170 lines
5.8 KiB
Markdown
170 lines
5.8 KiB
Markdown
# Rust Analyzer
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[](https://travis-ci.org/matklad/rust-analyzer)
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[](https://ci.appveyor.com/project/matklad/rust-analyzer/branch/master)
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Rust Analyzer is an **experimental** modular compiler frontend for the
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Rust language, which aims to lay a foundation for excellent IDE
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support.
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It doesn't implement much of compiler functionality yet, but the
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white-space preserving Rust parser works, and there are significant
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chunks of overall architecture (indexing, on-demand & lazy
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computation, snapshotable world view) in place. Some basic IDE
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functionality is provided via a language server.
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## Quick Start
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Rust analyzer builds on stable Rust >= 1.29.0.
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```
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# run tests
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$ cargo test
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# show syntax tree of a Rust file
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$ cargo run --package ra_cli parse < crates/ra_syntax/src/lib.rs
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# show symbols of a Rust file
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$ cargo run --package ra_cli symbols < crates/ra_syntax/src/lib.rs
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```
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To try out the language server, see [these
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instructions](./editors/README.md). Please note that the server is not
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ready for general use yet. If you are looking for a Rust IDE that
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works, use [IntelliJ
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Rust](https://github.com/intellij-rust/intellij-rust) or
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[RLS](https://github.com/rust-lang-nursery/rls). That being said, the
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basic stuff works, and rust analyzer is developed in the rust analyzer
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powered editor.
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## Current Status and Plans
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Rust analyzer aims to fill the same niche as the official [Rust
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Language Server](https://github.com/rust-lang-nursery/rls), but uses a
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significantly different architecture. More details can be found [in
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this
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thread](https://internals.rust-lang.org/t/2019-strategy-for-rustc-and-the-rls/8361),
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but the core issue is that RLS works in the "wait until user stops
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typing, run the build process, save the results of the analysis" mode,
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which arguably is the wrong foundation for IDE.
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Rust Analyzer is a hobby project at the moment, there's exactly zero
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guarantees that it becomes production-ready one day.
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The near/mid term plan is to work independently of the main rustc
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compiler and implement at least simplistic versions of name
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resolution, macro expansion and type inference. The purpose is two
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fold:
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* to quickly bootstrap usable and useful language server: solution
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that covers 80% of Rust code will be useful for IDEs, and will be
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vastly simpler than 100% solution.
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* to understand how the consumer-side of compiler API should look like
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(especially it's on-demand aspects). If you have
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`get_expression_type` function, you can write a ton of purely-IDE
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features on top of it, even if the function is only partially
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correct. Plugin in the precise function afterwards should just make
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IDE features more reliable.
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The long term plan is to merge with the mainline rustc compiler,
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probably around the HIR boundary? That is, use rust analyzer for
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parsing, macro expansion and related bits of name resolution, but
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leave the rest (including type inference and trait selection) to the
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existing rustc.
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## Code Walk-Through
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### `crates/ra_syntax`
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Rust syntax tree structure and parser. See
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[RFC](https://github.com/rust-lang/rfcs/pull/2256) for some design
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notes.
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- `yellow`, red/green syntax tree, heavily inspired [by this](https://github.com/apple/swift/tree/ab68f0d4cbf99cdfa672f8ffe18e433fddc8b371/lib/Syntax)
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- `grammar`, the actual parser
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- `parser_api/parser_impl` bridges the tree-agnostic parser from `grammar` with `yellow` trees
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- `grammar.ron` RON description of the grammar, which is used to
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generate `syntax_kinds` and `ast` modules.
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- `algo`: generic tree algorithms, including `walk` for O(1) stack
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space tree traversal (this is cool) and `visit` for type-driven
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visiting the nodes (this is double plus cool, if you understand how
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`Visitor` works, you understand rust-analyzer).
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### `crates/ra_editor`
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All IDE features which can be implemented if you only have access to a
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single file. `ra_editor` could be used to enhance editing of Rust code
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without the need to fiddle with build-systems, file
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synchronization and such.
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In a sense, `ra_editor` is just a bunch of pure functions which take a
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syntax tree as an input.
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### `crates/salsa`
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An implementation of red-green incremental compilation algorithm from
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rust compiler. It makes all rust-analyzer features on-demand.
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### `crates/ra_analysis`
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A stateful library for analyzing many Rust files as they change.
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`AnalysisHost` is a mutable entity (clojure's atom) which holds
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current state, incorporates changes and handles out `Analysis` --- an
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immutable consistent snapshot of world state at a point in time, which
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actually powers analysis.
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### `crates/ra_lsp_server`
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An LSP implementation which uses `ra_analysis` for managing state and
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`ra_editor` for actually doing useful stuff.
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### `crates/cli`
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A CLI interface to libsyntax
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### `crate/tools`
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Code-gen tasks, used to develop rust-analyzer:
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- `cargo gen-kinds` -- generate `ast` and `syntax_kinds`
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- `cargo gen-tests` -- collect inline tests from grammar
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- `cargo install-code` -- build and install VS Code extension and server
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### `editors/code`
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VS Code plugin
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## Performance
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Non-incremental, but seems pretty fast:
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```
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$ cargo build --release --package ra_cli
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$ wc -l ~/projects/rust/src/libsyntax/parse/parser.rs
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7546 /home/matklad/projects/rust/src/libsyntax/parse/parser.rs
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$ ./target/release/ra_cli parse < ~/projects/rust/src/libsyntax/parse/parser.rs --no-dump > /dev/null
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parsing: 21.067065ms
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```
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## Getting in touch
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@matklad can be found at Rust
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[discord](https://discordapp.com/invite/rust-lang), in
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#ides-and-editors.
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## License
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Rust analyzer is primarily distributed under the terms of both the MIT
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license and the Apache License (Version 2.0).
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See LICENSE-APACHE and LICENSE-MIT for details.
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