Retrieving the Scope of a statement

[Basile B.]

On Tuesday, 21 April 2020 at 06:58:47 UTC, Basile B. wrote:
> On Tuesday, 21 April 2020 at 01:52:49 UTC, Basile B. wrote:
>> On Monday, 20 April 2020 at 16:56:51 UTC, Cristian Creteanu 
>> wrote:
>>> Hi!
>>>
>>> I am trying to implement autocomplete in DCD using DMD as a 
>>> library.
>>> [...]
>> [...]
>> to an `AstNode` you CANT use a custom visitor.
>
> Sorry maybe I've been too opiniated.
>
> in DMD, because of the lazy compilation model, visitors usually 
> don't process a whole module so:
>
> - the scope for a statement is the scope that's passed to the 
> `StatementSemanticVisitor` class created when 
> `statementSemantic()` is called for this statement.
> - the scope for an expression is the scope that's passed to the 
> `ExpressionSemanticVisitor` class created when 
> `expressionSemantic()` is called for this expression.
> - the scope for a type is the scope that's passed to the 
> `TypeSemanticVisitor` class created when `typeSemantic()` is 
> called for this type.
>
> From your original message I have the impression that you want 
> to retrieve a scope by a node, and you noticed that this is not 
> always possible. The time where a scope is always linked to a 
> node is when its semantic is run, and it's a class member. So 
> maybe (and only maybe) there's something to do with that fact 
> but as said at first glance I don't see how, without a kind of 
> callback system.

Maybe that adding this in the compiler globals:

   alias OnStatementSemanticStart = void function(Statement, 
Scope*);
   alias OnStatementSemanticDone = void function(Statement, 
Scope*);
   alias OnExpressionSemanticStart = void function(Expression, 
Scope*);
   alias OnExpressionSemanticDone = void function(Expression, 
Scope*);

   OnStatementSemanticStart onStatementSemanticStart;
   OnStatementSemanticDone onStatementSemanticDone;
   OnExpressionSemanticStart onExpressionSemanticStart;
   OnExpressionSemanticDone onExpressionSemanticDone;

and add the handlers in statementSemantic() and 
expressionSemantic()

could help to build a useful enough hash map but without 
significant memory impact on the compiler. Actually just the 
"Done" events would be usefull because of the many lowering done 
during semantics.