Check in the pristine copy of ICU 4.6...

icu46/source/i18n/unicode/plurfmt.h

+/*
+*******************************************************************************
+* Copyright (C) 2007-2010, International Business Machines Corporation and
+* others. All Rights Reserved.
+*******************************************************************************
+*
+
+* File PLURFMT.H
+*
+* Modification History:*
+*   Date        Name        Description
+*
+********************************************************************************
+*/
+
+#ifndef PLURFMT
+#define PLURFMT
+
+#include "unicode/utypes.h"
+
+/**
+ * \file
+ * \brief C++ API: PluralFormat object
+ */
+
+#if !UCONFIG_NO_FORMATTING
+
+#include "unicode/numfmt.h"
+#include "unicode/plurrule.h"
+
+U_NAMESPACE_BEGIN
+
+class Hashtable;
+
+/**
+ * <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 users 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., paucal 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 locales. Thus, the programmer
+ *     need not worry about the plural cases of a language. On the flip side,
+ *     the localizer does not have to specify the plural cases; he 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 CLDR <i>Language Plural Rules</i> page at 
+ *    http://unicode.org/repos/cldr-tmp/trunk/diff/supplemental/language_plural_rules.html
+ * </ul>
+ * </p>
+ * <h4>Usage of <code>PluralFormat</code></h4>
+ * <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
+ * used locale. The pattern is a sequence of
+ * <code><i>caseKeyword</i>{<i>message</i>}</code> clauses, separated by white
+ * space characters. Each clause assigns the message <code><i>message</i></code>
+ * to the plural case identified by <code><i>caseKeyword</i></code>.
+ * </p><p>
+ * 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
+ * "<code>other</code>" which is contained in every rule set. If the plural
+ * rules of the <code>PluralFormat</code> object do not contain a plural case
+ * identified by <code><i>caseKeyword</i></code>, 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 "<code>other</code>" 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.
+ * <br>
+ * Spaces between <code><i>caseKeyword</i></code> and
+ * <code><i>message</i></code>  will be ignored; spaces within
+ * <code><i>message</i></code> will be preserved.
+ * </p><p>
+ * The message text for a particular plural case may contain other message
+ * format patterns. <code>PluralFormat</code> preserves these so that you
+ * can use the strings produced by <code>PluralFormat</code> with other
+ * formatters. If you are using <code>PluralFormat</code> inside a
+ * <code>MessageFormat</code> pattern, <code>MessageFormat</code> will
+ * automatically evaluate the resulting format pattern.<br>
+ * Thus, curly braces (<code>{</code>, <code>}</code>) are <i>only</i> allowed
+ * in message texts to define a nested format pattern.<br>
+ * The pound sign (<code>#</code>) will be interpreted as the number placeholder
+ * in the message text, if it is not contained in curly braces (to preserve
+ * <code>NumberFormat</code> patterns). <code>PluralFormat</code> will
+ * replace each of those pound signs by the number passed to the
+ * <code>format()</code> method. It will be formatted using a
+ * <code>NumberFormat</code> for the <code>PluralFormat</code>'s locale. If you
+ * need special number formatting, you have to explicitly specify a
+ * <code>NumberFormat</code> for the <code>PluralFormat</code> to use.
+ * </p>
+ * Example
+ * <pre>
+ * \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
+ * </pre>
+ * Produces the output:<br>
+ * <code>C'est 0,0 fichier dans la liste.</code><br>
+ * <code>Ce sont 3 fichiers dans la liste.</code>
+ * <p>
+ * <strong>Note:</strong><br>
+ *   Currently <code>PluralFormat</code>
+ *   does not make use of quotes like <code>MessageFormat</code>.
+ *   If you use plural format strings with <code>MessageFormat</code> and want
+ *   to use a quote sign <code>'</code>, you have to write <code>''</code>.
+ *   <code>MessageFormat</code> unquotes this pattern and  passes the unquoted
+ *   pattern to <code>PluralFormat</code>. It's a bit trickier if you use
+ *   nested formats that do quoting. In the example above, we wanted to insert
+ *   <code>'</code> in the number format pattern. Since
+ *   <code>NumberFormat</code> supports quotes, we had to insert
+ *   <code>''</code>. But since <code>MessageFormat</code> unquotes the
+ *   pattern before it gets passed to <code>PluralFormat</code>, we have to
+ *   double these quotes, i.e. write <code>''''</code>.
+ * </p>
+ * <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 <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 <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 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 <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);
+
+    /**
+      * 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;
+
+    /**
+     * 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, UErrorCode& status)}.
+     * @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.
+     * @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 <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;
+
+    /**
+     * 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