/*
 * 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: FuncExtFunction.java 468655 2006-10-28 07:12:06Z minchau $
 */
package org.apache.xpath.functions;

import java.util.Vector;

import org.apache.xalan.res.XSLMessages;
import org.apache.xpath.Expression;
import org.apache.xpath.ExpressionNode;
import org.apache.xpath.ExpressionOwner;
import org.apache.xpath.ExtensionsProvider;
import org.apache.xpath.XPathContext;
import org.apache.xpath.XPathVisitor;
import org.apache.xpath.objects.XNull;
import org.apache.xpath.objects.XObject;
import org.apache.xpath.res.XPATHErrorResources;
import org.apache.xpath.res.XPATHMessages;

An object of this class represents an extension call expression.  When
the expression executes, it calls ExtensionsTable#extFunction, and then
converts the result to the appropriate XObject.
@xsl.usage
advanced/**
 * An object of this class represents an extension call expression.  When
 * the expression executes, it calls ExtensionsTable#extFunction, and then
 * converts the result to the appropriate XObject.
 * @xsl.usage advanced
 */
public class FuncExtFunction extends Function
{
    static final long serialVersionUID = 5196115554693708718L;

  
The namespace for the extension function, which should not normally
 be null or empty.
 @serial    
/**
   * The namespace for the extension function, which should not normally
   *  be null or empty.
   *  @serial    
   */
  String m_namespace;

  
The local name of the extension.
 @serial   
/**
   * The local name of the extension.
   *  @serial   
   */
  String m_extensionName;

  
Unique method key, which is passed to ExtensionsTable#extFunction in
 order to allow caching of the method.
 @serial 
/**
   * Unique method key, which is passed to ExtensionsTable#extFunction in
   *  order to allow caching of the method.
   *  @serial 
   */
  Object m_methodKey;

  
Array of static expressions which represent the parameters to the
 function.
 @serial   
/**
   * Array of static expressions which represent the parameters to the
   *  function.
   *  @serial   
   */
  Vector m_argVec = new Vector();

  
This function is used to fixup variables from QNames to stack frame
indexes at stylesheet build time.
Params:
vars – List of QNames that correspond to variables.  This list
should be searched backwards for the first qualified name that
corresponds to the variable reference qname.  The position of the
QName in the vector from the start of the vector will be its position
in the stack frame (but variables above the globalsTop value will need
to be offset to the current stack frame).
NEEDSDOC @param globalsSize/**
   * This function is used to fixup variables from QNames to stack frame
   * indexes at stylesheet build time.
   * @param vars List of QNames that correspond to variables.  This list
   * should be searched backwards for the first qualified name that
   * corresponds to the variable reference qname.  The position of the
   * QName in the vector from the start of the vector will be its position
   * in the stack frame (but variables above the globalsTop value will need
   * to be offset to the current stack frame).
   * NEEDSDOC @param globalsSize
   */
  public void fixupVariables(java.util.Vector vars, int globalsSize)
  {

    if (null != m_argVec)
    {
      int nArgs = m_argVec.size();

      for (int i = 0; i < nArgs; i++)
      {
        Expression arg = (Expression) m_argVec.elementAt(i);

        arg.fixupVariables(vars, globalsSize);
      }
    }
  }
  
  
Return the namespace of the extension function.
Returns:
The namespace of the extension function./**
   * Return the namespace of the extension function.
   *
   * @return The namespace of the extension function.
   */
  public String getNamespace()
  {
    return m_namespace;
  }
  
  
Return the name of the extension function.
Returns:
The name of the extension function./**
   * Return the name of the extension function.
   *
   * @return The name of the extension function.
   */
  public String getFunctionName()
  {
    return m_extensionName;
  }
  
  
Return the method key of the extension function.
Returns:
The method key of the extension function./**
   * Return the method key of the extension function.
   *
   * @return The method key of the extension function.
   */
  public Object getMethodKey()
  {
    return m_methodKey;
  }

  
Return the nth argument passed to the extension function.
Params:
n – The argument number index.
Returns:
The Expression object at the given index./** 
   * Return the nth argument passed to the extension function.
   * 
   * @param n The argument number index.
   * @return The Expression object at the given index.
   */    
  public Expression getArg(int n) {
    if (n >= 0 && n < m_argVec.size())
      return (Expression) m_argVec.elementAt(n);
    else
      return null;
  }

  
Return the number of arguments that were passed
into this extension function.
Returns:
The number of arguments./**
   * Return the number of arguments that were passed
   * into this extension function.
   *
   * @return The number of arguments.
   */    
  public int getArgCount() {
    return m_argVec.size();
  }

  
Create a new FuncExtFunction based on the qualified name of the extension,
and a unique method key.
Params:
namespace – The namespace for the extension function, which should
                 not normally be null or empty.
extensionName – The local name of the extension.
methodKey – Unique method key, which is passed to
                 ExtensionsTable#extFunction in order to allow caching
                 of the method./**
   * Create a new FuncExtFunction based on the qualified name of the extension,
   * and a unique method key.
   *
   * @param namespace The namespace for the extension function, which should
   *                  not normally be null or empty.
   * @param extensionName The local name of the extension.
   * @param methodKey Unique method key, which is passed to
   *                  ExtensionsTable#extFunction in order to allow caching
   *                  of the method.
   */
  public FuncExtFunction(java.lang.String namespace,
                         java.lang.String extensionName, Object methodKey)
  {
    //try{throw new Exception("FuncExtFunction() " + namespace + " " + extensionName);} catch (Exception e){e.printStackTrace();}
    m_namespace = namespace;
    m_extensionName = extensionName;
    m_methodKey = methodKey;
  }

  
Execute the function.  The function must return
a valid object.
Params:
xctxt – The current execution context.
Throws:
TransformerException – 
Returns:
A valid XObject./**
   * 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
  {
    if (xctxt.isSecureProcessing())
      throw new javax.xml.transform.TransformerException(
        XPATHMessages.createXPATHMessage(
          XPATHErrorResources.ER_EXTENSION_FUNCTION_CANNOT_BE_INVOKED,
          new Object[] {toString()}));
      
    XObject result;
    Vector argVec = new Vector();
    int nArgs = m_argVec.size();

    for (int i = 0; i < nArgs; i++)
    {
      Expression arg = (Expression) m_argVec.elementAt(i);
      
      XObject xobj = arg.execute(xctxt);
      /*
       * Should cache the arguments for func:function
       */
      xobj.allowDetachToRelease(false); 
      argVec.addElement(xobj);
    }
    //dml
    ExtensionsProvider extProvider = (ExtensionsProvider)xctxt.getOwnerObject();
    Object val = extProvider.extFunction(this, argVec);

    if (null != val)
    {
      result = XObject.create(val, xctxt);
    }
    else
    {
      result = new XNull();
    }

    return result;
  }

  
Set an argument expression for a function.  This method is called by the
XPath compiler.
Params:
arg – non-null expression that represents the argument.
argNum – The argument number index.
Throws:
WrongNumberArgsException – If the argNum parameter is beyond what
is specified for this function./**
   * Set an argument expression for a function.  This method is called by the
   * XPath compiler.
   *
   * @param arg non-null expression that represents the argument.
   * @param argNum The argument number index.
   *
   * @throws WrongNumberArgsException If the argNum parameter is beyond what
   * is specified for this function.
   */
  public void setArg(Expression arg, int argNum)
          throws WrongNumberArgsException
  {
    m_argVec.addElement(arg);
    arg.exprSetParent(this);
  }

  
Check that the number of arguments passed to this function is correct.
Params:
argNum – The number of arguments that is being passed to the function.
Throws:
WrongNumberArgsException – /**
   * Check that the number of arguments passed to this function is correct.
   *
   *
   * @param argNum The number of arguments that is being passed to the function.
   *
   * @throws WrongNumberArgsException
   */
  public void checkNumberArgs(int argNum) throws WrongNumberArgsException{}


  class ArgExtOwner implements ExpressionOwner
  {
  
    Expression m_exp;
  	
  	ArgExtOwner(Expression exp)
  	{
  		m_exp = exp;
  	}
  	
    
See Also:
getExpression.getExpression()/**
     * @see ExpressionOwner#getExpression()
     */
    public Expression getExpression()
    {
      return m_exp;
    }


    
See Also:
setExpression.setExpression(Expression)/**
     * @see ExpressionOwner#setExpression(Expression)
     */
    public void setExpression(Expression exp)
    {
    	exp.exprSetParent(FuncExtFunction.this);
    	m_exp = exp;
    }
  }
  
  
  
Call the visitors for the function arguments.
/**
   * Call the visitors for the function arguments.
   */
  public void callArgVisitors(XPathVisitor visitor)
  {
      for (int i = 0; i < m_argVec.size(); i++)
      {
         Expression exp = (Expression)m_argVec.elementAt(i);
         exp.callVisitors(new ArgExtOwner(exp), visitor);
      }
    
  }

  
Set the parent node.
For an extension function, we also need to set the parent
node for all argument expressions.
Params:
n – The parent node/**
   * Set the parent node.
   * For an extension function, we also need to set the parent
   * node for all argument expressions.
   * 
   * @param n The parent node
   */
  public void exprSetParent(ExpressionNode n) 
  {
	
    super.exprSetParent(n);
      
    int nArgs = m_argVec.size();

    for (int i = 0; i < nArgs; i++)
    {
      Expression arg = (Expression) m_argVec.elementAt(i);

      arg.exprSetParent(n);
    }		
  }

  
Constructs and throws a WrongNumberArgException with the appropriate
message for this function object.  This class supports an arbitrary
number of arguments, so this method must never be called.
Throws:
WrongNumberArgsException – /**
   * Constructs and throws a WrongNumberArgException with the appropriate
   * message for this function object.  This class supports an arbitrary
   * number of arguments, so this method must never be called.
   *
   * @throws WrongNumberArgsException
   */
  protected void reportWrongNumberArgs() throws WrongNumberArgsException {
    String fMsg = XSLMessages.createXPATHMessage(
        XPATHErrorResources.ER_INCORRECT_PROGRAMMER_ASSERTION,
        new Object[]{ "Programmer's assertion:  the method FunctionMultiArgs.reportWrongNumberArgs() should never be called." });

    throw new RuntimeException(fMsg);
  }
  
  
Return the name of the extesion function in string format
/**
   * Return the name of the extesion function in string format
   */
  public String toString()
  {
    if (m_namespace != null && m_namespace.length() > 0)
      return "{" + m_namespace + "}" + m_extensionName;
    else
      return m_extensionName;
  }  
}