tor-browser

dtitvfmt.h (50689B)

---

// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/********************************************************************************
* Copyright (C) 2008-2016, International Business Machines Corporation and
* others. All Rights Reserved.
*******************************************************************************
*
* File DTITVFMT.H
*
*******************************************************************************
*/

#ifndef __DTITVFMT_H__
#define __DTITVFMT_H__


#include "unicode/utypes.h"

#if U_SHOW_CPLUSPLUS_API

/**
* \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"
#include "unicode/formattedvalue.h"
#include "unicode/udisplaycontext.h"

U_NAMESPACE_BEGIN


class FormattedDateIntervalData;
class DateIntervalFormat;

/**
* An immutable class containing the result of a date interval formatting operation.
*
* Instances of this class are immutable and thread-safe.
*
* When calling nextPosition():
* The fields are returned from left to right. The special field category
* UFIELD_CATEGORY_DATE_INTERVAL_SPAN is used to indicate which datetime
* primitives came from which arguments: 0 means fromCalendar, and 1 means
* toCalendar. The span category will always occur before the
* corresponding fields in UFIELD_CATEGORY_DATE
* in the nextPosition() iterator.
*
* Not intended for public subclassing.
*
* @stable ICU 64
*/
class U_I18N_API FormattedDateInterval : public UMemory, public FormattedValue {
 public:
   /**
    * Default constructor; makes an empty FormattedDateInterval.
    * @stable ICU 64
    */
   FormattedDateInterval() : fData(nullptr), fErrorCode(U_INVALID_STATE_ERROR) {}

   /**
    * Move constructor: Leaves the source FormattedDateInterval in an undefined state.
    * @stable ICU 64
    */
   FormattedDateInterval(FormattedDateInterval&& src) noexcept;

   /**
    * Destruct an instance of FormattedDateInterval.
    * @stable ICU 64
    */
   virtual ~FormattedDateInterval() override;

   /** Copying not supported; use move constructor instead. */
   FormattedDateInterval(const FormattedDateInterval&) = delete;

   /** Copying not supported; use move assignment instead. */
   FormattedDateInterval& operator=(const FormattedDateInterval&) = delete;

   /**
    * Move assignment: Leaves the source FormattedDateInterval in an undefined state.
    * @stable ICU 64
    */
   FormattedDateInterval& operator=(FormattedDateInterval&& src) noexcept;

   /** @copydoc FormattedValue::toString() */
   UnicodeString toString(UErrorCode& status) const override;

   /** @copydoc FormattedValue::toTempString() */
   UnicodeString toTempString(UErrorCode& status) const override;

   /** @copydoc FormattedValue::appendTo() */
   Appendable &appendTo(Appendable& appendable, UErrorCode& status) const override;

   /** @copydoc FormattedValue::nextPosition() */
   UBool nextPosition(ConstrainedFieldPosition& cfpos, UErrorCode& status) const override;

 private:
   FormattedDateIntervalData *fData;
   UErrorCode fErrorCode;
   explicit FormattedDateInterval(FormattedDateIntervalData *results)
       : fData(results), fErrorCode(U_ZERO_ERROR) {}
   explicit FormattedDateInterval(UErrorCode errorCode)
       : fData(nullptr), fErrorCode(errorCode) {}
   friend class DateIntervalFormat;
};


/**
* 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, minute, second,
* and millisecond.
* (though we do not currently have specific intervalFormat date for skeletons
* with seconds and millisecond).
* Those calendar fields can be defined in the following order:
* year >  month > date > hour (in day) >  minute > second > millisecond
*
* 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_CLASS 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
    */
   U_I18N_API static DateIntervalFormat* 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 the interval format is 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
    */

   U_I18N_API static DateIntervalFormat* 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
    */
   U_I18N_API static DateIntervalFormat* 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
    */
   U_I18N_API static DateIntervalFormat* createInstance(const UnicodeString& skeleton,
                                                        const Locale& locale,
                                                        const DateIntervalInfo& dtitvinf,
                                                        UErrorCode& status);

   /**
    * Destructor.
    * @stable ICU 4.0
    */
   U_I18N_API 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
    */
   U_I18N_API virtual DateIntervalFormat* clone() const override;

   /**
    * 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
    */
   U_I18N_API virtual bool operator==(const Format& other) const override;

   /**
    * 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
    */
   U_I18N_API bool 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.
    *                          There may be multiple instances of a given field type
    *                          in an interval format; in this case the fieldPosition
    *                          offsets refer to the first instance.
    * @param status            Output param filled with success/failure status.
    * @return                  Reference to 'appendTo' parameter.
    * @stable ICU 4.0
    */
   U_I18N_API virtual UnicodeString& format(const Formattable& obj,
                                            UnicodeString& appendTo,
                                            FieldPosition& fieldPosition,
                                            UErrorCode& status) const override;

   /**
    * 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.
    *                          There may be multiple instances of a given field type
    *                          in an interval format; in this case the fieldPosition
    *                          offsets refer to the first instance.
    * @param status            Output param filled with success/failure status.
    * @return                  Reference to 'appendTo' parameter.
    * @stable ICU 4.0
    */
   U_I18N_API UnicodeString& format(const DateInterval* dtInterval,
                                    UnicodeString& appendTo,
                                    FieldPosition& fieldPosition,
                                    UErrorCode& status) const;

   /**
    * Format a DateInterval to produce a FormattedDateInterval.
    *
    * The FormattedDateInterval exposes field information about the formatted string.
    *
    * @param dtInterval        DateInterval to be formatted.
    * @param status            Set if an error occurs.
    * @return                  A FormattedDateInterval containing the format result.
    * @stable ICU 64
    */
   U_I18N_API FormattedDateInterval formatToValue(const DateInterval& dtInterval,
                                                  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.
    *                          There may be multiple instances of a given field type
    *                          in an interval format; in this case the fieldPosition
    *                          offsets refer to the first instance.
    * @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
    */
   U_I18N_API UnicodeString& format(Calendar& fromCalendar,
                                    Calendar& toCalendar,
                                    UnicodeString& appendTo,
                                    FieldPosition& fieldPosition,
                                    UErrorCode& status) const;

   /**
    * Format 2 Calendars to produce a FormattedDateInterval.
    *
    * The FormattedDateInterval exposes field information about the formatted 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 status            Set if an error occurs.
    * @return                  A FormattedDateInterval containing the format result.
    * @stable ICU 64
    */
   U_I18N_API FormattedDateInterval formatToValue(Calendar& fromCalendar,
                                                  Calendar& toCalendar,
                                                  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 nullptr
    *                  on failure.  The caller owns this and should
    *                  delete it when done.
    * @internal ICU 4.0
    */
   U_I18N_API virtual void parseObject(const UnicodeString& source,
                                       Formattable& result,
                                       ParsePosition& parse_pos) const override;

   /**
    * Gets the date time interval patterns.
    * @return the date time interval patterns associated with
    * this date interval formatter.
    * @stable ICU 4.0
    */
   U_I18N_API const DateIntervalInfo* getDateIntervalInfo() 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
    */
   U_I18N_API void setDateIntervalInfo(const DateIntervalInfo& newIntervalPatterns, UErrorCode& status);

   /**
    * Gets the date formatter. The DateIntervalFormat instance continues to own
    * the returned DateFormatter object, and will use and possibly modify it
    * during format operations. In a multi-threaded environment, the returned
    * DateFormat can only be used if it is certain that no other threads are
    * concurrently using this DateIntervalFormatter, even for nominally const
    * functions.
    *
    * @return the date formatter associated with this date interval formatter.
    * @stable ICU 4.0
    */
   U_I18N_API const DateFormat* getDateFormat() const;

   /**
    * Returns a reference to the TimeZone used by this DateIntervalFormat's calendar.
    * @return the time zone associated with the calendar of DateIntervalFormat.
    * @stable ICU 4.8
    */
   U_I18N_API virtual const TimeZone& getTimeZone() const;

   /**
    * Sets the time zone for the calendar used by this DateIntervalFormat object. The
    * caller no longer owns the TimeZone object and should not delete it after this call.
    * @param zoneToAdopt the TimeZone to be adopted.
    * @stable ICU 4.8
    */
   U_I18N_API virtual void adoptTimeZone(TimeZone* zoneToAdopt);

   /**
    * Sets the time zone for the calendar used by this DateIntervalFormat object.
    * @param zone the new time zone.
    * @stable ICU 4.8
    */
   U_I18N_API virtual void setTimeZone(const TimeZone& zone);

   /**
    * Sets the calendar used by this DateIntervalFormat object. The caller no longer owns
    * the Calendar object and should not delete it after this call.
    * @param calendarToAdopt the Calendar to be adopted.
    */
   U_I18N_API virtual void adoptCalendar(Calendar *calendarToAdopt);

   /**
    * Set a particular UDisplayContext value in the formatter, such as
    * UDISPCTX_CAPITALIZATION_FOR_STANDALONE. This causes the formatted
    * result to be capitalized appropriately for the context in which
    * it is intended to be used, considering both the locale and the
    * type of field at the beginning of the formatted result.
    * @param value The UDisplayContext value to set.
    * @param status Input/output status. If at entry this indicates a failure
    *               status, the function will do nothing; otherwise this will be
    *               updated with any new status from the function.
    * @stable ICU 68
    */
   U_I18N_API virtual void setContext(UDisplayContext value, UErrorCode& status);

   /**
    * Get the formatter's UDisplayContext value for the specified UDisplayContextType,
    * such as UDISPCTX_TYPE_CAPITALIZATION.
    * @param type The UDisplayContextType whose value to return
    * @param status Input/output status. If at entry this indicates a failure
    *               status, the function will do nothing; otherwise this will be
    *               updated with any new status from the function.
    * @return The UDisplayContextValue for the specified type.
    * @stable ICU 68
    */
   U_I18N_API virtual UDisplayContext getContext(UDisplayContextType type, UErrorCode& status) 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
    */
   U_I18N_API static UClassID getStaticClassID();

   /**
    * 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
    */
   U_I18N_API virtual UClassID getDynamicClassID() const override;

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.
    */
   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
        * overridden 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
    */
   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 dtItvInfo 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
    */
   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.
    */
   U_I18N_API static DateIntervalFormat* create(const Locale& locale,
                                                DateIntervalInfo* dtitvinf,
                                                const UnicodeString* skeleton,
                                                UErrorCode& status);

   /**
    *  Below are for generating interval patterns local to the formatter
    */

   /** Like fallbackFormat, but only formats the range part of the fallback. */
   void fallbackFormatRange(
       Calendar& fromCalendar,
       Calendar& toCalendar,
       UnicodeString& appendTo,
       int8_t& firstIndex,
       FieldPositionHandler& fphandler,
       UErrorCode& status) const;

   /**
    * 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.
    *
    * gFormatterMutex must already be locked when calling this function.
    *
    * @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 fromToOnSameDay   true iff from and to dates are on the same day
    *                          (any difference is in ampm/hours or below)
    * @param appendTo          Output parameter to receive result.
    *                          Result is appended to existing contents.
    * @param firstIndex        See formatImpl for more information.
    * @param fphandler         See formatImpl for more information.
    * @param status            output param set to success/failure code on exit
    * @return                  Reference to 'appendTo' parameter.
    */
   UnicodeString& fallbackFormat(Calendar& fromCalendar,
                                 Calendar& toCalendar,
                                 UBool fromToOnSameDay,
                                 UnicodeString& appendTo,
                                 int8_t& firstIndex,
                                 FieldPositionHandler& fphandler,
                                 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
    */
   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
    */
   void setFallbackPattern(UCalendarDateFields field,
                           const UnicodeString& skeleton,
                           UErrorCode& status);
   


   /**
    * Converts special hour metacharacters (such as 'j') in the skeleton into locale-appropriate
    * pattern characters.
    *
    *
    *  @param skeleton               The skeleton to convert
    *  @return A copy of the skeleton, which "j" and any other special hour metacharacters converted to the regular ones.
    *
    */
   UnicodeString normalizeHourMetacharacters(const UnicodeString& skeleton) const;



   /**
    * 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.
    *
    */
   U_I18N_API static void 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.
    */
   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.
    */
   UBool setIntervalPattern(UCalendarDateFields field,
                            const UnicodeString* skeleton,
                            const UnicodeString* bestSkeleton,
                            int8_t differenceInfo,
                            UnicodeString* extendedSkeleton = nullptr,
                            UnicodeString* extendedBestSkeleton = nullptr);

   /**
    * 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 suppressDayPeriodField if true, remove the day period field from the pattern, if there is one
    * @param adjustedIntervalPattern  adjusted interval pattern
    */
   U_I18N_API static void adjustFieldWidth(const UnicodeString& inputSkeleton,
                                           const UnicodeString& bestMatchSkeleton,
                                           const UnicodeString& bestMatchIntervalPattern,
                                           int8_t differenceInfo,
                                           UBool suppressDayPeriodField,
                                           UnicodeString& adjustedIntervalPattern);

   /**
    * Does the same thing as UnicodeString::findAndReplace(), except that it won't perform
    * the substitution inside quoted literal text.
    * @param targetString The string to perform the find-replace operation on.
    * @param strToReplace The string to search for and replace in the target string.
    * @param strToReplaceWith The string to substitute in wherever `stringToReplace` was found.
    */
   U_I18N_API static void findReplaceInPattern(UnicodeString& targetString,
                                               const UnicodeString& strToReplace,
                                               const UnicodeString& strToReplaceWith);

   /**
    * 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 datePattern    date pattern
    * @param field          time calendar field: AM_PM, HOUR, MINUTE
    * @param status         output param set to success/failure code on exit
    */
   void concatSingleDate2TimeInterval(UnicodeString& format,
                                      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.
    */
   U_I18N_API static UBool 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
    */
   U_I18N_API static int32_t splitPatternInto2Part(const UnicodeString& intervalPattern);

   /**
    * Break interval patterns as 2 part and save them into pattern info.
    * @param field            calendar field
    * @param intervalPattern  interval pattern
    */
   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
    */
   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
    */
   void setPatternInfo(UCalendarDateFields field,
                       const UnicodeString* firstPart,
                       const UnicodeString* secondPart,
                       UBool laterDateFirst);

   /**
    * Format 2 Calendars to produce a string.
    * Implementation of the similar public format function.
    * Must be called with gFormatterMutex already locked.
    *
    * 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 firstIndex        0 if the first output date is fromCalendar;
    *                          1 if it corresponds to toCalendar;
    *                          -1 if there is only one date printed.
    * @param fphandler         Handler for field position information.
    *                          The fields will be from the UDateFormatField enum.
    * @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.
    */
   UnicodeString& formatImpl(Calendar& fromCalendar,
                             Calendar& toCalendar,
                             UnicodeString& appendTo,
                             int8_t& firstIndex,
                             FieldPositionHandler& fphandler,
                             UErrorCode& status) const ;

   /** Version of formatImpl for DateInterval. */
   UnicodeString& formatIntervalImpl(const DateInterval& dtInterval,
                             UnicodeString& appendTo,
                             int8_t& firstIndex,
                             FieldPositionHandler& fphandler,
                             UErrorCode& status) const;


   // from calendar field to pattern letter
   static const char16_t 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;

   Locale fLocale;

   /**
    * Following are interval information relevant (locale) to this formatter.
    */
   UnicodeString fSkeleton;
   PatternInfo fIntervalPatterns[DateIntervalInfo::kIPI_MAX_INDEX];

   /**
    * Patterns for fallback formatting.
    */
   UnicodeString* fDatePattern;
   UnicodeString* fTimePattern;
   UnicodeString* fDateTimeFormat;

   /**
    * Other formatting information
    */
   UDisplayContext fCapitalizationContext;
};

inline bool
DateIntervalFormat::operator!=(const Format& other) const  {
   return !operator==(other);
}

U_NAMESPACE_END

#endif /* #if !UCONFIG_NO_FORMATTING */

#endif /* U_SHOW_CPLUSPLUS_API */

#endif // _DTITVFMT_H__
//eof