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 // © 2016 and later: Unicode, Inc. and others.
 // License & terms of use: http://www.unicode.org/copyright.html
 /*
 *******************************************************************************
 * Copyright (C) 2007-2014, International Business Machines Corporation and
 * others. All Rights Reserved.
 *******************************************************************************
 *
 
 * File PLURFMT.H
 ********************************************************************************
 */
 
 #ifndef PLURFMT
 #define PLURFMT
 
 #include "unicode/utypes.h"
 
 #if U_SHOW_CPLUSPLUS_API
 
 /**
  * \file
  * \brief C++ API: PluralFormat object
  */
 
 #if !UCONFIG_NO_FORMATTING
 
 #include "unicode/messagepattern.h"
 #include "unicode/numfmt.h"
 #include "unicode/plurrule.h"
 
 U_NAMESPACE_BEGIN
 
 class Hashtable;
 class NFRule;
 
 /**
  * <p>
  * <code>PluralFormat</code> supports the creation of internationalized
  * messages with plural inflection. It is based on <i>plural
  * selection</i>, i.e. the caller specifies messages for each
  * plural case that can appear in the user's language and the
  * <code>PluralFormat</code> selects the appropriate message based on
  * the number.
  * </p>
  * <h4>The Problem of Plural Forms in Internationalized Messages</h4>
  * <p>
  * Different languages have different ways to inflect
  * plurals. Creating internationalized messages that include plural
  * forms is only feasible when the framework is able to handle plural
  * forms of <i>all</i> languages correctly. <code>ChoiceFormat</code>
  * doesn't handle this well, because it attaches a number interval to
  * each message and selects the message whose interval contains a
  * given number. This can only handle a finite number of
  * intervals. But in some languages, like Polish, one plural case
  * applies to infinitely many intervals (e.g., the plural case applies to
  * numbers ending with 2, 3, or 4 except those ending with 12, 13, or
  * 14). Thus <code>ChoiceFormat</code> is not adequate.
  * </p><p>
  * <code>PluralFormat</code> deals with this by breaking the problem
  * into two parts:
  * <ul>
  * <li>It uses <code>PluralRules</code> that can define more complex
  *     conditions for a plural case than just a single interval. These plural
  *     rules define both what plural cases exist in a language, and to
  *     which numbers these cases apply.
  * <li>It provides predefined plural rules for many languages. Thus, the programmer
  *     need not worry about the plural cases of a language and
  *     does not have to define the plural cases; they can simply
  *     use the predefined keywords. The whole plural formatting of messages can
  *     be done using localized patterns from resource bundles. For predefined plural
  *     rules, see the CLDR <i>Language Plural Rules</i> page at
  *     https://unicode-org.github.io/cldr-staging/charts/latest/supplemental/language_plural_rules.html
  * </ul>
  * </p>
  * <h4>Usage of <code>PluralFormat</code></h4>
  * <p>Note: Typically, plural formatting is done via <code>MessageFormat</code>
  * with a <code>plural</code> argument type,
  * rather than using a stand-alone <code>PluralFormat</code>.
  * </p><p>
  * This discussion assumes that you use <code>PluralFormat</code> with
  * a predefined set of plural rules. You can create one using one of
  * the constructors that takes a <code>locale</code> object. To
  * specify the message pattern, you can either pass it to the
  * constructor or set it explicitly using the
  * <code>applyPattern()</code> method. The <code>format()</code>
  * method takes a number object and selects the message of the
  * matching plural case. This message will be returned.
  * </p>
  * <h5>Patterns and Their Interpretation</h5>
  * <p>
  * The pattern text defines the message output for each plural case of the
  * specified locale. Syntax:
  * <pre>
  * pluralStyle = [offsetValue] (selector '{' message '}')+
  * offsetValue = "offset:" number
  * selector = explicitValue | keyword
  * explicitValue = '=' number  // adjacent, no white space in between
  * keyword = [^[[:Pattern_Syntax:][:Pattern_White_Space:]]]+
  * message: see {@link MessageFormat}
  * </pre>
  * Pattern_White_Space between syntax elements is ignored, except
  * between the {curly braces} and their sub-message,
  * and between the '=' and the number of an explicitValue.
  *
  * </p><p>
  * There are 6 predefined casekeyword in CLDR/ICU - 'zero', 'one', 'two', 'few', 'many' and
  * 'other'. You always have to define a message text for the default plural case
  * <code>other</code> which is contained in every rule set.
  * If you do not specify a message text for a particular plural case, the
  * message text of the plural case <code>other</code> gets assigned to this
  * plural case.
  * </p><p>
  * When formatting, the input number is first matched against the explicitValue clauses.
  * If there is no exact-number match, then a keyword is selected by calling
  * the <code>PluralRules</code> with the input number <em>minus the offset</em>.
  * (The offset defaults to 0 if it is omitted from the pattern string.)
  * If there is no clause with that keyword, then the "other" clauses is returned.
  * </p><p>
  * An unquoted pound sign (<code>#</code>) in the selected sub-message
  * itself (i.e., outside of arguments nested in the sub-message)
  * is replaced by the input number minus the offset.
  * The number-minus-offset value is formatted using a
  * <code>NumberFormat</code> for the <code>PluralFormat</code>'s locale. If you
  * need special number formatting, you have to use a <code>MessageFormat</code>
  * and explicitly specify a <code>NumberFormat</code> argument.
  * <strong>Note:</strong> That argument is formatting without subtracting the offset!
  * If you need a custom format and have a non-zero offset, then you need to pass the
  * number-minus-offset value as a separate parameter.
  * </p>
  * For a usage example, see the {@link MessageFormat} class documentation.
  *
  * <h4>Defining Custom Plural Rules</h4>
  * <p>If you need to use <code>PluralFormat</code> with custom rules, you can
  * create a <code>PluralRules</code> object and pass it to
  * <code>PluralFormat</code>'s constructor. If you also specify a locale in this
  * constructor, this locale will be used to format the number in the message
  * texts.
  * </p><p>
  * For more information about <code>PluralRules</code>, see
  * {@link PluralRules}.
  * </p>
  *
  * ported from Java
  * @stable ICU 4.0
  */
 
 class U_I18N_API PluralFormat : public Format {
 public:
 
     /**
      * Creates a new cardinal-number <code>PluralFormat</code> for the default locale.
      * This locale will be used to get the set of plural rules and for standard
      * number formatting.
      * @param status  output param set to success/failure code on exit, which
      *                must not indicate a failure before the function call.
      * @stable ICU 4.0
      */
     PluralFormat(UErrorCode& status);
 
     /**
      * Creates a new cardinal-number <code>PluralFormat</code> for a given locale.
      * @param locale the <code>PluralFormat</code> will be configured with
      *               rules for this locale. This locale will also be used for
      *               standard number formatting.
      * @param status output param set to success/failure code on exit, which
      *               must not indicate a failure before the function call.
      * @stable ICU 4.0
      */
     PluralFormat(const Locale& locale, UErrorCode& status);
 
     /**
      * Creates a new <code>PluralFormat</code> for a given set of rules.
      * The standard number formatting will be done using the default locale.
      * @param rules   defines the behavior of the <code>PluralFormat</code>
      *                object.
      * @param status  output param set to success/failure code on exit, which
      *                must not indicate a failure before the function call.
      * @stable ICU 4.0
      */
     PluralFormat(const PluralRules& rules, UErrorCode& status);
 
     /**
      * Creates a new <code>PluralFormat</code> for a given set of rules.
      * The standard number formatting will be done using the given locale.
      * @param locale  the default number formatting will be done using this
      *                locale.
      * @param rules   defines the behavior of the <code>PluralFormat</code>
      *                object.
      * @param status  output param set to success/failure code on exit, which
      *                must not indicate a failure before the function call.
      * @stable ICU 4.0
      */
     PluralFormat(const Locale& locale, const PluralRules& rules, UErrorCode& status);
 
     /**
      * Creates a new <code>PluralFormat</code> for the plural type.
      * The standard number formatting will be done using the given locale.
      * @param locale  the default number formatting will be done using this
      *                locale.
      * @param type    The plural type (e.g., cardinal or ordinal).
      * @param status  output param set to success/failure code on exit, which
      *                must not indicate a failure before the function call.
      * @stable ICU 50
      */
     PluralFormat(const Locale& locale, UPluralType type, UErrorCode& status);
 
     /**
      * Creates a new cardinal-number <code>PluralFormat</code> for a given pattern string.
      * The default locale will be used to get the set of plural rules and for
      * standard number formatting.
      * @param  pattern the pattern for this <code>PluralFormat</code>.
      *                 errors are returned to status if the pattern is invalid.
      * @param status   output param set to success/failure code on exit, which
      *                 must not indicate a failure before the function call.
      * @stable ICU 4.0
      */
     PluralFormat(const UnicodeString& pattern, UErrorCode& status);
 
     /**
      * Creates a new cardinal-number <code>PluralFormat</code> for a given pattern string and
      * locale.
      * The locale will be used to get the set of plural rules and for
      * standard number formatting.
      * @param locale   the <code>PluralFormat</code> will be configured with
      *                 rules for this locale. This locale will also be used for
      *                 standard number formatting.
      * @param pattern  the pattern for this <code>PluralFormat</code>.
      *                 errors are returned to status if the pattern is invalid.
      * @param status   output param set to success/failure code on exit, which
      *                 must not indicate a failure before the function call.
      * @stable ICU 4.0
      */
     PluralFormat(const Locale& locale, const UnicodeString& pattern, UErrorCode& status);
 
     /**
      * Creates a new <code>PluralFormat</code> for a given set of rules, a
      * pattern and a locale.
      * @param rules    defines the behavior of the <code>PluralFormat</code>
      *                 object.
      * @param pattern  the pattern for this <code>PluralFormat</code>.
      *                 errors are returned to status if the pattern is invalid.
      * @param status   output param set to success/failure code on exit, which
      *                 must not indicate a failure before the function call.
      * @stable ICU 4.0
      */
     PluralFormat(const PluralRules& rules,
                  const UnicodeString& pattern,
                  UErrorCode& status);
 
     /**
      * Creates a new <code>PluralFormat</code> for a given set of rules, a
      * pattern and a locale.
      * @param locale  the <code>PluralFormat</code> will be configured with
      *                rules for this locale. This locale will also be used for
      *                standard number formatting.
      * @param rules   defines the behavior of the <code>PluralFormat</code>
      *                object.
      * @param pattern the pattern for this <code>PluralFormat</code>.
      *                errors are returned to status if the pattern is invalid.
      * @param status  output param set to success/failure code on exit, which
      *                must not indicate a failure before the function call.
      * @stable ICU 4.0
      */
     PluralFormat(const Locale& locale,
                  const PluralRules& rules,
                  const UnicodeString& pattern,
                  UErrorCode& status);
 
     /**
      * Creates a new <code>PluralFormat</code> for a plural type, a
      * pattern and a locale.
      * @param locale  the <code>PluralFormat</code> will be configured with
      *                rules for this locale. This locale will also be used for
      *                standard number formatting.
      * @param type    The plural type (e.g., cardinal or ordinal).
      * @param pattern the pattern for this <code>PluralFormat</code>.
      *                errors are returned to status if the pattern is invalid.
      * @param status  output param set to success/failure code on exit, which
      *                must not indicate a failure before the function call.
      * @stable ICU 50
      */
     PluralFormat(const Locale& locale,
                  UPluralType type,
                  const UnicodeString& pattern,
                  UErrorCode& status);
 
     /**
       * copy constructor.
       * @stable ICU 4.0
       */
     PluralFormat(const PluralFormat& other);
 
     /**
      * Destructor.
      * @stable ICU 4.0
      */
     virtual ~PluralFormat();
 
     /**
      * Sets the pattern used by this plural format.
      * The method parses the pattern and creates a map of format strings
      * for the plural rules.
      * Patterns and their interpretation are specified in the class description.
      *
      * @param pattern the pattern for this plural format
      *                errors are returned to status if the pattern is invalid.
      * @param status  output param set to success/failure code on exit, which
      *                must not indicate a failure before the function call.
      * @stable ICU 4.0
      */
     void applyPattern(const UnicodeString& pattern, UErrorCode& status);
 
 
     using Format::format;
 
     /**
      * Formats a plural message for a given number.
      *
      * @param number  a number for which the plural message should be formatted
      *                for. If no pattern has been applied to this
      *                <code>PluralFormat</code> object yet, the formatted number
      *                will be returned.
      * @param status  output param set to success/failure code on exit, which
      *                must not indicate a failure before the function call.
      * @return        the string containing the formatted plural message.
      * @stable ICU 4.0
      */
     UnicodeString format(int32_t number, UErrorCode& status) const;
 
     /**
      * Formats a plural message for a given number.
      *
      * @param number  a number for which the plural message should be formatted
      *                for. If no pattern has been applied to this
      *                PluralFormat object yet, the formatted number
      *                will be returned.
      * @param status  output param set to success or failure code on exit, which
      *                must not indicate a failure before the function call.
      * @return        the string containing the formatted plural message.
      * @stable ICU 4.0
      */
     UnicodeString format(double number, UErrorCode& status) const;
 
     /**
      * Formats a plural message for a given number.
      *
      * @param number   a number for which the plural message should be formatted
      *                 for. If no pattern has been applied to this
      *                 <code>PluralFormat</code> object yet, the formatted number
      *                 will be returned.
      * @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, which
      *                 must not indicate a failure before the function call.
      * @return         the string containing the formatted plural message.
      * @stable ICU 4.0
      */
     UnicodeString& format(int32_t number,
                           UnicodeString& appendTo,
                           FieldPosition& pos,
                           UErrorCode& status) const;
 
     /**
      * Formats a plural message for a given number.
      *
      * @param number   a number for which the plural message should be formatted
      *                 for. If no pattern has been applied to this
      *                 PluralFormat object yet, the formatted number
      *                 will be returned.
      * @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, which
      *                 must not indicate a failure before the function call.
      * @return         the string containing the formatted plural message.
      * @stable ICU 4.0
      */
     UnicodeString& format(double number,
                           UnicodeString& appendTo,
                           FieldPosition& pos,
                           UErrorCode& status) const;
 
 #ifndef U_HIDE_DEPRECATED_API 
     /**
      * Sets the locale used by this <code>PluraFormat</code> object.
      * Note: Calling this method resets this <code>PluraFormat</code> object,
      *     i.e., a pattern that was applied previously will be removed,
      *     and the NumberFormat is set to the default number format for
      *     the locale.  The resulting format behaves the same as one
      *     constructed from {@link #PluralFormat(const Locale& locale, UPluralType type, UErrorCode& status)}
      *     with UPLURAL_TYPE_CARDINAL.
      * @param locale  the <code>locale</code> to use to configure the formatter.
      * @param status  output param set to success/failure code on exit, which
      *                must not indicate a failure before the function call.
      * @deprecated ICU 50 This method clears the pattern and might create
      *             a different kind of PluralRules instance;
      *             use one of the constructors to create a new instance instead.
      */
     void setLocale(const Locale& locale, UErrorCode& status);
 #endif  /* U_HIDE_DEPRECATED_API */
 
     /**
       * Sets the number format used by this formatter.  You only need to
       * call this if you want a different number format than the default
       * formatter for the locale.
       * @param format  the number format to use.
       * @param status  output param set to success/failure code on exit, which
       *                must not indicate a failure before the function call.
       * @stable ICU 4.0
       */
     void setNumberFormat(const NumberFormat* format, UErrorCode& status);
 
     /**
        * Assignment operator
        *
        * @param other    the PluralFormat object to copy from.
        * @stable ICU 4.0
        */
     PluralFormat& operator=(const PluralFormat& other);
 
     /**
       * Return true if another object is semantically equal to this one.
       *
       * @param other    the PluralFormat object to be compared with.
       * @return         true if other is semantically equal to this.
       * @stable ICU 4.0
       */
     virtual bool operator==(const Format& other) const override;
 
     /**
      * Return true if another object is semantically unequal to this one.
      *
      * @param other    the PluralFormat object to be compared with.
      * @return         true if other is semantically unequal to this.
      * @stable ICU 4.0
      */
     virtual bool operator!=(const Format& other) const;
 
     /**
      * Clones this Format object polymorphically.  The caller owns the
      * result and should delete it when done.
      * @stable ICU 4.0
      */
     virtual PluralFormat* clone() const override;
 
    /**
     * Formats a plural message for a number taken from a Formattable object.
     *
     * @param obj       The object containing a number for which the 
     *                  plural message should be formatted.
     *                  The object must be of a numeric type.
     * @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 filled with success/failure status.
     * @return          Reference to 'appendTo' parameter.
     * @stable ICU 4.0
     */
    UnicodeString& format(const Formattable& obj,
                          UnicodeString& appendTo,
                          FieldPosition& pos,
                          UErrorCode& status) const override;
 
    /**
     * Returns the pattern from applyPattern() or constructor().
     *
     * @param  appendTo  output parameter to receive result.
      *                  Result is appended to existing contents.
     * @return the UnicodeString with inserted pattern.
     * @stable ICU 4.0
     */
    UnicodeString& toPattern(UnicodeString& appendTo);
 
    /**
     * This method is not yet supported by <code>PluralFormat</code>.
     * <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. Upon return
     *                  this param is set to the position after the
     *                  last character successfully parsed. If the
     *                  source is not parsed successfully, this param
     *                  will remain unchanged.
     * @stable ICU 4.0
     */
    virtual void parseObject(const UnicodeString& source,
                             Formattable& result,
                             ParsePosition& parse_pos) const override;
 
     /**
      * ICU "poor man's RTTI", returns a UClassID for this class.
      *
      * @stable ICU 4.0
      *
      */
     static UClassID U_EXPORT2 getStaticClassID();
 
     /**
      * ICU "poor man's RTTI", returns a UClassID for the actual class.
      *
      * @stable ICU 4.0
      */
      virtual UClassID getDynamicClassID() const override;
 
 private:
      /**
       * @internal (private)
       */
     class U_I18N_API PluralSelector : public UMemory {
       public:
         virtual ~PluralSelector();
         /**
          * Given a number, returns the appropriate PluralFormat keyword.
          *
          * @param context worker object for the selector.
          * @param number The number to be plural-formatted.
          * @param ec Error code.
          * @return The selected PluralFormat keyword.
          * @internal (private)
          */
         virtual UnicodeString select(void *context, double number, UErrorCode& ec) const = 0;
     };
 
     class U_I18N_API PluralSelectorAdapter : public PluralSelector {
       public:
         PluralSelectorAdapter() : pluralRules(nullptr) {
         }
 
         virtual ~PluralSelectorAdapter();
 
         virtual UnicodeString select(void *context, double number, UErrorCode& /*ec*/) const override;
 
         void reset();
 
         PluralRules* pluralRules;
     };
 
     Locale  locale;
     MessagePattern msgPattern;
     NumberFormat*  numberFormat;
     double offset;
     PluralSelectorAdapter pluralRulesWrapper;
 
     PluralFormat() = delete;   // default constructor not implemented
     void init(const PluralRules* rules, UPluralType type, UErrorCode& status);
     /**
      * Copies dynamically allocated values (pointer fields).
      * Others are copied using their copy constructors and assignment operators.
      */
     void copyObjects(const PluralFormat& other);
 
     UnicodeString& format(const Formattable& numberObject, double number,
                           UnicodeString& appendTo,
                           FieldPosition& pos,
                           UErrorCode& status) const;
 
     /**
      * Finds the PluralFormat sub-message for the given number, or the "other" sub-message.
      * @param pattern A MessagePattern.
      * @param partIndex the index of the first PluralFormat argument style part.
      * @param selector the PluralSelector for mapping the number (minus offset) to a keyword.
      * @param context worker object for the selector.
      * @param number a number to be matched to one of the PluralFormat argument's explicit values,
      *        or mapped via the PluralSelector.
      * @param ec ICU error code.
      * @return the sub-message start part index.
      */
     static int32_t findSubMessage(
          const MessagePattern& pattern, int32_t partIndex,
          const PluralSelector& selector, void *context, double number, UErrorCode& ec);
 
     void parseType(const UnicodeString& source, const NFRule *rbnfLenientScanner,
         Formattable& result, FieldPosition& pos) const;
 
     friend class MessageFormat;
     friend class NFRule;
 };
 
 U_NAMESPACE_END
 
 #endif /* #if !UCONFIG_NO_FORMATTING */
 
 #endif /* U_SHOW_CPLUSPLUS_API */
 
 #endif // _PLURFMT
 //eof

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