/* * Copyright 2001-2004 The Apache Software Foundation. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ /* * $Id: ForEach.java,v 1.19 2004/02/16 22:24:29 minchau Exp $ */ package com.sun.org.apache.xalan.internal.xsltc.compiler; import java.util.Enumeration; import java.util.Vector; import com.sun.org.apache.bcel.internal.generic.BranchHandle; import com.sun.org.apache.bcel.internal.generic.ConstantPoolGen; import com.sun.org.apache.bcel.internal.generic.GOTO; import com.sun.org.apache.bcel.internal.generic.IFGT; import com.sun.org.apache.bcel.internal.generic.InstructionHandle; import com.sun.org.apache.bcel.internal.generic.InstructionList; import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ClassGenerator; import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ErrorMsg; import com.sun.org.apache.xalan.internal.xsltc.compiler.util.MethodGenerator; import com.sun.org.apache.xalan.internal.xsltc.compiler.util.NodeSetType; import com.sun.org.apache.xalan.internal.xsltc.compiler.util.NodeType; import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ReferenceType; import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ResultTreeType; import com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type; import com.sun.org.apache.xalan.internal.xsltc.compiler.util.TypeCheckError; import com.sun.org.apache.xalan.internal.xsltc.compiler.util.Util; /** * @author Jacek Ambroziak * @author Santiago Pericas-Geertsen * @author Morten Jorgensen */ final class ForEach extends Instruction { private Expression _select; private Type _type; public void display(int indent) { indent(indent); Util.println("ForEach"); indent(indent + IndentIncrement); Util.println("select " + _select.toString()); displayContents(indent + IndentIncrement); } public void parseContents(Parser parser) { _select = parser.parseExpression(this, "select", null); parseChildren(parser); // make sure required attribute(s) have been set if (_select.isDummy()) { reportError(this, parser, ErrorMsg.REQUIRED_ATTR_ERR, "select"); } } public Type typeCheck(SymbolTable stable) throws TypeCheckError { _type = _select.typeCheck(stable); if (_type instanceof ReferenceType || _type instanceof NodeType) { _select = new CastExpr(_select, Type.NodeSet); typeCheckContents(stable); return Type.Void; } if (_type instanceof NodeSetType||_type instanceof ResultTreeType) { typeCheckContents(stable); return Type.Void; } throw new TypeCheckError(this); } public void translate(ClassGenerator classGen, MethodGenerator methodGen) { final ConstantPoolGen cpg = classGen.getConstantPool(); final InstructionList il = methodGen.getInstructionList(); // Save current node and current iterator on the stack il.append(methodGen.loadCurrentNode()); il.append(methodGen.loadIterator()); // Collect sort objects associated with this instruction final Vector sortObjects = new Vector(); Enumeration children = elements(); while (children.hasMoreElements()) { final Object child = children.nextElement(); if (child instanceof Sort) { sortObjects.addElement(child); } } if ((_type != null) && (_type instanceof ResultTreeType)) { // Store existing DOM on stack - must be restored when loop is done il.append(methodGen.loadDOM()); // cannot be applied to a result tree - issue warning if (sortObjects.size() > 0) { ErrorMsg msg = new ErrorMsg(ErrorMsg.RESULT_TREE_SORT_ERR,this); getParser().reportError(WARNING, msg); } // Put the result tree on the stack (DOM) _select.translate(classGen, methodGen); // Get an iterator for the whole DOM - excluding the root node _type.translateTo(classGen, methodGen, Type.NodeSet); // Store the result tree as the default DOM il.append(SWAP); il.append(methodGen.storeDOM()); } else { // Compile node iterator if (sortObjects.size() > 0) { Sort.translateSortIterator(classGen, methodGen, _select, sortObjects); } else { _select.translate(classGen, methodGen); } if (_type instanceof ReferenceType == false) { il.append(methodGen.loadContextNode()); il.append(methodGen.setStartNode()); } } // Overwrite current iterator il.append(methodGen.storeIterator()); // Give local variables (if any) default values before starting loop initializeVariables(classGen, methodGen); final BranchHandle nextNode = il.append(new GOTO(null)); final InstructionHandle loop = il.append(NOP); translateContents(classGen, methodGen); nextNode.setTarget(il.append(methodGen.loadIterator())); il.append(methodGen.nextNode()); il.append(DUP); il.append(methodGen.storeCurrentNode()); il.append(new IFGT(loop)); // Restore current DOM (if result tree was used instead for this loop) if ((_type != null) && (_type instanceof ResultTreeType)) { il.append(methodGen.storeDOM()); } // Restore current node and current iterator from the stack il.append(methodGen.storeIterator()); il.append(methodGen.storeCurrentNode()); } /** * The code that is generated by nested for-each loops can appear to some * JVMs as if it is accessing un-initialized variables. We must add some * code that pushes the default variable value on the stack and pops it * into the variable slot. This is done by the Variable.initialize() * method. The code that we compile for this loop looks like this: * * initialize iterator * initialize variables <-- HERE!!! * goto Iterate * Loop: : * : (code for contents) * : * Iterate: node = iterator.next(); * if (node != END) goto Loop */ public void initializeVariables(ClassGenerator classGen, MethodGenerator methodGen) { final int n = elementCount(); for (int i = 0; i < n; i++) { final Object child = getContents().elementAt(i); if (child instanceof Variable) { Variable var = (Variable)child; var.initialize(classGen, methodGen); } } } }