org.antlr.v4.runtime.atn.LexerCustomAction Maven / Gradle / Ivy
/*
* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
* Use of this file is governed by the BSD 3-clause license that
* can be found in the LICENSE.txt file in the project root.
*/
package org.antlr.v4.runtime.atn;
import org.antlr.v4.runtime.CharStream;
import org.antlr.v4.runtime.Lexer;
import org.antlr.v4.runtime.Recognizer;
import org.antlr.v4.runtime.misc.MurmurHash;
/**
* Executes a custom lexer action by calling {@link 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 {@link 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
*/
public final class LexerCustomAction implements LexerAction {
private final int ruleIndex;
private final int actionIndex;
/**
* Constructs a custom lexer action with the specified rule and action
* indexes.
*
* @param ruleIndex The rule index to use for calls to
* {@link Recognizer#action}.
* @param actionIndex The action index to use for calls to
* {@link Recognizer#action}.
*/
public LexerCustomAction(int ruleIndex, int actionIndex) {
this.ruleIndex = ruleIndex;
this.actionIndex = actionIndex;
}
/**
* Gets the rule index to use for calls to {@link Recognizer#action}.
*
* @return The rule index for the custom action.
*/
public int getRuleIndex() {
return ruleIndex;
}
/**
* Gets the action index to use for calls to {@link Recognizer#action}.
*
* @return The action index for the custom action.
*/
public int getActionIndex() {
return actionIndex;
}
/**
* {@inheritDoc}
*
* @return This method returns {@link LexerActionType#CUSTOM}.
*/
@Override
public LexerActionType getActionType() {
return LexerActionType.CUSTOM;
}
/**
* Gets whether the lexer action is position-dependent. Position-dependent
* actions may have different semantics depending on the {@link 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
* {@link Lexer#getText}.
*
* @return This method returns {@code true}.
*/
@Override
public boolean isPositionDependent() {
return true;
}
/**
* {@inheritDoc}
*
* Custom actions are implemented by calling {@link Lexer#action} with the
* appropriate rule and action indexes.
*/
@Override
public void execute(Lexer lexer) {
lexer.action(null, ruleIndex, actionIndex);
}
@Override
public int hashCode() {
int hash = MurmurHash.initialize();
hash = MurmurHash.update(hash, getActionType().ordinal());
hash = MurmurHash.update(hash, ruleIndex);
hash = MurmurHash.update(hash, actionIndex);
return MurmurHash.finish(hash, 3);
}
@Override
public boolean equals(Object obj) {
if (obj == this) {
return true;
}
else if (!(obj instanceof LexerCustomAction)) {
return false;
}
LexerCustomAction other = (LexerCustomAction)obj;
return ruleIndex == other.ruleIndex
&& actionIndex == other.actionIndex;
}
}