001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements. See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership. The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the  "License");
007     * you may not use this file except in compliance with the License.
008     * You may obtain a copy of the License at
009     *
010     *     http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing, software
013     * distributed under the License is distributed on an "AS IS" BASIS,
014     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    /*
019     * $Id: Fallback.java 468650 2006-10-28 07:03:30Z minchau $
020     */
021    
022    package org.apache.xalan.xsltc.compiler;
023    
024    import org.apache.bcel.generic.ConstantPoolGen;
025    import org.apache.bcel.generic.InstructionList;
026    import org.apache.xalan.xsltc.compiler.util.ClassGenerator;
027    import org.apache.xalan.xsltc.compiler.util.MethodGenerator;
028    import org.apache.xalan.xsltc.compiler.util.Type;
029    import org.apache.xalan.xsltc.compiler.util.TypeCheckError;
030    
031    /**
032     * @author Morten Jorgensen
033     */
034    final class Fallback extends Instruction {
035    
036        private boolean _active = false;
037    
038        /**
039         * This element never produces any data on the stack
040         */
041        public Type typeCheck(SymbolTable stable) throws TypeCheckError {
042            if (_active) {
043                return(typeCheckContents(stable));
044            }
045            else {
046                return Type.Void;
047            }
048        }
049    
050        /**
051         * Activate this fallback element
052         */
053        public void activate() {
054            _active = true;
055        }
056    
057        public String toString() {
058            return("fallback");
059        }
060    
061        /**
062         * Parse contents only if this fallback element is put in place of
063         * some unsupported element or non-XSLTC extension element
064         */
065        public void parseContents(Parser parser) {
066            if (_active) parseChildren(parser);
067        }
068    
069        /**
070         * Translate contents only if this fallback element is put in place of
071         * some unsupported element or non-XSLTC extension element
072         */
073        public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
074            final ConstantPoolGen cpg = classGen.getConstantPool();
075            final InstructionList il = methodGen.getInstructionList();
076    
077            if (_active) translateContents(classGen, methodGen);
078        }
079    }