…and create `useLegacyTreeSitter` for those who want to opt into the previous default behavior.
(Legacy Tree-sitter grammars will soon be removed, but this is a step toward that future!)
I realized a few days ago that the `#is?` and `#is-not?` predicates — which
puzzled me upon first investigation back in February, and which I'd ignored ever
since — are exactly what I should've been using all along for scope tests.
They are counterparts to `#set!` in that they are two additional buckets in
which to store arbitrary data. And they remove the need to have both
`test.onlyIfFoo` and `test.onlyIfNotFoo`, since the presence of `test.onlyIfFoo`
in the `refutedProperties` bucket can behave opposite to the its presence in the
`assertedProperties` bucket.
This further means that a test called `test.onlyIfFoo` can be renamed
`test.foo`. The `onlyIf` was my way of making it clear through context that this
`#set!` predicate actually enforced a criterion — but that's implicit now that
it'll be using an `#is?` or `#is-not?` predicate.
I also took the opportunity to move `test.final` and `test.shy` to their own
namespace. `final` is an oddball in the sense that it sets criteria for _other_
captures as well as its own, and they're both oddballs in the sense that they
consider the effects of other captures on the same range. And I don't want to
introduce the idea that a predicate like `#is?` can have side effects.
So they stay on `#set!` and live at `capture.final` and `capture.shy`,
respectively.
To summarize, here's a before and after:
((string "\"" @punctuation.start)
(#set! test.onlyIfFirst true)
(#set! test.final true)
((bar) @baz
(#set! test.onlyIfNotDescendantOfType thud))
becomes
((string "\"" @punctuation.start)
(#is? test.first true)
(#set! capture.final true)
((bar) @baz
(#is-not? test.descendantOfType thud))
This PR changes all the built-in grammars. I don't know if there are any
third-party modern-Tree-sitter grammars out there except for mine, but I've
added a simple compatibility layer so that all of the old predicates should
still work for now. But I'm going to remove that code before we ship this stuff
for real.
