ICU 4.8.1.1
4.8.1.1
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Defines rules for mapping non-negative numeric values onto a small set of keywords. More...
#include <plurrule.h>
Public Member Functions | |
PluralRules (UErrorCode &status) | |
Constructor. | |
PluralRules (const PluralRules &other) | |
Copy constructor. | |
virtual | ~PluralRules () |
Destructor. | |
PluralRules * | clone () const |
Clone. | |
PluralRules & | operator= (const PluralRules &) |
Assignment operator. | |
UnicodeString | select (int32_t number) const |
Given a number, returns the keyword of the first rule that applies to the number. | |
UnicodeString | select (double number) const |
Given a number, returns the keyword of the first rule that applies to the number. | |
StringEnumeration * | getKeywords (UErrorCode &status) const |
Returns a list of all rule keywords used in this PluralRules object. | |
double | getUniqueKeywordValue (const UnicodeString &keyword) |
Returns a unique value for this keyword if it exists, else the constant UPLRULES_NO_UNIQUE_VALUE. | |
int32_t | getAllKeywordValues (const UnicodeString &keyword, double *dest, int32_t destCapacity, UErrorCode &status) |
Returns all the values for which select() would return the keyword. | |
int32_t | getSamples (const UnicodeString &keyword, double *dest, int32_t destCapacity, UErrorCode &status) |
Returns sample values for which select() would return the keyword. | |
UBool | isKeyword (const UnicodeString &keyword) const |
Returns TRUE if the given keyword is defined in this PluralRules object. | |
UnicodeString | getKeywordOther () const |
Returns keyword for default plural form. | |
virtual UBool | operator== (const PluralRules &other) const |
Compares the equality of two PluralRules objects. | |
UBool | operator!= (const PluralRules &other) const |
Compares the inequality of two PluralRules objects. | |
virtual UClassID | getDynamicClassID () const |
ICU "poor man's RTTI", returns a UClassID for the actual class. | |
Static Public Member Functions | |
static PluralRules * | createRules (const UnicodeString &description, UErrorCode &status) |
Creates a PluralRules from a description if it is parsable, otherwise returns NULL. | |
static PluralRules * | createDefaultRules (UErrorCode &status) |
The default rules that accept any number. | |
static PluralRules * | forLocale (const Locale &locale, UErrorCode &status) |
Provides access to the predefined PluralRules for a given locale. | |
static UClassID | getStaticClassID (void) |
ICU "poor man's RTTI", returns a UClassID for this class. |
Defines rules for mapping non-negative numeric values onto a small set of keywords.
Rules are constructed from a text description, consisting of a series of keywords and conditions. The select method examines each condition in order and returns the keyword for the first condition that matches the number. If none match, default rule(other) is returned.
For more information, details, and tips for writing rules, see the LDML spec, C.11 Language Plural Rules: http://www.unicode.org/draft/reports/tr35/tr35.html#Language_Plural_Rules
Examples:
"one: n is 1; few: n in 2..4"
This defines two rules, for 'one' and 'few'. The condition for 'one' is "n is 1" which means that the number must be equal to 1 for this condition to pass. The condition for 'few' is "n in 2..4" which means that the number must be between 2 and 4 inclusive for this condition to pass. All other numbers are assigned the keyword "other" by the default rule.
"zero: n is 0; one: n is 1; zero: n mod 100 in 1..19"
This illustrates that the same keyword can be defined multiple times. Each rule is examined in order, and the first keyword whose condition passes is the one returned. Also notes that a modulus is applied to n in the last rule. Thus its condition holds for 119, 219, 319...
"one: n is 1; few: n mod 10 in 2..4 and n mod 100 not in 12..14"
This illustrates conjunction and negation. The condition for 'few' has two parts, both of which must be met: "n mod 10 in 2..4" and "n mod 100 not in 12..14". The first part applies a modulus to n before the test as in the previous example. The second part applies a different modulus and also uses negation, thus it matches all numbers _not_ in 12, 13, 14, 112, 113, 114, 212, 213, 214...
Syntax:
rules = rule (';' rule)* rule = keyword ':' condition keyword = <identifier> condition = and_condition ('or' and_condition)* and_condition = relation ('and' relation)* relation = is_relation | in_relation | within_relation | 'n' <EOL> is_relation = expr 'is' ('not')? value in_relation = expr ('not')? 'in' range_list within_relation = expr ('not')? 'within' range expr = 'n' ('mod' value)? range_list = (range | value) (',' range_list)* value = digit+ digit = 0|1|2|3|4|5|6|7|8|9 range = value'..'value
An "identifier" is a sequence of characters that do not have the Unicode Pattern_Syntax or Pattern_White_Space properties.
The difference between 'in' and 'within' is that 'in' only includes integers in the specified range, while 'within' includes all values.
Keywords could be defined by users or from ICU locale data. There are 6 predefined values in ICU - 'zero', 'one', 'two', 'few', 'many' and 'other'. Callers need to check the value of keyword returned by select method.
Examples:
UnicodeString keyword = pl->select(number); if (keyword== UnicodeString("one") { ... } else if ( ... )
Note:
ICU defines plural rules for many locales based on CLDR Language Plural Rules. For these predefined rules, see CLDR page at http://unicode.org/repos/cldr-tmp/trunk/diff/supplemental/language_plural_rules.html
Definition at line 126 of file plurrule.h.
PluralRules::PluralRules | ( | UErrorCode & | status | ) |
Constructor.
status | Output param set to success/failure code on exit, which must not indicate a failure before the function call. |
PluralRules::PluralRules | ( | const PluralRules & | other | ) |
Copy constructor.
virtual PluralRules::~PluralRules | ( | ) | [virtual] |
Destructor.
PluralRules* PluralRules::clone | ( | ) | const |
Clone.
static PluralRules* PluralRules::createDefaultRules | ( | UErrorCode & | status | ) | [static] |
The default rules that accept any number.
status | Output param set to success/failure code on exit, which must not indicate a failure before the function call. |
static PluralRules* PluralRules::createRules | ( | const UnicodeString & | description, |
UErrorCode & | status | ||
) | [static] |
Creates a PluralRules from a description if it is parsable, otherwise returns NULL.
description | rule description |
status | Output param set to success/failure code on exit, which must not indicate a failure before the function call. |
static PluralRules* PluralRules::forLocale | ( | const Locale & | locale, |
UErrorCode & | status | ||
) | [static] |
Provides access to the predefined PluralRules
for a given locale.
locale | The locale for which a PluralRules object is returned. |
status | Output param set to success/failure code on exit, which must not indicate a failure before the function call. |
PluralRules
object pointer for this locale. If there's no predefined rules for this locale, the rules for the closest parent in the locale hierarchy that has one will be returned. The final fallback always returns the default 'other' rules. int32_t PluralRules::getAllKeywordValues | ( | const UnicodeString & | keyword, |
double * | dest, | ||
int32_t | destCapacity, | ||
UErrorCode & | status | ||
) |
Returns all the values for which select() would return the keyword.
If the keyword is unknown, returns no values, but this is not an error. If the number of values is unlimited, returns no values and -1 as the count.
The number of returned values is typically small.
keyword | The keyword. |
dest | Array into which to put the returned values. May be NULL if destCapacity is 0. |
destCapacity | The capacity of the array, must be at least 0. |
status | The error code. |
virtual UClassID PluralRules::getDynamicClassID | ( | ) | const [virtual] |
UnicodeString PluralRules::getKeywordOther | ( | ) | const |
StringEnumeration* PluralRules::getKeywords | ( | UErrorCode & | status | ) | const |
Returns a list of all rule keywords used in this PluralRules
object.
The rule 'other' is always present by default.
status | Output param set to success/failure code on exit, which must not indicate a failure before the function call. |
int32_t PluralRules::getSamples | ( | const UnicodeString & | keyword, |
double * | dest, | ||
int32_t | destCapacity, | ||
UErrorCode & | status | ||
) |
Returns sample values for which select() would return the keyword.
If the keyword is unknown, returns no values, but this is not an error.
The number of returned values is typically small.
keyword | The keyword. |
dest | Array into which to put the returned values. May be NULL if destCapacity is 0. |
destCapacity | The capacity of the array, must be at least 0. |
status | The error code. |
static UClassID PluralRules::getStaticClassID | ( | void | ) | [static] |
ICU "poor man's RTTI", returns a UClassID for this class.
double PluralRules::getUniqueKeywordValue | ( | const UnicodeString & | keyword | ) |
Returns a unique value for this keyword if it exists, else the constant UPLRULES_NO_UNIQUE_VALUE.
keyword | The keyword. |
UBool PluralRules::isKeyword | ( | const UnicodeString & | keyword | ) | const |
Returns TRUE if the given keyword is defined in this PluralRules
object.
keyword | the input keyword. |
UBool PluralRules::operator!= | ( | const PluralRules & | other | ) | const [inline] |
Compares the inequality of two PluralRules objects.
other | The PluralRules object to be compared with. |
Definition at line 331 of file plurrule.h.
References operator==().
PluralRules& PluralRules::operator= | ( | const PluralRules & | ) |
Assignment operator.
virtual UBool PluralRules::operator== | ( | const PluralRules & | other | ) | const [virtual] |
Compares the equality of two PluralRules objects.
other | The other PluralRules object to be compared with. |
UnicodeString PluralRules::select | ( | int32_t | number | ) | const |
Given a number, returns the keyword of the first rule that applies to the number.
This function can be used with isKeyword* functions to determine the keyword for default plural rules.
number | The number for which the rule has to be determined. |
UnicodeString PluralRules::select | ( | double | number | ) | const |
Given a number, returns the keyword of the first rule that applies to the number.
This function can be used with isKeyword* functions to determine the keyword for default plural rules.
number | The number for which the rule has to be determined. |