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Java > Open Source Codes > org > apache > xalan > xsltc > compiler > Fallback


1 /*
2  * Copyright 2001-2004 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 /*
17  * $Id: Fallback.java,v 1.7 2004/02/16 22:24:29 minchau Exp $
18  */
19
20 package org.apache.xalan.xsltc.compiler;
21
22 import org.apache.bcel.generic.ConstantPoolGen;
23 import org.apache.bcel.generic.InstructionList;
24 import org.apache.xalan.xsltc.compiler.util.ClassGenerator;
25 import org.apache.xalan.xsltc.compiler.util.MethodGenerator;
26 import org.apache.xalan.xsltc.compiler.util.Type;
27 import org.apache.xalan.xsltc.compiler.util.TypeCheckError;
28
29 /**
30  * @author Morten Jorgensen
31  */
32 final class Fallback extends Instruction {
33
34     private boolean _active = false;
35
36     /**
37      * This element never produces any data on the stack
38      */
39     public Type typeCheck(SymbolTable stable) throws TypeCheckError {
40     if (_active) {
41         return(typeCheckContents(stable));
42     }
43     else {
44         return Type.Void;
45     }
46     }
47
48     /**
49      * Activate this fallback element
50      */
51     public void activate() {
52     _active = true;
53     }
54
55     public String JavaDoc toString() {
56     return("fallback");
57     }
58
59     /**
60      * Parse contents only if this fallback element is put in place of
61      * some unsupported element or non-XSLTC extension element
62      */
63     public void parseContents(Parser parser) {
64     if (_active) parseChildren(parser);
65     }
66
67     /**
68      * Translate contents only if this fallback element is put in place of
69      * some unsupported element or non-XSLTC extension element
70      */
71     public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
72     final ConstantPoolGen cpg = classGen.getConstantPool();
73     final InstructionList il = methodGen.getInstructionList();
74
75     if (_active) translateContents(classGen, methodGen);
76     }
77 }
78
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