/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 468650 2006-10-28 07:03:30Z minchau $
*/
package org.apache.xalan.xsltc.compiler;
import java.util.Enumeration;
import java.util.Vector;
import org.apache.bcel.generic.BranchHandle;
import org.apache.bcel.generic.ConstantPoolGen;
import org.apache.bcel.generic.GOTO;
import org.apache.bcel.generic.IFGT;
import org.apache.bcel.generic.InstructionHandle;
import org.apache.bcel.generic.InstructionList;
import org.apache.xalan.xsltc.compiler.util.ClassGenerator;
import org.apache.xalan.xsltc.compiler.util.ErrorMsg;
import org.apache.xalan.xsltc.compiler.util.MethodGenerator;
import org.apache.xalan.xsltc.compiler.util.NodeSetType;
import org.apache.xalan.xsltc.compiler.util.NodeType;
import org.apache.xalan.xsltc.compiler.util.ReferenceType;
import org.apache.xalan.xsltc.compiler.util.ResultTreeType;
import org.apache.xalan.xsltc.compiler.util.Type;
import org.apache.xalan.xsltc.compiler.util.TypeCheckError;
import org.apache.xalan.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());
// <xsl:sort> 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 <xsl:for-each> 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);
}
}
}
}