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/*******************************************************************************
* Copyright (c) 2003, 2006 QNX Software Systems 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:
* QNX Software Systems - Initial API and implementation
*******************************************************************************/
package org.eclipse.cdt.internal.ui.text;
import org.eclipse.jface.text.rules.ICharacterScanner;
import org.eclipse.jface.text.rules.IWordDetector;
import org.eclipse.jface.text.rules.WordRule;
import org.eclipse.jface.text.rules.IRule;
import org.eclipse.jface.text.rules.IToken;
import org.eclipse.jface.text.rules.Token;
/**
* Implementation of <code>IRule</code> for C/C++ preprocessor scanning.
* It is capable of detecting a pattern which begins with 0 or more whitespaces
* at the beginning of the string, then '#' sign, then 0 or more whitespaces
* again, and then directive itself.
*/
public class PreprocessorRule extends WordRule implements IRule {
private StringBuffer fBuffer = new StringBuffer();
/**
* Creates a rule which, with the help of a word detector, will return the token
* associated with the detected word. If no token has been associated, the scanner
* will be rolled back and an undefined token will be returned in order to allow
* any subsequent rules to analyze the characters.
*
* @param detector the word detector to be used by this rule, may not be <code>null</code>
*
* @see #addWord
*/
public PreprocessorRule(IWordDetector detector) {
this(detector, Token.UNDEFINED);
}
/**
* Creates a rule which, with the help of an word detector, will return the token
* associated with the detected word. If no token has been associated, the
* specified default token will be returned.
*
* @param detector the word detector to be used by this rule, may not be <code>null</code>
* @param defaultToken the default token to be returned on success
* if nothing else is specified, may not be <code>null</code>
*
* @see #addWord
*/
public PreprocessorRule(IWordDetector detector, IToken defaultToken) {
super(detector, defaultToken);
}
/*
* @see IRule#evaluate
*/
public IToken evaluate(ICharacterScanner scanner) {
int c;
int nCharsToRollback = 0;
boolean hashSignDetected = false;
if (scanner.getColumn() > 0)
return Token.UNDEFINED;
do {
c = scanner.read();
nCharsToRollback++;
} while (Character.isWhitespace((char) c));
// Di- and trigraph support
if (c == '#') {
hashSignDetected = true;
} else if (c == '%') {
c = scanner.read();
nCharsToRollback++;
if (c == ':') {
hashSignDetected = true;
}
} else if (c == '?') {
c = scanner.read();
nCharsToRollback++;
if (c == '?') {
c = scanner.read();
nCharsToRollback++;
if (c == '=') {
hashSignDetected = true;
}
}
}
if (hashSignDetected) {
do {
c = scanner.read();
} while (Character.isWhitespace((char) c));
fBuffer.setLength(0);
do {
fBuffer.append((char) c);
c = scanner.read();
} while (Character.isJavaIdentifierPart((char) c));
scanner.unread();
IToken token = (IToken) fWords.get("#" + fBuffer.toString()); //$NON-NLS-1$
if (token != null)
return token;
return fDefaultToken;
}
// Doesn't start with '#', roll back scanner
for (int i = 0; i < nCharsToRollback; i++) {
scanner.unread();
}
return Token.UNDEFINED;
}
}
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