MessagePattern (ICU4J 58.1)

java.lang.Object
- com.ibm.icu.text.MessagePattern

All Implemented Interfaces:

Freezable<MessagePattern>, Cloneable
```
public final class MessagePattern
extends Object
implements Cloneable, Freezable<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)+
 
```
- Literal output text is not represented directly by "parts" but accessed between parts of a message, from one part's getLimit() to the next part's getIndex().
- ARG_START.CHOICE stands for an ARG_START Part with ArgType CHOICE.
- In the choiceStyle, the ARG_SELECTOR has the '<', the '#' or the less-than-or-equal-to sign (U+2264).
- In the pluralStyle, the first, optional numeric Part has the "offset:" value. The optional numeric Part between each (ARG_SELECTOR, message) pair is the value of an explicit-number selector like "=2", otherwise the selector is a non-numeric identifier.
- The REPLACE_NUMBER Part can occur only in an immediate sub-message of the pluralStyle.
This class is not intended for public subclassing.
Author:

Markus Scherer

Status:
Stable ICU 4.8.

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`static class`	`MessagePattern.ApostropheMode` Mode for when an apostrophe starts quoted literal text for MessageFormat output.
`static class`	`MessagePattern.ArgType` Argument type constants.
`static class`	`MessagePattern.Part` A message pattern "part", representing a pattern parsing event.

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`ARG_NAME_NOT_NUMBER` Return value from `validateArgumentName(String)` for when the string is a valid "pattern identifier" but not a number.
`static int`	`ARG_NAME_NOT_VALID` Return value from `validateArgumentName(String)` for when the string is invalid.
`static double`	`NO_NUMERIC_VALUE` Special value that is returned by getNumericValue(Part) when no numeric value is defined for a part.

Constructor Summary

Constructors
Constructor and Description
`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.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`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)`
`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.
`int`	`hashCode()`
`boolean`	`hasNamedArguments()` Does the parsed pattern have named arguments like {first_name}?
`boolean`	`hasNumberedArguments()` Does the parsed pattern have numbered arguments like {2}?
`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()`
`static int`	`validateArgumentName(String name)` Validates and parses an argument name or argument number string.

Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait

- Field Detail
  - ARG_NAME_NOT_NUMBER
```
public static final int ARG_NAME_NOT_NUMBER
```
    Return value from validateArgumentName(String) for when the string is a valid "pattern identifier" but not a number.
    
    See Also:
    
    Constant Field Values
    
    Status:
    Stable ICU 4.8.
  - ARG_NAME_NOT_VALID
```
public static final 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.
    
    See Also:
    
    Constant Field Values
    
    Status:
    Stable ICU 4.8.
  - NO_NUMERIC_VALUE
```
public static final double NO_NUMERIC_VALUE
```
    Special value that is returned by getNumericValue(Part) when no numeric value is defined for a part.
    
    See Also:
    
    getNumericValue(com.ibm.icu.text.MessagePattern.Part), Constant Field Values
    
    Status:
    Stable ICU 4.8.
- Constructor Detail
  - MessagePattern
```
public MessagePattern()
```
    Constructs an empty MessagePattern with default ApostropheMode.
    
    Status:
    Stable ICU 4.8.
  - MessagePattern
```
public MessagePattern(MessagePattern.ApostropheMode mode)
```
    Constructs an empty MessagePattern.
    
    Parameters:
    
    mode - Explicit ApostropheMode.
    
    Status:
    Stable ICU 4.8.
  - MessagePattern
```
public MessagePattern(String pattern)
```
    Constructs a MessagePattern with default ApostropheMode and parses the MessageFormat pattern string.
    
    Parameters:
    
    pattern - 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
    
    Status:
    Stable ICU 4.8.
- Method Detail
  - parse
```
public MessagePattern parse(String pattern)
```
    Parses a MessageFormat pattern string.
    
    Parameters:
    
    pattern - a MessageFormat pattern string
    
    Returns:
    
    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
    
    Status:
    Stable ICU 4.8.
  - parseChoiceStyle
```
public MessagePattern parseChoiceStyle(String pattern)
```
    Parses a ChoiceFormat pattern string.
    
    Parameters:
    
    pattern - a ChoiceFormat pattern string
    
    Returns:
    
    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
    
    Status:
    Stable ICU 4.8.
  - parsePluralStyle
```
public MessagePattern parsePluralStyle(String pattern)
```
    Parses a PluralFormat pattern string.
    
    Parameters:
    
    pattern - a PluralFormat pattern string
    
    Returns:
    
    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
    
    Status:
    Stable ICU 4.8.
  - parseSelectStyle
```
public MessagePattern parseSelectStyle(String pattern)
```
    Parses a SelectFormat pattern string.
    
    Parameters:
    
    pattern - a SelectFormat pattern string
    
    Returns:
    
    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
    
    Status:
    Stable ICU 4.8.
  - clear
```
public void clear()
```
    Clears this MessagePattern. countParts() will return 0.
    
    Status:
    Stable ICU 4.8.
  - clearPatternAndSetApostropheMode
```
public void clearPatternAndSetApostropheMode(MessagePattern.ApostropheMode mode)
```
    Clears this MessagePattern and sets the ApostropheMode. countParts() will return 0.
    
    Parameters:
    
    mode - The new ApostropheMode.
    
    Status:
    Stable ICU 4.8.
  - equals
```
public boolean equals(Object other)
```
    Overrides:
    
    equals in class Object
    
    Parameters:
    
    other - another object to compare with.
    
    Returns:
    
    true if this object is equivalent to the other one.
    
    Status:
    Stable ICU 4.8.
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class Object
    
    Status:
    Stable ICU 4.8.
  - getApostropheMode
```
public MessagePattern.ApostropheMode getApostropheMode()
```
    Returns:
    
    this instance's ApostropheMode.
    
    Status:
    Stable ICU 4.8.
  - getPatternString
```
public String getPatternString()
```
    Returns:
    
    the parsed pattern string (null if none was parsed).
    
    Status:
    Stable ICU 4.8.
  - hasNamedArguments
```
public boolean hasNamedArguments()
```
    Does the parsed pattern have named arguments like {first_name}?
    
    Returns:
    
    true if the parsed pattern has at least one named argument.
    
    Status:
    Stable ICU 4.8.
  - hasNumberedArguments
```
public boolean hasNumberedArguments()
```
    Does the parsed pattern have numbered arguments like {2}?
    
    Returns:
    
    true if the parsed pattern has at least one numbered argument.
    
    Status:
    Stable ICU 4.8.
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
    
    Status:
    Stable ICU 4.8.
  - validateArgumentName
```
public static 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 - Input string.
    
    Returns:
    
    >=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.
    
    Status:
    Stable ICU 4.8.
  - autoQuoteApostropheDeep
```
public 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:
    
    the deep-auto-quoted version of the parsed pattern string.
    
    See Also:
    
    MessageFormat.autoQuoteApostrophe(String)
    
    Status:
    Stable ICU 4.8.
  - countParts
```
public 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:
    
    the number of pattern parts.
    
    Status:
    Stable ICU 4.8.
  - getPart
```
public MessagePattern.Part getPart(int i)
```
    Gets the i-th pattern "part".
    
    Parameters:
    
    i - The index of the Part data. (0..countParts()-1)
    
    Returns:
    
    the i-th pattern "part".
    
    Throws:
    
    IndexOutOfBoundsException - if i is outside the (0..countParts()-1) range
    
    Status:
    Stable ICU 4.8.
  - getPartType
```
public MessagePattern.Part.Type getPartType(int i)
```
    Returns the Part.Type of the i-th pattern "part". Convenience method for getPart(i).getType().
    
    Parameters:
    
    i - The index of the Part data. (0..countParts()-1)
    
    Returns:
    
    The Part.Type of the i-th Part.
    
    Throws:
    
    IndexOutOfBoundsException - if i is outside the (0..countParts()-1) range
    
    Status:
    Stable ICU 4.8.
  - getPatternIndex
```
public int getPatternIndex(int partIndex)
```
    Returns the pattern index of the specified pattern "part". Convenience method for getPart(partIndex).getIndex().
    
    Parameters:
    
    partIndex - The index of the Part data. (0..countParts()-1)
    
    Returns:
    
    The pattern index of this Part.
    
    Throws:
    
    IndexOutOfBoundsException - if partIndex is outside the (0..countParts()-1) range
    
    Status:
    Stable ICU 4.8.
  - getSubstring
```
public 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 - a part of this MessagePattern.
    
    Returns:
    
    the substring associated with part.
    
    Status:
    Stable ICU 4.8.
  - partSubstringMatches
```
public boolean partSubstringMatches(MessagePattern.Part part,
                                    String s)
```
    Compares the part's substring with the input string s.
    
    Parameters:
    
    part - a part of this MessagePattern.
    
    s - a string.
    
    Returns:
    
    true if getSubstring(part).equals(s).
    
    Status:
    Stable ICU 4.8.
  - getNumericValue
```
public double getNumericValue(MessagePattern.Part part)
```
    Returns the numeric value associated with an ARG_INT or ARG_DOUBLE.
    
    Parameters:
    
    part - a part of this MessagePattern.
    
    Returns:
    
    the part's numeric value, or NO_NUMERIC_VALUE if this is not a numeric part.
    
    Status:
    Stable ICU 4.8.
  - getPluralOffset
```
public double getPluralOffset(int pluralStart)
```
    Returns the "offset:" value of a PluralFormat argument, or 0 if none is specified.
    
    Parameters:
    
    pluralStart - the index of the first PluralFormat argument style part. (0..countParts()-1)
    
    Returns:
    
    the "offset:" value.
    
    Throws:
    
    IndexOutOfBoundsException - if pluralStart is outside the (0..countParts()-1) range
    
    Status:
    Stable ICU 4.8.
  - getLimitPartIndex
```
public int getLimitPartIndex(int start)
```
    Returns the index of the ARG|MSG_LIMIT part corresponding to the ARG|MSG_START at start.
    
    Parameters:
    
    start - The index of some Part data (0..countParts()-1); this Part should be of Type ARG_START or MSG_START.
    
    Returns:
    
    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
    
    Status:
    Stable ICU 4.8.
  - clone
```
public Object clone()
```
    Creates and returns a copy of this object.
    
    Overrides:
    
    clone in class Object
    
    Returns:
    
    a copy of this object (or itself if frozen).
    
    Status:
    Stable ICU 4.8.
  - cloneAsThawed
```
public MessagePattern cloneAsThawed()
```
    Creates and returns an unfrozen copy of this object.
    
    Specified by:
    
    cloneAsThawed in interface Freezable<MessagePattern>
    
    Returns:
    
    a copy of this object.
    
    Status:
    Stable ICU 4.8.
  - freeze
```
public MessagePattern freeze()
```
    Freezes this object, making it immutable and thread-safe.
    
    Specified by:
    
    freeze in interface Freezable<MessagePattern>
    
    Returns:
    
    this
    
    Status:
    Stable ICU 4.8.
  - isFrozen
```
public boolean isFrozen()
```
    Determines whether this object is frozen (immutable) or not.
    
    Specified by:
    
    isFrozen in interface Freezable<MessagePattern>
    
    Returns:
    
    true if this object is frozen.
    
    Status:
    Stable ICU 4.8.

Class MessagePattern

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

ARG_NAME_NOT_NUMBER

ARG_NAME_NOT_VALID

NO_NUMERIC_VALUE

Constructor Detail

MessagePattern

MessagePattern

MessagePattern

Method Detail

parse

parseChoiceStyle

parsePluralStyle

parseSelectStyle

clear

clearPatternAndSetApostropheMode

equals

hashCode

getApostropheMode

getPatternString

hasNamedArguments

hasNumberedArguments

toString

validateArgumentName

autoQuoteApostropheDeep

countParts

getPart

getPartType

getPatternIndex

getSubstring

partSubstringMatches

getNumericValue

getPluralOffset

getLimitPartIndex

clone

cloneAsThawed

freeze

isFrozen