/*
* @(#)$Id: Variable.java,v 1.21 2001/10/30 08:42:55 morten Exp $
*
* The Apache Software License, Version 1.1
*
*
* Copyright (c) 2001 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution,
* if any, must include the following acknowledgment:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowledgment may appear in the software itself,
* if and wherever such third-party acknowledgments normally appear.
*
* 4. The names "Xalan" and "Apache Software Foundation" must
* not be used to endorse or promote products derived from this
* software without prior written permission. For written
* permission, please contact apache@apache.org.
*
* 5. Products derived from this software may not be called "Apache",
* nor may "Apache" appear in their name, without prior written
* permission of the Apache Software Foundation.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation and was
* originally based on software copyright (c) 2001, Sun
* Microsystems., http://www.sun.com. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*
* @author Jacek Ambroziak
* @author Santiago Pericas-Geertsen
* @author Morten Jorgensen
* @author Erwin Bolwidt <ejb@klomp.org>
* @author John Howard <JohnH@schemasoft.com>
*
*/
package org.apache.xalan.xsltc.compiler;
import java.util.Vector;
import org.apache.xalan.xsltc.compiler.util.Type;
import de.fub.bytecode.generic.Instruction;
import de.fub.bytecode.generic.*;
import de.fub.bytecode.classfile.Field;
import org.apache.xalan.xsltc.compiler.util.*;
import org.apache.xalan.xsltc.dom.Axis;
final class Variable extends VariableBase {
// Index of this variable in the variable stack relative to base ptr
private int _stackIndex = -1;
private boolean _escapes; // 'true' if the variable's value can change
/**
* This method returns 'true' if the variable value can change over time,
* such as with varibles inside a for-each loop.
*/
public void setEscapes() {
_escapes = true;
if (_stackIndex == -1) { // unassigned
Template template = getTemplate();
if (template != null) {
_stackIndex = template.allocateIndex(_name);
}
}
}
/**
*
*/
public int getStackIndex() {
return _stackIndex;
}
/**
* 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(_name.getLocalPart(),
_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();
final String name = getVariable();
// Make sure that a variable instance is only compiled once
if (_ignore) return;
_ignore = true;
if (isLocal()) {
// Push args to call addVariable()
if (_escapes) {
il.append(classGen.loadTranslet());
il.append(new PUSH(cpg, _stackIndex));
}
// Compile variable value computation
translateValue(classGen, methodGen);
// Dup value only when needed
if (_escapes) {
il.append(_type.DUP());
}
// Add a new local variable and store value
if (_refs.isEmpty()) { // Remove it if nobody uses the value
il.append(_type.POP());
_local = null;
}
else { // Store in local var slot if referenced
if (_local == null) mapRegister(methodGen);
il.append(_type.STORE(_local.getIndex()));
}
// Store boxed value into the template's variable stack
if (_escapes) {
_type.translateBox(classGen, methodGen);
il.append(new INVOKEVIRTUAL(cpg.addMethodref(TRANSLET_CLASS,
ADD_VARIABLE,
ADD_VARIABLE_SIG)));
}
}
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)));
}
}
}
}