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'databene commons' is an open source Java library by Volker Bergmann. It provides extensions to the Java core library by utility classes, abstract concepts and concrete implementations.

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/*
 * Copyright (C) 2004-2015 Volker Bergmann ([email protected]).
 * All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.databene.commons.io;

import java.io.IOException;
import java.io.PushbackReader;
import java.io.Reader;
import java.nio.CharBuffer;

/**
 * Special {@link PushbackReader} implementation which provides the current cursor offset.
 * Created: 19.03.2013 21:13:02
 * @since 0.5.23
 * @author Volker Bergmann
 */
public class OffsetPushbackReader extends PushbackReader {
	
	int offset;

	public OffsetPushbackReader(Reader in) {
		this(in, 1);
	}

	public OffsetPushbackReader(Reader in, int pushBackBufferSize) {
		super(in, pushBackBufferSize);
		this.offset = 0;
	}

	@Override
	public int read() throws IOException {
		offset++;
		return super.read();
	}
	
	@Override
	public int read(char[] charBuffer) throws IOException {
		int count = super.read(charBuffer);
		offset += count;
		return count;
	}
	
	@Override
	public int read(CharBuffer charVuffer) throws IOException {
		int count = super.read(charVuffer);
		offset += count;
		return count;
	}
	
	@Override
	public void unread(int c) throws IOException {
		offset--;
		super.unread(c);
	}
	
	@Override
	public void unread(char[] charBuffer) throws IOException {
		offset -= charBuffer.length;
		super.unread(charBuffer);
	}
	
	@Override
	public void unread(char[] charBuffer, int off, int len) throws IOException {
		offset -= len;
		super.unread(charBuffer, off, len);
	}
	
	public int getOffset() {
		return offset;
	}
	
}