/*
 * ====================================================================
 *
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 1999 The Apache Software Foundation.  All rights 
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:  
 *       "This product includes software developed by the 
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written 
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Group.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 * [Additional notices, if required by prior licensing conditions]
 *
 */ 

package org.apache.tomcat.util.buf;

/**
 * This class implements some basic ASCII character handling functions.
 *
 * @author dac@eng.sun.com
 * @author James Todd [gonzo@eng.sun.com]
 */
public final class Ascii {
    /*
     * Character translation tables.
     */

    private static final byte[] toUpper = new byte[256];
    private static final byte[] toLower = new byte[256];

    /*
     * Character type tables.
     */

    private static final boolean[] isAlpha = new boolean[256];
    private static final boolean[] isUpper = new boolean[256];
    private static final boolean[] isLower = new boolean[256];
    private static final boolean[] isWhite = new boolean[256];
    private static final boolean[] isDigit = new boolean[256];

    /*
     * Initialize character translation and type tables.
     */

    static {
	for (int i = 0; i < 256; i++) {
	    toUpper[i] = (byte)i;
	    toLower[i] = (byte)i;
	}

	for (int lc = 'a'; lc <= 'z'; lc++) {
	    int uc = lc + 'A' - 'a';

	    toUpper[lc] = (byte)uc;
	    toLower[uc] = (byte)lc;
	    isAlpha[lc] = true;
	    isAlpha[uc] = true;
	    isLower[lc] = true;
	    isUpper[uc] = true;
	}

	isWhite[ ' '] = true;
	isWhite['\t'] = true;
	isWhite['\r'] = true;
	isWhite['\n'] = true;
	isWhite['\f'] = true;
	isWhite['\b'] = true;

	for (int d = '0'; d <= '9'; d++) {
	    isDigit[d] = true;
	}
    }

    /**
     * Returns the upper case equivalent of the specified ASCII character.
     */

    public static int toUpper(int c) {
	return toUpper[c & 0xff] & 0xff;
    }

    /**
     * Returns the lower case equivalent of the specified ASCII character.
     */

    public static int toLower(int c) {
	return toLower[c & 0xff] & 0xff;
    }

    /**
     * Returns true if the specified ASCII character is upper or lower case.
     */

    public static boolean isAlpha(int c) {
	return isAlpha[c & 0xff];
    }

    /**
     * Returns true if the specified ASCII character is upper case.
     */

    public static boolean isUpper(int c) {
	return isUpper[c & 0xff];
    }

    /**
     * Returns true if the specified ASCII character is lower case.
     */

    public static boolean isLower(int c) {
	return isLower[c & 0xff];
    }

    /**
     * Returns true if the specified ASCII character is white space.
     */

    public static boolean isWhite(int c) {
	return isWhite[c & 0xff];
    }

    /**
     * Returns true if the specified ASCII character is a digit.
     */

    public static boolean isDigit(int c) {
	return isDigit[c & 0xff];
    }

    /**
     * Parses an unsigned integer from the specified subarray of bytes.
     * @param b the bytes to parse
     * @param off the start offset of the bytes
     * @param len the length of the bytes
     * @exception NumberFormatException if the integer format was invalid
     */
    public static int parseInt(byte[] b, int off, int len)
	throws NumberFormatException
    {
        int c;

	if (b == null || len <= 0 || !isDigit(c = b[off++])) {
	    throw new NumberFormatException();
	}

	int n = c - '0';

	while (--len > 0) {
	    if (!isDigit(c = b[off++])) {
		throw new NumberFormatException();
	    }
	    n = n * 10 + c - '0';
	}

	return n;
    }

    public static int parseInt(char[] b, int off, int len)
	throws NumberFormatException
    {
        int c;

	if (b == null || len <= 0 || !isDigit(c = b[off++])) {
	    throw new NumberFormatException();
	}

	int n = c - '0';

	while (--len > 0) {
	    if (!isDigit(c = b[off++])) {
		throw new NumberFormatException();
	    }
	    n = n * 10 + c - '0';
	}

	return n;
    }

}
