01: /**********************************************************************
02: Copyright (c) 2002 Mike Martin (TJDO) and others. All rights reserved.
03: Licensed under the Apache License, Version 2.0 (the "License");
04: you may not use this file except in compliance with the License.
05: You may obtain a copy of the License at
06:
07: http://www.apache.org/licenses/LICENSE-2.0
08:
09: Unless required by applicable law or agreed to in writing, software
10: distributed under the License is distributed on an "AS IS" BASIS,
11: WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12: See the License for the specific language governing permissions and
13: limitations under the License.
14:
15: Contributors:
16: 2003 Andy Jefferson - coding standards
17: 2008 Andy Jefferson - support for not()
18: ...
19: **********************************************************************/package org.jpox.store.expression;
20:
21: /**
22: * Representation of a Null comparison in a Query.
23: *
24: * @version $Revision: 1.4 $
25: **/
26: class NullComparisonExpression extends BooleanExpression {
27: private ScalarExpression expr;
28: private boolean equalityTest;
29: private NullLiteral lit;
30:
31: /**
32: * Creates comparison from a scalar expression, <code>expr</code>, and a null literal, <code>lit</code>.
33: * @param expr the ScalarExpression comparing to null
34: * @param equalityTest whether is comparing using equality operations
35: * @param lit the null literal
36: */
37: public NullComparisonExpression(ScalarExpression expr,
38: boolean equalityTest, NullLiteral lit) {
39: super (expr, equalityTest ? OP_IS : OP_ISNOT, lit);
40:
41: this .expr = expr;
42: this .equalityTest = equalityTest;
43: this .lit = lit;
44: }
45:
46: public BooleanExpression not() {
47: return new NullComparisonExpression(expr, !equalityTest, lit);
48: }
49: }
|