icuSources/i18n/unicode/plurrule.h

   1 /*
   2 *******************************************************************************
   3 * Copyright (C) 2008-2010, International Business Machines Corporation and
   4 * others. All Rights Reserved.
   5 *******************************************************************************
   6 *
   7 *
   8 * File PLURRULE.H
   9 *
  10 * Modification History:*
  11 *   Date        Name        Description
  12 *
  13 ********************************************************************************
  14 */
  15
  16 #ifndef PLURRULE
  17 #define PLURRULE
  18
  19 #include "unicode/utypes.h"
  20
  21 /**
  22  * \file
  23  * \brief C++ API: PluralRules object
  24  */
  25
  26 #if !UCONFIG_NO_FORMATTING
  27
  28 #include "unicode/format.h"
  29
  30 U_NAMESPACE_BEGIN
  31
  32 class Hashtable;
  33 class RuleChain;
  34 class RuleParser;
  35
  36 /**
  37  * Defines rules for mapping positive long values onto a small set of
  38  * keywords. Rules are constructed from a text description, consisting
  39  * of a series of keywords and conditions.  The {@link #select} method
  40  * examines each condition in order and returns the keyword for the
  41  * first condition that matches the number.  If none match,
  42  * default rule(other) is returned.
  43  *
  44  * Examples:<pre>
  45  *   "one: n is 1; few: n in 2..4"</pre>
  46  *  This defines two rules, for 'one' and 'few'.  The condition for
  47  *  'one' is "n is 1" which means that the number must be equal to
  48  *  1 for this condition to pass.  The condition for 'few' is
  49  *  "n in 2..4" which means that the number must be between 2 and
  50  *  4 inclusive for this condition to pass.  All other numbers
  51  *  are assigned the keyword "other" by the default rule.
  52  *  </p><pre>
  53  *    "zero: n is 0; one: n is 1; zero: n mod 100 in 1..19"</pre>
  54  *  This illustrates that the same keyword can be defined multiple times.
  55  *  Each rule is examined in order, and the first keyword whose condition
  56  *  passes is the one returned.  Also notes that a modulus is applied
  57  *  to n in the last rule.  Thus its condition holds for 119, 219, 319...
  58  *  </p><pre>
  59  *    "one: n is 1; few: n mod 10 in 2..4 and n mod 100 not in 12..14"</pre>
  60  *  This illustrates conjunction and negation.  The condition for 'few'
  61  *  has two parts, both of which must be met: "n mod 10 in 2..4" and
  62  *  "n mod 100 not in 12..14".  The first part applies a modulus to n
  63  *  before the test as in the previous example.  The second part applies
  64  *  a different modulus and also uses negation, thus it matches all
  65  *  numbers _not_ in 12, 13, 14, 112, 113, 114, 212, 213, 214...
  66  *  </p>
  67  *  <p>
  68  * Syntax:<pre>
  69  * \code
  70  * rules         = rule (';' rule)*
  71  * rule          = keyword ':' condition
  72  * keyword       = <identifier>
  73  * condition     = and_condition ('or' and_condition)*
  74  * and_condition = relation ('and' relation)*
  75  * relation      = is_relation | in_relation | within_relation | 'n' <EOL>
  76  * is_relation   = expr 'is' ('not')? value
  77  * in_relation   = expr ('not')? 'in' range
  78  * within_relation = expr ('not')? 'within' range
  79  * expr          = 'n' ('mod' value)?
  80  * value         = digit+
  81  * digit         = 0|1|2|3|4|5|6|7|8|9
  82  * range         = value'..'value
  83  * \endcode
  84  * </pre></p>
  85  * <p>
  86  *  The difference between 'in' and 'within' is that 'in' only includes
  87  *  integers in the specified range, while 'within' includes all values.</p>
  88  *  <p>
  89  *  Keywords
  90  *  could be defined by users or from ICU locale data. There are 6
  91  *  predefined values in ICU - 'zero', 'one', 'two', 'few', 'many' and
  92  *  'other'. Callers need to check the value of keyword returned by
  93  *  {@link #select} method.
  94  *  </p>
  95  *
  96  * Examples:<pre>
  97  * UnicodeString keyword = pl->select(number);
  98  * if (keyword== UnicodeString("one") {
  99  *     ...
 100  * }
 101  * else if ( ... )
 102  * </pre>
 103  * <strong>Note:</strong><br>
 104  *  <p>
 105  *   ICU defines plural rules for many locales based on CLDR <i>Language Plural Rules</i>.
 106  *   For these predefined rules, see CLDR page at
 107  *    http://unicode.org/repos/cldr-tmp/trunk/diff/supplemental/language_plural_rules.html
 108  * </p>
 109  */
 110 class U_I18N_API PluralRules : public UObject {
 111 public:
 112
 113     /**
 114      * Constructor.
 115      * @param status  Output param set to success/failure code on exit, which
 116      *                must not indicate a failure before the function call.
 117      *
 118      * @stable ICU 4.0
 119      */
 120     PluralRules(UErrorCode& status);
 121
 122     /**
 123      * Copy constructor.
 124      * @stable ICU 4.0
 125      */
 126     PluralRules(const PluralRules& other);
 127
 128     /**
 129      * Destructor.
 130      * @stable ICU 4.0
 131      */
 132     virtual ~PluralRules();
 133
 134     /**
 135      * Clone
 136      * @stable ICU 4.0
 137      */
 138     PluralRules* clone() const;
 139
 140     /**
 141       * Assignment operator.
 142       * @stable ICU 4.0
 143       */
 144     PluralRules& operator=(const PluralRules&);
 145
 146     /**
 147      * Creates a PluralRules from a description if it is parsable, otherwise
 148      * returns null.
 149      *
 150      * @param description rule description
 151      * @param status      Output param set to success/failure code on exit, which
 152      *                    must not indicate a failure before the function call.
 153      * @return            new PluralRules pointer. NULL if there is an error.
 154      * @stable ICU 4.0
 155      */
 156     static PluralRules* U_EXPORT2 createRules(const UnicodeString& description,
 157                                               UErrorCode& status);
 158
 159     /**
 160      * The default rules that accept any number.
 161      *
 162      * @param status  Output param set to success/failure code on exit, which
 163      *                must not indicate a failure before the function call.
 164      * @return        new PluralRules pointer. NULL if there is an error.
 165      * @stable ICU 4.0
 166      */
 167     static PluralRules* U_EXPORT2 createDefaultRules(UErrorCode& status);
 168
 169     /**
 170      * Provides access to the predefined <code>PluralRules</code> for a given
 171      * locale.
 172      *
 173      * @param locale  The locale for which a <code>PluralRules</code> object is
 174      *                returned.
 175      * @param status  Output param set to success/failure code on exit, which
 176      *                must not indicate a failure before the function call.
 177      * @return        The predefined <code>PluralRules</code> object pointer for
 178      *                this locale. If there's no predefined rules for this locale,
 179      *                the rules for the closest parent in the locale hierarchy
 180      *                that has one will  be returned.  The final fallback always
 181      *                returns the default 'other' rules.
 182      * @stable ICU 4.0
 183      */
 184     static PluralRules* U_EXPORT2 forLocale(const Locale& locale, UErrorCode& status);
 185
 186     /**
 187      * Given a number, returns the keyword of the first rule that applies to
 188      * the number.  This function can be used with isKeyword* functions to
 189      * determine the keyword for default plural rules.
 190      *
 191      * @param number  The number for which the rule has to be determined.
 192      * @return        The keyword of the selected rule.
 193      * @stable ICU 4.0
 194      */
 195     UnicodeString select(int32_t number) const;
 196
 197     /**
 198      * Given a number, returns the keyword of the first rule that applies to
 199      * the number.  This function can be used with isKeyword* functions to
 200      * determine the keyword for default plural rules.
 201      *
 202      * @param number  The number for which the rule has to be determined.
 203      * @return        The keyword of the selected rule.
 204      * @stable ICU 4.0
 205      */
 206     UnicodeString select(double number) const;
 207
 208     /**
 209      * Returns a list of all rule keywords used in this <code>PluralRules</code>
 210      * object.  The rule 'other' is always present by default.
 211      *
 212      * @param status Output param set to success/failure code on exit, which
 213      *               must not indicate a failure before the function call.
 214      * @return       StringEnumeration with the keywords.
 215      *               The caller must delete the object.
 216      * @stable ICU 4.0
 217      */
 218     StringEnumeration* getKeywords(UErrorCode& status) const;
 219
 220     /**
 221      * Returns TRUE if the given keyword is defined in this
 222      * <code>PluralRules</code> object.
 223      *
 224      * @param keyword  the input keyword.
 225      * @return         TRUE if the input keyword is defined.
 226      *                 Otherwise, return FALSE.
 227      * @stable ICU 4.0
 228      */
 229     UBool isKeyword(const UnicodeString& keyword) const;
 230
 231
 232     /**
 233      * Returns keyword for default plural form.
 234      *
 235      * @return         keyword for default plural form.
 236      * @internal 4.0
 237      * @stable ICU 4.0
 238      */
 239     UnicodeString getKeywordOther() const;
 240
 241     /**
 242      * Compares the equality of two PluralRules objects.
 243      *
 244      * @param other The other PluralRules object to be compared with.
 245      * @return      True if the given PluralRules is the same as this
 246      *              PluralRules; false otherwise.
 247      * @stable ICU 4.0
 248      */
 249     virtual UBool operator==(const PluralRules& other) const;
 250
 251     /**
 252      * Compares the inequality of two PluralRules objects.
 253      *
 254      * @param other The PluralRules object to be compared with.
 255      * @return      True if the given PluralRules is not the same as this
 256      *              PluralRules; false otherwise.
 257      * @stable ICU 4.0
 258      */
 259     UBool operator!=(const PluralRules& other) const  {return !operator==(other);}
 260
 261
 262     /**
 263      * ICU "poor man's RTTI", returns a UClassID for this class.
 264      *
 265      * @stable ICU 4.0
 266      *
 267     */
 268     static UClassID U_EXPORT2 getStaticClassID(void);
 269
 270     /**
 271      * ICU "poor man's RTTI", returns a UClassID for the actual class.
 272      *
 273      * @stable ICU 4.0
 274      */
 275     virtual UClassID getDynamicClassID() const;
 276
 277
 278 private:
 279     Hashtable       *fLocaleStringsHash;
 280     UnicodeString   mLocaleName;
 281     RuleChain       *mRules;
 282     RuleParser      *mParser;
 283
 284     PluralRules();   // default constructor not implemented
 285     int32_t getRepeatLimit() const;
 286     void parseDescription(UnicodeString& ruleData, RuleChain& rules, UErrorCode &status);
 287     void getNextLocale(const UnicodeString& localeData, int32_t* curIndex, UnicodeString& localeName);
 288     void addRules(RuleChain& rules);
 289     int32_t getNumberValue(const UnicodeString& token) const;
 290     UnicodeString getRuleFromResource(const Locale& locale, UErrorCode& status);
 291
 292 };
 293
 294 U_NAMESPACE_END
 295
 296 #endif /* #if !UCONFIG_NO_FORMATTING */
 297
 298 #endif // _PLURRULE
 299 //eof