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 * Licensed to the Apache Software Foundation (ASF) under one or more
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 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
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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/**
 * 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 FunctionTable, but may be a value installed by an external module. /** 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.   /** 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'.
Returns:
The class name of the {com.sun.org.apache.xpath.internal.functions.Function} class./**
   * 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
Params:
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'.
funcID –  The function ID, which may correspond to one of the FUNC_XXX values found in FunctionTable, but may be a value installed by an external module./**
   * 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.
Throws:
TransformerException – if ClassNotFoundException,
   IllegalAccessException, or InstantiationException is thrown.
Returns:
non-null reference to Function derivative./**
   * 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());
    }
  }
}