Top Description Fields Constructors Methods
org.antlr.v4.runtime.atn

public final Class LexerCustomAction

extends Object
implements LexerAction
Class Inheritance
All Implemented Interfaces
org.antlr.v4.runtime.atn.LexerAction
Imports
org.antlr.v4.runtime.CharStream, .Lexer, .Recognizer, org.antlr.v4.runtime.misc.MurmurHash
Executes a custom lexer action by calling Recognizer#action with the rule and action indexes assigned to the custom action. The implementation of a custom action is added to the generated code for the lexer in an override of Recognizer#action when the grammar is compiled.

This class may represent embedded actions created with the {...} syntax in ANTLR 4, as well as actions created for lexer commands where the command argument could not be evaluated when the grammar was compiled.

Author
Sam Harwell
Since
4.2

Field Summary

Modifier and TypeField and Description
private final int
actionIndex

private final int
ruleIndex

Constructor Summary

AccessConstructor and Description
public
LexerCustomAction(int
The rule index to use for calls to Recognizer#action.
ruleIndex, int
The action index to use for calls to Recognizer#action.
actionIndex)

Constructs a custom lexer action with the specified rule and action indexes.

Method Summary

Modifier and TypeMethod and Description
public boolean
equals(Object
the reference object with which to compare.
obj)

Overrides java.lang.Object.equals.

Indicates whether some other object is "equal to" this one.
public void
execute(Lexer
The lexer instance.
lexer)

Implements org.antlr.v4.runtime.atn.LexerAction.execute.

Execute the lexer action in the context of the specified Lexer.
public int

Returns:

The action index for the custom action.
getActionIndex()

Gets the action index to use for calls to Recognizer#action.

public LexerActionType

Returns:

This method returns LexerActionType#CUSTOM.
getActionType()

Implements org.antlr.v4.runtime.atn.LexerAction.getActionType.

Gets the serialization type of the lexer action.
public int

Returns:

The rule index for the custom action.
getRuleIndex()

Gets the rule index to use for calls to Recognizer#action.

public int
hashCode()

Overrides java.lang.Object.hashCode.

Returns a hash code value for this object.
public boolean

Returns:

This method returns true.
isPositionDependent()

Implements org.antlr.v4.runtime.atn.LexerAction.isPositionDependent.

Gets whether the lexer action is position-dependent.
Inherited from java.lang.Object:
clonefinalizegetClassnotifynotifyAlltoStringwaitwaitwait

Field Detail

actionIndexback to summary
private final int actionIndex
ruleIndexback to summary
private final int ruleIndex

Constructor Detail

LexerCustomActionback to summary
public LexerCustomAction(int ruleIndex, int actionIndex)

Constructs a custom lexer action with the specified rule and action indexes.

Parameters
ruleIndex:int

The rule index to use for calls to Recognizer#action.

actionIndex:int

The action index to use for calls to Recognizer#action.

Method Detail

equalsback to summary
public boolean equals(Object obj)

Overrides java.lang.Object.equals.

Doc from java.lang.Object.equals.

Indicates whether some other object is "equal to" this one.

The equals method implements an equivalence relation on non-null object references:

  • It is reflexive: for any non-null reference value x, x.equals(x) should return true.
  • It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
  • It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
  • It is consistent: for any non-null reference values 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.
  • For any non-null reference value x, x.equals(null) should return false.

An equivalence relation partitions the elements it operates on into equivalence classes; all the members of an equivalence class are equal to each other. Members of an equivalence class are substitutable for each other, at least for some purposes.

Parameters
obj:Object

the reference object with which to compare.

Returns:boolean

true if this object is the same as the obj argument; false otherwise.

Annotations
@Override
executeback to summary
public void execute(Lexer lexer)

Implements org.antlr.v4.runtime.atn.LexerAction.execute.

Doc from org.antlr.v4.runtime.atn.LexerAction.execute.

Execute the lexer action in the context of the specified Lexer.

For position-dependent actions, the input stream must already be positioned correctly prior to calling this method.

Custom actions are implemented by calling Lexer#action with the appropriate rule and action indexes.

Parameters
lexer:Lexer

The lexer instance.

Annotations
@Override
getActionIndexback to summary
public int getActionIndex()

Gets the action index to use for calls to Recognizer#action.

Returns:int

The action index for the custom action.

getActionTypeback to summary
public LexerActionType getActionType()

Implements org.antlr.v4.runtime.atn.LexerAction.getActionType.

Doc from org.antlr.v4.runtime.atn.LexerAction.getActionType.

Gets the serialization type of the lexer action.

Returns:LexerActionType

This method returns LexerActionType#CUSTOM.

Annotations
@Override
getRuleIndexback to summary
public int getRuleIndex()

Gets the rule index to use for calls to Recognizer#action.

Returns:int

The rule index for the custom action.

hashCodeback to summary
public int hashCode()

Overrides java.lang.Object.hashCode.

Doc from java.lang.Object.hashCode.

Returns a hash code value for this object. This method is supported for the benefit of hash tables such as those provided by java.util.HashMap.

The general contract of hashCode is:

  • Whenever it is invoked on the same object more than once during an execution of a Java application, the 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.
  • If two objects are equal according to the equals method, then calling the hashCode method on each of the two objects must produce the same integer result.
  • It is not required that if two objects are unequal according to the equals 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.
Returns:int

a hash code value for this object

Annotations
@Override
isPositionDependentback to summary
public boolean isPositionDependent()

Implements org.antlr.v4.runtime.atn.LexerAction.isPositionDependent.

Gets whether the lexer action is position-dependent. Position-dependent actions may have different semantics depending on the CharStream index at the time the action is executed.

Custom actions are position-dependent since they may represent a user-defined embedded action which makes calls to methods like Lexer#getText.

Returns:boolean

This method returns true.

Annotations
@Override