01: /*
02: * Licensed to the Apache Software Foundation (ASF) under one
03: * or more contributor license agreements. See the NOTICE file
04: * distributed with this work for additional information
05: * regarding copyright ownership. The ASF licenses this file
06: * to you under the Apache License, Version 2.0 (the
07: * "License"); you may not use this file except in compliance
08: * with the License. You may obtain a copy of the License at
09: *
10: * http://www.apache.org/licenses/LICENSE-2.0
11: *
12: * Unless required by applicable law or agreed to in writing,
13: * software distributed under the License is distributed on an
14: * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15: * KIND, either express or implied. See the License for the
16: * specific language governing permissions and limitations
17: * under the License.
18: */
19: package org.apache.openjpa.kernel.exps;
20:
21: import java.util.Collection;
22:
23: import org.apache.openjpa.kernel.StoreContext;
24:
25: /**
26: * An in-memory representation of an {@link Expression}.
27: *
28: * @author Abe White
29: */
30: class Exp implements Expression {
31:
32: /**
33: * Evaluate the expression for the given candidate.
34: */
35: public final boolean evaluate(Object candidate, Object orig,
36: StoreContext ctx, Object[] params) {
37: try {
38: return eval(candidate, candidate, ctx, params);
39: } catch (ClassCastException cce) {
40: return false;
41: } catch (NullPointerException npe) {
42: return false;
43: }
44: }
45:
46: /**
47: * Evaluate the expression for the given candidate group.
48: */
49: public final boolean evaluate(Collection candidates,
50: StoreContext ctx, Object[] params) {
51: try {
52: return eval(candidates, ctx, params);
53: } catch (ClassCastException cce) {
54: return false;
55: } catch (NullPointerException npe) {
56: return false;
57: }
58: }
59:
60: /**
61: * Evaluate the expression for the given context candidate and original
62: * candidate.
63: */
64: protected boolean eval(Object candidate, Object orig,
65: StoreContext ctx, Object[] params) {
66: return true;
67: }
68:
69: /**
70: * Evaluate the expression for the given group.
71: */
72: protected boolean eval(Collection candidates, StoreContext ctx,
73: Object[] params) {
74: return true;
75: }
76:
77: public void acceptVisit(ExpressionVisitor visitor) {
78: visitor.enter(this);
79: visitor.exit(this);
80: }
81: }
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