| /* |
| * 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; |
| } |
| } |