01: /**
02: * Copyright 2006 Webmedia Group Ltd.
03: *
04: * Licensed under the Apache License, Version 2.0 (the "License");
05: * you may not use this file except in compliance with the License.
06: * You may obtain a copy of the License at
07: *
08: * http://www.apache.org/licenses/LICENSE-2.0
09: *
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: **/package org.araneaframework.backend.list.memorybased.expression.compare;
16:
17: import org.araneaframework.backend.list.memorybased.Expression;
18: import org.araneaframework.backend.list.memorybased.ExpressionEvaluationException;
19: import org.araneaframework.backend.list.memorybased.expression.CompositeExpression;
20: import org.araneaframework.backend.list.memorybased.expression.VariableResolver;
21:
22: public class IsNullExpression implements CompositeExpression {
23:
24: private static final long serialVersionUID = 1L;
25:
26: protected Expression expr;
27:
28: public IsNullExpression(Expression expr) {
29: if (expr == null) {
30: throw new IllegalArgumentException(
31: "Expression must be provided");
32: }
33: this .expr = expr;
34: }
35:
36: public Object evaluate(VariableResolver resolver)
37: throws ExpressionEvaluationException {
38: return (this .expr.evaluate(resolver) == null) ? Boolean.TRUE
39: : Boolean.FALSE;
40: }
41:
42: public Expression[] getChildren() {
43: return new Expression[] { this.expr };
44: }
45: }
|