icuSources/i18n/unicode/plurrule.h

   1 /*
   2 *******************************************************************************
   3 * Copyright (C) 2008, 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  * rules         = rule (';' rule)*
  70  * rule          = keyword ':' condition
  71  * keyword       = <identifier>
  72  * condition     = and_condition ('or' and_condition)*
  73  * and_condition = relation ('and' relation)*
  74  * relation      = is_relation | in_relation | within_relation | 'n' <EOL>
  75  * is_relation   = expr 'is' ('not')? value
  76  * in_relation   = expr ('not')? 'in' range
  77  * within_relation = expr ('not')? 'within' range
  78  * expr          = 'n' ('mod' value)?
  79  * value         = digit+
  80  * digit         = 0|1|2|3|4|5|6|7|8|9
  81  * range         = value'..'value
  82  * </pre></p>
  83  * <p>
  84  *  The difference between 'in' and 'within' is that 'in' only includes
  85  *  integers in the specified range, while 'within' includes all values.</p>
  86  *  <p>
  87  *  Keywords
  88  *  could be defined by users or from ICU locale data. There are 6
  89  *  predefined values in ICU - 'zero', 'one', 'two', 'few', 'many' and
  90  *  'other'. Callers need to check the value of keyword returned by
  91  *  {@link #select} method.
  92  *  </p>
  93  *
  94  * Examples:<pre>
  95  * UnicodeString keyword = pl->select(number);
  96  * if (keyword== UnicodeString("one") {
  97  *     ...
  98  * }
  99  * else if ( ... )
 100  * </pre>
 101  */
 102 class U_I18N_API PluralRules : public UObject {
 103 public:
 104
 105     /**
 106      * Constructor.
 107      * @param status  Output param set to success/failure code on exit, which
 108      *                must not indicate a failure before the function call.
 109      *
 110      * @draft ICU 4.0
 111      */
 112     PluralRules(UErrorCode& status);
 113
 114     /**
 115      * Copy constructor.
 116      * @draft ICU 4.0
 117      */
 118     PluralRules(const PluralRules& other);
 119
 120     /**
 121      * Destructor.
 122      * @draft ICU 4.0
 123      */
 124     virtual ~PluralRules();
 125
 126     /**
 127      * Clone
 128      * @draft ICU 4.0
 129      */
 130     PluralRules* clone() const;
 131
 132     /**
 133       * Assignment operator.
 134       * @draft ICU 4.0
 135       */
 136     PluralRules& operator=(const PluralRules&);
 137
 138     /**
 139      * Creates a PluralRules from a description if it is parsable, otherwise
 140      * returns null.
 141      *
 142      * @param description rule description
 143      * @param status      Output param set to success/failure code on exit, which
 144      *                    must not indicate a failure before the function call.
 145      * @return            new PluralRules pointer. NULL if there is an error.
 146      * @draft ICU 4.0
 147      */
 148     static PluralRules* U_EXPORT2 createRules(const UnicodeString& description,
 149                                               UErrorCode& status);
 150
 151     /**
 152      * The default rules that accept any number.
 153      *
 154      * @param status  Output param set to success/failure code on exit, which
 155      *                must not indicate a failure before the function call.
 156      * @return        new PluralRules pointer. NULL if there is an error.
 157      * @draft ICU 4.0
 158      */
 159     static PluralRules* U_EXPORT2 createDefaultRules(UErrorCode& status);
 160
 161     /**
 162      * Provides access to the predefined <code>PluralRules</code> for a given
 163      * locale.
 164      *
 165      * @param locale  The locale for which a <code>PluralRules</code> object is
 166      *                returned.
 167      * @param status  Output param set to success/failure code on exit, which
 168      *                must not indicate a failure before the function call.
 169      * @return        The predefined <code>PluralRules</code> object pointer for
 170      *                this locale. If there's no predefined rules for this locale,
 171      *                the rules for the closest parent in the locale hierarchy
 172      *                that has one will  be returned.  The final fallback always
 173      *                returns the default 'other' rules.
 174      * @draft ICU 4.0
 175      */
 176     static PluralRules* U_EXPORT2 forLocale(const Locale& locale, UErrorCode& status);
 177
 178     /**
 179      * Given a number, returns the keyword of the first rule that applies to
 180      * the number.  This function can be used with isKeyword* functions to
 181      * determine the keyword for default plural rules.
 182      *
 183      * @param number  The number for which the rule has to be determined.
 184      * @return        The keyword of the selected rule.
 185      * @draft ICU 4.0
 186      */
 187     UnicodeString select(int32_t number) const;
 188
 189     /**
 190      * Given a number, returns the keyword of the first rule that applies to
 191      * the number.  This function can be used with isKeyword* functions to
 192      * determine the keyword for default plural rules.
 193      *
 194      * @param number  The number for which the rule has to be determined.
 195      * @return        The keyword of the selected rule.
 196      * @draft ICU 4.0
 197      */
 198     UnicodeString select(double number) const;
 199
 200     /**
 201      * Returns a list of all rule keywords used in this <code>PluralRules</code>
 202      * object.  The rule 'other' is always present by default.
 203      *
 204      * @param status Output param set to success/failure code on exit, which
 205      *               must not indicate a failure before the function call.
 206      * @return       StringEnumeration with the keywords.
 207      *               The caller must delete the object.
 208      * @draft ICU 4.0
 209      */
 210     StringEnumeration* getKeywords(UErrorCode& status) const;
 211
 212     /**
 213      * Returns TRUE if the given keyword is defined in this
 214      * <code>PluralRules</code> object.
 215      *
 216      * @param keyword  the input keyword.
 217      * @return         TRUE if the input keyword is defined.
 218      *                 Otherwise, return FALSE.
 219      * @draft ICU 4.0
 220      */
 221     UBool isKeyword(const UnicodeString& keyword) const;
 222
 223
 224     /**
 225      * Returns keyword for default plural form.
 226      *
 227      * @return         keyword for default plural form.
 228      * @internal 4.0
 229      * @draft ICU 4.0
 230      */
 231     UnicodeString getKeywordOther() const;
 232
 233     /**
 234      * Compares the equality of two PluralRules objects.
 235      *
 236      * @param other The other PluralRules object to be compared with.
 237      * @return      True if the given PluralRules is the same as this
 238      *              PluralRules; false otherwise.
 239      * @draft ICU 4.0
 240      */
 241     virtual UBool operator==(const PluralRules& other) const;
 242
 243     /**
 244      * Compares the inequality of two PluralRules objects.
 245      *
 246      * @param other The PluralRules object to be compared with.
 247      * @return      True if the given PluralRules is not the same as this
 248      *              PluralRules; false otherwise.
 249      * @draft ICU 4.0
 250      */
 251     UBool operator!=(const PluralRules& other) const  {return !operator==(other);}
 252
 253
 254     /**
 255      * ICU "poor man's RTTI", returns a UClassID for this class.
 256      *
 257      * @draft ICU 4.0
 258      *
 259     */
 260     static UClassID U_EXPORT2 getStaticClassID(void);
 261
 262     /**
 263      * ICU "poor man's RTTI", returns a UClassID for the actual class.
 264      *
 265      * @draft ICU 4.0
 266      */
 267     virtual UClassID getDynamicClassID() const;
 268
 269
 270 private:
 271     Hashtable       *fLocaleStringsHash;
 272     UnicodeString   mLocaleName;
 273     RuleChain       *mRules;
 274     RuleParser      *mParser;
 275
 276     PluralRules();   // default constructor not implemented
 277     int32_t getRepeatLimit() const;
 278     void parseDescription(UnicodeString& ruleData, RuleChain& rules, UErrorCode &status);
 279     void getNextLocale(const UnicodeString& localeData, int32_t* curIndex, UnicodeString& localeName);
 280     void addRules(RuleChain& rules);
 281     int32_t getNumberValue(const UnicodeString& token) const;
 282     UnicodeString getRuleFromResource(const Locale& locale, UErrorCode& status);
 283
 284 };
 285
 286 U_NAMESPACE_END
 287
 288 #endif /* #if !UCONFIG_NO_FORMATTING */
 289
 290 #endif // _PLURRULE
 291 //eof