Auto merge of #12251 - matklad:lsp-server, r=matklad

internal: vendor lsp-server

Cargo.lock

@@ -866,11 +866,10 @@ dependencies = [
 [[package]]
 name = "lsp-server"
 version = "0.6.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f70570c1c29cf6654029b8fe201a5507c153f0d85be6f234d471d756bc36775a"
 dependencies = [
  "crossbeam-channel",
  "log",
+ "lsp-types",
  "serde",
  "serde_json",
 ]

crates/hir-def/Cargo.toml

@@ -26,7 +26,7 @@ itertools = "0.10.3"
 indexmap = "1.8.0"
 smallvec = "1.8.0"
 arrayvec = "0.7.2"
-la-arena = { version = "0.3.0", path = "../../lib/arena" }
+la-arena = { version = "0.3.0", path = "../../lib/la-arena" }
 
 stdx = { path = "../stdx", version = "0.0.0" }
 base-db = { path = "../base-db", version = "0.0.0" }

crates/hir-expand/Cargo.toml

@@ -14,7 +14,7 @@ cov-mark = "2.0.0-pre.1"
 tracing = "0.1.32"
 either = "1.6.1"
 rustc-hash = "1.1.0"
-la-arena = { version = "0.3.0", path = "../../lib/arena" }
+la-arena = { version = "0.3.0", path = "../../lib/la-arena" }
 itertools = "0.10.3"
 hashbrown = { version = "0.12.0", features = [
     "inline-more",

crates/hir-ty/Cargo.toml

@@ -21,7 +21,7 @@ scoped-tls = "1.0.0"
 chalk-solve = { version = "0.82.0", default-features = false }
 chalk-ir = "0.82.0"
 chalk-recursive = { version = "0.82.0", default-features = false }
-la-arena = { version = "0.3.0", path = "../../lib/arena" }
+la-arena = { version = "0.3.0", path = "../../lib/la-arena" }
 once_cell = "1.10.0"
 typed-arena = "2.0.1"
 

crates/profile/Cargo.toml

@@ -13,7 +13,7 @@ doctest = false
 once_cell = "1.10.0"
 cfg-if = "1.0.0"
 libc = "0.2.121"
-la-arena = { version = "0.3.0", path = "../../lib/arena" }
+la-arena = { version = "0.3.0", path = "../../lib/la-arena" }
 countme = { version = "3.0.1", features = ["enable"] }
 jemalloc-ctl = { version = "0.4.2", package = "tikv-jemalloc-ctl", optional = true }
 

crates/project-model/Cargo.toml

@@ -18,7 +18,7 @@ serde = { version = "1.0.136", features = ["derive"] }
 serde_json = "1.0.79"
 anyhow = "1.0.56"
 expect-test = "1.2.2"
-la-arena = { version = "0.3.0", path = "../../lib/arena" }
+la-arena = { version = "0.3.0", path = "../../lib/la-arena" }
 
 cfg = { path = "../cfg", version = "0.0.0" }
 base-db = { path = "../base-db", version = "0.0.0" }

crates/rust-analyzer/Cargo.toml

@@ -33,7 +33,7 @@ threadpool = "1.8.1"
 rayon = "1.5.1"
 num_cpus = "1.13.1"
 mimalloc = { version = "0.1.28", default-features = false, optional = true }
-lsp-server = "0.6.0"
+lsp-server = { version = "0.6.0", path = "../../lib/lsp-server" }
 tracing = "0.1.32"
 tracing-subscriber = { version = "0.3.9", default-features = false, features = [
     "env-filter",

lib/la-arena/Cargo.toml

@@ -3,7 +3,7 @@ name = "la-arena"
 version = "0.3.0"
 description = "Simple index-based arena without deletion."
 license = "MIT OR Apache-2.0"
-repository = "https://github.com/rust-lang/rust-analyzer"
+repository = "https://github.com/rust-lang/rust-analyzer/tree/master/lib/la-arena"
 documentation = "https://docs.rs/la-arena"
 categories = ["data-structures", "memory-management", "rust-patterns"]
 edition = "2021"

lib/lsp-server/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "lsp-server"
+version = "0.6.0"
+description = "Generic LSP server scaffold."
+license = "MIT OR Apache-2.0"
+repository = "https://github.com/rust-analyzer/rust-analyzer/tree/master/lib/lsp-server"
+edition = "2021"
+
+[dependencies]
+log = "0.4.3"
+serde_json = "1.0.34"
+serde = { version = "1.0.83", features = ["derive"] }
+crossbeam-channel = "0.5.4"
+
+[dev-dependencies]
+lsp-types = "0.93.0"

lib/lsp-server/examples/goto_def.rs

@@ -0,0 +1,121 @@
+//! A minimal example LSP server that can only respond to the `gotoDefinition` request. To use
+//! this example, execute it and then send an `initialize` request.
+//!
+//! ```no_run
+//! Content-Length: 85
+//!
+//! {"jsonrpc": "2.0", "method": "initialize", "id": 1, "params": {"capabilities": {}}}
+//! ```
+//!
+//! This will respond with a server response. Then send it a `initialized` notification which will
+//! have no response.
+//!
+//! ```no_run
+//! Content-Length: 59
+//!
+//! {"jsonrpc": "2.0", "method": "initialized", "params": {}}
+//! ```
+//!
+//! Once these two are sent, then we enter the main loop of the server. The only request this
+//! example can handle is `gotoDefinition`:
+//!
+//! ```no_run
+//! Content-Length: 159
+//!
+//! {"jsonrpc": "2.0", "method": "textDocument/definition", "id": 2, "params": {"textDocument": {"uri": "file://temp"}, "position": {"line": 1, "character": 1}}}
+//! ```
+//!
+//! To finish up without errors, send a shutdown request:
+//!
+//! ```no_run
+//! Content-Length: 67
+//!
+//! {"jsonrpc": "2.0", "method": "shutdown", "id": 3, "params": null}
+//! ```
+//!
+//! The server will exit the main loop and finally we send a `shutdown` notification to stop
+//! the server.
+//!
+//! ```
+//! Content-Length: 54
+//!
+//! {"jsonrpc": "2.0", "method": "exit", "params": null}
+//! ```
+use std::error::Error;
+
+use lsp_types::OneOf;
+use lsp_types::{
+    request::GotoDefinition, GotoDefinitionResponse, InitializeParams, ServerCapabilities,
+};
+
+use lsp_server::{Connection, ExtractError, Message, Request, RequestId, Response};
+
+fn main() -> Result<(), Box<dyn Error + Sync + Send>> {
+    // Note that  we must have our logging only write out to stderr.
+    eprintln!("starting generic LSP server");
+
+    // Create the transport. Includes the stdio (stdin and stdout) versions but this could
+    // also be implemented to use sockets or HTTP.
+    let (connection, io_threads) = Connection::stdio();
+
+    // Run the server and wait for the two threads to end (typically by trigger LSP Exit event).
+    let server_capabilities = serde_json::to_value(&ServerCapabilities {
+        definition_provider: Some(OneOf::Left(true)),
+        ..Default::default()
+    })
+    .unwrap();
+    let initialization_params = connection.initialize(server_capabilities)?;
+    main_loop(connection, initialization_params)?;
+    io_threads.join()?;
+
+    // Shut down gracefully.
+    eprintln!("shutting down server");
+    Ok(())
+}
+
+fn main_loop(
+    connection: Connection,
+    params: serde_json::Value,
+) -> Result<(), Box<dyn Error + Sync + Send>> {
+    let _params: InitializeParams = serde_json::from_value(params).unwrap();
+    eprintln!("starting example main loop");
+    for msg in &connection.receiver {
+        eprintln!("got msg: {:?}", msg);
+        match msg {
+            Message::Request(req) => {
+                if connection.handle_shutdown(&req)? {
+                    return Ok(());
+                }
+                eprintln!("got request: {:?}", req);
+                match cast::<GotoDefinition>(req) {
+                    Ok((id, params)) => {
+                        eprintln!("got gotoDefinition request #{}: {:?}", id, params);
+                        let result = Some(GotoDefinitionResponse::Array(Vec::new()));
+                        let result = serde_json::to_value(&result).unwrap();
+                        let resp = Response { id, result: Some(result), error: None };
+                        connection.sender.send(Message::Response(resp))?;
+                        continue;
+                    }
+                    Err(err @ ExtractError::JsonError { .. }) => panic!("{:?}", err),
+                    Err(ExtractError::MethodMismatch(req)) => req,
+                };
+                // ...
+            }
+            Message::Response(resp) => {
+                eprintln!("got response: {:?}", resp);
+            }
+            Message::Notification(not) => {
+                eprintln!("got notification: {:?}", not);
+            }
+        }
+    }
+    Ok(())
+}
+
+fn cast<R>(req: Request) -> Result<(RequestId, R::Params), ExtractError<Request>>
+where
+    R: lsp_types::request::Request,
+    R::Params: serde::de::DeserializeOwned,
+{
+    req.extract(R::METHOD)
+}

lib/lsp-server/src/error.rs

@@ -0,0 +1,50 @@
+use std::fmt;
+
+use crate::{Notification, Request};
+
+#[derive(Debug, Clone)]
+pub struct ProtocolError(pub(crate) String);
+
+impl std::error::Error for ProtocolError {}
+
+impl fmt::Display for ProtocolError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(&self.0, f)
+    }
+}
+
+#[derive(Debug)]
+pub enum ExtractError<T> {
+    /// The extracted message was of a different method than expected.
+    MethodMismatch(T),
+    /// Failed to deserialize the message.
+    JsonError { method: String, error: serde_json::Error },
+}
+
+impl std::error::Error for ExtractError<Request> {}
+impl fmt::Display for ExtractError<Request> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            ExtractError::MethodMismatch(req) => {
+                write!(f, "Method mismatch for request '{}'", req.method)
+            }
+            ExtractError::JsonError { method, error } => {
+                write!(f, "Invalid request\nMethod: {method}\n error: {error}",)
+            }
+        }
+    }
+}
+
+impl std::error::Error for ExtractError<Notification> {}
+impl fmt::Display for ExtractError<Notification> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            ExtractError::MethodMismatch(req) => {
+                write!(f, "Method mismatch for notification '{}'", req.method)
+            }
+            ExtractError::JsonError { method, error } => {
+                write!(f, "Invalid notification\nMethod: {method}\n error: {error}")
+            }
+        }
+    }
+}

lib/lsp-server/src/lib.rs

@@ -0,0 +1,229 @@
+//! A language server scaffold, exposing a synchronous crossbeam-channel based API.
+//! This crate handles protocol handshaking and parsing messages, while you
+//! control the message dispatch loop yourself.
+//!
+//! Run with `RUST_LOG=lsp_server=debug` to see all the messages.
+mod msg;
+mod stdio;
+mod error;
+mod socket;
+mod req_queue;
+
+use std::{
+    io,
+    net::{TcpListener, TcpStream, ToSocketAddrs},
+};
+
+use crossbeam_channel::{Receiver, Sender};
+
+pub use crate::{
+    error::{ExtractError, ProtocolError},
+    msg::{ErrorCode, Message, Notification, Request, RequestId, Response, ResponseError},
+    req_queue::{Incoming, Outgoing, ReqQueue},
+    stdio::IoThreads,
+};
+
+/// Connection is just a pair of channels of LSP messages.
+pub struct Connection {
+    pub sender: Sender<Message>,
+    pub receiver: Receiver<Message>,
+}
+
+impl Connection {
+    /// Create connection over standard in/standard out.
+    ///
+    /// Use this to create a real language server.
+    pub fn stdio() -> (Connection, IoThreads) {
+        let (sender, receiver, io_threads) = stdio::stdio_transport();
+        (Connection { sender, receiver }, io_threads)
+    }
+
+    /// Open a connection over tcp.
+    /// This call blocks until a connection is established.
+    ///
+    /// Use this to create a real language server.
+    pub fn connect<A: ToSocketAddrs>(addr: A) -> io::Result<(Connection, IoThreads)> {
+        let stream = TcpStream::connect(addr)?;
+        let (sender, receiver, io_threads) = socket::socket_transport(stream);
+        Ok((Connection { sender, receiver }, io_threads))
+    }
+
+    /// Listen for a connection over tcp.
+    /// This call blocks until a connection is established.
+    ///
+    /// Use this to create a real language server.
+    pub fn listen<A: ToSocketAddrs>(addr: A) -> io::Result<(Connection, IoThreads)> {
+        let listener = TcpListener::bind(addr)?;
+        let (stream, _) = listener.accept()?;
+        let (sender, receiver, io_threads) = socket::socket_transport(stream);
+        Ok((Connection { sender, receiver }, io_threads))
+    }
+
+    /// Creates a pair of connected connections.
+    ///
+    /// Use this for testing.
+    pub fn memory() -> (Connection, Connection) {
+        let (s1, r1) = crossbeam_channel::unbounded();
+        let (s2, r2) = crossbeam_channel::unbounded();
+        (Connection { sender: s1, receiver: r2 }, Connection { sender: s2, receiver: r1 })
+    }
+
+    /// Starts the initialization process by waiting for an initialize
+    /// request from the client. Use this for more advanced customization than
+    /// `initialize` can provide.
+    ///
+    /// Returns the request id and serialized `InitializeParams` from the client.
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// use std::error::Error;
+    /// use lsp_types::{ClientCapabilities, InitializeParams, ServerCapabilities};
+    ///
+    /// use lsp_server::{Connection, Message, Request, RequestId, Response};
+    ///
+    /// fn main() -> Result<(), Box<dyn Error + Sync + Send>> {
+    ///    // Create the transport. Includes the stdio (stdin and stdout) versions but this could
+    ///    // also be implemented to use sockets or HTTP.
+    ///    let (connection, io_threads) = Connection::stdio();
+    ///
+    ///    // Run the server
+    ///    let (id, params) = connection.initialize_start()?;
+    ///
+    ///    let init_params: InitializeParams = serde_json::from_value(params).unwrap();
+    ///    let client_capabilities: ClientCapabilities = init_params.capabilities;
+    ///    let server_capabilities = ServerCapabilities::default();
+    ///
+    ///    let initialize_data = serde_json::json!({
+    ///        "capabilities": server_capabilities,
+    ///        "serverInfo": {
+    ///            "name": "lsp-server-test",
+    ///            "version": "0.1"
+    ///        }
+    ///    });
+    ///
+    ///    connection.initialize_finish(id, initialize_data)?;
+    ///
+    ///    // ... Run main loop ...
+    ///
+    ///    Ok(())
+    /// }
+    /// ```
+    pub fn initialize_start(&self) -> Result<(RequestId, serde_json::Value), ProtocolError> {
+        loop {
+            match self.receiver.recv() {
+                Ok(Message::Request(req)) if req.is_initialize() => {
+                    return Ok((req.id, req.params))
+                }
+                // Respond to non-initialize requests with ServerNotInitialized
+                Ok(Message::Request(req)) => {
+                    let resp = Response::new_err(
+                        req.id.clone(),
+                        ErrorCode::ServerNotInitialized as i32,
+                        format!("expected initialize request, got {:?}", req),
+                    );
+                    self.sender.send(resp.into()).unwrap();
+                }
+                Ok(msg) => {
+                    return Err(ProtocolError(format!(
+                        "expected initialize request, got {:?}",
+                        msg
+                    )))
+                }
+                Err(e) => {
+                    return Err(ProtocolError(format!(
+                        "expected initialize request, got error: {}",
+                        e
+                    )))
+                }
+            };
+        }
+    }
+
+    /// Finishes the initialization process by sending an `InitializeResult` to the client
+    pub fn initialize_finish(
+        &self,
+        initialize_id: RequestId,
+        initialize_result: serde_json::Value,
+    ) -> Result<(), ProtocolError> {
+        let resp = Response::new_ok(initialize_id, initialize_result);
+        self.sender.send(resp.into()).unwrap();
+        match &self.receiver.recv() {
+            Ok(Message::Notification(n)) if n.is_initialized() => (),
+            Ok(msg) => {
+                return Err(ProtocolError(format!(
+                    "expected Message::Notification, got: {:?}",
+                    msg,
+                )))
+            }
+            Err(e) => {
+                return Err(ProtocolError(format!(
+                    "expected initialized notification, got error: {}",
+                    e,
+                )))
+            }
+        }
+        Ok(())
+    }
+
+    /// Initialize the connection. Sends the server capabilities
+    /// to the client and returns the serialized client capabilities
+    /// on success. If more fine-grained initialization is required use
+    /// `initialize_start`/`initialize_finish`.
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// use std::error::Error;
+    /// use lsp_types::ServerCapabilities;
+    ///
+    /// use lsp_server::{Connection, Message, Request, RequestId, Response};
+    ///
+    /// fn main() -> Result<(), Box<dyn Error + Sync + Send>> {
+    ///    // Create the transport. Includes the stdio (stdin and stdout) versions but this could
+    ///    // also be implemented to use sockets or HTTP.
+    ///    let (connection, io_threads) = Connection::stdio();
+    ///
+    ///    // Run the server
+    ///    let server_capabilities = serde_json::to_value(&ServerCapabilities::default()).unwrap();
+    ///    let initialization_params = connection.initialize(server_capabilities)?;
+    ///
+    ///    // ... Run main loop ...
+    ///
+    ///    Ok(())
+    /// }
+    /// ```
+    pub fn initialize(
+        &self,
+        server_capabilities: serde_json::Value,
+    ) -> Result<serde_json::Value, ProtocolError> {
+        let (id, params) = self.initialize_start()?;
+
+        let initialize_data = serde_json::json!({
+            "capabilities": server_capabilities,
+        });
+
+        self.initialize_finish(id, initialize_data)?;
+
+        Ok(params)
+    }
+
+    /// If `req` is `Shutdown`, respond to it and return `true`, otherwise return `false`
+    pub fn handle_shutdown(&self, req: &Request) -> Result<bool, ProtocolError> {
+        if !req.is_shutdown() {
+            return Ok(false);
+        }
+        let resp = Response::new_ok(req.id.clone(), ());
+        let _ = self.sender.send(resp.into());
+        match &self.receiver.recv_timeout(std::time::Duration::from_secs(30)) {
+            Ok(Message::Notification(n)) if n.is_exit() => (),
+            Ok(msg) => {
+                return Err(ProtocolError(format!("unexpected message during shutdown: {:?}", msg)))
+            }
+            Err(e) => {
+                return Err(ProtocolError(format!("unexpected error during shutdown: {}", e)))
+            }
+        }
+        Ok(true)
+    }
+}

lib/lsp-server/src/msg.rs

@@ -0,0 +1,343 @@
+use std::{
+    fmt,
+    io::{self, BufRead, Write},
+};
+
+use serde::{de::DeserializeOwned, Deserialize, Serialize};
+
+use crate::error::ExtractError;
+
+#[derive(Serialize, Deserialize, Debug, Clone)]
+#[serde(untagged)]
+pub enum Message {
+    Request(Request),
+    Response(Response),
+    Notification(Notification),
+}
+
+impl From<Request> for Message {
+    fn from(request: Request) -> Message {
+        Message::Request(request)
+    }
+}
+
+impl From<Response> for Message {
+    fn from(response: Response) -> Message {
+        Message::Response(response)
+    }
+}
+
+impl From<Notification> for Message {
+    fn from(notification: Notification) -> Message {
+        Message::Notification(notification)
+    }
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+#[serde(transparent)]
+pub struct RequestId(IdRepr);
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+#[serde(untagged)]
+enum IdRepr {
+    I32(i32),
+    String(String),
+}
+
+impl From<i32> for RequestId {
+    fn from(id: i32) -> RequestId {
+        RequestId(IdRepr::I32(id))
+    }
+}
+
+impl From<String> for RequestId {
+    fn from(id: String) -> RequestId {
+        RequestId(IdRepr::String(id))
+    }
+}
+
+impl fmt::Display for RequestId {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match &self.0 {
+            IdRepr::I32(it) => fmt::Display::fmt(it, f),
+            // Use debug here, to make it clear that `92` and `"92"` are
+            // different, and to reduce WTF factor if the sever uses `" "` as an
+            // ID.
+            IdRepr::String(it) => fmt::Debug::fmt(it, f),
+        }
+    }
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub struct Request {
+    pub id: RequestId,
+    pub method: String,
+    #[serde(default = "serde_json::Value::default")]
+    #[serde(skip_serializing_if = "serde_json::Value::is_null")]
+    pub params: serde_json::Value,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub struct Response {
+    // JSON RPC allows this to be null if it was impossible
+    // to decode the request's id. Ignore this special case
+    // and just die horribly.
+    pub id: RequestId,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub result: Option<serde_json::Value>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub error: Option<ResponseError>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub struct ResponseError {
+    pub code: i32,
+    pub message: String,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub data: Option<serde_json::Value>,
+}
+
+#[derive(Clone, Copy, Debug)]
+#[allow(unused)]
+pub enum ErrorCode {
+    // Defined by JSON RPC:
+    ParseError = -32700,
+    InvalidRequest = -32600,
+    MethodNotFound = -32601,
+    InvalidParams = -32602,
+    InternalError = -32603,
+    ServerErrorStart = -32099,
+    ServerErrorEnd = -32000,
+
+    /// Error code indicating that a server received a notification or
+    /// request before the server has received the `initialize` request.
+    ServerNotInitialized = -32002,
+    UnknownErrorCode = -32001,
+
+    // Defined by the protocol:
+    /// The client has canceled a request and a server has detected
+    /// the cancel.
+    RequestCanceled = -32800,
+
+    /// The server detected that the content of a document got
+    /// modified outside normal conditions. A server should
+    /// NOT send this error code if it detects a content change
+    /// in it unprocessed messages. The result even computed
+    /// on an older state might still be useful for the client.
+    ///
+    /// If a client decides that a result is not of any use anymore
+    /// the client should cancel the request.
+    ContentModified = -32801,
+
+    /// The server cancelled the request. This error code should
+    /// only be used for requests that explicitly support being
+    /// server cancellable.
+    ///
+    /// @since 3.17.0
+    ServerCancelled = -32802,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub struct Notification {
+    pub method: String,
+    #[serde(default = "serde_json::Value::default")]
+    #[serde(skip_serializing_if = "serde_json::Value::is_null")]
+    pub params: serde_json::Value,
+}
+
+impl Message {
+    pub fn read(r: &mut impl BufRead) -> io::Result<Option<Message>> {
+        Message::_read(r)
+    }
+    fn _read(r: &mut dyn BufRead) -> io::Result<Option<Message>> {
+        let text = match read_msg_text(r)? {
+            None => return Ok(None),
+            Some(text) => text,
+        };
+        let msg = serde_json::from_str(&text)?;
+        Ok(Some(msg))
+    }
+    pub fn write(self, w: &mut impl Write) -> io::Result<()> {
+        self._write(w)
+    }
+    fn _write(self, w: &mut dyn Write) -> io::Result<()> {
+        #[derive(Serialize)]
+        struct JsonRpc {
+            jsonrpc: &'static str,
+            #[serde(flatten)]
+            msg: Message,
+        }
+        let text = serde_json::to_string(&JsonRpc { jsonrpc: "2.0", msg: self })?;
+        write_msg_text(w, &text)
+    }
+}
+
+impl Response {
+    pub fn new_ok<R: Serialize>(id: RequestId, result: R) -> Response {
+        Response { id, result: Some(serde_json::to_value(result).unwrap()), error: None }
+    }
+    pub fn new_err(id: RequestId, code: i32, message: String) -> Response {
+        let error = ResponseError { code, message, data: None };
+        Response { id, result: None, error: Some(error) }
+    }
+}
+
+impl Request {
+    pub fn new<P: Serialize>(id: RequestId, method: String, params: P) -> Request {
+        Request { id, method, params: serde_json::to_value(params).unwrap() }
+    }
+    pub fn extract<P: DeserializeOwned>(
+        self,
+        method: &str,
+    ) -> Result<(RequestId, P), ExtractError<Request>> {
+        if self.method != method {
+            return Err(ExtractError::MethodMismatch(self));
+        }
+        match serde_json::from_value(self.params) {
+            Ok(params) => Ok((self.id, params)),
+            Err(error) => Err(ExtractError::JsonError { method: self.method, error }),
+        }
+    }
+
+    pub(crate) fn is_shutdown(&self) -> bool {
+        self.method == "shutdown"
+    }
+    pub(crate) fn is_initialize(&self) -> bool {
+        self.method == "initialize"
+    }
+}
+
+impl Notification {
+    pub fn new(method: String, params: impl Serialize) -> Notification {
+        Notification { method, params: serde_json::to_value(params).unwrap() }
+    }
+    pub fn extract<P: DeserializeOwned>(
+        self,
+        method: &str,
+    ) -> Result<P, ExtractError<Notification>> {
+        if self.method != method {
+            return Err(ExtractError::MethodMismatch(self));
+        }
+        match serde_json::from_value(self.params) {
+            Ok(params) => Ok(params),
+            Err(error) => Err(ExtractError::JsonError { method: self.method, error }),
+        }
+    }
+    pub(crate) fn is_exit(&self) -> bool {
+        self.method == "exit"
+    }
+    pub(crate) fn is_initialized(&self) -> bool {
+        self.method == "initialized"
+    }
+}
+
+fn read_msg_text(inp: &mut dyn BufRead) -> io::Result<Option<String>> {
+    fn invalid_data(error: impl Into<Box<dyn std::error::Error + Send + Sync>>) -> io::Error {
+        io::Error::new(io::ErrorKind::InvalidData, error)
+    }
+    macro_rules! invalid_data {
+        ($($tt:tt)*) => (invalid_data(format!($($tt)*)))
+    }
+
+    let mut size = None;
+    let mut buf = String::new();
+    loop {
+        buf.clear();
+        if inp.read_line(&mut buf)? == 0 {
+            return Ok(None);
+        }
+        if !buf.ends_with("\r\n") {
+            return Err(invalid_data!("malformed header: {:?}", buf));
+        }
+        let buf = &buf[..buf.len() - 2];
+        if buf.is_empty() {
+            break;
+        }
+        let mut parts = buf.splitn(2, ": ");
+        let header_name = parts.next().unwrap();
+        let header_value =
+            parts.next().ok_or_else(|| invalid_data!("malformed header: {:?}", buf))?;
+        if header_name == "Content-Length" {
+            size = Some(header_value.parse::<usize>().map_err(invalid_data)?);
+        }
+    }
+    let size: usize = size.ok_or_else(|| invalid_data!("no Content-Length"))?;
+    let mut buf = buf.into_bytes();
+    buf.resize(size, 0);
+    inp.read_exact(&mut buf)?;
+    let buf = String::from_utf8(buf).map_err(invalid_data)?;
+    log::debug!("< {}", buf);
+    Ok(Some(buf))
+}
+
+fn write_msg_text(out: &mut dyn Write, msg: &str) -> io::Result<()> {
+    log::debug!("> {}", msg);
+    write!(out, "Content-Length: {}\r\n\r\n", msg.len())?;
+    out.write_all(msg.as_bytes())?;
+    out.flush()?;
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{Message, Notification, Request, RequestId};
+
+    #[test]
+    fn shutdown_with_explicit_null() {
+        let text = "{\"jsonrpc\": \"2.0\",\"id\": 3,\"method\": \"shutdown\", \"params\": null }";
+        let msg: Message = serde_json::from_str(text).unwrap();
+
+        assert!(
+            matches!(msg, Message::Request(req) if req.id == 3.into() && req.method == "shutdown")
+        );
+    }
+
+    #[test]
+    fn shutdown_with_no_params() {
+        let text = "{\"jsonrpc\": \"2.0\",\"id\": 3,\"method\": \"shutdown\"}";
+        let msg: Message = serde_json::from_str(text).unwrap();
+
+        assert!(
+            matches!(msg, Message::Request(req) if req.id == 3.into() && req.method == "shutdown")
+        );
+    }
+
+    #[test]
+    fn notification_with_explicit_null() {
+        let text = "{\"jsonrpc\": \"2.0\",\"method\": \"exit\", \"params\": null }";
+        let msg: Message = serde_json::from_str(text).unwrap();
+
+        assert!(matches!(msg, Message::Notification(not) if not.method == "exit"));
+    }
+
+    #[test]
+    fn notification_with_no_params() {
+        let text = "{\"jsonrpc\": \"2.0\",\"method\": \"exit\"}";
+        let msg: Message = serde_json::from_str(text).unwrap();
+
+        assert!(matches!(msg, Message::Notification(not) if not.method == "exit"));
+    }
+
+    #[test]
+    fn serialize_request_with_null_params() {
+        let msg = Message::Request(Request {
+            id: RequestId::from(3),
+            method: "shutdown".into(),
+            params: serde_json::Value::Null,
+        });
+        let serialized = serde_json::to_string(&msg).unwrap();
+
+        assert_eq!("{\"id\":3,\"method\":\"shutdown\"}", serialized);
+    }
+
+    #[test]
+    fn serialize_notification_with_null_params() {
+        let msg = Message::Notification(Notification {
+            method: "exit".into(),
+            params: serde_json::Value::Null,
+        });
+        let serialized = serde_json::to_string(&msg).unwrap();
+
+        assert_eq!("{\"method\":\"exit\"}", serialized);
+    }
+}

lib/lsp-server/src/req_queue.rs

@@ -0,0 +1,62 @@
+use std::collections::HashMap;
+
+use serde::Serialize;
+
+use crate::{ErrorCode, Request, RequestId, Response, ResponseError};
+
+/// Manages the set of pending requests, both incoming and outgoing.
+#[derive(Debug)]
+pub struct ReqQueue<I, O> {
+    pub incoming: Incoming<I>,
+    pub outgoing: Outgoing<O>,
+}
+
+impl<I, O> Default for ReqQueue<I, O> {
+    fn default() -> ReqQueue<I, O> {
+        ReqQueue {
+            incoming: Incoming { pending: HashMap::default() },
+            outgoing: Outgoing { next_id: 0, pending: HashMap::default() },
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct Incoming<I> {
+    pending: HashMap<RequestId, I>,
+}
+
+#[derive(Debug)]
+pub struct Outgoing<O> {
+    next_id: i32,
+    pending: HashMap<RequestId, O>,
+}
+
+impl<I> Incoming<I> {
+    pub fn register(&mut self, id: RequestId, data: I) {
+        self.pending.insert(id, data);
+    }
+    pub fn cancel(&mut self, id: RequestId) -> Option<Response> {
+        let _data = self.complete(id.clone())?;
+        let error = ResponseError {
+            code: ErrorCode::RequestCanceled as i32,
+            message: "canceled by client".to_string(),
+            data: None,
+        };
+        Some(Response { id, result: None, error: Some(error) })
+    }
+    pub fn complete(&mut self, id: RequestId) -> Option<I> {
+        self.pending.remove(&id)
+    }
+}
+
+impl<O> Outgoing<O> {
+    pub fn register<P: Serialize>(&mut self, method: String, params: P, data: O) -> Request {
+        let id = RequestId::from(self.next_id);
+        self.pending.insert(id.clone(), data);
+        self.next_id += 1;
+        Request::new(id, method, params)
+    }
+    pub fn complete(&mut self, id: RequestId) -> Option<O> {
+        self.pending.remove(&id)
+    }
+}

lib/lsp-server/src/socket.rs

@@ -0,0 +1,46 @@
+use std::{
+    io::{self, BufReader},
+    net::TcpStream,
+    thread,
+};
+
+use crossbeam_channel::{bounded, Receiver, Sender};
+
+use crate::{
+    stdio::{make_io_threads, IoThreads},
+    Message,
+};
+
+pub(crate) fn socket_transport(
+    stream: TcpStream,
+) -> (Sender<Message>, Receiver<Message>, IoThreads) {
+    let (reader_receiver, reader) = make_reader(stream.try_clone().unwrap());
+    let (writer_sender, writer) = make_write(stream.try_clone().unwrap());
+    let io_threads = make_io_threads(reader, writer);
+    (writer_sender, reader_receiver, io_threads)
+}
+
+fn make_reader(stream: TcpStream) -> (Receiver<Message>, thread::JoinHandle<io::Result<()>>) {
+    let (reader_sender, reader_receiver) = bounded::<Message>(0);
+    let reader = thread::spawn(move || {
+        let mut buf_read = BufReader::new(stream);
+        while let Some(msg) = Message::read(&mut buf_read).unwrap() {
+            let is_exit = matches!(&msg, Message::Notification(n) if n.is_exit());
+            reader_sender.send(msg).unwrap();
+            if is_exit {
+                break;
+            }
+        }
+        Ok(())
+    });
+    (reader_receiver, reader)
+}
+
+fn make_write(mut stream: TcpStream) -> (Sender<Message>, thread::JoinHandle<io::Result<()>>) {
+    let (writer_sender, writer_receiver) = bounded::<Message>(0);
+    let writer = thread::spawn(move || {
+        writer_receiver.into_iter().try_for_each(|it| it.write(&mut stream)).unwrap();
+        Ok(())
+    });
+    (writer_sender, writer)
+}

lib/lsp-server/src/stdio.rs

@@ -0,0 +1,71 @@
+use std::{
+    io::{self, stdin, stdout},
+    thread,
+};
+
+use crossbeam_channel::{bounded, Receiver, Sender};
+
+use crate::Message;
+
+/// Creates an LSP connection via stdio.
+pub(crate) fn stdio_transport() -> (Sender<Message>, Receiver<Message>, IoThreads) {
+    let (writer_sender, writer_receiver) = bounded::<Message>(0);
+    let writer = thread::spawn(move || {
+        let stdout = stdout();
+        let mut stdout = stdout.lock();
+        writer_receiver.into_iter().try_for_each(|it| it.write(&mut stdout))?;
+        Ok(())
+    });
+    let (reader_sender, reader_receiver) = bounded::<Message>(0);
+    let reader = thread::spawn(move || {
+        let stdin = stdin();
+        let mut stdin = stdin.lock();
+        while let Some(msg) = Message::read(&mut stdin)? {
+            let is_exit = match &msg {
+                Message::Notification(n) => n.is_exit(),
+                _ => false,
+            };
+
+            reader_sender.send(msg).unwrap();
+
+            if is_exit {
+                break;
+            }
+        }
+        Ok(())
+    });
+    let threads = IoThreads { reader, writer };
+    (writer_sender, reader_receiver, threads)
+}
+
+// Creates an IoThreads
+pub(crate) fn make_io_threads(
+    reader: thread::JoinHandle<io::Result<()>>,
+    writer: thread::JoinHandle<io::Result<()>>,
+) -> IoThreads {
+    IoThreads { reader, writer }
+}
+
+pub struct IoThreads {
+    reader: thread::JoinHandle<io::Result<()>>,
+    writer: thread::JoinHandle<io::Result<()>>,
+}
+
+impl IoThreads {
+    pub fn join(self) -> io::Result<()> {
+        match self.reader.join() {
+            Ok(r) => r?,
+            Err(err) => {
+                println!("reader panicked!");
+                std::panic::panic_any(err)
+            }
+        }
+        match self.writer.join() {
+            Ok(r) => r,
+            Err(err) => {
+                println!("writer panicked!");
+                std::panic::panic_any(err);
+            }
+        }
+    }
+}