feat(codeintel): Add scip-ctags support for Magik

[mmanela]

Adds scip-ctags support for Magik. Some of the interesting pieces are that Magik uses a more prototype style of classes (called examplars) and tried to map those properly as classes. In addition, it has Mixins defined in a similar way and I also mapped those are classes as well

Test plan

• Add test cases
• Validate symbol browser in product

Changelog

• Add symbol browsing support for the Magik language

[kritzcreek]

1. When / why would I use @enclosing versus @scope

From what I can tell at a glance @enclosing is trying to match this SCIP concept: https://github.com/sourcegraph/scip/blob/e7242d57e6ac8e9461378822fb3b5fd8a7a0acb8/scip.proto#L669-L721

Marking a global definition as @enclosing means, that the closest surrounding scope will be added to its occurrence. So the global is the enclosed thing here. A @scope is used to mark a node in the tree that encloses other things.

2. For a magik exemplar, should I call it a object or a struct or a class? (I went with struct)

From a quick read I'd say it's closest to a class.

3. You can also define a mixin in Magik. I labeled mixin as a class but I am not sure that is correct.

Mixins are meta-classes. The closest mainstream analogy might be a "decorator"... Looking at the list of capture kinds I don't see anything that matches better than class.

[varungandhi-src]

@sebastiaanspeck is it common/possible to have non-trivial tree structures of declarations in Magik? I.e.

1. A def_slotted_exemplar or def_mixin inside a method body (if this is possible, is it accessible outside the method)
2. Another method definition inside a method body.
3. Method bodies inside a slotted exemplar or mixin definition (similar to other languages like Java or Ruby)

[mmanela]

@sebastiaanspeck Ping on this if you can help us.

[sebastiaanspeck]

Ah sorry, missed this comment completely.

1. def_slotted_exemplar and def_mixin are invokable proc's. You could definitely call those inside a method body. The class (or in Magik exemplar) will be available to the package it is declared in.

Question 2:

_method example.method_a
    _method example.method_b
        >> "Hello World"
    _endmethod
_endmethod
$

This will not work.

Question 3:

def_slotted_examplar(:example, {}, 
    _method example.method_a
        >> "Hello World"
    _endmethod)
$

def_slotted_examplar(:example, {})
$

_method example.method_a
    >> "Hello World"
_endmethod
$

If you are talking about the second snippet, that is absolutely possible:

[mmanela]

@sebastiaanspeck Does defining a global inside of a block or a method create a new top-level global, or does it only let you refer to an existing top-level global?

[sebastiaanspeck]

If the referring global variable already exists, it will access that one.

If the name does not include a package qualifier (@sw: or sw:) and there is no matching top level global, then the value of !global_auto_declare?! determines the subsequent behaviour:

• if true, the Magik compiler creates a global variable with value unset
• if maybe, the Magik compiler interactively queries the user if you want to declare a global variable.
• if false, the Magik compiler raises an error