/*
* reserved comment block
* DO NOT REMOVE OR ALTER!
*/
/*
* 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: Expression.java,v 1.2.4.1 2005/09/01 14:17:51 pvedula Exp $
*/
package com.sun.org.apache.xalan.internal.xsltc.compiler;
import java.util.Vector;
import com.sun.org.apache.bcel.internal.generic.BranchHandle;
import com.sun.org.apache.bcel.internal.generic.ConstantPoolGen;
import com.sun.org.apache.bcel.internal.generic.GOTO_W;
import com.sun.org.apache.bcel.internal.generic.IFEQ;
import com.sun.org.apache.bcel.internal.generic.InstructionHandle;
import com.sun.org.apache.bcel.internal.generic.InstructionList;
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.MethodGenerator;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.MethodType;
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.TypeCheckError;
/**
* @author Jacek Ambroziak
* @author Santiago Pericas-Geertsen
* @author Morten Jorgensen
* @author Erwin Bolwidt <ejb@klomp.org>
*/
abstract class Expression extends SyntaxTreeNode {
/**
* The type of this expression. It is set after calling
* <code>typeCheck()</code>.
*/
protected Type _type;
/**
* Instruction handles that comprise the true list.
*/
protected FlowList _trueList = new FlowList();
/**
* Instruction handles that comprise the false list.
*/
protected FlowList _falseList = new FlowList();
public Type getType() {
return _type;
}
public abstract String toString();
public boolean hasPositionCall() {
return false; // default should be 'false' for StepPattern
}
public boolean hasLastCall() {
return false;
}
/**
* Returns an object representing the compile-time evaluation
* of an expression. We are only using this for function-available
* and element-available at this time.
*/
public Object evaluateAtCompileTime() {
return null;
}
/**
* Type check all the children of this node.
*/
public Type typeCheck(SymbolTable stable) throws TypeCheckError {
return typeCheckContents(stable);
}
/**
* Translate this node into JVM bytecodes.
*/
public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
ErrorMsg msg = new ErrorMsg(ErrorMsg.NOT_IMPLEMENTED_ERR,
getClass(), this);
getParser().reportError(FATAL, msg);
}
/**
* Translate this node into a fresh instruction list.
* The original instruction list is saved and restored.
*/
public final InstructionList compile(ClassGenerator classGen,
MethodGenerator methodGen) {
final InstructionList result, save = methodGen.getInstructionList();
methodGen.setInstructionList(result = new InstructionList());
translate(classGen, methodGen);
methodGen.setInstructionList(save);
return result;
}
/**
* Redefined by expressions of type boolean that use flow lists.
*/
public void translateDesynthesized(ClassGenerator classGen,
MethodGenerator methodGen) {
translate(classGen, methodGen);
if (_type instanceof BooleanType) {
desynthesize(classGen, methodGen);
}
}
/**
* If this expression is of type node-set and it is not a variable
* reference, then call setStartNode() passing the context node.
*/
public void startIterator(ClassGenerator classGen,
MethodGenerator methodGen) {
// Ignore if type is not node-set
if (_type instanceof NodeSetType == false) {
return;
}
// setStartNode() should not be called if expr is a variable ref
Expression expr = this;
if (expr instanceof CastExpr) {
expr = ((CastExpr) expr).getExpr();
}
if (expr instanceof VariableRefBase == false) {
final InstructionList il = methodGen.getInstructionList();
il.append(methodGen.loadContextNode());
il.append(methodGen.setStartNode());
}
}
/**
* Synthesize a boolean expression, i.e., either push a 0 or 1 onto the
* operand stack for the next statement to succeed. Returns the handle
* of the instruction to be backpatched.
*/
public void synthesize(ClassGenerator classGen, MethodGenerator methodGen) {
final ConstantPoolGen cpg = classGen.getConstantPool();
final InstructionList il = methodGen.getInstructionList();
_trueList.backPatch(il.append(ICONST_1));
final BranchHandle truec = il.append(new GOTO_W(null));
_falseList.backPatch(il.append(ICONST_0));
truec.setTarget(il.append(NOP));
}
public void desynthesize(ClassGenerator classGen,
MethodGenerator methodGen) {
final InstructionList il = methodGen.getInstructionList();
_falseList.add(il.append(new IFEQ(null)));
}
public FlowList getFalseList() {
return _falseList;
}
public FlowList getTrueList() {
return _trueList;
}
public void backPatchFalseList(InstructionHandle ih) {
_falseList.backPatch(ih);
}
public void backPatchTrueList(InstructionHandle ih) {
_trueList.backPatch(ih);
}
/**
* Search for a primop in the symbol table that matches the method type
* <code>ctype</code>. Two methods match if they have the same arity.
* If a primop is overloaded then the "closest match" is returned. The
* first entry in the vector of primops that has the right arity is
* considered to be the default one.
*/
public MethodType lookupPrimop(SymbolTable stable, String op,
MethodType ctype) {
MethodType result = null;
final Vector primop = stable.lookupPrimop(op);
if (primop != null) {
final int n = primop.size();
int minDistance = Integer.MAX_VALUE;
for (int i = 0; i < n; i++) {
final MethodType ptype = (MethodType) primop.elementAt(i);
// Skip if different arity
if (ptype.argsCount() != ctype.argsCount()) {
continue;
}
// The first method with the right arity is the default
if (result == null) {
result = ptype; // default method
}
// Check if better than last one found
final int distance = ctype.distanceTo(ptype);
if (distance < minDistance) {
minDistance = distance;
result = ptype;
}
}
}
return result;
}
}