/*******************************************************************************
* Copyright (c) 2007, 2011 David Green 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:
* David Green - initial API and implementation
*******************************************************************************/
package org.eclipse.mylyn.wikitext.util;
import java.io.IOException;
import java.io.Reader;
/**
* A reader class that tracks the character offset based on the number of characters read. Also provides a means for
* reading lines of text, tracking the offset of the last line read.
*
* @author David Green
* @since 3.0
*/
public class LocationTrackingReader extends Reader {
private final Reader delegate;
private int offset = -1;
private int lineOffset = -1;
private int lineNumber = -1;
private char[] buf;
private int bufOffset = 0;
private int bufLength = 0;
public LocationTrackingReader(Reader delegate) {
this(delegate, 2048);
}
public LocationTrackingReader(Reader delegate, int bufferSize) {
this.delegate = delegate;
buf = new char[bufferSize];
}
@Override
public void close() throws IOException {
delegate.close();
}
@Override
public int read(char[] cbuf, int off, int len) throws IOException {
if (bufLength > 0) {
int length = Math.min(len, bufLength);
System.arraycopy(buf, bufOffset, cbuf, off, length);
bufLength -= length;
bufOffset += length;
if (bufLength == 0) {
bufOffset = 0;
}
offset += length;
return length;
} else {
int read = delegate.read(cbuf, off, len);
if (read != -1) {
offset += read;
}
return read;
}
}
@Override
public int read() throws IOException {
if (bufLength > 0) {
int c = buf[bufOffset];
bufLength -= 1;
bufOffset += 1;
if (bufLength == 0) {
bufOffset = 0;
}
offset += 1;
return c;
} else {
int read = delegate.read();
if (read != -1) {
++offset;
}
return read;
}
}
/**
* Read a line of text, omitting the line delimiters.
*
* @return the text or null if the end of input has been reached
* @see #getLineOffset()
*/
public String readLine() throws IOException {
lineOffset = offset + 1;
int lineBufOffset = bufOffset;
int c = -1;
for (int x = lineBufOffset;; ++x) {
if (x >= (bufOffset + bufLength)) {
if (bufOffset > 0 && bufLength > 0) {
System.arraycopy(buf, bufOffset, buf, 0, bufLength);
x -= bufOffset;
bufOffset = 0;
lineBufOffset = 0;
}
if (bufOffset + bufLength >= buf.length) {
// expand the buffer
char[] newBuf = new char[buf.length * 2];
if (bufLength > 0) {
System.arraycopy(buf, bufOffset, newBuf, 0, bufLength);
}
x -= bufOffset;
bufOffset = 0;
lineBufOffset = 0;
buf = newBuf;
}
int emptyOffset = bufOffset + bufLength;
int read = delegate.read(buf, emptyOffset, buf.length - emptyOffset);
if (read > 0) {
bufLength += read;
} else {
// end of input
break;
}
}
if (x >= (bufOffset + bufLength)) {
// end of input
break;
}
int nc = buf[x];
if (nc == '\n') {
// eol
int length = x - lineBufOffset + 1;
bufOffset += length;
bufLength -= length;
offset += length;
int stringLength = c == '\r' ? length - 2 : length - 1;
++lineNumber;
return new String(buf, lineBufOffset, stringLength);
} else if (c == '\r') {
int length = x - lineBufOffset;
bufOffset += length;
bufLength -= length;
offset += length;
int stringLength = length - 1;
++lineNumber;
return new String(buf, lineBufOffset, stringLength);
}
c = nc;
}
if (bufLength > 0) {
String line = new String(buf, bufOffset, c == '\r' ? bufLength - 1 : bufLength);
bufOffset = 0;
offset += bufLength;
bufLength = 0;
++lineNumber;
return line;
} else {
++lineNumber;
return null;
}
}
/**
* Get the character offset of the last character read.
*/
public int getOffset() {
return offset;
}
/**
* Get the character offset of the first character of the last line read. The result of calling this method is only
* meaningful immediately after having called {@link #readLine()}.
*
* @see #readLine()
*/
public int getLineOffset() {
return lineOffset;
}
/**
* get the 0-based line number of the last line read. The result of calling this method is only meaningful
* immediately after having called {@link #readLine()}.
*
* @see #readLine()
*/
public int getLineNumber() {
return lineNumber;
}
}
