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: AbsoluteLocationPath.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.ALOAD;
025 import org.apache.bcel.generic.ASTORE;
026 import org.apache.bcel.generic.ConstantPoolGen;
027 import org.apache.bcel.generic.INVOKEINTERFACE;
028 import org.apache.bcel.generic.INVOKESPECIAL;
029 import org.apache.bcel.generic.InstructionList;
030 import org.apache.bcel.generic.LocalVariableGen;
031 import org.apache.bcel.generic.NEW;
032 import org.apache.xalan.xsltc.compiler.util.ClassGenerator;
033 import org.apache.xalan.xsltc.compiler.util.MethodGenerator;
034 import org.apache.xalan.xsltc.compiler.util.NodeType;
035 import org.apache.xalan.xsltc.compiler.util.Type;
036 import org.apache.xalan.xsltc.compiler.util.TypeCheckError;
037 import org.apache.xalan.xsltc.compiler.util.Util;
038
039 /**
040 * @author Jacek Ambroziak
041 * @author Santiago Pericas-Geertsen
042 */
043 final class AbsoluteLocationPath extends Expression {
044 private Expression _path; // may be null
045
046 public AbsoluteLocationPath() {
047 _path = null;
048 }
049
050 public AbsoluteLocationPath(Expression path) {
051 _path = path;
052 if (path != null) {
053 _path.setParent(this);
054 }
055 }
056
057 public void setParser(Parser parser) {
058 super.setParser(parser);
059 if (_path != null) {
060 _path.setParser(parser);
061 }
062 }
063
064 public Expression getPath() {
065 return(_path);
066 }
067
068 public String toString() {
069 return "AbsoluteLocationPath(" +
070 (_path != null ? _path.toString() : "null") + ')';
071 }
072
073 public Type typeCheck(SymbolTable stable) throws TypeCheckError {
074 if (_path != null) {
075 final Type ptype = _path.typeCheck(stable);
076 if (ptype instanceof NodeType) { // promote to node-set
077 _path = new CastExpr(_path, Type.NodeSet);
078 }
079 }
080 return _type = Type.NodeSet;
081 }
082
083 public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
084 final ConstantPoolGen cpg = classGen.getConstantPool();
085 final InstructionList il = methodGen.getInstructionList();
086 if (_path != null) {
087 final int initAI = cpg.addMethodref(ABSOLUTE_ITERATOR,
088 "<init>",
089 "("
090 + NODE_ITERATOR_SIG
091 + ")V");
092
093 // Compile relative path iterator(s)
094 //
095 // Backwards branches are prohibited if an uninitialized object is
096 // on the stack by section 4.9.4 of the JVM Specification, 2nd Ed.
097 // We don't know whether this code might contain backwards branches,
098 // so we mustn't create the new object until after we've created
099 // this argument to its constructor. Instead we calculate the
100 // value of the argument to the constructor first, store it in
101 // a temporary variable, create the object and reload the argument
102 // from the temporary to avoid the problem.
103 _path.translate(classGen, methodGen);
104 LocalVariableGen relPathIterator
105 = methodGen.addLocalVariable("abs_location_path_tmp",
106 Util.getJCRefType(NODE_ITERATOR_SIG),
107 null, null);
108 relPathIterator.setStart(
109 il.append(new ASTORE(relPathIterator.getIndex())));
110
111 // Create new AbsoluteIterator
112 il.append(new NEW(cpg.addClass(ABSOLUTE_ITERATOR)));
113 il.append(DUP);
114 relPathIterator.setEnd(
115 il.append(new ALOAD(relPathIterator.getIndex())));
116
117 // Initialize AbsoluteIterator with iterator from the stack
118 il.append(new INVOKESPECIAL(initAI));
119 }
120 else {
121 final int gitr = cpg.addInterfaceMethodref(DOM_INTF,
122 "getIterator",
123 "()"+NODE_ITERATOR_SIG);
124 il.append(methodGen.loadDOM());
125 il.append(new INVOKEINTERFACE(gitr, 1));
126 }
127 }
128 }