Problem: Every LSP capability that sends a request on a document change
to update its state was using its own buffer-local autocmd to do so.
That means there is a separate autocmd per buffer per active
capability/feature, and the actual code inside the autocmd callback was
virtually identical. The same problem occurred for capabilities that had
components to draw on the screen that had their own decoration providers.
Solution: Introduce a central `LspNotify` autocmd and decoration
provider in the capability module itself. New base class methods
`on_close` and `on_change` that take a client_id have been provided, for
`didClose` and `didOpen`/`didChange` notifications respectively. New
base class method `on_win` that takes topline and botline has been
provided to add extmarks or perform other work when lines of a buffer
are being drawn.
The autocmd callback loops through each active capability instance for
the buffer and calls a corresponding method with the triggering
client_id if it is currently attached to the buffer that triggered the
autocmd. The decoration provider just calls on_win for all active
capabilities on the buffer.
This slightly tweaks folding range to make use of these new client-id
specific callbacks.
Problem:
Inlay hints used separate global and per-buffer bufstates tables and
bespoke global autocmds for managing the inlay hint state across buffers
and clients, duplicating the lifecycle logic already provided by the
Capability framework. This caused inconsistencies in how client state
was handled and inlay hint state lifecycle was managed compared to other
LSP features.
Solution:
Replace the ad-hoc bufstate tracking and global autocmds in
vim.lsp.inlay_hint with a proper InlayHint subclass of Capability.
This also refactors the way inlay hint state is managed and fixes bugs I
found while doing this:
1. For each line with inlay hints, the list of the hints along with
whether they have been applied is stored in a current result on the
client state. This allows the on_win decorator to clear all inlay
hints for an old document version once, and then re-add the new
version's hints line-by-line as they are drawn to the screen,
modeling the semantic tokens module.
2. It fixes problems with mixing results from multiple clients attached
to the buffer by fully moving each client's state to its own table.
Previously, only the most recent document version used to populate a
line's inlay hints was stored, but there was no distinction for which
client the hints may have come from. (Fixes#36318)
3. It fixes the workspace/inlayHint/refresh server->client notification
behavior. Previously it would only re-request inlay hints for buffers
currently displayed in a window but would not invalidate them in
non-displayed buffers (or provide any mechanism for those buffers to
re-request at a later time). Model semantic token module here again
by invalidating all buffers, and adding a BufWinEnter autocmd to
refresh hints.
4. Add a mechanism to cancel in-flight requests if a new request for a
newer document version is made before the last one returned
5. Handle stale results by simply dropping them.
Problem:
Diagnostic tracking used a separate bufstates table and manual
LspDetach/LspNotify autocmd management via _enable()/_refresh(),
duplicating the lifecycle logic already provided by the Capability
framework. This caused inconsistencies in how client attach/detach and
buffer teardown were handled compared to other LSP features.
Solution:
Replace the ad-hoc bufstate tracking and _enable/_refresh pattern in
vim.lsp.diagnostic with a proper Diagnostics subclass of Capability.
This cleans up a few random places in the main lsp module and client
module that were poking the diagnostics. It also fixes some pre-existing
bugs and inconsistencies that were discovered:
- Refresh diagnostics immediately on attach instead of lazily by the
first didOpen/didChange notification
- Fix Capability.active lookup in M.enable() to key by it_bufnr instead
of the filter bufnr
- Set lsp defaults before calling the _text_document_did_open_handler in
Client:on_attach() so defaults are there before any lsp notification
occurs
- Log (and return early) on any error from a diagnostic request result
instead of only returning early for server cancelled errors
Today there is a constraint that these arguments to the enable filter be
mutually exclusive, but I do not know why such a constraint exists (it
is perfectly reasonable to want to enable a capabilility for just one
buffer and just one client).
Problem:
Our LSP type system didnt have a concept of RegistrationMethods, this is where the method to dynamically register for a capability is sent to a different method endpoint then is used to call it. Eg `textDocument/semanticTokens` rather than the specific full/range/delta methods
Solution:
Extended generator to create `vim.lsp.protocol.Methods.Registration` with these registration methods. Also extend `_request_name_to_client_capability` to cover these methods. Adjust typing to suit
Problem:
Closes#31453
Solution:
Introduce `vim.lsp.Capability`, which may serve as the base class for
all LSP features that require caching data. it
- was created if there is at least one client that supports the specific method;
- was destroyed if all clients that support the method were detached.
- Apply the refactor for `folding_range.lua` and `semantic_tokens.lua`.
- Show active features in :checkhealth.
Future:
I found that these features that are expected to be refactored by
`vim.lsp.Capability` have one characteristic in common: they all send
LSP requests once the document is modified. The following code is
different, but they are all for this purpose.
- semantic tokens:
fb8dba413f/runtime/lua/vim/lsp/semantic_tokens.lua (L192-L198)
- inlay hints, folding ranges, document color
fb8dba413f/runtime/lua/vim/lsp/inlay_hint.lua (L250-L266)
I think I can sum up this characteristic as the need to keep certain
data synchronized with the latest version computed by the server.
I believe we can handle this at the `vim.lsp.Capability` level, and
I think it will be very useful.
Therefore, my next step is to implement LSP request sending and data
synchronization on `vim.lsp.Capability`, rather than limiting it to the
current create/destroy data approach.
