From: Karl Lieberherr [lieber@ccs.neu.edu]
Sent: Monday, June 27, 2005 2:37 PM
To: ydu@ccs.neu.edu; Jingsong Feng (jingsong@ccs.neu.edu);
jpalm@ccs.neu.edu; lieber@ccs.neu.edu; Pengcheng Wu; Therapon
Skotiniotis
Subject: display visitor example

Hi Theo:

Do you agree with the Completion and AllCompletion problems as being relevant for aspect interfaces?

-- Karl

Aspect interface study for the display visitor generator in DemeterJ:

We need a traversal that goes to all class definitions.

Aspect interface for: /proj/adaptive/www/software/src/generate/gendisplayvis.beh 

Why is this .beh file an aspect?

Definition:
An aspect is a module whose ad-hoc implementation cuts across multiple components.

Method generateDisplayVisitor. Its ad-hoc implementation would cut across dozens of classes. (Check DemeterJ generated code)

Interface Class Graph:

Program = <classDefs> List(ClassDef).
ClassDef = ClassName <parts> List(Part).
Part = [PartName] ClassName .

PartName = Ident.
ClassName = Ident.

visitor signature:
  before Program
  after Program
  before Classdef
  before Part

strategies:
from Program to {ClassDef, Part}

Important note:
from Program to {Part}
is sufficient because the interface class graph
guarantees that "from Program to Part" has 
"from Program to ClassDef" as a prefix.
(G,s2) is a completion of (G,s1) 
1. if for every path p in the path set
of (G,s1) there is a completion in the path set of (G,s2).

What is the complexity of the Completion decision problem? Given G, s1 and s2: Is (G,s2) a completion of (G,s1)?

What is the complexity of the AllCompletion problem:
Given G and s1, list all strategies s2 so that 
(G,s2) a completion of (G,s1).

In the above example:
"from Program to Part" is a completion of "from Program toClassdef". A strategy and its completion have the same source.

composition example:
Replace 
ClassDef = ClassName List(Part). 
by
ClassDef = Classname ClassParts.
ClassParts : KindA | KindB common List(Part).
KindA = "a".
KindB = "b".

visitor signature:
  before Classdef
   if s1 succeeds ...
   if s2 succeeds ...
    

strategies
s1 = from ClassDef to KindA
s2 = from ClassDef to KindB


Instantiation:
{ Program, ClassDef } {
  traversal allParts(PartVisitor v) { to { Part, RepeatedPart }; }

What is the class graph? See generate.cd.

Mapping:


=================
gentracevis.beh is a little simpler