/*
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 1999 The Apache Software Foundation.  All rights 
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:  
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Xalan" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written 
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation and was
 * originally based on software copyright (c) 1999, Lotus
 * Development Corporation., http://www.lotus.com.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */
package org.apache.xpath.functions;

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.VariableComposeState;
import org.apache.xpath.XPathVisitor;

/**
 * <meta name="usage" content="advanced"/>
 * Base class for functions that accept two arguments.
 */
public class Function2Args extends FunctionOneArg
{

  /** The second argument passed to the function (at index 1).
   *  @serial  */
  Expression m_arg1;

  /**
   * Return the second argument passed to the function (at index 1).
   *
   * @return An expression that represents the second argument passed to the 
   *         function.
   */
  public Expression getArg1()
  {
    return m_arg1;
  }
  
  /**
   * 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).
   */
  public void fixupVariables(VariableComposeState vcs)
  {
    super.fixupVariables(vcs);
    if(null != m_arg1)
      m_arg1.fixupVariables(vcs);
  }


  /**
   * 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 greater than 1.
   */
  public void setArg(Expression arg, int argNum)
          throws WrongNumberArgsException
  {

    // System.out.println("argNum: "+argNum);
    if (argNum == 0)
      super.setArg(arg, argNum);
    else if (1 == argNum)
    {
      m_arg1 = arg;
      arg.exprSetParent(this);
    }
    else
		  reportWrongNumberArgs();
  }

  /**
   * 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
  {
    if (argNum != 2)
      reportWrongNumberArgs();
  }

  /**
   * Constructs and throws a WrongNumberArgException with the appropriate
   * message for this function object.
   *
   * @throws WrongNumberArgsException
   */
  protected void reportWrongNumberArgs() throws WrongNumberArgsException {
      throw new WrongNumberArgsException(XSLMessages.createXPATHMessage("two", null));
  }
  
  /**
   * Tell if this expression or it's subexpressions can traverse outside 
   * the current subtree.
   * 
   * @return true if traversal outside the context node's subtree can occur.
   */
   public boolean canTraverseOutsideSubtree()
   {
    return super.canTraverseOutsideSubtree() 
    ? true : m_arg1.canTraverseOutsideSubtree();
   }
   
  class Arg1Owner implements ExpressionOwner
  {
    /**
     * @see ExpressionOwner#getExpression()
     */
    public Expression getExpression()
    {
      return m_arg1;
    }


    /**
     * @see ExpressionOwner#setExpression(Expression)
     */
    public void setExpression(Expression exp)
    {
    	exp.exprSetParent(Function2Args.this);
    	m_arg1 = exp;
    }
  }

   
  /**
   * @see XPathVisitable#callVisitors(ExpressionOwner, XPathVisitor)
   */
  public void callArgVisitors(XPathVisitor visitor)
  {
  	super.callArgVisitors(visitor);
  	if(null != m_arg1)
  		m_arg1.callVisitors(new Arg1Owner(), visitor);
  }

  /**
   * @see Expression#deepEquals(Expression)
   */
  public boolean deepEquals(Expression expr)
  {
  	if(!super.deepEquals(expr))
  		return false;
  		
  	if(null != m_arg1)
  	{
  		if(null == ((Function2Args)expr).m_arg1)
  			return false;
  			
  		if(!m_arg1.deepEquals(((Function2Args)expr).m_arg1))
  			return false;
  	}
  	else if(null != ((Function2Args)expr).m_arg1)
  		return false;
  		
  	return true;
  }
  
  /** This method returns a child node.  The children are numbered
     from zero, left to right. */
  public ExpressionNode exprGetChild(int i)
  {
  	assertion(i <= 1, "Function2Args only allows index one or less to be accessed at this level!");
  	return (1 == i) ? m_arg1 : super.exprGetChild(i);
  }

  /** Return the number of children the node has. */
  public int exprGetNumChildren()
  {
  	return 2;
  }


}