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# libsyntax2.0
[](https://travis-ci.org/matklad/libsyntax2)
[](https://ci.appveyor.com/project/matklad/libsyntax2/branch/master)
libsyntax2.0 is an **experimental** parser of the Rust language,
intended for the use in IDEs.
[RFC](https://github.com/rust-lang/rfcs/pull/2256).
## Quick Start
```
$ cargo test
$ cargo parse < crates/libsyntax2/src/lib.rs
```
## Trying It Out
This installs experimental VS Code plugin
```
$ cargo install-code
```
It's better to remove existing Rust plugins to avoid interference.
Warning: plugin is not intended for general use, has a lot of rough
edges and missing features (notably, no code completion). That said,
while originally libsyntax2 was developed in IntelliJ, @matklad now
uses this plugin (and thus, libsytax2) to develop libsyntax2, and it
doesn't hurt too much :-)
### Features:
* syntax highlighting (LSP does not have API for it, so impl is hacky
and sometimes fall-backs to the horrible built-in highlighting)
* commands (`ctrl+shift+p` or keybindings)
- **Show Rust Syntax Tree** (use it to verify that plugin works)
- **Rust Extend Selection** (works with multiple cursors)
- **Rust Matching Brace** (knows the difference between `<` and `<`)
- **Rust Parent Module**
- **Rust Join Lines** (deals with trailing commas)
* **Go to symbol in file**
* **Go to symbol in workspace** (no support for Cargo deps yet)
* code actions:
- Flip `,` in comma separated lists
- Add `#[derive]` to struct/enum
- Add `impl` block to struct/enum
- Run tests at caret
* **Go to definition** ("correct" for `mod foo;` decls, index-based for functions).
## Code Walk-Through
### `crates/libsyntax2`
- `yellow`, red/green syntax tree, heavily inspired [by this](https://github.com/apple/swift/tree/ab68f0d4cbf99cdfa672f8ffe18e433fddc8b371/lib/Syntax)
- `grammar`, the actual parser
- `parser_api/parser_impl` bridges the tree-agnostic parser from `grammar` with `yellow` trees
- `grammar.ron` RON description of the grammar, which is used to
generate `syntax_kinds` and `ast` modules.
- `algo`: generic tree algorithms, including `walk` for O(1) stack
space tree traversal (this is cool) and `visit` for type-driven
visiting the nodes (this is double plus cool, if you understand how
`Visitor` works, you understand libsyntax2).
### `crates/libeditor`
Most of IDE features leave here, unlike `libanalysis`, `libeditor` is
single-file and is basically a bunch of pure functions.
### `crates/libanalysis`
A stateful library for analyzing many Rust files as they change.
`WorldState` is a mutable entity (clojure's atom) which holds current
state, incorporates changes and handles out `World`s --- immutable
consistent snapshots of `WorldState`, which actually power analysis.
### `crates/server`
An LSP implementation which uses `libanalysis` for managing state and
`libeditor` for actually doing useful stuff.
### `crates/cli`
A CLI interface to libsyntax
### `crate/tools`
Code-gen tasks, used to develop libsyntax2:
- `cargo gen-kinds` -- generate `ast` and `syntax_kinds`
- `cargo gen-tests` -- collect inline tests from grammar
- `cargo install-code` -- build and install VS Code extension and server
### `code`
VS Code plugin
## Performance
Non-incremental, but seems pretty fast:
```
$ cargo build --release --package cli
$ wc -l ~/projects/rust/src/libsyntax/parse/parser.rs
7546 /home/matklad/projects/rust/src/libsyntax/parse/parser.rs
$ ./target/release/cli parse < ~/projects/rust/src/libsyntax/parse/parser.rs --no-dump > /dev/null
parsing: 21.067065ms
```
## Getting in touch
@matklad can be found at Rust
[discord](https://discordapp.com/invite/rust-lang), in
#ides-and-editors.
## License
libsyntax2 is primarily distributed under the terms of both the MIT license
and the Apache License (Version 2.0).
See LICENSE-APACHE and LICENSE-MIT for details.
|
