LineNumberingPushbackReader.java

/**
 * Copyright (c) Rich Hickey. All rights reserved.
 * The use and distribution terms for this software are covered by the
 * Eclipse Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php)
 * which can be found in the file epl-v10.html at the root of this distribution.
 * By using this software in any fashion, you are agreeing to be bound by
 * the terms of this license.
 * You must not remove this notice, or any other, from this software.
 */

package clojure.lang;

import java.io.PushbackReader;
import java.io.Reader;
import java.io.LineNumberReader;
import java.io.IOException;


public class LineNumberingPushbackReader extends PushbackReader{

// This class is a PushbackReader that wraps a LineNumberReader. The code
// here to handle line terminators only mentions '\n' because
// LineNumberReader collapses all occurrences of CR, LF, and CRLF into a
// single '\n'.

private static final int newline = (int) '\n';

private boolean _atLineStart = true;
private boolean _prev;

public LineNumberingPushbackReader(Reader r){
	super(new LineNumberReader(r));
}

public int getLineNumber(){
	return ((LineNumberReader) in).getLineNumber() + 1;
}

public int read() throws IOException{
    int c = super.read();
    _prev = _atLineStart;
    _atLineStart = (c == newline) || (c == -1);
    return c;
}

public void unread(int c) throws IOException{
    super.unread(c);
    _atLineStart = _prev;
}

public String readLine() throws IOException{
    int c = read();
    String line;
    switch (c) {
    case -1:
        line = null;
        break;
    case newline:
        line = "";
        break;
    default:
        String first = String.valueOf((char) c);
        String rest = ((LineNumberReader)in).readLine();
        line = (rest == null) ? first : first + rest;
        _prev = false;
        _atLineStart = true;
        break;
    }
    return line;
}

public boolean atLineStart(){
    return _atLineStart;
}
}