// ===========================================================================
// Copyright (c) 1996 Mort Bay Consulting Pty. Ltd. All rights reserved.
// $Id: StringUtil.java,v 1.3 2001/10/23 12:56:02 gregwilkins Exp $
// ---------------------------------------------------------------------------

package org.mortbay.util;

// ====================================================================
/** Fast String Utilities.
 *
 * @version $Revision: 1.3 $
 * @author Greg Wilkins (gregw)
 */
public class StringUtil
{
    public static String __ISO_8859_1;
    static
    {
        String iso=System.getProperty("ISO_8859_1");
        if (iso!=null)
            __ISO_8859_1=iso;
        else
        {
            try{
                new String(new byte[]{(byte)20},"ISO-8859-1");
                __ISO_8859_1="ISO-8859-1";
            }
            catch(java.io.UnsupportedEncodingException e)
            {
                __ISO_8859_1="ISO8859_1";
            }        
        }
    }
    
    private static char[] lowercases = {
          '\000','\001','\002','\003','\004','\005','\006','\007',
          '\010','\011','\012','\013','\014','\015','\016','\017',
          '\020','\021','\022','\023','\024','\025','\026','\027',
          '\030','\031','\032','\033','\034','\035','\036','\037',
          '\040','\041','\042','\043','\044','\045','\046','\047',
          '\050','\051','\052','\053','\054','\055','\056','\057',
          '\060','\061','\062','\063','\064','\065','\066','\067',
          '\070','\071','\072','\073','\074','\075','\076','\077',
          '\100','\141','\142','\143','\144','\145','\146','\147',
          '\150','\151','\152','\153','\154','\155','\156','\157',
          '\160','\161','\162','\163','\164','\165','\166','\167',
          '\170','\171','\172','\133','\134','\135','\136','\137',
          '\140','\141','\142','\143','\144','\145','\146','\147',
          '\150','\151','\152','\153','\154','\155','\156','\157',
          '\160','\161','\162','\163','\164','\165','\166','\167',
          '\170','\171','\172','\173','\174','\175','\176','\177' };

    /* ------------------------------------------------------------ */
    /**
     * fast lower case conversion. Only works on ascii (not unicode)
     * @author Jesper Jørgensen, Caput
     * @param s the string to convert
     * @return a lower case version of s
     */
    public static String asciiToLowerCase(String s)
    {
        char[] c = s.toCharArray();
        for(int i=c.length;i-->0;)
        {
            if(c[i]<=127)
                c[i] = lowercases[c[i]];
        }
        return(new String(c));
    }
    
    /* ------------------------------------------------------------ */
    /**
     * returns the next index of a character from the chars string
     */
    public static int indexFrom(String s,String chars)
    {
        for (int i=0;i<s.length();i++)
           if (chars.indexOf(s.charAt(i))>=0)
              return i;
        return -1;
    }


    /* ------------------------------------------------------------ */
    /**
     * replace substrings within string.
     */
    public static String replace(String s, String sub, String with)
    {
        int c=0;
        int i=s.indexOf(sub,c);
        if (i == -1)
            return s;
    
        StringBuffer buf = new StringBuffer(s.length()+with.length());

        synchronized(buf)
        {
            do
            {
                buf.append(s.substring(c,i));
                buf.append(with);
                c=i+sub.length();
            } while ((i=s.indexOf(sub,c))!=-1);
            
            if (c<s.length())
                buf.append(s.substring(c,s.length()));
            
            return buf.toString();
        }
    }

    /* ------------------------------------------------------------ */
    /** Remove single or double quotes. 
     * @param s 
     * @return 
     */
    public static String unquote(String s)
    {
        if ((s.startsWith("\"") && s.endsWith("\"")) ||
            (s.startsWith("'") && s.endsWith("'")))
            s=s.substring(1,s.length()-1);
        return s;
    }


    /* ------------------------------------------------------------ */
    /** Append substring to StringBuffer 
     * @param buf StringBuffer to append to
     * @param s String to append from
     * @param offset The offset of the substring
     * @param length The length of the substring
     */
    public static void append(StringBuffer buf,
                              String s,
                              int offset,
                              int length)
    {
        synchronized(buf)
        {
            int end=offset+length;
            for (int i=offset; i<end;i++)
            {
                if (i>=s.length())
                    break;
                buf.append(s.charAt(i));
            }
        }
    }

    /* ------------------------------------------------------------ */
    /** Return a non null string.
     * @param s String
     * @return The string passed in or empty string if it is null. 
     */
    public static String nonNull(String s)
    {
        if (s==null)
            return "";
        return s;
    }
    
}