/**
    * Copyright 2005-2011 The Kuali Foundation
    *
    * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
    *
   * 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.
   */
  package org.kuali.rice.krms.framework.engine.expression;
  
  import org.kuali.rice.krms.api.engine.ExecutionEnvironment;
  import org.kuali.rice.krms.api.engine.IncompatibleTypeException;
  
  /**
   * TODO... 
   * 
   * @author Kuali Rice Team (rice.collab@kuali.org)
   *
   */
  public final class BooleanValidatingExpression implements Expression<Boolean> {
  
  	private final Expression<? extends Object> expression;
  	
  	public BooleanValidatingExpression(Expression<? extends Object> expression) {
  		this.expression = expression;
  	}
  	
  	public Boolean invoke(ExecutionEnvironment environment) {
  		Object result = expression.invoke(environment);
  		if (result instanceof Boolean) {
  			return (Boolean)result;
  		}
  		throw new IncompatibleTypeException("Type mismatch when executing expression.", result, Boolean.class);
  	}
  	
  }