/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the  "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id$
 */
package org.apache.xpath.functions;

import org.apache.xpath.XPathContext;
import org.apache.xpath.objects.XObject;
import org.apache.xpath.objects.XString;

/**
 * Execute the SubstringBefore() function.
 * @xsl.usage advanced
 */
public class FuncSubstringBefore extends Function2Args
{
    static final long serialVersionUID = 4110547161672431775L;

  /**
   * Execute the function.  The function must return
   * a valid object.
   * @param xctxt The current execution context.
   * @return A valid XObject.
   *
   * @throws javax.xml.transform.TransformerException
   */
  public XObject execute(XPathContext xctxt) throws javax.xml.transform.TransformerException
  {

    String s1 = m_arg0.execute(xctxt).str();
    String s2 = m_arg1.execute(xctxt).str();
    int index = s1.indexOf(s2);

    return (-1 == index)
           ? XString.EMPTYSTRING : new XString(s1.substring(0, index));
  }
}