- /*
- * 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 1.20 2004/02/16 22:24:28 minchau 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;
- }
- }