/*******************************************************************************
* Copyright (c) 2005, 2012 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
* QNX Software System
*******************************************************************************/
package org.eclipse.cdt.internal.ui.text;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.rules.ICharacterScanner;
import org.eclipse.core.runtime.Assert;
/**
* A buffered document scanner. The buffer always contains a section
* of a fixed size of the document to be scanned.
*/
public final class BufferedDocumentScanner implements ICharacterScanner {
/** The document being scanned. */
private IDocument fDocument;
/** The offset of the document range to scan. */
private int fRangeOffset;
/** The length of the document range to scan. */
private int fRangeLength;
/** The delimiters of the document. */
private char[][] fDelimiters;
/** The buffer. */
private final char[] fBuffer;
/** The offset of the buffer within the document. */
private int fBufferOffset;
/** The valid length of the buffer for access. */
private int fBufferLength;
/** The offset of the scanner within the buffer. */
private int fOffset;
/**
* Creates a new buffered document scanner.
* The buffer size is set to the given number of characters.
*
* @param size the buffer size
*/
public BufferedDocumentScanner(int size) {
Assert.isTrue(size >= 1);
fBuffer= new char[size];
}
/**
* Fills the buffer with the contents of the document starting at the given offset.
*
* @param offset the document offset at which the buffer starts
*/
private final void updateBuffer(int offset) {
// Clamp at start of the file document range
if (offset < 0)
offset = 0;
fBufferOffset= offset;
fBufferLength= fBuffer.length;
// assert(offset >= fRangeOffset && offset < fRangeOffset + fRangeLength);
if (fBufferOffset + fBufferLength > fRangeOffset + fRangeLength)
fBufferLength= fRangeOffset + fRangeLength - fBufferOffset;
try {
final String content= fDocument.get(fBufferOffset, fBufferLength);
content.getChars(0, fBufferLength, fBuffer, 0);
} catch (BadLocationException e) {
}
}
/**
* Configures the scanner by providing access to the document range over which to scan.
*
* @param document the document to scan
* @param offset the offset of the document range to scan
* @param length the length of the document range to scan
*/
public final void setRange(IDocument document, int offset, int length) {
fDocument= document;
fRangeOffset= offset;
fRangeLength= length;
// Clamp at end of the real document
if (fRangeLength + fRangeOffset > fDocument.getLength())
fRangeLength = fDocument.getLength() - fRangeOffset;
String[] delimiters= document.getLegalLineDelimiters();
fDelimiters= new char[delimiters.length][];
for (int i= 0; i < delimiters.length; i++)
fDelimiters[i]= delimiters[i].toCharArray();
updateBuffer(offset);
fOffset= 0;
}
/*
* @see ICharacterScanner#read()
*/
@Override
public final int read() {
if (fOffset >= fBufferLength) {
if (fBufferOffset + fBufferLength >= fRangeOffset + fRangeLength)
return EOF;
updateBuffer(fBufferOffset + fBufferLength);
fOffset= 0;
}
return fBuffer[fOffset++];
}
/*
* @see ICharacterScanner#unread
*/
@Override
public final void unread() {
if (fOffset <= 0) {
if (fBufferOffset <= fRangeOffset) {
// error: BOF
} else {
updateBuffer(fBufferOffset - fBuffer.length);
fOffset = fBuffer.length - 1; // should always be a valid place
}
} else {
--fOffset;
}
}
/*
* @see ICharacterScanner#getColumn()
*/
@Override
public final int getColumn() {
try {
final int offset= fBufferOffset + fOffset;
final int line= fDocument.getLineOfOffset(offset);
final int start= fDocument.getLineOffset(line);
return offset - start;
} catch (BadLocationException e) {
}
return -1;
}
/*
* @see ICharacterScanner#getLegalLineDelimiters()
*/
@Override
public final char[][] getLegalLineDelimiters() {
return fDelimiters;
}
}