/*
 * TranslateFunction.java
 * Copyright (C) 2004 The Free Software Foundation
 * 
 * This file is part of GNU JAXP, a library.
 *
 * GNU JAXP 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.
 * 
 * GNU JAXP 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Linking this library statically or dynamically with other modules is
 * making a combined work based on this library.  Thus, the terms and
 * conditions of the GNU General Public License cover the whole
 * combination.
 *
 * As a special exception, the copyright holders of this library give you
 * permission to link this library with independent modules to produce an
 * executable, regardless of the license terms of these independent
 * modules, and to copy and distribute the resulting executable under
 * terms of your choice, provided that you also meet, for each linked
 * independent module, the terms and conditions of the license of that
 * module.  An independent module is a module which is not derived from
 * or based on this library.  If you modify this library, you may extend
 * this exception to your version of the library, but you are not
 * obliged to do so.  If you do not wish to do so, delete this
 * exception statement from your version. 
 */

package gnu.xml.xpath;

import java.util.List;
import org.w3c.dom.Node;

/**
 * The <code>translate</code> function returns the first argument string
 * with occurrences of characters in the second argument string replaced by
 * the character at the corresponding position in the third argument string.
 * For example, translate("bar","abc","ABC") returns the string BAr. If
 * there is a character in the second argument string with no character at a
 * corresponding position in the third argument string (because the second
 * argument string is longer than the third argument string), then
 * occurrences of that character in the first argument string are removed.
 * For example, translate("--aaa--","abc-","ABC") returns "AAA". If a
 * character occurs more than once in the second argument string, then the
 * first occurrence determines the replacement character. If the third
 * argument string is longer than the second argument string, then excess
 * characters are ignored.
 *
 * @author <a href='mailto:dog@gnu.org'>Chris Burdess</a>
 */
final class TranslateFunction
  extends Expr
{

  final Expr arg1;
  final Expr arg2;
  final Expr arg3;

  TranslateFunction(List args)
  {
    this((Expr) args.get(0), (Expr) args.get(1), (Expr) args.get(2));
  }

  TranslateFunction(Expr arg1, Expr arg2, Expr arg3)
  {
    this.arg1 = arg1;
    this.arg2 = arg2;
    this.arg3 = arg3;
  }

  public Object evaluate(Node context, int pos, int len)
  {
    Object val1 = arg1.evaluate(context, pos, len);
    Object val2 = arg2.evaluate(context, pos, len);
    Object val3 = arg3.evaluate(context, pos, len);
    String string = _string(context, val1);
    String search = _string(context, val2);
    String replace = _string(context, val3);
    StringBuffer buf = new StringBuffer();
    int l1 = string.length();
    int l2 = search.length();
    int l3 = replace.length();
    for (int i = 0; i < l1; i++)
      {
        char c = string.charAt(i);
        boolean replaced = false;
        for (int j = 0; j < l2; j++)
          {
            if (c == search.charAt(j))
              {
                if (j < l3)
                  {
                    buf.append(replace.charAt(j));
                  }
                replaced = true;
              }
          }
        if (!replaced)
          {
            buf.append(c);
          } 
      } 
    return new String(buf);
  }

  public Expr clone(Object context)
  {
    return new TranslateFunction(arg1.clone(context), arg2.clone(context),
                                 arg3.clone(context));
  }
  
  public String toString()
  {
    return "translate(" + arg1 + "," + arg2 + "," + arg3 + ")";
  }
  
}
