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package org.apache.taglibs.standard.lang.jstl;

/**
 *
 * <p>The implementation of the or operator
 * 
 * @author Nathan Abramson - Art Technology Group
 * @version $Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: tcfujii $
 **/

public class OrOperator
  extends BinaryOperator
{
  //-------------------------------------
  // Singleton
  //-------------------------------------

  public static final OrOperator SINGLETON =
    new OrOperator ();

  //-------------------------------------
  /**
   *
   * Constructor
   **/
  public OrOperator ()
  {
  }

  //-------------------------------------
  // Expression methods
  //-------------------------------------
  /**
   *
   * Returns the symbol representing the operator
   **/
  public String getOperatorSymbol ()
  {
    return "or";
  }

  //-------------------------------------
  /**
   *
   * Applies the operator to the given value
   **/
  public Object apply (Object pLeft,
		       Object pRight,
		       Object pContext,
		       Logger pLogger)
    throws ELException
  {
    // Coerce the values to booleans
    boolean left = 
      Coercions.coerceToBoolean (pLeft, pLogger).booleanValue ();
    boolean right = 
      Coercions.coerceToBoolean (pRight, pLogger).booleanValue ();

    return PrimitiveObjects.getBoolean (left || right);
  }

  //-------------------------------------
  /**
   *
   * Returns true if evaluation is necessary given the specified Left
   * value.  The And/OrOperators make use of this
   **/
  public boolean shouldEvaluate (Object pLeft)
  {
    return
      (pLeft instanceof Boolean) &&
      ((Boolean) pLeft).booleanValue () == false;
  }

  //-------------------------------------
  /**
   *
   * Returns true if the operator expects its arguments to be coerced
   * to Booleans.  The And/Or operators set this to true.
   **/
  public boolean shouldCoerceToBoolean ()
  {
    return true;
  }

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