);
+
+
+    /**
+     * Break interval patterns as 2 part and save them into pattern info.
+     * @param field            calendar field
+     * @param intervalPattern  interval pattern
+     * @param laterDateFirst   whether later date appear first in interval pattern
+     * @internal ICU 4.0
+     */
+    void setIntervalPattern(UCalendarDateFields field,
+                            const UnicodeString& intervalPattern,
+                            UBool laterDateFirst);
+
+
+    /**
+     * Set pattern information.
+     *
+     * @param field            calendar field
+     * @param firstPart        the first part in interval pattern
+     * @param secondPart       the second part in interval pattern
+     * @param laterDateFirst   whether the first date in intervalPattern
+     *                         is earlier date or later date
+     * @internal ICU 4.0
+     */
+    void setPatternInfo(UCalendarDateFields field,
+                        const UnicodeString* firstPart,
+                        const UnicodeString* secondpart,
+                        UBool laterDateFirst);
+
+
+    // from calendar field to pattern letter
+    static const UChar fgCalendarFieldToPatternLetter[];
+
+
+    /**
+     * The interval patterns for this locale.
+     */
+    DateIntervalInfo*     fInfo;
+
+    /**
+     * The DateFormat object used to format single pattern
+     */
+    SimpleDateFormat*     fDateFormat;
+
+    /**
+     * The 2 calendars with the from and to date.
+     * could re-use the calendar in fDateFormat,
+     * but keeping 2 calendars make it clear and clean.
+     */
+    Calendar* fFromCalendar;
+    Calendar* fToCalendar;
+
+    /**
+     * Date time pattern generator
+     */
+    DateTimePatternGenerator* fDtpng;
+
+    /**
+     * Following are interval information relavent (locale) to this formatter.
+     */
+    UnicodeString fSkeleton;
+    PatternInfo fIntervalPatterns[DateIntervalInfo::kIPI_MAX_INDEX];
+};
+
+inline UBool
+DateIntervalFormat::operator!=(const Format& other) const  {
+    return !operator==(other);
+}
+
+U_NAMESPACE_END
+
+#endif /* #if !UCONFIG_NO_FORMATTING */
+
+#endif // _DTITVFMT_H__
+//eof