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*******************************************************************************
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* Copyright (C) 2007-2010, International Business Machines Corporation and
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* others. All Rights Reserved.
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*******************************************************************************
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* Modification History:*
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* Date Name Description
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********************************************************************************
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#include "unicode/utypes.h"
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* \brief C++ API: PluralFormat object
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#if !UCONFIG_NO_FORMATTING
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#include "unicode/numfmt.h"
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#include "unicode/plurrule.h"
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* <code>PluralFormat</code> supports the creation of internationalized
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* messages with plural inflection. It is based on <i>plural
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* selection</i>, i.e. the caller specifies messages for each
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* plural case that can appear in the users language and the
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* <code>PluralFormat</code> selects the appropriate message based on
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* <h4>The Problem of Plural Forms in Internationalized Messages</h4>
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* Different languages have different ways to inflect
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* plurals. Creating internationalized messages that include plural
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* forms is only feasible when the framework is able to handle plural
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* forms of <i>all</i> languages correctly. <code>ChoiceFormat</code>
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* doesn't handle this well, because it attaches a number interval to
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* each message and selects the message whose interval contains a
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* given number. This can only handle a finite number of
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* intervals. But in some languages, like Polish, one plural case
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* applies to infinitely many intervals (e.g., paucal applies to
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* numbers ending with 2, 3, or 4 except those ending with 12, 13, or
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* 14). Thus <code>ChoiceFormat</code> is not adequate.
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* <code>PluralFormat</code> deals with this by breaking the problem
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* <li>It uses <code>PluralRules</code> that can define more complex
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* conditions for a plural case than just a single interval. These plural
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* rules define both what plural cases exist in a language, and to
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* which numbers these cases apply.
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* <li>It provides predefined plural rules for many locales. Thus, the programmer
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* need not worry about the plural cases of a language. On the flip side,
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* the localizer does not have to specify the plural cases; he can simply
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* use the predefined keywords. The whole plural formatting of messages can
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* be done using localized patterns from resource bundles. For predefined plural
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* rules, see CLDR <i>Language Plural Rules</i> page at
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* http://unicode.org/repos/cldr-tmp/trunk/diff/supplemental/language_plural_rules.html
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* <h4>Usage of <code>PluralFormat</code></h4>
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* This discussion assumes that you use <code>PluralFormat</code> with
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* a predefined set of plural rules. You can create one using one of
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* the constructors that takes a <code>locale</code> object. To
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* specify the message pattern, you can either pass it to the
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* constructor or set it explicitly using the
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* <code>applyPattern()</code> method. The <code>format()</code>
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* method takes a number object and selects the message of the
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* matching plural case. This message will be returned.
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* <h5>Patterns and Their Interpretation</h5>
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* The pattern text defines the message output for each plural case of the
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* used locale. The pattern is a sequence of
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* <code><i>caseKeyword</i>{<i>message</i>}</code> clauses, separated by white
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* space characters. Each clause assigns the message <code><i>message</i></code>
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* to the plural case identified by <code><i>caseKeyword</i></code>.
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* There are 6 predefined casekeyword in ICU - 'zero', 'one', 'two', 'few', 'many' and
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* 'other'. You always have to define a message text for the default plural case
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* "<code>other</code>" which is contained in every rule set. If the plural
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* rules of the <code>PluralFormat</code> object do not contain a plural case
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* identified by <code><i>caseKeyword</i></code>, U_DEFAULT_KEYWORD_MISSING
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* will be set to status.
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* If you do not specify a message text for a particular plural case, the
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* message text of the plural case "<code>other</code>" gets assigned to this
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* plural case. If you specify more than one message for the same plural case,
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* U_DUPLICATE_KEYWORD will be set to status.
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* Spaces between <code><i>caseKeyword</i></code> and
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* <code><i>message</i></code> will be ignored; spaces within
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* <code><i>message</i></code> will be preserved.
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* The message text for a particular plural case may contain other message
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* format patterns. <code>PluralFormat</code> preserves these so that you
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* can use the strings produced by <code>PluralFormat</code> with other
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* formatters. If you are using <code>PluralFormat</code> inside a
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* <code>MessageFormat</code> pattern, <code>MessageFormat</code> will
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* automatically evaluate the resulting format pattern.<br>
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* Thus, curly braces (<code>{</code>, <code>}</code>) are <i>only</i> allowed
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* in message texts to define a nested format pattern.<br>
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* The pound sign (<code>#</code>) will be interpreted as the number placeholder
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* in the message text, if it is not contained in curly braces (to preserve
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* <code>NumberFormat</code> patterns). <code>PluralFormat</code> will
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* replace each of those pound signs by the number passed to the
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* <code>format()</code> method. It will be formatted using a
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* <code>NumberFormat</code> for the <code>PluralFormat</code>'s locale. If you
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* need special number formatting, you have to explicitly specify a
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* <code>NumberFormat</code> for the <code>PluralFormat</code> to use.
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* UErrorCode status = U_ZERO_ERROR;
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* MessageFormat* msgFmt = new MessageFormat(UnicodeString("{0, plural,
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* one{{0, number, C''est #,##0.0# fichier}} other {Ce sont # fichiers}} dans la liste."),
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* Locale("fr"), status);
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* if (U_FAILURE(status)) {
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* Formattable args1[] = {(int32_t)0};
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* Formattable args2[] = {(int32_t)3};
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* FieldPosition ignore(FieldPosition::DONT_CARE);
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* UnicodeString result;
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* msgFmt->format(args1, 1, result, ignore, status);
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* cout << result << endl;
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* msgFmt->format(args2, 1, result, ignore, status);
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* cout << result << endl;
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* Produces the output:<br>
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* <code>C'est 0,0 fichier dans la liste.</code><br>
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* <code>Ce sont 3 fichiers dans la liste.</code>
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* <strong>Note:</strong><br>
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* Currently <code>PluralFormat</code>
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* does not make use of quotes like <code>MessageFormat</code>.
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* If you use plural format strings with <code>MessageFormat</code> and want
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* to use a quote sign <code>'</code>, you have to write <code>''</code>.
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* <code>MessageFormat</code> unquotes this pattern and passes the unquoted
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* pattern to <code>PluralFormat</code>. It's a bit trickier if you use
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* nested formats that do quoting. In the example above, we wanted to insert
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* <code>'</code> in the number format pattern. Since
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* <code>NumberFormat</code> supports quotes, we had to insert
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* <code>''</code>. But since <code>MessageFormat</code> unquotes the
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* pattern before it gets passed to <code>PluralFormat</code>, we have to
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* double these quotes, i.e. write <code>''''</code>.
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* <h4>Defining Custom Plural Rules</h4>
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* <p>If you need to use <code>PluralFormat</code> with custom rules, you can
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* create a <code>PluralRules</code> object and pass it to
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* <code>PluralFormat</code>'s constructor. If you also specify a locale in this
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* constructor, this locale will be used to format the number in the message
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* For more information about <code>PluralRules</code>, see
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* {@link PluralRules}.
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class U_I18N_API PluralFormat : public Format {
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* Creates a new <code>PluralFormat</code> for the default locale.
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* This locale will be used to get the set of plural rules and for standard
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* @param status output param set to success/failure code on exit, which
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* must not indicate a failure before the function call.
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PluralFormat(UErrorCode& status);
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* Creates a new <code>PluralFormat</code> for a given locale.
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* @param locale the <code>PluralFormat</code> will be configured with
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* rules for this locale. This locale will also be used for
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* standard number formatting.
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* @param status output param set to success/failure code on exit, which
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* must not indicate a failure before the function call.
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PluralFormat(const Locale& locale, UErrorCode& status);
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* Creates a new <code>PluralFormat</code> for a given set of rules.
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* The standard number formatting will be done using the default locale.
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* @param rules defines the behavior of the <code>PluralFormat</code>
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* @param status output param set to success/failure code on exit, which
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* must not indicate a failure before the function call.
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PluralFormat(const PluralRules& rules, UErrorCode& status);
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* Creates a new <code>PluralFormat</code> for a given set of rules.
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* The standard number formatting will be done using the given locale.
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* @param locale the default number formatting will be done using this
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* @param rules defines the behavior of the <code>PluralFormat</code>
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* @param status output param set to success/failure code on exit, which
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* must not indicate a failure before the function call.
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PluralFormat(const Locale& locale, const PluralRules& rules, UErrorCode& status);
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* Creates a new <code>PluralFormat</code> for a given pattern string.
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* The default locale will be used to get the set of plural rules and for
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* standard number formatting.
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* @param pattern the pattern for this <code>PluralFormat</code>.
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* errors are returned to status if the pattern is invalid.
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* @param status output param set to success/failure code on exit, which
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* must not indicate a failure before the function call.
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PluralFormat(const UnicodeString& pattern, UErrorCode& status);
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* Creates a new <code>PluralFormat</code> for a given pattern string and
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* The locale will be used to get the set of plural rules and for
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* standard number formatting.
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* @param locale the <code>PluralFormat</code> will be configured with
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* rules for this locale. This locale will also be used for
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* standard number formatting.
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* @param pattern the pattern for this <code>PluralFormat</code>.
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* errors are returned to status if the pattern is invalid.
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* @param status output param set to success/failure code on exit, which
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* must not indicate a failure before the function call.
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PluralFormat(const Locale& locale, const UnicodeString& pattern, UErrorCode& status);
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* Creates a new <code>PluralFormat</code> for a given set of rules, a
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* pattern and a locale.
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* @param rules defines the behavior of the <code>PluralFormat</code>
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* @param pattern the pattern for this <code>PluralFormat</code>.
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* errors are returned to status if the pattern is invalid.
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* @param status output param set to success/failure code on exit, which
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* must not indicate a failure before the function call.
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PluralFormat(const PluralRules& rules,
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const UnicodeString& pattern,
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* Creates a new <code>PluralFormat</code> for a given set of rules, a
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* pattern and a locale.
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* @param locale the <code>PluralFormat</code> will be configured with
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* rules for this locale. This locale will also be used for
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* standard number formatting.
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* @param rules defines the behavior of the <code>PluralFormat</code>
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* @param pattern the pattern for this <code>PluralFormat</code>.
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* errors are returned to status if the pattern is invalid.
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* @param status output param set to success/failure code on exit, which
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* must not indicate a failure before the function call.
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PluralFormat(const Locale& locale,
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const PluralRules& rules,
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const UnicodeString& pattern,
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PluralFormat(const PluralFormat& other);
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virtual ~PluralFormat();
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* Sets the pattern used by this plural format.
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* The method parses the pattern and creates a map of format strings
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* for the plural rules.
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* Patterns and their interpretation are specified in the class description.
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* @param pattern the pattern for this plural format
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* errors are returned to status if the pattern is invalid.
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* @param status output param set to success/failure code on exit, which
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* must not indicate a failure before the function call.
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void applyPattern(const UnicodeString& pattern, UErrorCode& status);
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using Format::format;
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* Formats a plural message for a given number.
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* @param number a number for which the plural message should be formatted
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* for. If no pattern has been applied to this
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* <code>PluralFormat</code> object yet, the formatted number
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* @param status output param set to success/failure code on exit, which
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* must not indicate a failure before the function call.
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* @return the string containing the formatted plural message.
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UnicodeString format(int32_t number, UErrorCode& status) const;
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* Formats a plural message for a given number.
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* @param number a number for which the plural message should be formatted
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* for. If no pattern has been applied to this
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* PluralFormat object yet, the formatted number
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* @param status output param set to success or failure code on exit, which
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* must not indicate a failure before the function call.
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* @return the string containing the formatted plural message.
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UnicodeString format(double number, UErrorCode& status) const;
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* Formats a plural message for a given number.
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* @param number a number for which the plural message should be formatted
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* for. If no pattern has been applied to this
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* <code>PluralFormat</code> object yet, the formatted number
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* @param appendTo output parameter to receive result.
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* result is appended to existing contents.
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* @param pos On input: an alignment field, if desired.
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* On output: the offsets of the alignment field.
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* @param status output param set to success/failure code on exit, which
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* must not indicate a failure before the function call.
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* @return the string containing the formatted plural message.
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UnicodeString& format(int32_t number,
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UnicodeString& appendTo,
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UErrorCode& status) const;
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* Formats a plural message for a given number.
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* @param number a number for which the plural message should be formatted
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* for. If no pattern has been applied to this
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* PluralFormat object yet, the formatted number
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* @param appendTo output parameter to receive result.
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* result is appended to existing contents.
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* @param pos On input: an alignment field, if desired.
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* On output: the offsets of the alignment field.
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* @param status output param set to success/failure code on exit, which
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* must not indicate a failure before the function call.
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* @return the string containing the formatted plural message.
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UnicodeString& format(double number,
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UnicodeString& appendTo,
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UErrorCode& status) const;
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* Sets the locale used by this <code>PluraFormat</code> object.
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* Note: Calling this method resets this <code>PluraFormat</code> object,
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* i.e., a pattern that was applied previously will be removed,
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* and the NumberFormat is set to the default number format for
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* the locale. The resulting format behaves the same as one
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* constructed from {@link #PluralFormat(const Locale& locale, UErrorCode& status)}.
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* @param locale the <code>locale</code> to use to configure the formatter.
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* @param status output param set to success/failure code on exit, which
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* must not indicate a failure before the function call.
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void setLocale(const Locale& locale, UErrorCode& status);
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* Sets the number format used by this formatter. You only need to
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* call this if you want a different number format than the default
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* formatter for the locale.
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* @param format the number format to use.
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* @param status output param set to success/failure code on exit, which
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* must not indicate a failure before the function call.
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void setNumberFormat(const NumberFormat* format, UErrorCode& status);
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* Assignment operator
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* @param other the PluralFormat object to copy from.
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PluralFormat& operator=(const PluralFormat& other);
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* Return true if another object is semantically equal to this one.
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* @param other the PluralFormat object to be compared with.
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* @return true if other is semantically equal to this.
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virtual UBool operator==(const Format& other) const;
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* Return true if another object is semantically unequal to this one.
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* @param other the PluralFormat object to be compared with.
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* @return true if other is semantically unequal to this.
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virtual UBool operator!=(const Format& other) const;
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* Clones this Format object polymorphically. The caller owns the
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* result and should delete it when done.
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virtual Format* clone(void) const;
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* Redeclared Format method.
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* @param obj The object to be formatted into a string.
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* @param appendTo output parameter to receive result.
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* Result is appended to existing contents.
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* @param pos On input: an alignment field, if desired.
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* On output: the offsets of the alignment field.
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* @param status output param filled with success/failure status.
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* @return Reference to 'appendTo' parameter.
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UnicodeString& format(const Formattable& obj,
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UnicodeString& appendTo,
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UErrorCode& status) const;
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* Returns the pattern from applyPattern() or constructor().
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* @param appendTo output parameter to receive result.
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* Result is appended to existing contents.
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* @return the UnicodeString with inserted pattern.
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UnicodeString& toPattern(UnicodeString& appendTo);
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* This method is not yet supported by <code>PluralFormat</code>.
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* Before calling, set parse_pos.index to the offset you want to start
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* parsing at in the source. After calling, parse_pos.index is the end of
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* the text you parsed. If error occurs, index is unchanged.
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* When parsing, leading whitespace is discarded (with a successful parse),
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* while trailing whitespace is left as is.
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* See Format::parseObject() for more.
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* @param source The string to be parsed into an object.
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* @param result Formattable to be set to the parse result.
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* If parse fails, return contents are undefined.
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* @param parse_pos The position to start parsing at. Upon return
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* this param is set to the position after the
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* last character successfully parsed. If the
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* source is not parsed successfully, this param
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* will remain unchanged.
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virtual void parseObject(const UnicodeString& source,
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ParsePosition& parse_pos) const;
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* ICU "poor man's RTTI", returns a UClassID for this class.
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static UClassID U_EXPORT2 getStaticClassID(void);
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* ICU "poor man's RTTI", returns a UClassID for the actual class.
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virtual UClassID getDynamicClassID() const;
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typedef enum fmtToken {
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PluralRules* pluralRules;
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UnicodeString pattern;
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Hashtable *fParsedValuesHash;
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NumberFormat* numberFormat;
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NumberFormat* replacedNumberFormat;
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PluralFormat(); // default constructor not implemented
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void init(const PluralRules* rules, const Locale& curlocale, UErrorCode& status);
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UBool inRange(UChar ch, fmtToken& type);
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UBool checkSufficientDefinition();
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void parsingFailure();
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UnicodeString insertFormattedNumber(double number,
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UnicodeString& message,
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UnicodeString& appendTo,
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FieldPosition& pos) const;
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void copyHashtable(Hashtable *other, UErrorCode& status);
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#endif /* #if !UCONFIG_NO_FORMATTING */