# @willbooster/tree-sitter-java
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[](https://github.com/WillBooster/shared/tree/main/packages/wbfy)
[](https://crates.io/crates/willbooster-tree-sitter-java)
Java grammar for [tree-sitter](https://github.com/tree-sitter/tree-sitter), forked from
[tree-sitter/tree-sitter-java](https://github.com/tree-sitter/tree-sitter-java). We are grateful
to its authors and contributors. This is not an official release of that project.
This fork is based on tree-sitter-java 0.23.5 and accepts `final` modifiers on switch type patterns
and typed record-pattern components, plus qualified names in record patterns. Unnamed variables in switch and
`instanceof` type patterns, including typed record-pattern components, use `underscore_pattern` nodes. It ships the
parser as the compact tables that the [WillBooster/tree-sitter](https://github.com/WillBooster/tree-sitter) generator
emits under that fork's own ABI number (`0x57420001`), so the parser loads only with that runtime, version 2.0.0 or
later, and not with upstream's tree-sitter.
## Usage
The npm package ships `tree-sitter-java.wasm` for
[@willbooster/web-tree-sitter](https://www.npmjs.com/package/@willbooster/web-tree-sitter) version 2.0.0 or later, which runs in Node.js, Bun, browsers, and Cloudflare Workers. In Node.js and Bun, load the grammar from its path:
```js
import { fileURLToPath } from 'node:url';
import { Language, Parser } from '@willbooster/web-tree-sitter';
await Parser.init();
const parser = new Parser();
const wasmPath = fileURLToPath(import.meta.resolve('@willbooster/tree-sitter-java/tree-sitter-java.wasm'));
parser.setLanguage(await Language.load(wasmPath));
const tree = parser.parse('class Main { int answer() { return 42; } }\n');
```
In browsers, serve both `.wasm` files and load them by URL (the example uses Vite's `?url` imports):
```js
import { Language, Parser } from '@willbooster/web-tree-sitter';
import runtimeUrl from '@willbooster/web-tree-sitter/web-tree-sitter.wasm?url';
import javaUrl from '@willbooster/tree-sitter-java/tree-sitter-java.wasm?url';
await Parser.init({ locateFile: () => runtimeUrl });
const parser = new Parser();
parser.setLanguage(await Language.load(javaUrl));
```
Cloudflare Workers do not allow compiling Wasm at run time, so import both `.wasm` files as modules, with or without
Node.js compatibility:
```js
import { Language, Parser } from '@willbooster/web-tree-sitter';
import runtime from '@willbooster/web-tree-sitter/web-tree-sitter.wasm';
import java from '@willbooster/tree-sitter-java/tree-sitter-java.wasm';
await Parser.init({ wasmModule: runtime });
const parser = new Parser();
parser.setLanguage(await Language.load(java));
```
The package also ships `grammar.js`, the queries in `queries/`, and the node types in `src/node-types.json`.
In Rust, depend on the [crate](https://crates.io/crates/willbooster-tree-sitter-java) and on
[willbooster-tree-sitter](https://crates.io/crates/willbooster-tree-sitter), the runtime this package is tested and
fuzzed with:
```toml
[dependencies]
tree-sitter = { package = "willbooster-tree-sitter", version = "2" }
tree-sitter-java = { package = "willbooster-tree-sitter-java", version = "2" }
```
```rust
let mut parser = tree_sitter::Parser::new();
parser.set_language(&tree_sitter_java::LANGUAGE.into())?;
```
## Development
```sh
mise install
bun install --frozen-lockfile
bun run test/ci-setup # installs Chromium for the browser test
bun run build/ci
bun run test
script/parse-examples
cargo test
```
The scripts and tests generate, build, test, and parse with `script/tree-sitter`, the tree-sitter CLI of the
WillBooster/tree-sitter runtime version locked in `Cargo.lock`, since the generator and the runtime of upstream's CLI are
not the ones this package ships with. Its first run downloads that CLI from the runtime's GitHub Release, or builds it
with `cargo` (whose build runs the CMake that `mise.toml` pins) when the download fails or the release has no binary that runs here. Run other CLI commands through it as
well (e.g. `script/tree-sitter parse File.java`).
`grammar.js` stays as upstream wrote and formatted it, apart from rule changes, so that it can be compared with
upstream's grammar; the linter and the formatter skip it.
`bun run generate` records a fresh generation profile from the applicable `test/corpus` cases and any Git-tracked
files in `examples/`, then generates compact parser tables. The parser also embeds metadata from `tree-sitter.json`. After changing a grammar,
`tree-sitter.json`, a corpus case, a tracked example, or the `willbooster-tree-sitter` version in `Cargo.lock` (whose
CLI generates the parser),
regenerate and commit `src/`. Stage added or removed examples with `git add -A examples` before generation so the profile uses the intended file list.
Profiles in `.tmp/generation-profiles/` are temporary and must not be committed. `bun run build-wasm`, `bun run build/ci`,
and the release build regenerate the parsers before compiling them.
`bun run test` runs:
- the corpus in `test/corpus`, with the native build and with the Wasm build (the first run downloads the WASI SDK);
- an incremental-parsing check (`test/unit/incremental.test.ts`): `script/fuzz-corpus` runs `tree-sitter fuzz`, which
edits each corpus case at random, reparses it, undoes the edits, and reparses again. `TREE_SITTER_SEED`,
`TREE_SITTER_ITERATIONS`, and `TREE_SITTER_EDITS` run other or more edits;
- a check that the real-world Java files of the repositories cloned into `examples/` fail to parse exactly as listed in
`script/known-failures.txt`. The first run clones the repositories. The example
repositories are pinned to commits in `script/parse-examples`. After a grammar change or a moved pin alters that
list, `script/parse-examples` rewrites it; review its diff before committing;
- a performance check (`test/unit/performance.test.ts`) that recovering from an error on each line takes linear
time, since consumers parse files while they are being edited. It loads the Wasm build through
@willbooster/web-tree-sitter, which `bun run build/ci` rebuilds after regenerating the parser;
- a check (`test/unit/runtimeVersion.test.ts`) that `@willbooster/web-tree-sitter` in `package.json` and
`willbooster-tree-sitter` in `Cargo.lock` are the same version, since the Wasm tests run on the former and the Rust
tests, the fuzzer, and the CLI on the latter;
- tests that load the Wasm build with @willbooster/web-tree-sitter in Chromium (`test/e2e/browser.test.ts`) and in
Cloudflare Workers with and without Node.js compatibility (`test/e2e/workers.test.ts`).
The tests and `script/parse-examples` compile the parser into `.tmp/tree-sitter-lib` rather than the CLI's cache shared
by every checkout; `script/fuzz-corpus` builds a parser of its own in `.tmp/fuzz` for each run and deletes it
afterwards.
CI also runs these tests on Linux arm64 and macOS, where the CLI compiles the parser with each platform's C compiler,
and fuzzes the parser with libFuzzer and sanitizers (`.github/workflows/robustness.yml`).