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Java > Open Source Codes > org > apache > commons > jxpath > ri > compiler > CoreOperationUnion


1 /*
2  * Copyright 2002-2004 The Apache Software Foundation
3  *
4  * Licensed under the Apache 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.apache.org/licenses/LICENSE-2.0
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.apache.commons.jxpath.ri.compiler;
17
18 import org.apache.commons.jxpath.ri.EvalContext;
19 import org.apache.commons.jxpath.ri.axes.UnionContext;
20
21 /**
22  * Implementation of Expression for the operation "|".
23  *
24  * @author Dmitri Plotnikov
25  * @version $Revision: 1.3 $ $Date: 2004/02/29 14:17:39 $
26  */
27 public class CoreOperationUnion extends CoreOperation {
28
29     public CoreOperationUnion(Expression args[]) {
30         super(args);
31     }
32
33     public Object JavaDoc computeValue(EvalContext context) {
34         EvalContext argCtxs[] = new EvalContext[args.length];
35         for (int i = 0; i < args.length; i++) {
36             Object JavaDoc value = args[i].compute(context);
37             if (value instanceof EvalContext) {
38                 argCtxs[i] = (EvalContext) value;
39             }
40             else {
41                 argCtxs[i] = context.getRootContext().getConstantContext(value);
42             }
43         }
44         return new UnionContext(context.getRootContext(), argCtxs);
45     }
46     
47     protected int getPrecedence() {
48         return 7;
49     }
50
51     protected boolean isSymmetric() {
52         return true;
53     }
54     
55     public String JavaDoc getSymbol() {
56         return "|";
57     }
58 }
59
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