International Components for Unicode for Java (icu4j) 74.2 · com.ibm.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)+

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.

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

Modifier and Type	Field and Description
private MessagePattern.ApostropheMode	aposMode
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.
public static final int	ARG_NAME_NOT_VALID Return value from `validateArgumentName(String)` for when the string is invalid.
private static final MessagePattern.ArgType[]	argTypes
private static final MessagePattern.ApostropheMode	defaultAposMode
private volatile boolean	frozen
private boolean	hasArgNames
private boolean	hasArgNumbers
private static final int	MAX_PREFIX_LENGTH
private String	msg
private boolean	needsAutoQuoting
public static final double	NO_NUMERIC_VALUE Special value that is returned by getNumericValue(Part) when no numeric value is defined for a part.
private ArrayList<Double>	numericValues
private ArrayList<MessagePattern.Part>	parts

Access	Constructor and Description
public	MessagePattern() Constructs an empty MessagePattern with default ApostropheMode.
public	MessagePattern(MessagePattern.ApostropheMode Explicit ApostropheMode. mode) Constructs an empty MessagePattern.
public	MessagePattern(String a MessageFormat pattern string pattern) Constructs a MessagePattern with default ApostropheMode and parses the MessageFormat pattern string.

Method Summary

Modifier and Type	Method and Description
private void	addArgDoublePart(double numericValue, int start, int length)
private void	addLimitPart(int start, MessagePattern.Part.Type type, int index, int length, int value)
private void	addPart(MessagePattern.Part.Type type, int index, int length, int value)
pack-priv static void	appendReducedApostrophes(String s, int start, int limit, StringBuilder sb) Appends the s[start, limit[ substring to sb, but with only half of the apostrophes according to JDK pattern behavior.
public String	Returns: the deep-auto-quoted version of the parsed pattern 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.
public void	clear() Clears this MessagePattern.
public void	clearPatternAndSetApostropheMode(MessagePattern.ApostropheMode The new ApostropheMode. mode) Clears this MessagePattern and sets the ApostropheMode.
public Object	Returns: a copy of this object (or itself if frozen). clone() Overrides java.lang.Object.clone. Creates and returns a copy of this object.
public MessagePattern	Returns: a copy of this object. cloneAsThawed() Implements com.ibm.icu.util.Freezable.cloneAsThawed. Creates and returns an unfrozen copy of this object.
public int	Returns: the number of pattern parts. countParts() Returns the number of "parts" created by parsing the pattern string.
public boolean	Returns: true if this object is equivalent to the other one. equals(Object another object to compare with. other) Overrides java.lang.Object.equals. Indicates whether some other object is "equal to" this one.
public MessagePattern	Returns: this freeze() Implements com.ibm.icu.util.Freezable.freeze. Freezes this object, making it immutable and thread-safe.
public MessagePattern.ApostropheMode	Returns: this instance's ApostropheMode. getApostropheMode()
public int	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. getLimitPartIndex(int The index of some Part data (0..countParts()-1); this Part should be of Type ARG_START or MSG_START. start) Returns the index of the ARG\|MSG_LIMIT part corresponding to the ARG\|MSG_START at start.
public double	Returns: the part's numeric value, or NO_NUMERIC_VALUE if this is not a numeric part. getNumericValue(MessagePattern.Part a part of this MessagePattern. part) Returns the numeric value associated with an ARG_INT or ARG_DOUBLE.
public MessagePattern.Part	Returns: the i-th pattern "part". getPart(int The index of the Part data. (0..countParts()-1) i) Gets the i-th pattern "part".
public MessagePattern.Part.Type	Returns: The Part.Type of the i-th Part. getPartType(int The index of the Part data. (0..countParts()-1) i) Returns the Part.Type of the i-th pattern "part".
public int	Returns: The pattern index of this Part. getPatternIndex(int The index of the Part data. (0..countParts()-1) partIndex) Returns the pattern index of the specified pattern "part".
public String	Returns: the parsed pattern string (null if none was parsed). getPatternString()
public double	Returns: the "offset:" value. getPluralOffset(int the index of the first PluralFormat argument style part. (0..countParts()-1) pluralStart) Returns the "offset:" value of a PluralFormat argument, or 0 if none is specified.
public String	Returns: the substring associated with part. getSubstring(MessagePattern.Part a part of this MessagePattern. part) Returns the substring of the pattern string indicated by the Part.
public int	hashCode() Overrides java.lang.Object.hashCode. Returns a hash code value for the object.
public boolean	Returns: true if the parsed pattern has at least one named argument. hasNamedArguments() Does the parsed pattern have named arguments like {first_name}?
public boolean	Returns: true if the parsed pattern has at least one numbered argument. hasNumberedArguments() Does the parsed pattern have numbered arguments like {2}?
private boolean	Returns: true if we are inside a MessageFormat (sub-)pattern, as opposed to inside a top-level choice/plural/select pattern. inMessageFormatPattern(int nestingLevel)
private boolean	Returns: true if we are in a MessageFormat sub-pattern of a top-level ChoiceFormat pattern. inTopLevelChoiceMessage(int nestingLevel, MessagePattern.ArgType parentType)
private static boolean	isArgTypeChar(int c)
private boolean	isChoice(int index)
public boolean	Returns: true if this object is frozen. isFrozen() Implements com.ibm.icu.util.Freezable.isFrozen. Determines whether this object is frozen (immutable) or not.
private boolean	isOrdinal(int index)
private boolean	isPlural(int index)
private boolean	isSelect(int index)
pack-priv boolean	Returns: true if getApostropheMode() == ApostropheMode.DOUBLE_REQUIRED jdkAposMode()
public MessagePattern	Returns: this parse(String a MessageFormat pattern string pattern) Parses a MessageFormat pattern string.
private int	parseArg(int index, int argStartLength, int nestingLevel)
private static int	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. parseArgNumber(CharSequence s, int start, int limit) Validates and parses an argument name or argument number string.
private int	parseArgNumber(int start, int limit)
public MessagePattern	Returns: this parseChoiceStyle(String a ChoiceFormat pattern string pattern) Parses a ChoiceFormat pattern string.
private int	parseChoiceStyle(int index, int nestingLevel)
private void	parseDouble(int start index into the message string start, int limit index into the message string, must be startlimit, boolean true if U+221E is allowed (for ChoiceFormat) allowInfinity) Parses a number from the specified message substring.
private int	parseMessage(int index, int msgStartLength, int nestingLevel, MessagePattern.ArgType parentType)
private int	parsePluralOrSelectStyle(MessagePattern.ArgType argType, int index, int nestingLevel)
public MessagePattern	Returns: this parsePluralStyle(String a PluralFormat pattern string pattern) Parses a PluralFormat pattern string.
public MessagePattern	Returns: this parseSelectStyle(String a SelectFormat pattern string pattern) Parses a SelectFormat pattern string.
private int	parseSimpleStyle(int index)
public boolean	Returns: true if getSubstring(part).equals(s). partSubstringMatches(MessagePattern.Part a part of this MessagePattern. part, String a string. s) Compares the part's substring with the input string s.
private void	postParse()
private static String	Returns: s.substring(start) or a prefix of that prefix(String s, int start index in s start) Returns a prefix of s.substring(start).
private static String	prefix(String s)
private String	prefix(int start)
private String	prefix()
private void	preParse(String pattern)
private int	skipDouble(int index) Skips a sequence of characters that could occur in a double value.
private int	skipIdentifier(int index)
private int	skipWhiteSpace(int index)
public String	toString() Overrides java.lang.Object.toString. Returns a string representation of the object.
public static int	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. validateArgumentName(String Input string. name) Validates and parses an argument name or argument number string.

Inherited from java.lang.Object:: finalize getClass notify notifyAll wait wait wait

public final Class MessagePattern

Nested and Inner Type Summary

Field Summary

Constructor Summary

Method Summary