/FileExtraction/Java_unseen/dlitz_resin/modules/resin/src/com/caucho/jsp/el/ExpressionImpl.java
/*
 * Copyright (c) 1998-2011 Caucho Technology -- all rights reserved
 *
 * This file is part of Resin(R) Open Source
 *
 * Each copy or derived work must preserve the copyright notice and this
 * notice unmodified.
 *
 * Resin Open Source is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * Resin Open Source is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
 * of NON-INFRINGEMENT.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Resin Open Source; if not, write to the
 *   Free SoftwareFoundation, Inc.
 *   59 Temple Place, Suite 330
 *   Boston, MA 02111-1307  USA
 *
 * @author Scott Ferguson
 */

package com.caucho.jsp.el;

import com.caucho.el.Expr;

import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.el.ELException;
import javax.servlet.jsp.el.Expression;
import javax.servlet.jsp.el.VariableResolver;

/**
 * Implementation of the expression evaluator.
 */
public class ExpressionImpl extends Expression {
  private Expr _expr;

  /**
   * Implements the expression.
   */
  ExpressionImpl(Expr expr)
  {
    _expr = expr;
  }
  
  /**
   * Evaluates an expression.
   */
  public Object evaluate(VariableResolver resolver)
    throws ELException
  {
    if (resolver instanceof PageContext)
      return _expr.evalObject(((PageContext) resolver).getELContext());
    else
      return _expr.evalObject(new ELContextAdapter(resolver));
  }
}
