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*
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/*
* $Id: VariableBase.java,v 1.12 2010-11-01 04:34:18 joehw Exp $
*/
package com.sun.org.apache.xalan.internal.xsltc.compiler;
import java.util.Vector;
import com.sun.org.apache.bcel.internal.generic.ConstantPoolGen;
import com.sun.org.apache.bcel.internal.generic.Instruction;
import com.sun.org.apache.bcel.internal.generic.InstructionList;
import com.sun.org.apache.bcel.internal.generic.INVOKESPECIAL;
import com.sun.org.apache.bcel.internal.generic.LocalVariableGen;
import com.sun.org.apache.bcel.internal.generic.NEW;
import com.sun.org.apache.bcel.internal.generic.PUSH;
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.MethodGenerator;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.NodeSetType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.Util;
import com.sun.org.apache.xml.internal.utils.XML11Char;
/**
* @author Jacek Ambroziak
* @author Santiago Pericas-Geertsen
* @author Morten Jorgensen
* @author Erwin Bolwidt
* @author John Howard
*/
class VariableBase extends TopLevelElement {
protected QName _name; // The name of the variable.
protected String _escapedName; // The escaped qname of the variable.
protected Type _type; // The type of this variable.
protected boolean _isLocal; // True if the variable is local.
protected LocalVariableGen _local; // Reference to JVM variable
protected Instruction _loadInstruction; // Instruction to load JVM variable
protected Instruction _storeInstruction; // Instruction to load JVM variable
protected Expression _select; // Reference to variable expression
protected String select; // Textual repr. of variable expr.
// References to this variable (when local)
protected Vector _refs = new Vector(2);
// Dependencies to other variables/parameters (for globals only)
protected Vector _dependencies = null;
// Used to make sure parameter field is not added twice
protected boolean _ignore = false;
/**
* Disable this variable/parameter
*/
public void disable() {
_ignore = true;
}
/**
* Add a reference to this variable. Called by VariableRef when an
* expression contains a reference to this variable.
*/
public void addReference(VariableRefBase vref) {
_refs.addElement(vref);
}
/**
* Remove a reference to this variable. Called by VariableRef when this
* variable goes out of scope.
*/
public void removeReference(VariableRefBase vref) {
_refs.remove(vref);
}
/**
* When a variable is overriden by another, e.g. via xsl:import,
* its references need to be copied or otherwise it may be
* compiled away as dead code. This method can be used for that
* purpose.
*/
public void copyReferences(VariableBase var) {
final int size = _refs.size();
for (int i = 0; i < size; i++) {
var.addReference((VariableRefBase) _refs.get(i));
}
}
/**
* Map this variable to a register
*/
public void mapRegister(MethodGenerator methodGen) {
if (_local == null) {
final InstructionList il = methodGen.getInstructionList();
final String name = getEscapedName(); // TODO: namespace ?
final com.sun.org.apache.bcel.internal.generic.Type varType = _type.toJCType();
_local = methodGen.addLocalVariable2(name, varType, il.getEnd());
}
}
/**
* Remove the mapping of this variable to a register.
* Called when we leave the AST scope of the variable's declaration
*/
public void unmapRegister(MethodGenerator methodGen) {
if (_refs.isEmpty() && (_local != null)) {
_local.setEnd(methodGen.getInstructionList().getEnd());
methodGen.removeLocalVariable(_local);
_refs = null;
_local = null;
}
}
/**
* Returns an instruction for loading the value of this variable onto
* the JVM stack.
*/
public Instruction loadInstruction() {
final Instruction instr = _loadInstruction;
if (_loadInstruction == null) {
_loadInstruction = _type.LOAD(_local.getIndex());
}
return _loadInstruction;
}
/**
* Returns an instruction for storing a value from the JVM stack
* into this variable.
*/
public Instruction storeInstruction() {
final Instruction instr = _storeInstruction;
if (_storeInstruction == null) {
_storeInstruction = _type.STORE(_local.getIndex());
}
return _storeInstruction;
}
/**
* Returns the expression from this variable's select attribute (if any)
*/
public Expression getExpression() {
return(_select);
}
/**
* Display variable as single string
*/
public String toString() {
return("variable("+_name+")");
}
/**
* Display variable in a full AST dump
*/
public void display(int indent) {
indent(indent);
System.out.println("Variable " + _name);
if (_select != null) {
indent(indent + IndentIncrement);
System.out.println("select " + _select.toString());
}
displayContents(indent + IndentIncrement);
}
/**
* Returns the type of the variable
*/
public Type getType() {
return _type;
}
/**
* Returns the name of the variable or parameter as it will occur in the
* compiled translet.
*/
public QName getName() {
return _name;
}
/**
* Returns the escaped qname of the variable or parameter
*/
public String getEscapedName() {
return _escapedName;
}
/**
* Set the name of the variable or paremeter. Escape all special chars.
*/
public void setName(QName name) {
_name = name;
_escapedName = Util.escape(name.getStringRep());
}
/**
* Returns the true if the variable is local
*/
public boolean isLocal() {
return _isLocal;
}
/**
* Parse the contents of the element.
*/
public void parseContents(Parser parser) {
// Get the 'name attribute
String name = getAttribute("name");
if (name.length() > 0) {
if (!XML11Char.isXML11ValidQName(name)) {
ErrorMsg err = new ErrorMsg(ErrorMsg.INVALID_QNAME_ERR, name, this);
parser.reportError(Constants.ERROR, err);
}
setName(parser.getQNameIgnoreDefaultNs(name));
}
else
reportError(this, parser, ErrorMsg.REQUIRED_ATTR_ERR, "name");
// Check whether variable/param of the same name is already in scope
VariableBase other = parser.lookupVariable(_name);
if ((other != null) && (other.getParent() == getParent())) {
reportError(this, parser, ErrorMsg.VARIABLE_REDEF_ERR, name);
}
select = getAttribute("select");
if (select.length() > 0) {
_select = getParser().parseExpression(this, "select", null);
if (_select.isDummy()) {
reportError(this, parser, ErrorMsg.REQUIRED_ATTR_ERR, "select");
return;
}
}
// Children must be parsed first -> static scoping
parseChildren(parser);
}
/**
* Compile the value of the variable, which is either in an expression in
* a 'select' attribute, or in the variable elements body
*/
public void translateValue(ClassGenerator classGen,
MethodGenerator methodGen) {
// Compile expression is 'select' attribute if present
if (_select != null) {
_select.translate(classGen, methodGen);
// Create a CachedNodeListIterator for select expressions
// in a variable or parameter.
if (_select.getType() instanceof NodeSetType) {
final ConstantPoolGen cpg = classGen.getConstantPool();
final InstructionList il = methodGen.getInstructionList();
final int initCNI = cpg.addMethodref(CACHED_NODE_LIST_ITERATOR_CLASS,
"",
"("
+NODE_ITERATOR_SIG
+")V");
il.append(new NEW(cpg.addClass(CACHED_NODE_LIST_ITERATOR_CLASS)));
il.append(DUP_X1);
il.append(SWAP);
il.append(new INVOKESPECIAL(initCNI));
}
_select.startIterator(classGen, methodGen);
}
// If not, compile result tree from parameter body if present.
else if (hasContents()) {
compileResultTree(classGen, methodGen);
}
// If neither are present then store empty string in variable
else {
final ConstantPoolGen cpg = classGen.getConstantPool();
final InstructionList il = methodGen.getInstructionList();
il.append(new PUSH(cpg, Constants.EMPTYSTRING));
}
}
}