**Problem:** `vim.treesitter.get_parser` will throw an error if no parser
can be found.
- This means the caller is responsible for wrapping it in a `pcall`,
which is easy to forget
- It also makes it slightly harder to potentially memoize `get_parser`
in the future
- It's a bit unintuitive since many other `get_*` style functions
conventionally return `nil` if no object is found (e.g. `get_node`,
`get_lang`, `query.get`, etc.)
**Solution:** Return `nil` if no parser can be found or created
- This requires a function signature change, and some new assertions in
places where the parser will always (or should always) be found.
- This commit starts by making this change internally, since it is
breaking. Eventually it will be rolled out to the public API.
Problem: Installing treesitter parser is hard (harder than
climbing to heaven).
Solution: Add optional support for wasm parsers with `wasmtime`.
Notes:
* Needs to be enabled by setting `ENABLE_WASMTIME` for tree-sitter and
Neovim. Build with
`make CMAKE_EXTRA_FLAGS=-DENABLE_WASMTIME=ON
DEPS_CMAKE_FLAGS=-DENABLE_WASMTIME=ON`
* Adds optional Rust (obviously) and C11 dependencies.
* Wasmtime comes with a lot of features that can negatively affect
Neovim performance due to library and symbol table size. Make sure to
build with minimal features and full LTO.
* To reduce re-compilation times, install `sccache` and build with
`RUSTC_WRAPPER=<path/to/sccache> make ...`
Problem:
Tests have lots of exec_lua calls which input blocks of code
provided as unformatted strings.
Solution:
Teach exec_lua how to handle functions.
This is identical to `named_node_for_range` except that it includes
anonymous nodes. This maintains consistency in the API because we
already have `descendant_for_range` and `named_descendant_for_range`.
Specifically, functions that are run in the context of the test runner
are put in module `test/testutil.lua` while the functions that are run
in the context of the test session are put in
`test/functional/testnvim.lua`.
Closes https://github.com/neovim/neovim/issues/27004.
Problem:
vim.treesitter does not know how to map a specific filetype to a parser.
This creates problems since in a few places (including in vim.treesitter itself), the filetype is incorrectly used in place of lang.
Solution:
Add an API to enable this:
- Add vim.treesitter.language.add() as a replacement for vim.treesitter.language.require_language().
- Optional arguments are now passed via an opts table.
- Also takes a filetype (or list of filetypes) so we can keep track of what filetypes are associated with which langs.
- Deprecated vim.treesitter.language.require_language().
- Add vim.treesitter.language.get_lang() which returns the associated lang for a given filetype.
- Add vim.treesitter.language.register() to associate filetypes to a lang without loading the parser.
Problem: Some injections (like markdown) allow specifying arbitrary
language names for code blocks, which may be lead to errors when
looking for a corresponding parser in runtime path.
Solution: Validate that the language name only contains alphanumeric
characters and `_` (e.g., for `c_sharp`) and error otherwise.
