public class PluralRules
extends java.lang.Object
implements java.io.Serializable
Defines rules for mapping positive double values onto a small set of
keywords. Serializable so can be used in formatters, which are
serializable. Rules are constructed from a text description, consisting
of a series of keywords and conditions. The select(double)
method
examines each condition in order and returns the keyword for the
first condition that matches the number. If none match,
KEYWORD_OTHER
is returned.
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 - and be an integer - 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 =condition = and_condition ('or' and_condition)* and_condition = relation ('and' relation)* relation = is_relation | in_relation | within_relation | 'n' is_relation = expr 'is' ('not')? value in_relation = expr ('not')? 'in' range within_relation = expr ('not')? 'within' range expr = 'n' ('mod' value)? value = digit+ digit = 0|1|2|3|4|5|6|7|8|9 range = value'..'value
The difference between 'in' and 'within' is that 'in' only includes integers in the specified range, while 'within' includes all values.
Modifier and Type | Field and Description |
---|---|
static PluralRules |
DEFAULT
The default rules that accept any number and return
KEYWORD_OTHER . |
static java.lang.String |
KEYWORD_FEW
Common name for the 'paucal' or other special plural form.
|
static java.lang.String |
KEYWORD_MANY
Common name for the arabic (11 to 99) plural form.
|
static java.lang.String |
KEYWORD_ONE
Common name for the 'singular' plural form.
|
static java.lang.String |
KEYWORD_OTHER
Common name for the default plural form.
|
static java.lang.String |
KEYWORD_TWO
Common name for the 'dual' plural form.
|
static java.lang.String |
KEYWORD_ZERO
Common name for the 'zero' plural form.
|
Modifier and Type | Method and Description |
---|---|
static PluralRules |
createRules(java.lang.String description)
Creates a PluralRules from a description if it is parsable,
otherwise returns null.
|
boolean |
equals(java.lang.Object rhs) |
boolean |
equals(PluralRules rhs)
Return tif rhs is equal to this.
|
static PluralRules |
forLocale(ULocale locale)
Provides access to the predefined
PluralRules for a given
locale. |
static ULocale[] |
getAvailableULocales()
Returns the set of locales for which PluralRules are known.
|
static ULocale |
getFunctionalEquivalent(ULocale locale,
boolean[] isAvailable)
Returns the 'functionally equivalent' locale with respect to
plural rules.
|
java.util.Set<java.lang.String> |
getKeywords()
Returns a set of all rule keywords used in this
PluralRules
object. |
int |
hashCode() |
static PluralRules |
parseDescription(java.lang.String description)
Parses a plural rules description and returns a PluralRules.
|
java.lang.String |
select(double number)
Given a number, returns the keyword of the first rule that applies to
the number.
|
java.lang.String |
toString() |
public static final java.lang.String KEYWORD_ZERO
public static final java.lang.String KEYWORD_ONE
public static final java.lang.String KEYWORD_TWO
public static final java.lang.String KEYWORD_FEW
public static final java.lang.String KEYWORD_MANY
public static final java.lang.String KEYWORD_OTHER
public static final PluralRules DEFAULT
KEYWORD_OTHER
.public static PluralRules parseDescription(java.lang.String description) throws java.text.ParseException
description
- the rule description.java.text.ParseException
- if the description cannot be parsed.
The exception index is typically not set, it will be -1.public static PluralRules createRules(java.lang.String description)
description
- the rule description.public static PluralRules forLocale(ULocale locale)
PluralRules
for a given
locale.locale
- The locale for which a PluralRules
object is
returned.PluralRules
object 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
rules.public java.lang.String select(double number)
number
- The number for which the rule has to be determined.public java.util.Set<java.lang.String> getKeywords()
PluralRules
object. The rule "other" is always present by default.public static ULocale[] getAvailableULocales()
public static ULocale getFunctionalEquivalent(ULocale locale, boolean[] isAvailable)
locale
- the locale to checkisAvailable
- if not null and of length > 0, this will hold 'true' at
index 0 if locale is directly defined (without fallback) as having plural rulespublic java.lang.String toString()
toString
in class java.lang.Object
public int hashCode()
hashCode
in class java.lang.Object
public boolean equals(java.lang.Object rhs)
equals
in class java.lang.Object
public boolean equals(PluralRules rhs)
rhs
- the PluralRules to compare to.Copyright (c) 2011 IBM Corporation and others.