Build the project with Bazel.

[zadlg]

Build the project with Bazel.

This commit introduces a Bazel-based build system for the core library
of tree-sitter.

In order not to "pollute" the existing source directories, an overlay directory
has been created at bazel/.

People can build the tree-sitter C API by doing:

$ cd bazel/
$ bazel build @tree-sitter

The following two flags are available to enable or disable specific features:

• --@tree-sitter//build_config:wasm=<true|false>: enable WASM. not yet supported.
• --@tree-sitter//build_config:hide_symbols=<true|false>: if enabled, do not expose tree-sitter symbols.

Bazel users can import tree-sitter into their existing Bazel workspace by
adding the following to their WORKSPACE file:

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")

# The git commit.
_COMMIT = ""

# SHA-256 digest of the archive.
_SHA256SUM = ""
http_archive(
    name = "tree-sitter-raw",
    sha256 = _SHA256SUM,
    urls = [
        "https://github.com/tree-sitter/tree-sitter/archive/{commit}.tar.gz".format(
            commit = _COMMIT,
        ),
    ],
    strip_prefix = "tree-sitter-{commit}".format(
        commit = _COMMIT,
    ),
)

load("@tree-sitter-raw//bazel:configure.bzl", "tree_sitter_configure")

# Configures the repository `tree-sitter`.
tree_sitter_configure(name = "tree-sitter")

# Fetches `tree-sitter` Bazel dependencies.
load("@tree-sitter//:repositories.bzl", "tree_sitter_repositories")

tree_sitter_repositories()

# Loads `tree-sitter` Bazel dependencies.
load("@tree-sitter//:deps.bzl", "tree_sitter_dependencies")

tree_sitter_dependencies()

Then, users can link their libraries/binaries against tree-sitter:

cc_library(
    name = "my-parser",
    srcs = ["my-parser.cc"],
    deps = ["@tree-sitter"],
)

[ObserverOfTime]

Several CMake PRs were rejected for being too much. Now this, this is way too much.

[zadlg]

Several CMake PRs were rejected for being too much. Now this, this is way too much.

Hi @ObserverOfTime, thanks for your reply.
Could you elaborate on why you think this is too much?

[ObserverOfTime]

16 files for a build system that very few people use.

[zadlg]

16 files for a build system that very few people use.

I'm not going to debate Bazel's popularity, because it's pretty hard to get numbers.

I understand your feeling about having 16 files exclusively for a build system. However, since the project is quite ""simple"" (it doesn't have tons of external dependencies), I think it would be easy to maintain it.

I was inspired by what was done for LLVM's monorepo. I made a directory to self-contain everything related to Bazel (/bazel), so that it does not ""pollute"" the source tree.
About maintaining it, I suggest the following (again, inspired by what was done for LLVM):

• the Bazel based build system can be broken at anytime, meaning that people who contribute to tree-sitter don't have to care about Bazel.
• from time to time, someone updates/fixes the Bazel build system.

I've added new GitHub jobs, I'll make them non-blocking to ensure that non-Bazel-aware contributors won't be blocked.

What do you think?

[ObserverOfTime]

In my opinion, if we were to add another (optional) build system it should be CMake (just one or two files).

[zadlg]

It seems that we cannot flag a job as non-blocking, we can only use continue-on-error, which does not make sense here.

However, an admin can flag these jobs as non-required.

[zadlg]

In my opinion, if we were to add another (optional) build system it should be CMake (just one or two files).

I can also add an optional CMake-based build system for tree-sitter if you want.
The reason I added Bazel in the first place is that I use it for my personal projects and for a few projects in the company I work for.
In other words, I'm not trying to add Bazel because it's popular (or not).

[ObserverOfTime]

Downstream projects can use whatever build system they want. It doesn't need to be added here.

[zadlg]

Downstream projects can use whatever build system they want. It doesn't need to be added here.

I agree.

I've decided to make this PR in case other people want to use tree-sitter without them writing the build system themselves. As I wrote in my commit's description, the idea is to be able to easily integrate tree-sitter using http_archive, this is quite common in Bazel.
(The ultimate goal being having tree-sitter in the Bazel Central Registry).

[maxbrunsfeld]

Hi, this is great work but I don’t want to maintain this in this repository.

[zadlg]

Hi, this is great work but I don’t want to maintain this in this repository.

I understand. Thanks anyway for your reply.

[zadlg]

Quick note: I've put the overlay in a repository: https://github.com/zadlg/tree-sitter-bazel/
and I've submitted a Bazel module called tree-sitter-bazel: https://registry.bazel.build/modules/tree-sitter-bazel.

[maxbrunsfeld]

Awesome, thank you @zadlg !