LookAheadReader.java

/*
 * Created on Mar 19, 2003
 * 
 * @author henkel@cs.colorado.edu
 *  
 */
package bibtex.parser;
import java.io.IOException;
import java.io.Reader;
/**
 * This implementation now features a buffer. This is more efficient than
 * relying on BufferedReader since BufferedReader is synchronized.
 * 
 * @author henkel
 */
final class LookAheadReader {
	private final int BUFFERLEN = 512;
	public LookAheadReader(Reader input) throws IOException {
		this.input = input;
		this.bufferPos = -1;
		this.bufferFilledUntil = 0;
		this.buffer = new char[BUFFERLEN];
		this.eof = false;
		this.line = 1;
		this.column = 0;
		step();
	}
	private final Reader input;
	private boolean eof;
	private int line, column;
	private char buffer[];
	private int bufferFilledUntil;
	private int bufferPos;
	public void step() throws IOException {
		if (this.eof)
			return;
		this.bufferPos++;
		if (this.bufferFilledUntil <= this.bufferPos) {
			this.bufferFilledUntil = input.read(buffer);
			if (this.bufferFilledUntil == -1) {
				this.eof = true;
				input.close();
			}
			this.bufferPos = 0;
		}
		char currentChar = this.buffer[bufferPos];
		if (currentChar == '\n') {
			line++;
			column = 0;
		} else {
			column++;
		}
	}
	public char getCurrent() {
		assert (!this.eof);
		return this.buffer[this.bufferPos];
	}
	public boolean eof() {
		return this.eof;
	}
	public int getLine() {
		return line;
	}
	public int getColumn() {
		return column;
	}
}