| /******************************************************************************* |
| * Copyright (c) 2013 IBM Corporation and others. |
| * All rights reserved. This program and the accompanying materials |
| * are made available under the terms of the Eclipse Public License v1.0 |
| * which accompanies this distribution, and is available at |
| * http://www.eclipse.org/legal/epl-v10.html |
| * |
| * Contributors: |
| * IBM Corporation - initial API and implementation |
| *******************************************************************************/ |
| package org.aspectj.org.eclipse.jdt.internal.compiler.parser; |
| |
| import org.aspectj.org.eclipse.jdt.core.compiler.InvalidInputException; |
| import org.aspectj.org.eclipse.jdt.internal.compiler.ast.Statement; |
| |
| public abstract class CommitRollbackParser implements TerminalTokens, ParserBasicInformation { |
| |
| // resumeOnSyntaxError codes: |
| protected static final int HALT = 0; // halt and throw up hands. |
| protected static final int RESTART = 1; // stacks adjusted, alternate goal from check point. |
| protected static final int RESUME = 2; // stacks untouched, just continue from where left off. |
| |
| public Scanner scanner; |
| public int currentToken; |
| |
| public CommitRollbackParser snapShot; |
| private static final int[] RECOVERY_TOKENS = new int [] { TokenNameSEMICOLON, TokenNameRPAREN,}; |
| |
| protected CommitRollbackParser createSnapShotParser() { |
| return new Parser(); |
| } |
| |
| protected void commit() { |
| if (this.snapShot == null) { |
| this.snapShot = createSnapShotParser(); |
| } |
| this.snapShot.copyState(this); |
| } |
| |
| public void copyState(CommitRollbackParser commitRollbackParser) { |
| // Subclasses should implement. |
| } |
| |
| protected int getNextToken() { |
| try { |
| return this.scanner.getNextToken(); |
| } catch (InvalidInputException e) { |
| return TokenNameEOF; |
| } |
| } |
| |
| protected void shouldStackAssistNode() { |
| // Not relevant here. |
| } |
| |
| // We get here on real syntax error or syntax error triggered by fake EOF at completion site, never due to triggered recovery. |
| protected int fallBackToSpringForward(Statement unused) { |
| int nextToken; |
| boolean atCompletionSite = false; |
| int automatonState = automatonState(); |
| |
| // If triggered fake EOF at completion site, see if the real next token would have passed muster. |
| if (this.currentToken == TokenNameEOF) { |
| if (this.scanner.eofPosition < this.scanner.source.length) { |
| atCompletionSite = true; |
| this.scanner.eofPosition = this.scanner.source.length; |
| nextToken = getNextToken(); |
| if (automatonWillShift(nextToken, automatonState)) { |
| this.currentToken = nextToken; |
| return RESUME; |
| } |
| } else { |
| nextToken = TokenNameEOF; |
| } |
| } else { |
| nextToken = this.currentToken; |
| } |
| if (nextToken == TokenNameEOF) |
| return HALT; // don't know how to proceed. |
| this.scanner.ungetToken(nextToken); // spit out what has been bitten more than we can chew. |
| // OK, next token is no good to resume "in place", attempt some local repair. FIXME: need to make sure we don't get stuck keep reducing empty statements !! |
| for (int i = 0, length = RECOVERY_TOKENS.length; i < length; i++) { |
| if (automatonWillShift(RECOVERY_TOKENS[i], automatonState)) { |
| this.currentToken = RECOVERY_TOKENS[i]; |
| return RESUME; |
| } |
| } |
| // OK, no in place resumption, no local repair, fast forward to next statement. |
| if (this.snapShot == null) |
| return RESTART; |
| |
| this.copyState(this.snapShot); |
| if (atCompletionSite) { |
| this.currentToken = TokenNameSEMICOLON; |
| shouldStackAssistNode(); |
| return RESUME; |
| } |
| this.currentToken = this.scanner.fastForward(unused); |
| return RESUME; |
| } |
| |
| public abstract int automatonState(); |
| |
| public abstract boolean automatonWillShift(int nextToken, int lastAction); |
| } |
| |