/*

 * reserved comment block

 * DO NOT REMOVE OR ALTER!

 */

/*

 * Copyright 1999-2004 The Apache Software Foundation.

 *

 * Licensed 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: FuncLoader.java,v 1.1.2.1 2005/08/01 01:30:35 jeffsuttor Exp $

 */

package com.sun.org.apache.xpath.internal.compiler;

import javax.xml.transform.TransformerException;

import com.sun.org.apache.xpath.internal.functions.Function;

import com.sun.org.apache.xalan.internal.utils.ObjectFactory;

import com.sun.org.apache.xalan.internal.utils.ConfigurationError;

/**

 * Lazy load of functions into the function table as needed, so we don't

 * have to load all the functions allowed in XPath and XSLT on startup.

 * @xsl.usage advanced

 */

public class FuncLoader

{

  /** The function ID, which may correspond to one of the FUNC_XXX values

   *  found in {@link com.sun.org.apache.xpath.internal.compiler.FunctionTable}, but may

   *  be a value installed by an external module.  */

  private int m_funcID;

  /** The class name of the function.  Must not be null.   */

  private String m_funcName;

  /**

   * Get the local class name of the function class.  If function name does

   * not have a '.' in it, it is assumed to be relative to

   * 'com.sun.org.apache.xpath.internal.functions'.

   *

   * @return The class name of the {com.sun.org.apache.xpath.internal.functions.Function} class.

   */

  public String getName()

  {

    return m_funcName;

  }

  /**

   * Construct a function loader

   *

   * @param funcName The class name of the {com.sun.org.apache.xpath.internal.functions.Function}

   *             class, which, if it does not have a '.' in it, is assumed to

   *             be relative to 'com.sun.org.apache.xpath.internal.functions'.

   * @param funcID  The function ID, which may correspond to one of the FUNC_XXX

   *    values found in {@link com.sun.org.apache.xpath.internal.compiler.FunctionTable}, but may

   *    be a value installed by an external module.

   */

  public FuncLoader(String funcName, int funcID)

  {

    super();

    m_funcID = funcID;

    m_funcName = funcName;

  }

  /**

   * Get a Function instance that this instance is liaisoning for.

   *

   * @return non-null reference to Function derivative.

   *

   * @throws javax.xml.transform.TransformerException if ClassNotFoundException,

   *    IllegalAccessException, or InstantiationException is thrown.

   */

  Function getFunction() throws TransformerException

  {

    try

    {

      String className = m_funcName;

      if (className.indexOf(".") < 0) {

        className = "com.sun.org.apache.xpath.internal.functions." + className;

      }

      //hack for loading only built-in function classes.

      String subString = className.substring(0,className.lastIndexOf('.'));

      if(!(subString.equals ("com.sun.org.apache.xalan.internal.templates") ||

           subString.equals ("com.sun.org.apache.xpath.internal.functions"))) {

            throw new TransformerException("Application can't install his own xpath function.");

      }

      return (Function) ObjectFactory.newInstance(className, true);

    }

    catch (ConfigurationError e)

    {

      throw new TransformerException(e.getException());

    }

  }

}