/*
* Copyright 2001-2005 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: FilterExpr.java,v 1.12 2005/06/30 21:04:16 zongaro Exp $
*/
package org.apache.xalan.xsltc.compiler;
import java.util.Vector;
import org.apache.bcel.generic.ALOAD;
import org.apache.bcel.generic.ASTORE;
import org.apache.bcel.generic.ConstantPoolGen;
import org.apache.bcel.generic.NEW;
import org.apache.bcel.generic.INVOKEINTERFACE;
import org.apache.bcel.generic.INVOKESPECIAL;
import org.apache.bcel.generic.INVOKESTATIC;
import org.apache.bcel.generic.InstructionList;
import org.apache.bcel.generic.LocalVariableGen;
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.NodeSetType;
import org.apache.xalan.xsltc.compiler.util.ReferenceType;
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
*/
class FilterExpr extends Expression {
/**
* Primary expression of this filter. I.e., 'e' in '(e)[p1]...[pn]'.
*/
private Expression _primary;
/**
* Array of predicates in '(e)[p1]...[pn]'.
*/
private final Vector _predicates;
public FilterExpr(Expression primary, Vector predicates) {
_primary = primary;
_predicates = predicates;
primary.setParent(this);
}
protected Expression getExpr() {
if (_primary instanceof CastExpr)
return ((CastExpr)_primary).getExpr();
else
return _primary;
}
public void setParser(Parser parser) {
super.setParser(parser);
_primary.setParser(parser);
if (_predicates != null) {
final int n = _predicates.size();
for (int i = 0; i < n; i++) {
final Expression exp = (Expression)_predicates.elementAt(i);
exp.setParser(parser);
exp.setParent(this);
}
}
}
public String toString() {
return "filter-expr(" + _primary + ", " + _predicates + ")";
}
/**
* Type check a FilterParentPath. If the filter is not a node-set add a
* cast to node-set only if it is of reference type. This type coercion
* is needed for expressions like $x where $x is a parameter reference.
* All optimizations are turned off before type checking underlying
* predicates.
*/
public Type typeCheck(SymbolTable stable) throws TypeCheckError {
Type ptype = _primary.typeCheck(stable);
if (ptype instanceof NodeSetType == false) {
if (ptype instanceof ReferenceType) {
_primary = new CastExpr(_primary, Type.NodeSet);
}
else {
throw new TypeCheckError(this);
}
}
// Type check predicates and turn all optimizations off
int n = _predicates.size();
for (int i = 0; i < n; i++) {
Predicate pred = (Predicate) _predicates.elementAt(i);
pred.dontOptimize();
pred.typeCheck(stable);
}
return _type = Type.NodeSet;
}
/**
* Translate a filter expression by pushing the appropriate iterator
* onto the stack.
*/
public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
if (_predicates.size() > 0) {
translatePredicates(classGen, methodGen);
}
else {
_primary.translate(classGen, methodGen);
}
}
/**
* Translate a sequence of predicates. Each predicate is translated
* by constructing an instance of <code>CurrentNodeListIterator</code>
* which is initialized from another iterator (recursive call), a
* filter and a closure (call to translate on the predicate) and "this".
*/
public void translatePredicates(ClassGenerator classGen,
MethodGenerator methodGen) {
final ConstantPoolGen cpg = classGen.getConstantPool();
final InstructionList il = methodGen.getInstructionList();
// If not predicates left, translate primary expression
if (_predicates.size() == 0) {
translate(classGen, methodGen);
}
else {
// Translate predicates from right to left
final int initCNLI = cpg.addMethodref(CURRENT_NODE_LIST_ITERATOR,
"<init>",
"("+NODE_ITERATOR_SIG+"Z"+
CURRENT_NODE_LIST_FILTER_SIG +
NODE_SIG+TRANSLET_SIG+")V");
// Backwards branches are prohibited if an uninitialized object is
// on the stack by section 4.9.4 of the JVM Specification, 2nd Ed.
// We don't know whether this code might contain backwards branches,
// so we mustn't create the new object until after we've created
// the suspect arguments to its constructor. Instead we calculate
// the values of the arguments to the constructor first, store them
// in temporary variables, create the object and reload the
// arguments from the temporaries to avoid the problem.
// Remove the next predicate to be translated
Predicate predicate = (Predicate)_predicates.lastElement();
_predicates.remove(predicate);
// Translate the rest of the predicates from right to left
translatePredicates(classGen, methodGen);
LocalVariableGen nodeIteratorTemp =
methodGen.addLocalVariable("filter_expr_tmp1",
Util.getJCRefType(NODE_ITERATOR_SIG),
il.getEnd(), null);
il.append(new ASTORE(nodeIteratorTemp.getIndex()));
predicate.translate(classGen, methodGen);
LocalVariableGen filterTemp =
methodGen.addLocalVariable("filter_expr_tmp2",
Util.getJCRefType(CURRENT_NODE_LIST_FILTER_SIG),
il.getEnd(), null);
il.append(new ASTORE(filterTemp.getIndex()));
// Create a CurrentNodeListIterator
il.append(new NEW(cpg.addClass(CURRENT_NODE_LIST_ITERATOR)));
il.append(DUP);
// Initialize CurrentNodeListIterator
il.append(new ALOAD(nodeIteratorTemp.getIndex()));
il.append(ICONST_1);
il.append(new ALOAD(filterTemp.getIndex()));
il.append(methodGen.loadCurrentNode());
il.append(classGen.loadTranslet());
il.append(new INVOKESPECIAL(initCNLI));
}
}
}