feat: Stylua LSP server (#970)

* feat: Stylua LSP server

* Reorganise, handle range formatting

* Add integration tests

* Update help text

* Update changelog

* Gate LSP behind feature (enabled by default)

* Update readme

* Fix flakiness of integration tests

---------

Co-authored-by: JohnnyMorganz <[email protected]>

Author: PolyMeilex

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 
 - Added option `block_newline_gaps` to determine whether newline gaps at the start / end of blocks should be preserved. Defaults to `Never`, which is the original behaviour. ([#857](https://github.com/JohnnyMorganz/StyLua/pull/857))
+- StyLua can now run in a language server mode. Start StyLua with `stylua --lsp` and connect with a language client. ([#936](https://github.com/JohnnyMorganz/StyLua/issues/936))
 
 ### Changed
 

Cargo.lock

@@ -23,7 +23,7 @@ path = "src/cli/main.rs"
 bench = false
 
 [features]
-default = ["editorconfig", "wasm-bindgen"]
+default = ["editorconfig", "wasm-bindgen", "lsp"]
 serialize = []
 fromstr = ["strum"]
 luau = ["full_moon/roblox"]
@@ -33,6 +33,7 @@ lua54 = ["lua53", "full_moon/lua54"]
 luajit = ["full_moon/luajit"]
 cfxlua = ["lua54", "full_moon/cfxlua"]
 editorconfig = ["ec4rs"]
+lsp = ["lsp-server", "lsp-types", "lsp-textdocument"]
 
 [dependencies]
 anyhow = "1.0.75"
@@ -56,6 +57,9 @@ strum = { version = "0.25.0", features = ["derive"], optional = true }
 thiserror = "1.0.49"
 threadpool = "1.8.1"
 toml = "0.8.1"
+lsp-server = { version = "0.7", optional = true }
+lsp-types = { version = "0.97", optional = true }
+lsp-textdocument = { version = "0.4.2", optional = true }
 
 [target.'cfg(target_arch = "wasm32")'.dependencies]
 wasm-bindgen = { version = "0.2.81", optional = true }

Cargo.toml

@@ -238,6 +238,20 @@ Requires sorting is off by default. To enable it, add the following to your `sty
 enabled = true
 ```
 
+### Language Server Mode
+
+StyLua can run as a language server, connecting with language clients that follow the [Language Server Protocol](https://microsoft.github.io/language-server-protocol/).
+It will then respond to `textDocument/formatting` and `textDocument/rangeFormatting` requests.
+Formatting is only performed on files with a `lua` or `luau` language ID.
+
+You can start the language server by running:
+
+```sh
+stylua --lsp
+```
+
+StyLua will listen to LSP messages on stdin and respond on stdout.
+
 ## Configuration
 
 StyLua has opinionated defaults, but also provides a few options that can be set per project.
@@ -293,7 +307,7 @@ StyLua only offers the following options:
 | `quote_style`                | `AutoPreferDouble` | Quote style for string literals. Possible options: `AutoPreferDouble`, `AutoPreferSingle`, `ForceDouble`, `ForceSingle`. `AutoPrefer` styles will prefer the specified quote style, but fall back to the alternative if it has fewer string escapes. `Force` styles always use the specified style regardless of escapes.                                                                                                                                                                                                                                                                                                                                                                                                                             |
 | `call_parentheses`           | `Always`           | Whether parentheses should be applied on function calls with a single string/table argument. Possible options: `Always`, `NoSingleString`, `NoSingleTable`, `None`, `Input`. `Always` applies parentheses in all cases. `NoSingleString` omits parentheses on calls with a single string argument. Similarly, `NoSingleTable` omits parentheses on calls with a single table argument. `None` omits parentheses in both cases. Note: parentheses are still kept in situations where removal can lead to obscurity (e.g. `foo "bar".setup -> foo("bar").setup`, since the index is on the call result, not the string). `Input` removes all automation and preserves parentheses only if they were present in input code: consistency is not enforced. |
 | `space_after_function_names` | `Never`            | Specify whether to add a space between the function name and parentheses. Possible options: `Never`, `Definitions`, `Calls`, or `Always`                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
-| `block_newline_gaps`         | `Never`            | Specify whether to preserve leading and trailing newline gaps for blocks. Possible options: `Never`, `Preserve`                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
+| `block_newline_gaps`         | `Never`            | Specify whether to preserve leading and trailing newline gaps for blocks. Possible options: `Never`, `Preserve`                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
 | `collapse_simple_statement`  | `Never`            | Specify whether to collapse simple statements. Possible options: `Never`, `FunctionOnly`, `ConditionalOnly`, or `Always`                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
 
 Default `stylua.toml`, note you do not need to explicitly specify each option if you want to use the defaults: