/*
* 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: KeyCall.java,v 1.16 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.BranchHandle;
import org.apache.bcel.generic.ConstantPoolGen;
import org.apache.bcel.generic.GOTO;
import org.apache.bcel.generic.IFGT;
import org.apache.bcel.generic.INVOKEINTERFACE;
import org.apache.bcel.generic.INVOKESPECIAL;
import org.apache.bcel.generic.INVOKEVIRTUAL;
import org.apache.bcel.generic.InstructionHandle;
import org.apache.bcel.generic.InstructionList;
import org.apache.bcel.generic.LocalVariableGen;
import org.apache.bcel.generic.NEW;
import org.apache.bcel.generic.PUSH;
import org.apache.xalan.xsltc.compiler.util.ClassGenerator;
import org.apache.xalan.xsltc.compiler.util.MethodGenerator;
import org.apache.xalan.xsltc.compiler.util.StringType;
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 Morten Jorgensen
* @author Santiago Pericas-Geertsen
*/
final class KeyCall extends FunctionCall {
/**
* The name of the key.
*/
private Expression _name;
/**
* The value to look up in the key/index.
*/
private Expression _value;
/**
* The value's data type.
*/
private Type _valueType; // The value's data type
/**
* Expanded qname when name is literal.
*/
private QName _resolvedQName = null;
/**
* Get the parameters passed to function:
* key(String name, String value)
* key(String name, NodeSet value)
* The 'arguments' vector should contain two parameters for key() calls,
* one holding the key name and one holding the value(s) to look up. The
* vector has only one parameter for id() calls (the key name is always
* "##id" for id() calls).
*
* @param fname The function name (should be 'key' or 'id')
* @param arguments A vector containing the arguments the the function
*/
public KeyCall(QName fname, Vector arguments) {
super(fname, arguments);
switch(argumentCount()) {
case 1:
_name = null;
_value = argument(0);
break;
case 2:
_name = argument(0);
_value = argument(1);
break;
default:
_name = _value = null;
break;
}
}
/**
* Type check the parameters for the id() or key() function.
* The index name (for key() call only) must be a string or convertable
* to a string, and the lookup-value must be a string or a node-set.
* @param stable The parser's symbol table
* @throws TypeCheckError When the parameters have illegal type
*/
public Type typeCheck(SymbolTable stable) throws TypeCheckError {
final Type returnType = super.typeCheck(stable);
// Run type check on the key name (first argument) - must be a string,
// and if it is not it must be converted to one using string() rules.
if (_name != null) {
final Type nameType = _name.typeCheck(stable);
if (_name instanceof LiteralExpr) {
final LiteralExpr literal = (LiteralExpr) _name;
_resolvedQName =
getParser().getQNameIgnoreDefaultNs(literal.getValue());
}
else if (nameType instanceof StringType == false) {
_name = new CastExpr(_name, Type.String);
}
}
// Run type check on the value for this key. This value can be of
// any data type, so this should never cause any type-check errors.
// If the value is not a node-set then it should be converted to a
// string before the lookup is done. If the value is a node-set then
// this process (convert to string, then do lookup) should be applied
// to every node in the set, and the result from all lookups should
// be added to the resulting node-set.
_valueType = _value.typeCheck(stable);
if (_valueType != Type.NodeSet && _valueType != Type.String)
{
_value = new CastExpr(_value, Type.String);
}
return returnType;
}
/**
* This method is called when the constructor is compiled in
* Stylesheet.compileConstructor() and not as the syntax tree is traversed.
* This method is a wrapper for the real translation method, which is
* the private method translateCall() below. All this method does is to
* wrap the KeyIndex that this function returns inside a duplicate filter.
* The duplicate filter is used both to eliminate duplicates and to
* cache the nodes in the index.
* @param classGen The Java class generator
* @param methodGen The method generator
*/
public void translate(ClassGenerator classGen,
MethodGenerator methodGen) {
final ConstantPoolGen cpg = classGen.getConstantPool();
final InstructionList il = methodGen.getInstructionList();
final int getNodeHandle = cpg.addInterfaceMethodref(DOM_INTF,
"getNodeHandle",
"(I)"+NODE_SIG);
// Wrap the KeyIndex (iterator) inside a duplicate filter iterator
// to pre-read the indexed nodes and cache them.
final int dupInit = cpg.addMethodref(DUP_FILTERED_ITERATOR,
"<init>",
"("+NODE_ITERATOR_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.
LocalVariableGen keyIterator = translateCall(classGen, methodGen);
il.append(new NEW(cpg.addClass(DUP_FILTERED_ITERATOR)));
il.append(DUP);
il.append(new ALOAD(keyIterator.getIndex()));
il.append(new INVOKESPECIAL(dupInit));
}
/**
* Translate the actual index lookup - leaves KeyIndex (iterator) stored
* in a temporary that the caller will need to load.
* @param classGen The Java class generator
* @param methodGen The method generator
* @return A <code>org.apache.bcel.generic.LocalVariableGen</code>
* object that will contain the iterator for the key call.
*/
private LocalVariableGen translateCall(ClassGenerator classGen,
MethodGenerator methodGen) {
final ConstantPoolGen cpg = classGen.getConstantPool();
final InstructionList il = methodGen.getInstructionList();
// Returns the string value for a node in the DOM
final int getNodeValue = cpg.addInterfaceMethodref(DOM_INTF,
GET_NODE_VALUE,
"(I)"+STRING_SIG);
// Returns the KeyIndex object of a given name
final int getKeyIndex = cpg.addMethodref(TRANSLET_CLASS,
"getKeyIndex",
"(Ljava/lang/String;)"+
KEY_INDEX_SIG);
// Initialises a KeyIndex to return nodes with specific values
final int lookupId = cpg.addMethodref(KEY_INDEX_CLASS,
"lookupId",
"(Ljava/lang/Object;)V");
final int lookupKey = cpg.addMethodref(KEY_INDEX_CLASS,
"lookupKey",
"(Ljava/lang/Object;)V");
// Merges the nodes in two KeyIndex objects
final int merge = cpg.addMethodref(KEY_INDEX_CLASS,
"merge",
"("+KEY_INDEX_SIG+")V");
// Constructor for KeyIndex class
final int indexConstructor = cpg.addMethodref(TRANSLET_CLASS,
"createKeyIndex",
"()"+KEY_INDEX_SIG);
// KeyIndex.setDom(Dom) => void
final int keyDom = cpg.addMethodref(XSLT_PACKAGE + ".dom.KeyIndex",
"setDom",
"("+DOM_INTF_SIG+")V");
// This local variable holds the index/iterator we will return
final LocalVariableGen returnIndex =
methodGen.addLocalVariable("returnIndex",
Util.getJCRefType(KEY_INDEX_SIG),
il.getEnd(), null);
// This local variable holds the index we're using for search
final LocalVariableGen searchIndex =
methodGen.addLocalVariable("searchIndex",
Util.getJCRefType(KEY_INDEX_SIG),
il.getEnd(), null);
// If the second paramter is a node-set we need to go through each
// node in the set, convert each one to a string and do a look up in
// the named index, and then merge all the resulting node sets.
if (_valueType == Type.NodeSet) {
// Save current node and current iterator on the stack
il.append(methodGen.loadCurrentNode());
il.append(methodGen.loadIterator());
// Get new iterator from 2nd parameter node-set & store in variable
_value.translate(classGen, methodGen);
_value.startIterator(classGen, methodGen);
il.append(methodGen.storeIterator());
// Create the KeyIndex object (the iterator) we'll return
il.append(classGen.loadTranslet());
il.append(new INVOKEVIRTUAL(indexConstructor));
il.append(DUP);
il.append(methodGen.loadDOM());
il.append(new INVOKEVIRTUAL(keyDom));
il.append(new ASTORE(returnIndex.getIndex()));
// Initialise the index specified in the first parameter of key()
il.append(classGen.loadTranslet());
if (_name == null) {
il.append(new PUSH(cpg,"##id"));
}
else if (_resolvedQName != null) {
il.append(new PUSH(cpg, _resolvedQName.toString()));
}
else {
_name.translate(classGen, methodGen);
}
il.append(new INVOKEVIRTUAL(getKeyIndex));
il.append(new ASTORE(searchIndex.getIndex()));
// LOOP STARTS HERE
// Now we're ready to start traversing the node-set given in
// the key() function's second argument....
final BranchHandle nextNode = il.append(new GOTO(null));
final InstructionHandle loop = il.append(NOP);
// Push returnIndex on stack to prepare for call to merge()
il.append(new ALOAD(returnIndex.getIndex()));
// Lookup index using the string value from the current node
il.append(new ALOAD(searchIndex.getIndex()));
il.append(DUP);
il.append(methodGen.loadDOM());
il.append(methodGen.loadCurrentNode());
il.append(new INVOKEINTERFACE(getNodeValue, 2));
if (_name == null) {
il.append(new INVOKEVIRTUAL(lookupId));
}
else {
il.append(new INVOKEVIRTUAL(lookupKey));
}
// Call to returnIndex.merge(searchIndex);
il.append(new INVOKEVIRTUAL(merge));
// Go on with next node in the 2nd parameter node-set
nextNode.setTarget(il.append(methodGen.loadIterator()));
il.append(methodGen.nextNode());
il.append(DUP);
il.append(methodGen.storeCurrentNode());
il.append(new IFGT(loop));
// LOOP ENDS HERE
// Restore current node and current iterator from the stack
il.append(methodGen.storeIterator());
il.append(methodGen.storeCurrentNode());
}
// If the second parameter is a single value we just lookup the named
// index and initialise the iterator to return nodes with this value.
else {
// Call getKeyIndex in AbstractTranslet with the name of the key
// to get the index for this key (which is also a node iterator).
il.append(classGen.loadTranslet());
if (_name == null) {
il.append(new PUSH(cpg,"##id"));
}
else if (_resolvedQName != null) {
il.append(new PUSH(cpg, _resolvedQName.toString()));
}
else {
_name.translate(classGen, methodGen);
}
il.append(new INVOKEVIRTUAL(getKeyIndex));
// Now use the value in the second argument to determine what nodes
// the iterator should return.
il.append(DUP);
_value.translate(classGen, methodGen);
if (_name == null) {
il.append(new INVOKEVIRTUAL(lookupId));
}
else {
il.append(new INVOKEVIRTUAL(lookupKey));
}
il.append(new ASTORE(returnIndex.getIndex()));
}
return returnIndex;
}
}