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ANTLR Runtime Source Code
ANTLR is a powerful parser generator for multiple programming languages including Java.
ANTLR contains 2 major modules:
ANTLR Runtime Source Code files are provided in the distribution packge (antlr4-4.10.1.zip). You can download them at ANTLR Website.
You can also browse the source code below:
✍: FYIcenter
⏎ org/antlr/v4/runtime/atn/LexerActionExecutor.java
/* * 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.IntStream; import org.antlr.v4.runtime.Lexer; import org.antlr.v4.runtime.dfa.DFA; import org.antlr.v4.runtime.misc.MurmurHash; import java.util.Arrays; /** * Represents an executor for a sequence of lexer actions which traversed during * the matching operation of a lexer rule (token). * * <p>The executor tracks position information for position-dependent lexer actions * efficiently, ensuring that actions appearing only at the end of the rule do * not cause bloating of the {@link DFA} created for the lexer.</p> * * @author Sam Harwell * @since 4.2 */ public class LexerActionExecutor { private final LexerAction[] lexerActions; /** * Caches the result of {@link #hashCode} since the hash code is an element * of the performance-critical {@link LexerATNConfig#hashCode} operation. */ private final int hashCode; /** * Constructs an executor for a sequence of {@link LexerAction} actions. * @param lexerActions The lexer actions to execute. */ public LexerActionExecutor(LexerAction[] lexerActions) { this.lexerActions = lexerActions; int hash = MurmurHash.initialize(); for (LexerAction lexerAction : lexerActions) { hash = MurmurHash.update(hash, lexerAction); } this.hashCode = MurmurHash.finish(hash, lexerActions.length); } /** * Creates a {@link LexerActionExecutor} which executes the actions for * the input {@code lexerActionExecutor} followed by a specified * {@code lexerAction}. * * @param lexerActionExecutor The executor for actions already traversed by * the lexer while matching a token within a particular * {@link LexerATNConfig}. If this is {@code null}, the method behaves as * though it were an empty executor. * @param lexerAction The lexer action to execute after the actions * specified in {@code lexerActionExecutor}. * * @return A {@link LexerActionExecutor} for executing the combine actions * of {@code lexerActionExecutor} and {@code lexerAction}. */ public static LexerActionExecutor append(LexerActionExecutor lexerActionExecutor, LexerAction lexerAction) { if (lexerActionExecutor == null) { return new LexerActionExecutor(new LexerAction[] { lexerAction }); } LexerAction[] lexerActions = Arrays.copyOf(lexerActionExecutor.lexerActions, lexerActionExecutor.lexerActions.length + 1); lexerActions[lexerActions.length - 1] = lexerAction; return new LexerActionExecutor(lexerActions); } /** * Creates a {@link LexerActionExecutor} which encodes the current offset * for position-dependent lexer actions. * * <p>Normally, when the executor encounters lexer actions where * {@link LexerAction#isPositionDependent} returns {@code true}, it calls * {@link IntStream#seek} on the input {@link CharStream} to set the input * position to the <em>end</em> of the current token. This behavior provides * for efficient DFA representation of lexer actions which appear at the end * of a lexer rule, even when the lexer rule matches a variable number of * characters.</p> * * <p>Prior to traversing a match transition in the ATN, the current offset * from the token start index is assigned to all position-dependent lexer * actions which have not already been assigned a fixed offset. By storing * the offsets relative to the token start index, the DFA representation of * lexer actions which appear in the middle of tokens remains efficient due * to sharing among tokens of the same length, regardless of their absolute * position in the input stream.</p> * * <p>If the current executor already has offsets assigned to all * position-dependent lexer actions, the method returns {@code this}.</p> * * @param offset The current offset to assign to all position-dependent * lexer actions which do not already have offsets assigned. * * @return A {@link LexerActionExecutor} which stores input stream offsets * for all position-dependent lexer actions. */ public LexerActionExecutor fixOffsetBeforeMatch(int offset) { LexerAction[] updatedLexerActions = null; for (int i = 0; i < lexerActions.length; i++) { if (lexerActions[i].isPositionDependent() && !(lexerActions[i] instanceof LexerIndexedCustomAction)) { if (updatedLexerActions == null) { updatedLexerActions = lexerActions.clone(); } updatedLexerActions[i] = new LexerIndexedCustomAction(offset, lexerActions[i]); } } if (updatedLexerActions == null) { return this; } return new LexerActionExecutor(updatedLexerActions); } /** * Gets the lexer actions to be executed by this executor. * @return The lexer actions to be executed by this executor. */ public LexerAction[] getLexerActions() { return lexerActions; } /** * Execute the actions encapsulated by this executor within the context of a * particular {@link Lexer}. * * <p>This method calls {@link IntStream#seek} to set the position of the * {@code input} {@link CharStream} prior to calling * {@link LexerAction#execute} on a position-dependent action. Before the * method returns, the input position will be restored to the same position * it was in when the method was invoked.</p> * * @param lexer The lexer instance. * @param input The input stream which is the source for the current token. * When this method is called, the current {@link IntStream#index} for * {@code input} should be the start of the following token, i.e. 1 * character past the end of the current token. * @param startIndex The token start index. This value may be passed to * {@link IntStream#seek} to set the {@code input} position to the beginning * of the token. */ public void execute(Lexer lexer, CharStream input, int startIndex) { boolean requiresSeek = false; int stopIndex = input.index(); try { for (LexerAction lexerAction : lexerActions) { if (lexerAction instanceof LexerIndexedCustomAction) { int offset = ((LexerIndexedCustomAction)lexerAction).getOffset(); input.seek(startIndex + offset); lexerAction = ((LexerIndexedCustomAction)lexerAction).getAction(); requiresSeek = (startIndex + offset) != stopIndex; } else if (lexerAction.isPositionDependent()) { input.seek(stopIndex); requiresSeek = false; } lexerAction.execute(lexer); } } finally { if (requiresSeek) { input.seek(stopIndex); } } } @Override public int hashCode() { return this.hashCode; } @Override public boolean equals(Object obj) { if (obj == this) { return true; } else if (!(obj instanceof LexerActionExecutor)) { return false; } LexerActionExecutor other = (LexerActionExecutor)obj; return hashCode == other.hashCode && Arrays.equals(lexerActions, other.lexerActions); } }
⏎ org/antlr/v4/runtime/atn/LexerActionExecutor.java
Or download all of them as a single archive file:
File name: antlr-runtime-4.10.1-sources.jar File size: 308953 bytes Release date: 2022-04-15 Download
⇐ What Is ANTLR Parser Generator
2018-10-21, 31790👍, 0💬
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