1 /**
2 * Copyright 2005-2012 The Kuali Foundation
3 *
4 * Licensed under the Educational Community License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.opensource.org/licenses/ecl2.php
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16 package org.kuali.rice.krms.framework.engine.expression;
17
18 import org.kuali.rice.krms.api.engine.ExecutionEnvironment;
19 import org.kuali.rice.krms.api.engine.IncompatibleTypeException;
20
21 /**
22 * The {@link Expression} used in construction, will be invoked with the given {@link ExecutionEnvironment}.
23 *
24 * @author Kuali Rice Team (rice.collab@kuali.org)
25 *
26 */
27 public final class BooleanValidatingExpression implements Expression<Boolean> {
28
29 private final Expression<? extends Object> expression;
30
31 /**
32 * Constructor
33 * @param expression {@link Expression} to set the expression to
34 */
35 public BooleanValidatingExpression(Expression<? extends Object> expression) {
36 this.expression = expression;
37 }
38
39 @Override
40 public Boolean invoke(ExecutionEnvironment environment) {
41 Object result = expression.invoke(environment);
42 if (result instanceof Boolean) {
43 return (Boolean)result;
44 }
45 throw new IncompatibleTypeException("Type mismatch when executing expression.", result, Boolean.class);
46 }
47
48 }