code: /*
   * 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.xalan.res.XSLMessages;
  import org.apache.xpath.Expression;
  import org.apache.xpath.ExpressionOwner;
  import org.apache.xpath.XPathVisitor;
  
  /**
   * Base class for functions that accept one argument.
   * @xsl.usage advanced
   */
  public class FunctionOneArg extends Function implements ExpressionOwner
  {
      static final long serialVersionUID = -5180174180765609758L;
  
    /** The first argument passed to the function (at index 0).
     *  @serial  */
    Expression m_arg0;
  
    /**
     * Return the first argument passed to the function (at index 0).
     *
     * @return An expression that represents the first argument passed to the 
     *         function.
     */
    public Expression getArg0()
    {
      return m_arg0;
    }
    
    /**
     * 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 0.
     */
    public void setArg(Expression arg, int argNum)
            throws WrongNumberArgsException
    {
  
      if (0 == argNum)
      {
        m_arg0 = 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 != 1)
        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("one", 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 m_arg0.canTraverseOutsideSubtree();
     }
     
    /**
     * 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(java.util.Vector vars, int globalsSize)
    {
      if(null != m_arg0)
        m_arg0.fixupVariables(vars, globalsSize);
    }
    
    /**
     * @see org.apache.xpath.XPathVisitable#callVisitors(ExpressionOwner, XPathVisitor)
     */
    public void callArgVisitors(XPathVisitor visitor)
    {
    	if(null != m_arg0)
    		m_arg0.callVisitors(this, visitor);
    }
  
  
    /**
     * @see ExpressionOwner#getExpression()
     */
    public Expression getExpression()
    {
      return m_arg0;
    }
  
    /**
     * @see ExpressionOwner#setExpression(Expression)
     */
    public void setExpression(Expression exp)
    {
    	exp.exprSetParent(this);
    	m_arg0 = exp;
    }
    
    /**
     * @see Expression#deepEquals(Expression)
     */
    public boolean deepEquals(Expression expr)
    {
    	if(!super.deepEquals(expr))
    		return false;
    		
    	if(null != m_arg0)
    	{
    		if(null == ((FunctionOneArg)expr).m_arg0)
    			return false;
    			
    		if(!m_arg0.deepEquals(((FunctionOneArg)expr).m_arg0))
    			return false;
    	}
    	else if(null != ((FunctionOneArg)expr).m_arg0)
    		return false;
  
    	return true;
    }
  
  
  }
  