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The AspectJ weaver introduces advices to java classes
/* *******************************************************************
* Copyright (c) 2002 Palo Alto Research Center, Incorporated (PARC).
* All rights reserved.
* This program and the accompanying materials are made available
* under the terms of the Eclipse Public License v1.0
* which accompanies this distribution and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* PARC initial implementation
* ******************************************************************/
package org.aspectj.weaver.bcel;
import java.lang.reflect.Modifier;
import org.aspectj.apache.bcel.Constants;
import org.aspectj.apache.bcel.generic.InstructionFactory;
import org.aspectj.apache.bcel.generic.InstructionHandle;
import org.aspectj.apache.bcel.generic.InstructionList;
import org.aspectj.apache.bcel.generic.ObjectType;
import org.aspectj.apache.bcel.generic.ReferenceType;
import org.aspectj.apache.bcel.generic.Type;
import org.aspectj.weaver.BCException;
import org.aspectj.weaver.Member;
import org.aspectj.weaver.MemberImpl;
import org.aspectj.weaver.UnresolvedType;
import org.aspectj.weaver.ast.And;
import org.aspectj.weaver.ast.Call;
import org.aspectj.weaver.ast.CallExpr;
import org.aspectj.weaver.ast.Expr;
import org.aspectj.weaver.ast.FieldGet;
import org.aspectj.weaver.ast.FieldGetCall;
import org.aspectj.weaver.ast.HasAnnotation;
import org.aspectj.weaver.ast.IExprVisitor;
import org.aspectj.weaver.ast.ITestVisitor;
import org.aspectj.weaver.ast.Instanceof;
import org.aspectj.weaver.ast.Literal;
import org.aspectj.weaver.ast.Not;
import org.aspectj.weaver.ast.Or;
import org.aspectj.weaver.ast.Test;
import org.aspectj.weaver.ast.Var;
import org.aspectj.weaver.internal.tools.MatchingContextBasedTest;
// we generate right to left, btw.
public final class BcelRenderer implements ITestVisitor, IExprVisitor {
private InstructionList instructions;
private InstructionFactory fact;
private BcelWorld world;
InstructionHandle sk, fk, next = null;
private BcelRenderer(InstructionFactory fact, BcelWorld world) {
super();
this.fact = fact;
this.world = world;
this.instructions = new InstructionList();
}
// ---- renderers
public static InstructionList renderExpr(InstructionFactory fact, BcelWorld world, Expr e) {
BcelRenderer renderer = new BcelRenderer(fact, world);
e.accept(renderer);
return renderer.instructions;
}
public static InstructionList renderExpr(InstructionFactory fact, BcelWorld world, Expr e, Type desiredType) {
BcelRenderer renderer = new BcelRenderer(fact, world);
e.accept(renderer);
InstructionList il = renderer.instructions;
il.append(Utility.createConversion(fact, BcelWorld.makeBcelType(e.getType()), desiredType));
return il;
}
public static InstructionList renderExprs(InstructionFactory fact, BcelWorld world, Expr[] es) {
BcelRenderer renderer = new BcelRenderer(fact, world);
for (int i = es.length - 1; i >= 0; i--) {
es[i].accept(renderer);
}
return renderer.instructions;
}
/*
* Get the instructions representing this test.
*
* @param e test to render
*
* @param sk instructionHandle to jump to if our rendered check succeeds (typically start of advice)
*
* @param fk instructionHandle to jump to if our rendered check fails (typically after end of advice)
*
* @param next instructionHandle that will follow this generated code. Passing in null will generate one unnecessary GOTO
* instruction.
*
* @returns the instruction list representing this expression
*/
public static InstructionList renderTest(InstructionFactory fact, BcelWorld world, Test e, InstructionHandle sk,
InstructionHandle fk, InstructionHandle next) {
BcelRenderer renderer = new BcelRenderer(fact, world);
renderer.recur(e, sk, fk, next);
return renderer.instructions;
}
// ---- recurrers
private void recur(Test e, InstructionHandle sk, InstructionHandle fk, InstructionHandle next) {
this.sk = sk;
this.fk = fk;
this.next = next;
e.accept(this);
}
// ---- test visitors
public void visit(And e) {
InstructionHandle savedFk = fk;
recur(e.getRight(), sk, fk, next);
InstructionHandle ning = instructions.getStart();
recur(e.getLeft(), ning, savedFk, ning);
}
public void visit(Or e) {
InstructionHandle savedSk = sk;
recur(e.getRight(), sk, fk, next);
recur(e.getLeft(), savedSk, instructions.getStart(), instructions.getStart());
}
public void visit(Not e) {
recur(e.getBody(), fk, sk, next);
}
public void visit(Instanceof i) {
instructions.insert(createJumpBasedOnBooleanOnStack());
instructions.insert(Utility.createInstanceof(fact, (ReferenceType) BcelWorld.makeBcelType(i.getType())));
i.getVar().accept(this);
}
public void visit(HasAnnotation hasAnnotation) {
// in Java:
// foo.class.isAnnotationPresent(annotationClass);
// in bytecode:
// ifnull? skip to the end if it is as getClass() will fail (see pr 257833)
// load var onto the stack (done for us later)
// invokevirtual java/lang/Object.getClass:()Ljava/lang/Class
// ldc_w annotationClass
// invokevirtual java/lang/Class.isAnnotationPresent:(Ljava/lang/Class;)Z
InstructionList il = new InstructionList();
// If it is null jump past the advice call
il.append(InstructionFactory.createBranchInstruction(Constants.IFNULL, fk));
// Load up the var again
il.append(((BcelVar) hasAnnotation.getVar()).createLoad(fact));
Member getClass = MemberImpl.method(UnresolvedType.OBJECT, 0, UnresolvedType.JL_CLASS, "getClass", UnresolvedType.NONE);
il.append(Utility.createInvoke(fact, world, getClass));
// aload annotationClass
il.append(fact.createConstant(new ObjectType(hasAnnotation.getAnnotationType().getName())));
// int annClassIndex = fact.getConstantPool().addClass(hasAnnotation.getAnnotationType().getSignature());
// il.append(new LDC_W(annClassIndex));
Member isAnnotationPresent = MemberImpl.method(UnresolvedType.JL_CLASS, 0, UnresolvedType.BOOLEAN, "isAnnotationPresent",
new UnresolvedType[] { UnresolvedType.JL_CLASS });
il.append(Utility.createInvoke(fact, world, isAnnotationPresent));
il.append(createJumpBasedOnBooleanOnStack());
instructions.insert(il);
hasAnnotation.getVar().accept(this);
}
/*
* (non-Javadoc)
*
* @see org.aspectj.weaver.ast.ITestVisitor#visit(org.aspectj.weaver.internal.tools.MatchingContextBasedTest)
*/
public void visit(MatchingContextBasedTest matchingContextTest) {
throw new UnsupportedOperationException("matching context extension not supported in bytecode weaving");
}
private InstructionList createJumpBasedOnBooleanOnStack() {
InstructionList il = new InstructionList();
if (sk == fk) {
// don't bother generating if it doesn't matter
if (sk != next) {
il.insert(InstructionFactory.createBranchInstruction(Constants.GOTO, sk));
}
return il;
}
if (fk == next) {
il.insert(InstructionFactory.createBranchInstruction(Constants.IFNE, sk));
} else if (sk == next) {
il.insert(InstructionFactory.createBranchInstruction(Constants.IFEQ, fk));
} else {
il.insert(InstructionFactory.createBranchInstruction(Constants.GOTO, sk));
il.insert(InstructionFactory.createBranchInstruction(Constants.IFEQ, fk));
}
return il;
}
public void visit(Literal literal) {
if (literal == Literal.FALSE) {
throw new BCException("visiting a false expression");
}
}
public void visit(Call call) {
Member method = call.getMethod();
// assert method.isStatic()
Expr[] args = call.getArgs();
InstructionList callIl = new InstructionList();
for (int i = 0, len = args.length; i < len; i++) {
// XXX only correct for static method calls
Type desiredType = BcelWorld.makeBcelType(method.getParameterTypes()[i]);
Expr arg = args[i];
// if arg is null it is because we couldn't bind it properly, for example see 162135
if (arg == null) {
InstructionList iList = new InstructionList();
iList.append(InstructionFactory.createNull(desiredType));
callIl.append(iList);
} else {
callIl.append(renderExpr(fact, world, arg, desiredType));
}
}
// System.out.println("rendered args: " + callIl);
callIl.append(Utility.createInvoke(fact, world, method));
callIl.append(createJumpBasedOnBooleanOnStack());
instructions.insert(callIl);
}
public void visit(FieldGetCall fieldGetCall) {
Member field = fieldGetCall.getField();
Member method = fieldGetCall.getMethod();
InstructionList il = new InstructionList();
il.append(Utility.createGet(fact, field));
// assert !method.isStatic()
Expr[] args = fieldGetCall.getArgs();
// System.out.println("args: " + Arrays.asList(args));
il.append(renderExprs(fact, world, args));
// System.out.println("rendered args: " + callIl);
il.append(Utility.createInvoke(fact, world, method));
il.append(createJumpBasedOnBooleanOnStack());
instructions.insert(il);
}
// ---- expr visitors
public void visit(Var var) {
BcelVar bvar = (BcelVar) var;
bvar.insertLoad(instructions, fact);
}
public void visit(FieldGet fieldGet) {
Member field = fieldGet.getField();
// assert field.isStatic()
instructions.insert(Utility.createGet(fact, field));
}
public void visit(CallExpr call) {
Member method = call.getMethod();
// assert method.isStatic()
Expr[] args = call.getArgs();
InstructionList callIl = renderExprs(fact, world, args);
callIl.append(Utility.createInvoke(fact, world, method));
instructions.insert(callIl);
}
}