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/*
 * 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; } }




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