/*
* 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: UnionPathExpr.java 468650 2006-10-28 07:03:30Z minchau $
*/
package org.apache.xalan.xsltc.compiler;
import java.util.Vector;
import org.apache.bcel.generic.ConstantPoolGen;
import org.apache.bcel.generic.INVOKEINTERFACE;
import org.apache.bcel.generic.INVOKESPECIAL;
import org.apache.bcel.generic.INVOKEVIRTUAL;
import org.apache.bcel.generic.InstructionList;
import org.apache.bcel.generic.NEW;
import org.apache.xalan.xsltc.compiler.util.ClassGenerator;
import org.apache.xalan.xsltc.compiler.util.MethodGenerator;
import org.apache.xalan.xsltc.compiler.util.Type;
import org.apache.xalan.xsltc.compiler.util.TypeCheckError;
import org.apache.xml.dtm.Axis;
import org.apache.xml.dtm.DTM;
/**
* @author Jacek Ambroziak
* @author Santiago Pericas-Geertsen
*/
final class UnionPathExpr extends Expression {
private final Expression _pathExpr;
private final Expression _rest;
private boolean _reverse = false;
// linearization for top level UnionPathExprs
private Expression[] _components;
public UnionPathExpr(Expression pathExpr, Expression rest) {
_pathExpr = pathExpr;
_rest = rest;
}
public void setParser(Parser parser) {
super.setParser(parser);
// find all expressions in this Union
final Vector components = new Vector();
flatten(components);
final int size = components.size();
_components = (Expression[])components.toArray(new Expression[size]);
for (int i = 0; i < size; i++) {
_components[i].setParser(parser);
_components[i].setParent(this);
if (_components[i] instanceof Step) {
final Step step = (Step)_components[i];
final int axis = step.getAxis();
final int type = step.getNodeType();
// Put attribute iterators first
if ((axis == Axis.ATTRIBUTE) || (type == DTM.ATTRIBUTE_NODE)) {
_components[i] = _components[0];
_components[0] = step;
}
// Check if the union contains a reverse iterator
if (Axis.isReverse(axis)) _reverse = true;
}
}
// No need to reverse anything if another expression lies on top of this
if (getParent() instanceof Expression) _reverse = false;
}
public Type typeCheck(SymbolTable stable) throws TypeCheckError {
final int length = _components.length;
for (int i = 0; i < length; i++) {
if (_components[i].typeCheck(stable) != Type.NodeSet) {
_components[i] = new CastExpr(_components[i], Type.NodeSet);
}
}
return _type = Type.NodeSet;
}
public String toString() {
return "union(" + _pathExpr + ", " + _rest + ')';
}
private void flatten(Vector components) {
components.addElement(_pathExpr);
if (_rest != null) {
if (_rest instanceof UnionPathExpr) {
((UnionPathExpr)_rest).flatten(components);
}
else {
components.addElement(_rest);
}
}
}
public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
final ConstantPoolGen cpg = classGen.getConstantPool();
final InstructionList il = methodGen.getInstructionList();
final int init = cpg.addMethodref(UNION_ITERATOR_CLASS,
"<init>",
"("+DOM_INTF_SIG+")V");
final int iter = cpg.addMethodref(UNION_ITERATOR_CLASS,
ADD_ITERATOR,
ADD_ITERATOR_SIG);
// Create the UnionIterator and leave it on the stack
il.append(new NEW(cpg.addClass(UNION_ITERATOR_CLASS)));
il.append(DUP);
il.append(methodGen.loadDOM());
il.append(new INVOKESPECIAL(init));
// Add the various iterators to the UnionIterator
final int length = _components.length;
for (int i = 0; i < length; i++) {
_components[i].translate(classGen, methodGen);
il.append(new INVOKEVIRTUAL(iter));
}
// Order the iterator only if strictly needed
if (_reverse) {
final int order = cpg.addInterfaceMethodref(DOM_INTF,
ORDER_ITERATOR,
ORDER_ITERATOR_SIG);
il.append(methodGen.loadDOM());
il.append(SWAP);
il.append(methodGen.loadContextNode());
il.append(new INVOKEINTERFACE(order, 3));
}
}
}