Parent fix

[Luke-Michael-Brown]

Changes how the compiler finds parents. Removes the parent map and adds an argument to IClafer.

See i255.

[JLiangWaterloo]

Everything looks fine. Luke, can you clarify what it means to be a parent of a PExp?

For example, here's the model:

A -> int ? [ this.ref = 3 ]

So the parent of the expression "this.ref = 3" should be "A". Is the parent of the subexpression "this.ref" also "A"?

[mantkiew]

We have just clarified it - the parent of a PExp can be only another PExp. Otherwise, the PExp is top-level and it is nested under IConstraint, ISuper, IReference, etc. Luke will fix that directly in develop.

We are making a compromise here - it would be an overkill to have every single IR element have a parent pointer. So, we're adding them only to the major ones (IClafer, IConstraint, IGoal, PExp) and for the rest, the functions will have to carry around the context (say, I am analyzing ISuper of clafer X, since there's no parent link from ISuper back to IClafer, then my function will have to carry IClafer for X around). We might consider adding parents everywhere later if we find it needed.

A consequence of this change is that we can now remove the SClafer infrastructure.

Jimmy, do you think we should have parents for every IR node? It's a huge change - maybe we should introduce them once there's a concrete need?

[Luke-Michael-Brown]

Me and Michael just had a talk about this I'm going to change it to PExp parent to Maybe PExp. So if the PExp's exp has a PExp that PExp will point to the orgianl PExp.

On Tue, Aug 20, 2013 at 10:29 AM, Jimmy Liang notifications@github.comwrote:

Everything looks fine. Luke, can you clarify what it means to be a parent of a PExp?

For example, here's the model:

A -> int ? [ this.ref = 3 ]

So the parent of the expression "this.ref = 3" should be "A". Is the parent of the subexpression "this.ref" also "A"?

— Reply to this email directly or view it on GitHubhttps://github.com/gsdlab/clafer/pull/37#issuecomment-22948794 .

[mantkiew]

Jimmy, for your model, the constraint is top-level, the parent of this.ref = 3 is the constraint (but we don't have a pointer for that in IR for now), the parent of both this.ref and 3 is the PExp for the whole this.ref = 3. So, PExps form a hierarchy and PExpParent will point to the parent PExp if nested or be Nothing if the PExp is top-level (e.g., directly in IConstraint or ISuper).

[mantkiew]

I clarified these issues in i255 on Bugbot.