Provide constant type differentiation in semantic highlighting request

[mateusdeap]

Motivation

Fixes #1128 (Potentially)

This PR aims to modify the SemanticHighlighting class so that it can properly determine what type of constant is being referenced in a given piece of code. The details and discussion can be found in the issue, but we want syntax highlighting to know that Foo in Foo.new below is referencing the class Foo and isn't just some other constant Foo, for example:

class Foo
  THIS_IS_A_CONSTANT = 1

  def self.create_instance
    Foo.new
  end
end

Implementation

Following @vinistock's recommendations, I made sure an instance of RubyIndexer::Index is given to the request and created a variable to keep track of nesting. Additionally subscribed to events needed to keep track of this nesting.

At the time of submission, the PR is incomplete, however. I wasn't able to figure out how to properly set up the index in the tests, so the lines where I call index_single are definitely something that needs fixing.

Finally, one thing discussed in the issue is that, even if this is implemented correctly, it might be too resource intensive, so if this gets finished, benchmarks will be required

Automated Tests

Haven't added any new tests so far but only tried to modify the current test to reflect the needed changes.

Manual Tests

The issue was opened referencing neovim, so I'm not sure if this affects VS Code. However the request doesn't have this specific capability so I think it's surely possible to replicate this by opening the example file provided in the issue.

[vinistock]

Keeping track of the nesting is looking good. Now, when we find a constant reference, we need to use the constant name, the nesting and the index to determine what the constant is declared as.

def on_constant_read_node_enter(node)
  entries = @index.resolve(node.name, @nesting)
  # if entries is nil, we didn't find the declaration for it
  # it might be defined with meta-programming or using C code
  unless entries
    # Push a constant semantic token
  end

  # Otherwise, we can check the type of entry to determine the
  # type of constant
  first_entry = T.must(entries.first)

  case first_entry
  when RubyIndexer::Entry::Class
    # push a class.declaration token
  when RubyIndexer::Entry::Module
    # push a namespace.declaration token
  when RubyIndexer::Entry::Constant
    # push a constant.declaration token
  end
end

[mateusdeap]

Awesome. Will try to implement this as soon as I can.

[mateusdeap]

Closed it by accident while trying to update my main branch. Finally found some time to squeeze out some work here, so I'll be making updates soon