/*
 * @(#)StringBufferInputStream.java	1.11 96/04/02 Jonathan Payne
 *
 * Copyright (c) 1994 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Permission to use, copy, modify, and distribute this software
 * and its documentation for NON-COMMERCIAL purposes and without
 * fee is hereby granted provided that this copyright notice
 * appears in all copies. Please refer to the file "copyright.html"
 * for further important copyright and licensing information.
 *
 * SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF
 * THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
 * TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR
 * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
 * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
 */

package java.io;

/**
 * This class implements a String buffer that can be
 * used as an InputStream. 
 * @version 	1.11, 02 Apr 1996
 * @author	Arthur van Hoff
 */

public
class StringBufferInputStream extends InputStream {

    /**
     * The buffer where data is stored.
     */
    protected String buffer;

    /**
     * The position in the buffer.
     */
    protected int pos;

    /**
     * The number of characters to use in the buffer.
     */
    protected int count;


    /**
     * Creates an StringBufferInputStream from the specified array of 
     * bytes.
     * @param s	the input buffer (not copied)
     */
    public StringBufferInputStream(String s) {
	this.buffer = s;
	count = s.length();
    }

    /**
     * Reads a byte of data.
     * @return 	the byte read, or -1 if the end of the
     * stream is reached.
     */
    public synchronized int read() {
	return (pos < count) ? (buffer.charAt(pos++) & 0xFF) : -1;
    }

    /**
     * Reads into an array of bytes.
     * @param b	the buffer into which the data is read
     * @param off the start offset of the data
     * @param len the maximum number of bytes read
     * @return  the actual number of bytes read; -1 is
     * returned when the end of the stream is reached.
     */
    public synchronized int read(byte b[], int off, int len) {
	if (pos >= count) {
	    return -1;
	}
	if (pos + len > count) {
	    len = count - pos;
	}
	if (len <= 0) {
	    return 0;
	}
	String	s = buffer;
	int cnt = len;
	while (--cnt >= 0) {
	    b[off++] = (byte)s.charAt(pos++);
	}

	return len;
    }

    /**
     * Skips n bytes of input.
     * @param n the number of bytes to be skipped
     * @return	the actual number of bytes skipped.
     */
    public synchronized long skip(long n) {
	if (pos + n > count) {
	    n = count - pos;
	}
	if (n < 0) {
	    return 0;
	}
	pos += n;
	return n;
    }

    /**
     * Returns the number of available bytes in the buffer.
     */
    public synchronized int available() {
	return count - pos;
    }

    /**
     * Resets the buffer to the beginning.
     */
    public synchronized void reset() {
	pos = 0;
    }
}