C++ has been a headache to deal with throughout the ecosystem and for
several downstream projects. It is difficult to get working with WASM,
and induces potential issues with compilation on Windows. It has been
proven that writing scanners in C is a much better alternative, and is
the recommended way to write scanners now. C++ support will likely be
removed in 0.21.0
Previously, `tree-sitter build-wasm` had the ability to build WASM
by using docker to pull in an image with a complete emscripten toolchain.
This commit adds the ability to use podman to do the same thing.
Using podman requires two notable changes:
1. Using the fully-qualified image name. Docker defaults to prepending
`docker.io` to the image name, but podman does not.
2. Podman will mount the `/src/` volume as belonging to root unless
`--userns=keep-id` is passed. I think podman's different
volume-ownership is related to podman's daemonless execution and
`--uidmap` functionality, but I'm not 100% sure.
To test, I ran
```sh
script/fetch-fixtures
script/generate-fixtures
script/generate-fixtures-wasm # <- the important one!
```
which worked as well as the docker version.
This patch adds the `tree-sitter-config` crate, which manages
tree-sitter's configuration file. This new setup allows different
components to define their own serializable configuration types, instead
of having to create a single monolithic configuration type. But the
configuration itself is still stored in a single JSON file.
Before, the default location for the configuration file was
`~/.tree-sitter/config.json`. This patch updates the default location
to follow the XDG Base Directory spec (or other relevant platform-
specific spec). So on Linux, for instance, the new default location is
`~/.config/tree-sitter/config.json`. We will look in the new location
_first_, and fall back on reading from the legacy location if we can't
find anything.
This patch adds a new `tree-sitter-loader` crate, which holds the CLI's
logic for finding and building local grammar definitions at runtime.
This allows other command-line tools to use this logic too!
