add . to zig-re-identifier to highlight namespaced types

[mega-dean]

This change adds . to the zig-re-identifier regex so that namespaced types are entirely highlighted using font-lock-type-face, instead of only highlighting the first namespace.

Before:

After:

I tried to look at what zig-re-identifier is used for to make sure there wouldn't be any unintended side effects from this change, but I can't tell for sure. I skimmed some zig files and it looked like it only affected struct field types and function arguments.

[joachimschmidt557]

Thanks for your contribution! I would like to suggest a change though: For me, zig-re-identifier should represent something similar to IDENTIFIER in the zig grammar, so . isn't allowed. As . do appear in type names (zig-re-type-annotation) though, this is where I would add matching for ..

[mega-dean]

I update the PR so now it adds (defconst zig-re-type "[[:word:]_.][[:word:]_.[:digit:]]*") and uses that in zig-re-type-annotation.

At first I tried updating the zig-re-type-annotation regex to keep using zig-re-identifier and I got it working with this:

(defconst zig-re-type-annotation
  (concat (zig-re-grab zig-re-identifier)
          "[[:space:]]*:[[:space:]]*"
          zig-re-optionals-pointers-arrays
          (zig-re-grab (concat (zig-re-grab (concat zig-re-identifier "\\.?")) "*"))))

But I think it's probably better to just define the new constant. Let me know if you want me to change it though.

[joachimschmidt557]

Thanks! For now, this is perfectly fine. I think the regexes need to be revamped altogether in future to more closely match the zig grammar – or use tree sitter as basis.