/*
 * 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. 
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 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
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 *    distribution.
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 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:  
 *       "This product includes software developed by the 
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
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 *    Foundation" must not be used to endorse or promote products derived
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 * ====================================================================
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 */ 

package org.jbpm.jpdl.el.impl;

import java.util.List;

import org.jbpm.jpdl.el.ELException;
import org.jbpm.jpdl.el.FunctionMapper;
import org.jbpm.jpdl.el.VariableResolver;

/**
 *
 * <p>An expression representing a binary operator on a value
 * 
 * @author Nathan Abramson - Art Technology Group
 * @author Shawn Bayern
 * @version $Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author$
 **/

public class BinaryOperatorExpression
  extends Expression
{
  //-------------------------------------
  // Properties
  //-------------------------------------
  // property expression

  Expression mExpression;
  public Expression getExpression ()
  { return mExpression; }
  public void setExpression (Expression pExpression)
  { mExpression = pExpression; }

  //-------------------------------------
  // property operators

  List mOperators;
  public List getOperators ()
  { return mOperators; }
  public void setOperators (List pOperators)
  { mOperators = pOperators; }

  //-------------------------------------
  // property expressions

  List mExpressions;
  public List getExpressions ()
  { return mExpressions; }
  public void setExpressions (List pExpressions)
  { mExpressions = pExpressions; }

  //-------------------------------------
  /**
   *
   * Constructor
   **/
  public BinaryOperatorExpression (Expression pExpression,
				   List pOperators,
				   List pExpressions)
  {
    mExpression = pExpression;
    mOperators = pOperators;
    mExpressions = pExpressions;
  }

  //-------------------------------------
  // Expression methods
  //-------------------------------------
  /**
   *
   * Returns the expression in the expression language syntax
   **/
  public String getExpressionString ()
  {
    StringBuffer buf = new StringBuffer ();
    buf.append ("(");
    buf.append (mExpression.getExpressionString ());
    for (int i = 0; i < mOperators.size (); i++) {
      BinaryOperator operator = (BinaryOperator) mOperators.get (i);
      Expression expression = (Expression) mExpressions.get (i);
      buf.append (" ");
      buf.append (operator.getOperatorSymbol ());
      buf.append (" ");
      buf.append (expression.getExpressionString ());
    }
    buf.append (")");

    return buf.toString ();
  }

  //-------------------------------------
  /**
   *
   * Evaluates to the literal value
   **/
  public Object evaluate (VariableResolver pResolver,
			  FunctionMapper functions,
			  Logger pLogger)
    throws ELException
  {
    Object value = mExpression.evaluate (pResolver, functions, pLogger);
    for (int i = 0; i < mOperators.size (); i++) {
      BinaryOperator operator = (BinaryOperator) mOperators.get (i);

      // For the And/Or operators, we need to coerce to a boolean
      // before testing if we shouldEvaluate
      if (operator.shouldCoerceToBoolean ()) {
	value = Coercions.coerceToBoolean (value, pLogger);
      }

      if (operator.shouldEvaluate (value)) {
	Expression expression = (Expression) mExpressions.get (i);
	Object nextValue = expression.evaluate (pResolver,
						functions,
						pLogger);

	value = operator.apply (value, nextValue, pLogger);
      }
    }
    return value;
  }

  //-------------------------------------
}