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: FilterParentPath.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.INVOKEVIRTUAL;
030 import org.apache.bcel.generic.InstructionList;
031 import org.apache.bcel.generic.LocalVariableGen;
032 import org.apache.bcel.generic.NEW;
033 import org.apache.xalan.xsltc.compiler.util.ClassGenerator;
034 import org.apache.xalan.xsltc.compiler.util.MethodGenerator;
035 import org.apache.xalan.xsltc.compiler.util.NodeSetType;
036 import org.apache.xalan.xsltc.compiler.util.NodeType;
037 import org.apache.xalan.xsltc.compiler.util.ReferenceType;
038 import org.apache.xalan.xsltc.compiler.util.Type;
039 import org.apache.xalan.xsltc.compiler.util.TypeCheckError;
040 import org.apache.xalan.xsltc.compiler.util.Util;
041
042 /**
043 * @author Jacek Ambroziak
044 * @author Santiago Pericas-Geertsen
045 */
046 final class FilterParentPath extends Expression {
047
048 private Expression _filterExpr;
049 private Expression _path;
050 private boolean _hasDescendantAxis = false;
051
052 public FilterParentPath(Expression filterExpr, Expression path) {
053 (_path = path).setParent(this);
054 (_filterExpr = filterExpr).setParent(this);
055 }
056
057 public void setParser(Parser parser) {
058 super.setParser(parser);
059 _filterExpr.setParser(parser);
060 _path.setParser(parser);
061 }
062
063 public String toString() {
064 return "FilterParentPath(" + _filterExpr + ", " + _path + ')';
065 }
066
067 public void setDescendantAxis() {
068 _hasDescendantAxis = true;
069 }
070
071 /**
072 * Type check a FilterParentPath. If the filter is not a node-set add a
073 * cast to node-set only if it is of reference type. This type coercion is
074 * needed for expressions like $x/LINE where $x is a parameter reference.
075 */
076 public Type typeCheck(SymbolTable stable) throws TypeCheckError {
077 final Type ftype = _filterExpr.typeCheck(stable);
078 if (ftype instanceof NodeSetType == false) {
079 if (ftype instanceof ReferenceType) {
080 _filterExpr = new CastExpr(_filterExpr, Type.NodeSet);
081 }
082 /*
083 else if (ftype instanceof ResultTreeType) {
084 _filterExpr = new CastExpr(_filterExpr, Type.NodeSet);
085 }
086 */
087 else if (ftype instanceof NodeType) {
088 _filterExpr = new CastExpr(_filterExpr, Type.NodeSet);
089 }
090 else {
091 throw new TypeCheckError(this);
092 }
093 }
094
095 // Wrap single node path in a node set
096 final Type ptype = _path.typeCheck(stable);
097 if (!(ptype instanceof NodeSetType)) {
098 _path = new CastExpr(_path, Type.NodeSet);
099 }
100
101 return _type = Type.NodeSet;
102 }
103
104 public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
105 final ConstantPoolGen cpg = classGen.getConstantPool();
106 final InstructionList il = methodGen.getInstructionList();
107 // Create new StepIterator
108 final int initSI = cpg.addMethodref(STEP_ITERATOR_CLASS,
109 "<init>",
110 "("
111 +NODE_ITERATOR_SIG
112 +NODE_ITERATOR_SIG
113 +")V");
114
115 // Backwards branches are prohibited if an uninitialized object is
116 // on the stack by section 4.9.4 of the JVM Specification, 2nd Ed.
117 // We don't know whether this code might contain backwards branches,
118 // so we mustn't create the new object until after we've created
119 // the suspect arguments to its constructor. Instead we calculate
120 // the values of the arguments to the constructor first, store them
121 // in temporary variables, create the object and reload the
122 // arguments from the temporaries to avoid the problem.
123
124 // Recursively compile 2 iterators
125 _filterExpr.translate(classGen, methodGen);
126 LocalVariableGen filterTemp =
127 methodGen.addLocalVariable("filter_parent_path_tmp1",
128 Util.getJCRefType(NODE_ITERATOR_SIG),
129 null, null);
130 filterTemp.setStart(il.append(new ASTORE(filterTemp.getIndex())));
131
132 _path.translate(classGen, methodGen);
133 LocalVariableGen pathTemp =
134 methodGen.addLocalVariable("filter_parent_path_tmp2",
135 Util.getJCRefType(NODE_ITERATOR_SIG),
136 null, null);
137 pathTemp.setStart(il.append(new ASTORE(pathTemp.getIndex())));
138
139 il.append(new NEW(cpg.addClass(STEP_ITERATOR_CLASS)));
140 il.append(DUP);
141 filterTemp.setEnd(il.append(new ALOAD(filterTemp.getIndex())));
142 pathTemp.setEnd(il.append(new ALOAD(pathTemp.getIndex())));
143
144 // Initialize StepIterator with iterators from the stack
145 il.append(new INVOKESPECIAL(initSI));
146
147 // This is a special case for the //* path with or without predicates
148 if (_hasDescendantAxis) {
149 final int incl = cpg.addMethodref(NODE_ITERATOR_BASE,
150 "includeSelf",
151 "()" + NODE_ITERATOR_SIG);
152 il.append(new INVOKEVIRTUAL(incl));
153 }
154
155 SyntaxTreeNode parent = getParent();
156
157 boolean parentAlreadyOrdered =
158 (parent instanceof RelativeLocationPath)
159 || (parent instanceof FilterParentPath)
160 || (parent instanceof KeyCall)
161 || (parent instanceof CurrentCall)
162 || (parent instanceof DocumentCall);
163
164 if (!parentAlreadyOrdered) {
165 final int order = cpg.addInterfaceMethodref(DOM_INTF,
166 ORDER_ITERATOR,
167 ORDER_ITERATOR_SIG);
168 il.append(methodGen.loadDOM());
169 il.append(SWAP);
170 il.append(methodGen.loadContextNode());
171 il.append(new INVOKEINTERFACE(order, 3));
172 }
173 }
174 }