public
final
class
MessagePattern
extends Object
implements
Cloneable,
Freezable<MessagePattern>
java.lang.Object | |
↳ | android.icu.text.MessagePattern |
Parses and represents ICU MessageFormat patterns. Also handles patterns for ChoiceFormat, PluralFormat and SelectFormat. Used in the implementations of those classes as well as in tools for message validation, translation and format conversion.
The parser handles all syntax relevant for identifying message arguments. This includes "complex" arguments whose style strings contain nested MessageFormat pattern substrings. For "simple" arguments (with no nested MessageFormat pattern substrings), the argument style is not parsed any further.
The parser handles named and numbered message arguments and allows both in one message.
Once a pattern has been parsed successfully, iterate through the parsed data with countParts(), getPart() and related methods.
The data logically represents a parse tree, but is stored and accessed
as a list of "parts" for fast and simple parsing and to minimize object allocations.
Arguments and nested messages are best handled via recursion.
For every _START "part", getLimitPartIndex(int)
efficiently returns
the index of the corresponding _LIMIT "part".
List of "parts":
message = MSG_START (SKIP_SYNTAX | INSERT_CHAR | REPLACE_NUMBER | argument)* MSG_LIMIT argument = noneArg | simpleArg | complexArg complexArg = choiceArg | pluralArg | selectArg noneArg = ARG_START.NONE (ARG_NAME | ARG_NUMBER) ARG_LIMIT.NONE simpleArg = ARG_START.SIMPLE (ARG_NAME | ARG_NUMBER) ARG_TYPE [ARG_STYLE] ARG_LIMIT.SIMPLE choiceArg = ARG_START.CHOICE (ARG_NAME | ARG_NUMBER) choiceStyle ARG_LIMIT.CHOICE pluralArg = ARG_START.PLURAL (ARG_NAME | ARG_NUMBER) pluralStyle ARG_LIMIT.PLURAL selectArg = ARG_START.SELECT (ARG_NAME | ARG_NUMBER) selectStyle ARG_LIMIT.SELECT choiceStyle = ((ARG_INT | ARG_DOUBLE) ARG_SELECTOR message)+ pluralStyle = [ARG_INT | ARG_DOUBLE] (ARG_SELECTOR [ARG_INT | ARG_DOUBLE] message)+ selectStyle = (ARG_SELECTOR message)+
ARG_START.CHOICE
stands for an ARG_START Part with ArgType CHOICE.
This class is not intended for public subclassing.
Nested classes | |
---|---|
enum |
MessagePattern.ApostropheMode
Mode for when an apostrophe starts quoted literal text for MessageFormat output. |
enum |
MessagePattern.ArgType
Argument type constants. |
class |
MessagePattern.Part
A message pattern "part", representing a pattern parsing event. |
Constants | |
---|---|
int |
ARG_NAME_NOT_NUMBER
Return value from |
int |
ARG_NAME_NOT_VALID
Return value from |
double |
NO_NUMERIC_VALUE
Special value that is returned by getNumericValue(Part) when no numeric value is defined for a part. |
Public constructors | |
---|---|
MessagePattern()
Constructs an empty MessagePattern with default ApostropheMode. |
|
MessagePattern(MessagePattern.ApostropheMode mode)
Constructs an empty MessagePattern. |
|
MessagePattern(String pattern)
Constructs a MessagePattern with default ApostropheMode and parses the MessageFormat pattern string. |
Public methods | |
---|---|
String
|
autoQuoteApostropheDeep()
Returns a version of the parsed pattern string where each ASCII apostrophe is doubled (escaped) if it is not already, and if it is not interpreted as quoting syntax. |
void
|
clear()
Clears this MessagePattern. |
void
|
clearPatternAndSetApostropheMode(MessagePattern.ApostropheMode mode)
Clears this MessagePattern and sets the ApostropheMode. |
Object
|
clone()
Creates and returns a copy of this object. |
MessagePattern
|
cloneAsThawed()
Creates and returns an unfrozen copy of this object. |
int
|
countParts()
Returns the number of "parts" created by parsing the pattern string. |
boolean
|
equals(Object other)
Indicates whether some other object is "equal to" this one. |
MessagePattern
|
freeze()
Freezes this object, making it immutable and thread-safe. |
MessagePattern.ApostropheMode
|
getApostropheMode()
|
int
|
getLimitPartIndex(int start)
Returns the index of the ARG|MSG_LIMIT part corresponding to the ARG|MSG_START at start. |
double
|
getNumericValue(MessagePattern.Part part)
Returns the numeric value associated with an ARG_INT or ARG_DOUBLE. |
MessagePattern.Part
|
getPart(int i)
Gets the i-th pattern "part". |
MessagePattern.Part.Type
|
getPartType(int i)
Returns the Part.Type of the i-th pattern "part". |
int
|
getPatternIndex(int partIndex)
Returns the pattern index of the specified pattern "part". |
String
|
getPatternString()
|
double
|
getPluralOffset(int pluralStart)
Returns the "offset:" value of a PluralFormat argument, or 0 if none is specified. |
String
|
getSubstring(MessagePattern.Part part)
Returns the substring of the pattern string indicated by the Part. |
boolean
|
hasNamedArguments()
Does the parsed pattern have named arguments like {first_name}? |
boolean
|
hasNumberedArguments()
Does the parsed pattern have numbered arguments like {2}? |
int
|
hashCode()
Returns a hash code value for the object. |
boolean
|
isFrozen()
Determines whether this object is frozen (immutable) or not. |
MessagePattern
|
parse(String pattern)
Parses a MessageFormat pattern string. |
MessagePattern
|
parseChoiceStyle(String pattern)
Parses a ChoiceFormat pattern string. |
MessagePattern
|
parsePluralStyle(String pattern)
Parses a PluralFormat pattern string. |
MessagePattern
|
parseSelectStyle(String pattern)
Parses a SelectFormat pattern string. |
boolean
|
partSubstringMatches(MessagePattern.Part part, String s)
Compares the part's substring with the input string s. |
String
|
toString()
Returns a string representation of the object. |
static
int
|
validateArgumentName(String name)
Validates and parses an argument name or argument number string. |
Inherited methods | |
---|---|
From
class
java.lang.Object
| |
From
interface
android.icu.util.Freezable
|
int ARG_NAME_NOT_NUMBER
Return value from validateArgumentName(String)
for when
the string is a valid "pattern identifier" but not a number.
Constant Value: -1 (0xffffffff)
int ARG_NAME_NOT_VALID
Return value from validateArgumentName(String)
for when
the string is invalid.
It might not be a valid "pattern identifier",
or it have only ASCII digits but there is a leading zero or the number is too large.
Constant Value: -2 (0xfffffffe)
double NO_NUMERIC_VALUE
Special value that is returned by getNumericValue(Part) when no numeric value is defined for a part.
See also:
Constant Value: -1.23456789E8
MessagePattern ()
Constructs an empty MessagePattern with default ApostropheMode.
MessagePattern (MessagePattern.ApostropheMode mode)
Constructs an empty MessagePattern.
Parameters | |
---|---|
mode |
MessagePattern.ApostropheMode :
Explicit ApostropheMode.
|
MessagePattern (String pattern)
Constructs a MessagePattern with default ApostropheMode and parses the MessageFormat pattern string.
Parameters | |
---|---|
pattern |
String :
a MessageFormat pattern string |
Throws | |
---|---|
IllegalArgumentException |
for syntax errors in the pattern string |
IndexOutOfBoundsException |
if certain limits are exceeded (e.g., argument number too high, argument name too long, etc.) |
NumberFormatException |
if a number could not be parsed |
String autoQuoteApostropheDeep ()
Returns a version of the parsed pattern string where each ASCII apostrophe is doubled (escaped) if it is not already, and if it is not interpreted as quoting syntax.
For example, this turns "I don't '{know}' {gender,select,female{h''er}other{h'im}}." into "I don''t '{know}' {gender,select,female{h''er}other{h''im}}."
Returns | |
---|---|
String |
the deep-auto-quoted version of the parsed pattern string. |
See also:
void clearPatternAndSetApostropheMode (MessagePattern.ApostropheMode mode)
Clears this MessagePattern and sets the ApostropheMode. countParts() will return 0.
Parameters | |
---|---|
mode |
MessagePattern.ApostropheMode :
The new ApostropheMode.
|
Object clone ()
Creates and returns a copy of this object.
Returns | |
---|---|
Object |
a copy of this object (or itself if frozen). |
MessagePattern cloneAsThawed ()
Creates and returns an unfrozen copy of this object.
Returns | |
---|---|
MessagePattern |
a copy of this object. |
int countParts ()
Returns the number of "parts" created by parsing the pattern string. Returns 0 if no pattern has been parsed or clear() was called.
Returns | |
---|---|
int |
the number of pattern parts. |
boolean equals (Object other)
Indicates whether some other object is "equal to" this one.
The equals
method implements an equivalence relation
on non-null object references:
x
, x.equals(x)
should return
true
.
x
and y
, x.equals(y)
should return true
if and only if
y.equals(x)
returns true
.
x
, y
, and z
, if
x.equals(y)
returns true
and
y.equals(z)
returns true
, then
x.equals(z)
should return true
.
x
and y
, multiple invocations of
x.equals(y)
consistently return true
or consistently return false
, provided no
information used in equals
comparisons on the
objects is modified.
x
,
x.equals(null)
should return false
.
The equals
method for class Object
implements
the most discriminating possible equivalence relation on objects;
that is, for any non-null reference values x
and
y
, this method returns true
if and only
if x
and y
refer to the same object
(x == y
has the value true
).
Note that it is generally necessary to override the hashCode
method whenever this method is overridden, so as to maintain the
general contract for the hashCode
method, which states
that equal objects must have equal hash codes.
Parameters | |
---|---|
other |
Object :
another object to compare with. |
Returns | |
---|---|
boolean |
true if this object is equivalent to the other one. |
MessagePattern freeze ()
Freezes this object, making it immutable and thread-safe.
Returns | |
---|---|
MessagePattern |
this |
MessagePattern.ApostropheMode getApostropheMode ()
Returns | |
---|---|
MessagePattern.ApostropheMode |
this instance's ApostropheMode. |
int getLimitPartIndex (int start)
Returns the index of the ARG|MSG_LIMIT part corresponding to the ARG|MSG_START at start.
Parameters | |
---|---|
start |
int :
The index of some Part data (0..countParts()-1);
this Part should be of Type ARG_START or MSG_START. |
Returns | |
---|---|
int |
The first i>start where getPart(i).getType()==ARG|MSG_LIMIT at the same nesting level, or start itself if getPartType(msgStart)!=ARG|MSG_START. |
Throws | |
---|---|
IndexOutOfBoundsException |
if start is outside the (0..countParts()-1) range |
double getNumericValue (MessagePattern.Part part)
Returns the numeric value associated with an ARG_INT or ARG_DOUBLE.
Parameters | |
---|---|
part |
MessagePattern.Part :
a part of this MessagePattern. |
Returns | |
---|---|
double |
the part's numeric value, or NO_NUMERIC_VALUE if this is not a numeric part. |
MessagePattern.Part getPart (int i)
Gets the i-th pattern "part".
Parameters | |
---|---|
i |
int :
The index of the Part data. (0..countParts()-1) |
Returns | |
---|---|
MessagePattern.Part |
the i-th pattern "part". |
Throws | |
---|---|
IndexOutOfBoundsException |
if i is outside the (0..countParts()-1) range |
MessagePattern.Part.Type getPartType (int i)
Returns the Part.Type of the i-th pattern "part". Convenience method for getPart(i).getType().
Parameters | |
---|---|
i |
int :
The index of the Part data. (0..countParts()-1) |
Returns | |
---|---|
MessagePattern.Part.Type |
The Part.Type of the i-th Part. |
Throws | |
---|---|
IndexOutOfBoundsException |
if i is outside the (0..countParts()-1) range |
int getPatternIndex (int partIndex)
Returns the pattern index of the specified pattern "part". Convenience method for getPart(partIndex).getIndex().
Parameters | |
---|---|
partIndex |
int :
The index of the Part data. (0..countParts()-1) |
Returns | |
---|---|
int |
The pattern index of this Part. |
Throws | |
---|---|
IndexOutOfBoundsException |
if partIndex is outside the (0..countParts()-1) range |
String getPatternString ()
Returns | |
---|---|
String |
the parsed pattern string (null if none was parsed). |
double getPluralOffset (int pluralStart)
Returns the "offset:" value of a PluralFormat argument, or 0 if none is specified.
Parameters | |
---|---|
pluralStart |
int :
the index of the first PluralFormat argument style part. (0..countParts()-1) |
Returns | |
---|---|
double |
the "offset:" value. |
Throws | |
---|---|
IndexOutOfBoundsException |
if pluralStart is outside the (0..countParts()-1) range |
String getSubstring (MessagePattern.Part part)
Returns the substring of the pattern string indicated by the Part. Convenience method for getPatternString().substring(part.getIndex(), part.getLimit()).
Parameters | |
---|---|
part |
MessagePattern.Part :
a part of this MessagePattern. |
Returns | |
---|---|
String |
the substring associated with part. |
boolean hasNamedArguments ()
Does the parsed pattern have named arguments like {first_name}?
Returns | |
---|---|
boolean |
true if the parsed pattern has at least one named argument. |
boolean hasNumberedArguments ()
Does the parsed pattern have numbered arguments like {2}?
Returns | |
---|---|
boolean |
true if the parsed pattern has at least one numbered argument. |
int hashCode ()
Returns a hash code value for the object. This method is
supported for the benefit of hash tables such as those provided by
HashMap
.
The general contract of hashCode
is:
hashCode
method
must consistently return the same integer, provided no information
used in equals
comparisons on the object is modified.
This integer need not remain consistent from one execution of an
application to another execution of the same application.
equals(Object)
method, then calling the hashCode
method on each of
the two objects must produce the same integer result.
equals(java.lang.Object)
method, then calling the hashCode
method on each of the
two objects must produce distinct integer results. However, the
programmer should be aware that producing distinct integer results
for unequal objects may improve the performance of hash tables.
As much as is reasonably practical, the hashCode method defined by
class Object
does return distinct integers for distinct
objects. (This is typically implemented by converting the internal
address of the object into an integer, but this implementation
technique is not required by the
JavaTM programming language.)
Returns | |
---|---|
int |
a hash code value for this object. |
boolean isFrozen ()
Determines whether this object is frozen (immutable) or not.
Returns | |
---|---|
boolean |
true if this object is frozen. |
MessagePattern parse (String pattern)
Parses a MessageFormat pattern string.
Parameters | |
---|---|
pattern |
String :
a MessageFormat pattern string |
Returns | |
---|---|
MessagePattern |
this |
Throws | |
---|---|
IllegalArgumentException |
for syntax errors in the pattern string |
IndexOutOfBoundsException |
if certain limits are exceeded (e.g., argument number too high, argument name too long, etc.) |
NumberFormatException |
if a number could not be parsed |
MessagePattern parseChoiceStyle (String pattern)
Parses a ChoiceFormat pattern string.
Parameters | |
---|---|
pattern |
String :
a ChoiceFormat pattern string |
Returns | |
---|---|
MessagePattern |
this |
Throws | |
---|---|
IllegalArgumentException |
for syntax errors in the pattern string |
IndexOutOfBoundsException |
if certain limits are exceeded (e.g., argument number too high, argument name too long, etc.) |
NumberFormatException |
if a number could not be parsed |
MessagePattern parsePluralStyle (String pattern)
Parses a PluralFormat pattern string.
Parameters | |
---|---|
pattern |
String :
a PluralFormat pattern string |
Returns | |
---|---|
MessagePattern |
this |
Throws | |
---|---|
IllegalArgumentException |
for syntax errors in the pattern string |
IndexOutOfBoundsException |
if certain limits are exceeded (e.g., argument number too high, argument name too long, etc.) |
NumberFormatException |
if a number could not be parsed |
MessagePattern parseSelectStyle (String pattern)
Parses a SelectFormat pattern string.
Parameters | |
---|---|
pattern |
String :
a SelectFormat pattern string |
Returns | |
---|---|
MessagePattern |
this |
Throws | |
---|---|
IllegalArgumentException |
for syntax errors in the pattern string |
IndexOutOfBoundsException |
if certain limits are exceeded (e.g., argument number too high, argument name too long, etc.) |
NumberFormatException |
if a number could not be parsed |
boolean partSubstringMatches (MessagePattern.Part part, String s)
Compares the part's substring with the input string s.
Parameters | |
---|---|
part |
MessagePattern.Part :
a part of this MessagePattern. |
s |
String :
a string. |
Returns | |
---|---|
boolean |
true if getSubstring(part).equals(s). |
String toString ()
Returns a string representation of the object. In general, the
toString
method returns a string that
"textually represents" this object. The result should
be a concise but informative representation that is easy for a
person to read.
It is recommended that all subclasses override this method.
The toString
method for class Object
returns a string consisting of the name of the class of which the
object is an instance, the at-sign character `@
', and
the unsigned hexadecimal representation of the hash code of the
object. In other words, this method returns a string equal to the
value of:
getClass().getName() + '@' + Integer.toHexString(hashCode())
Returns | |
---|---|
String |
a string representation of the object. |
int validateArgumentName (String name)
Validates and parses an argument name or argument number string. An argument name must be a "pattern identifier", that is, it must contain no Unicode Pattern_Syntax or Pattern_White_Space characters. If it only contains ASCII digits, then it must be a small integer with no leading zero.
Parameters | |
---|---|
name |
String :
Input string. |
Returns | |
---|---|
int |
>=0 if the name is a valid number, ARG_NAME_NOT_NUMBER (-1) if it is a "pattern identifier" but not all ASCII digits, ARG_NAME_NOT_VALID (-2) if it is neither. |