/usr/include/unicode/plurfmt.h (25847B)
* PluralFormat supports the creation of internationalized
* messages with plural inflection. It is based on plural
* selection, i.e. the caller specifies messages for each
* plural case that can appear in the user's language and the
* PluralFormat selects the appropriate message based on
* the number.
*
* 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 all languages correctly. ChoiceFormat
* 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 ChoiceFormat is not adequate.
*
* PluralFormat deals with this by breaking the problem
* into two parts:
*
PluralRules 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.
* PluralFormatNote: Typically, plural formatting is done via MessageFormat
* with a plural argument type,
* rather than using a stand-alone PluralFormat.
*
* This discussion assumes that you use PluralFormat with
* a predefined set of plural rules. You can create one using one of
* the constructors that takes a locale object. To
* specify the message pattern, you can either pass it to the
* constructor or set it explicitly using the
* applyPattern() method. The format()
* method takes a number object and selects the message of the
* matching plural case. This message will be returned.
*
* The pattern text defines the message output for each plural case of the * specified locale. Syntax: *
* 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}
*
* 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.
*
*
* 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
* other 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 other gets assigned to this
* plural case.
*
* 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 PluralRules with the input number minus the offset.
* (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.
*
* An unquoted pound sign (#) 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
* NumberFormat for the PluralFormat's locale. If you
* need special number formatting, you have to use a MessageFormat
* and explicitly specify a NumberFormat argument.
* Note: 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.
*
If you need to use PluralFormat with custom rules, you can
* create a PluralRules object and pass it to
* PluralFormat's constructor. If you also specify a locale in this
* constructor, this locale will be used to format the number in the message
* texts.
*
* For more information about PluralRules, see
* {@link PluralRules}.
*
PluralFormat 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 PluralFormat for a given locale.
* @param locale the PluralFormat 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 PluralFormat for a given set of rules.
* The standard number formatting will be done using the default locale.
* @param rules defines the behavior of the PluralFormat
* 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 PluralFormat 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 PluralFormat
* 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 PluralFormat 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 PluralFormat 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 PluralFormat.
* 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 PluralFormat 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 PluralFormat will be configured with
* rules for this locale. This locale will also be used for
* standard number formatting.
* @param pattern the pattern for this PluralFormat.
* 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 PluralFormat for a given set of rules, a
* pattern and a locale.
* @param rules defines the behavior of the PluralFormat
* object.
* @param pattern the pattern for this PluralFormat.
* 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 PluralFormat for a given set of rules, a
* pattern and a locale.
* @param locale the PluralFormat 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 PluralFormat
* object.
* @param pattern the pattern for this PluralFormat.
* 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 PluralFormat for a plural type, a
* pattern and a locale.
* @param locale the PluralFormat 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 PluralFormat.
* 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
* PluralFormat 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
* 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(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 PluraFormat object.
* Note: Calling this method resets this PluraFormat 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 locale 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 PluralFormat.
*
* 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. *
* When parsing, leading whitespace is discarded (with a successful parse), * while trailing whitespace is left as is. *
* 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(void); /** * 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(NULL) { } 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(); // 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