/*
* 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: Variable.java,v 1.2.4.1 2005/09/12 11:36:46 pvedula Exp $
*/
package com.sun.org.apache.xalan.internal.xsltc.compiler;
import com.sun.org.apache.bcel.internal.classfile.Field;
import com.sun.org.apache.bcel.internal.generic.ACONST_NULL;
import com.sun.org.apache.bcel.internal.generic.ConstantPoolGen;
import com.sun.org.apache.bcel.internal.generic.DCONST;
import com.sun.org.apache.bcel.internal.generic.ICONST;
import com.sun.org.apache.bcel.internal.generic.InstructionList;
import com.sun.org.apache.bcel.internal.generic.PUTFIELD;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.BooleanType;
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.IntType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.MethodGenerator;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.NodeType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.RealType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.TypeCheckError;
final class Variable extends VariableBase {
public int getIndex() {
return (_local != null) ? _local.getIndex() : -1;
}
/**
* Parse the contents of the variable
*/
public void parseContents(Parser parser) {
// Parse 'name' and 'select' attributes plus parameter contents
super.parseContents(parser);
// Add a ref to this var to its enclosing construct
SyntaxTreeNode parent = getParent();
if (parent instanceof Stylesheet) {
// Mark this as a global variable
_isLocal = false;
// Check if a global variable with this name already exists...
Variable var = parser.getSymbolTable().lookupVariable(_name);
// ...and if it does we need to check import precedence
if (var != null) {
final int us = this.getImportPrecedence();
final int them = var.getImportPrecedence();
// It is an error if the two have the same import precedence
if (us == them) {
final String name = _name.toString();
reportError(this, parser, ErrorMsg.VARIABLE_REDEF_ERR,name);
}
// Ignore this if previous definition has higher precedence
else if (them > us) {
_ignore = true;
return;
}
else {
var.disable();
}
// Add this variable if we have higher precedence
}
((Stylesheet)parent).addVariable(this);
parser.getSymbolTable().addVariable(this);
}
else {
_isLocal = true;
}
}
/**
* Runs a type check on either the variable element body or the
* expression in the 'select' attribute
*/
public Type typeCheck(SymbolTable stable) throws TypeCheckError {
// Type check the 'select' expression if present
if (_select != null) {
_type = _select.typeCheck(stable);
}
// Type check the element contents otherwise
else if (hasContents()) {
typeCheckContents(stable);
_type = Type.ResultTree;
}
else {
_type = Type.Reference;
}
// The return type is void as the variable element does not leave
// anything on the JVM's stack. The '_type' global will be returned
// by the references to this variable, and not by the variable itself.
return Type.Void;
}
/**
* This method is part of a little trick that is needed to use local
* variables inside nested for-each loops. See the initializeVariables()
* method in the ForEach class for an explanation
*/
public void initialize(ClassGenerator classGen, MethodGenerator methodGen) {
final ConstantPoolGen cpg = classGen.getConstantPool();
final InstructionList il = methodGen.getInstructionList();
// This is only done for local variables that are actually used
if (isLocal() && !_refs.isEmpty()) {
// Create a variable slot if none is allocated
if (_local == null) {
_local = methodGen.addLocalVariable2(getEscapedName(),
_type.toJCType(),
il.getEnd());
}
// Push the default value on the JVM's stack
if ((_type instanceof IntType) ||
(_type instanceof NodeType) ||
(_type instanceof BooleanType))
il.append(new ICONST(0)); // 0 for node-id, integer and boolean
else if (_type instanceof RealType)
il.append(new DCONST(0)); // 0.0 for floating point numbers
else
il.append(new ACONST_NULL()); // and 'null' for anything else
il.append(_type.STORE(_local.getIndex()));
}
}
public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
final ConstantPoolGen cpg = classGen.getConstantPool();
final InstructionList il = methodGen.getInstructionList();
// Don't generate code for unreferenced variables
if (_refs.isEmpty()) {
_ignore = true;
}
// Make sure that a variable instance is only compiled once
if (_ignore) return;
_ignore = true;
final String name = getEscapedName();
if (isLocal()) {
// Compile variable value computation
translateValue(classGen, methodGen);
// Add a new local variable and store value
if (_local == null) {
mapRegister(methodGen);
}
il.append(_type.STORE(_local.getIndex()));
}
else {
String signature = _type.toSignature();
// Global variables are store in class fields
if (classGen.containsField(name) == null) {
classGen.addField(new Field(ACC_PUBLIC,
cpg.addUtf8(name),
cpg.addUtf8(signature),
null, cpg.getConstantPool()));
// Push a reference to "this" for putfield
il.append(classGen.loadTranslet());
// Compile variable value computation
translateValue(classGen, methodGen);
// Store the variable in the allocated field
il.append(new PUTFIELD(cpg.addFieldref(classGen.getClassName(),
name, signature)));
}
}
}
}