CleaningInputStream.java

/*
 *  Freeplane - mind map editor
 *  Copyright (C) 2009 Dimitry
 *
 *  This file author is Dimitry
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.freeplane.features.url;

import java.io.IOException;
import java.io.InputStream;
import java.io.PushbackInputStream;

/**
 * @author Dimitry Polivaev
 * 27.08.2009
 */
public class CleaningInputStream extends InputStream {
	private static final int MAX_PUSHED_BACK = 4;
	private final PushbackInputStream in;
	private int pushedBack = 0;
	private boolean isUtf8 = false;
	public CleaningInputStream(final InputStream pIn) {
		super();
		this.in = new PushbackInputStream(pIn, MAX_PUSHED_BACK);
		try {
			final byte[] bytes = new byte[3];
			int i = 0;
			int b;
			b = in.read();
			bytes[i++] = (byte)b;
			if(b == 0xef){
				b = in.read();
				bytes[i++] = (byte)b;
				if(b == 0xbb){
					b = in.read();
					bytes[i++] = (byte)b;
					if(b == 0xbf){
						isUtf8 = true;
						return;
					}
				}
			}
			this.in.unread(bytes, 0, i);
			pushedBack = i;
	        
        }
        catch (IOException e) {
        }
	}

	public boolean isUtf8() {
    	return isUtf8;
    }

	@Override
	public int read() throws IOException {
		byte b = (byte) in.read();
		if (pushedBack > 0) {
			pushedBack--;
			return b;
		}
		if (b == '&') {
			final byte[] bytes = new byte[MAX_PUSHED_BACK];
			int i = 0;
			bytes[i++] = b = (byte) in.read();
			if (b == '#') {
				bytes[i++] = b = (byte) in.read();
				if (b == 'x' || b >= '0' || b <= '3') {
					bytes[i++] = (byte) in.read();
					bytes[i++] = (byte) in.read();
				}
			}
			if (isValidInput(i, bytes)) {
				pushedBack = i;
				in.unread(bytes, 0, i);
				return '&';
			}
			else {
				return ' ';
			}
		}
		return b;
	}

	private boolean isValidInput(final int i, final byte[] bytes) {
		if (i != MAX_PUSHED_BACK || bytes[i - 1] != ';') {
			return true;
		}
		final int c;
		if (bytes[1] == 'x') {
			c = Character.digit(bytes[2], 16);
		}
		else {
			c = Character.digit(bytes[1], 10) * 10 + Character.digit(bytes[2], 10);
		}
		return c >= ' ' || c == '\t' || c == '\r' || c == '\n';
	}
}