* 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 users 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., paucal 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.
* 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
* used locale. The pattern is a sequence of
* caseKeyword{message} clauses, separated by white
* space characters. Each clause assigns the message message
* to the plural case identified by caseKeyword.
*
* There are 6 predefined casekeyword in 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 the plural
* rules of the PluralFormat object do not contain a plural case
* identified by caseKeyword, U_DEFAULT_KEYWORD_MISSING
* will be set to status.
* 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. If you specify more than one message for the same plural case,
* U_DUPLICATE_KEYWORD will be set to status.
*
* Spaces between caseKeyword and
* message will be ignored; spaces within
* message will be preserved.
*
* The message text for a particular plural case may contain other message
* format patterns. PluralFormat preserves these so that you
* can use the strings produced by PluralFormat with other
* formatters. If you are using PluralFormat inside a
* MessageFormat pattern, MessageFormat will
* automatically evaluate the resulting format pattern.
* Thus, curly braces ({, }) are only allowed
* in message texts to define a nested format pattern.
* The pound sign (#) will be interpreted as the number placeholder
* in the message text, if it is not contained in curly braces (to preserve
* NumberFormat patterns). PluralFormat will
* replace each of those pound signs by the number passed to the
* format() method. It will be formatted using a
* NumberFormat for the PluralFormat's locale. If you
* need special number formatting, you have to explicitly specify a
* NumberFormat for the PluralFormat to use.
*
* \code
* UErrorCode status = U_ZERO_ERROR;
* MessageFormat* msgFmt = new MessageFormat(UnicodeString("{0, plural,
* one{{0, number, C''est #,##0.0# fichier}} other {Ce sont # fichiers}} dans la liste."),
* Locale("fr"), status);
* if (U_FAILURE(status)) {
* return;
* }
* Formattable args1[] = {(int32_t)0};
* Formattable args2[] = {(int32_t)3};
* FieldPosition ignore(FieldPosition::DONT_CARE);
* UnicodeString result;
* msgFmt->format(args1, 1, result, ignore, status);
* cout << result << endl;
* result.remove();
* msgFmt->format(args2, 1, result, ignore, status);
* cout << result << endl;
* \endcode
*
* Produces the output:C'est 0,0 fichier dans la liste.Ce sont 3 fichiers dans la liste.
*
* Note:
* Currently PluralFormat
* does not make use of quotes like MessageFormat.
* If you use plural format strings with MessageFormat and want
* to use a quote sign ', you have to write ''.
* MessageFormat unquotes this pattern and passes the unquoted
* pattern to PluralFormat. It's a bit trickier if you use
* nested formats that do quoting. In the example above, we wanted to insert
* ' in the number format pattern. Since
* NumberFormat supports quotes, we had to insert
* ''. But since MessageFormat unquotes the
* pattern before it gets passed to PluralFormat, we have to
* double these quotes, i.e. write ''''.
*
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 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 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 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);
/**
* 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;
/**
* 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, UErrorCode& status)}.
* @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.
* @stable ICU 4.0
*/
void setLocale(const Locale& locale, UErrorCode& status);
/**
* 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 UBool operator==(const Format& other) const;
/**
* 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 UBool 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 Format* clone(void) const;
/**
* Redeclared Format method.
*
* @param obj The object to be formatted into a string.
* @param appendTo output parameter to receive result.
* Result is appended to existing contents.
* @param pos On input: an alignment field, if desired.
* On output: the offsets of the alignment field.
* @param status output param 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;
/**
* 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; /** * 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; private: typedef enum fmtToken { none, tLetter, tNumber, tSpace, tNumberSign, tLeftBrace, tRightBrace }fmtToken; Locale locale; PluralRules* pluralRules; UnicodeString pattern; Hashtable *fParsedValuesHash; NumberFormat* numberFormat; NumberFormat* replacedNumberFormat; PluralFormat(); // default constructor not implemented void init(const PluralRules* rules, const Locale& curlocale, UErrorCode& status); UBool inRange(UChar ch, fmtToken& type); UBool checkSufficientDefinition(); void parsingFailure(); UnicodeString insertFormattedNumber(double number, UnicodeString& message, UnicodeString& appendTo, FieldPosition& pos) const; void copyHashtable(Hashtable *other, UErrorCode& status); }; U_NAMESPACE_END #endif /* #if !UCONFIG_NO_FORMATTING */ #endif // _PLURFMT //eof