/** Rewrites a field reference to another field access. */
MemberAdapter fieldToField(Field f) {
final String newName = f.getName();
final Type newType = Type.getType(f.getType());
final String newTypeDescriptor = newType.getDescriptor();
final String newTypeInternalName =
isReferenceType(newType) ? newType.getInternalName() : null;
return new MemberAdapter(f) {
@Override
boolean adapt(int opcode, String owner, String name, String desc, MethodVisitor delegate) {
switch (opcode) {
case GETFIELD:
case GETSTATIC:
// rewrite "x.y" to "(T)x.z".
// we'll leave it up to HotSpot to optimize away casts
delegate.visitFieldInsn(opcode, owner, newName, newTypeDescriptor);
Type t = Type.getType(desc);
if (isReferenceType(t)) delegate.visitTypeInsn(CHECKCAST, t.getInternalName());
return true;
case PUTFIELD:
case PUTSTATIC:
// rewrite "x.y=v" to "x.z=(T)v"
if (isReferenceType(newType)) delegate.visitTypeInsn(CHECKCAST, newTypeInternalName);
delegate.visitFieldInsn(opcode, owner, newName, newTypeDescriptor);
return true;
}
return false;
}
};
}
@Override
boolean adapt(int opcode, String owner, String name, String desc, MethodVisitor delegate) {
if (opcode == fieldOpcode) {
Type t = Type.getType(desc);
boolean expectedReference = isReferenceType(t);
if (actuallyPrimitive ^ expectedReference) {
// rewrite "x.y" to "(T)x.z()".
// we'll leave it up to HotSpot to optimize away casts
delegate.visitMethodInsn(invokeOpcode, owner, methodName, methodDescriptor);
if (expectedReference) delegate.visitTypeInsn(CHECKCAST, t.getInternalName());
return true;
}
}
return false;
}
public FieldToMethodAdapter(Method m, int fieldOpcode, int invokeOpcode) {
super(m);
methodName = m.getName();
methodDescriptor = Type.getMethodDescriptor(m);
Class<?>[] params = m.getParameterTypes();
boolean isGetter = params.length == 0;
actuallyPrimitive = isGetter ? m.getReturnType().isPrimitive() : params[0].isPrimitive();
this.fieldOpcode = fieldOpcode;
this.invokeOpcode = invokeOpcode;
}
@Override
boolean adapt(int opcode, String owner, String name, String desc, MethodVisitor delegate) {
if (opcode == fieldOpcode) {
Type t = Type.getType(desc);
boolean expectedReference = isReferenceType(t);
if (actuallyPrimitive ^ expectedReference) {
// rewrite "x.y=v" to "x.z(v)"
// we expect the argument type to match
delegate.visitMethodInsn(invokeOpcode, owner, methodName, methodDescriptor);
return true;
}
}
return false;
}
private static boolean isReferenceType(Type t) {
return t.getSort() == ARRAY || t.getSort() == OBJECT;
}
