Started work on LSP server

Cargo.toml

@@ -1,3 +1,3 @@
 [workspace]
-members = [ "harper-core", "harper-serve", "harper-wasm"]
+members = [ "harper-core", "harper-ls", "harper-serve", "harper-wasm"]
 resolver = "2"

harper-ls/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "harper-ls"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+anyhow = "1.0.79"
+ctrlc = "3.4.2"
+lsp-server = "0.7.6"
+lsp-types = "0.95.0"
+serde = "1.0.195"
+serde_json = "1.0.111"
+tracing = "0.1.40"
+tracing-subscriber = "0.3.18"

harper-ls/src/main.rs

@@ -0,0 +1,97 @@
+use lsp_types::{
+    request::GotoDefinition, GotoDefinitionResponse, InitializeParams, ServerCapabilities,
+};
+use lsp_types::{Location, OneOf, Position};
+
+use lsp_server::{Connection, ExtractError, Message, Request, RequestId, Response};
+use tracing::{info, Level};
+
+fn main() -> anyhow::Result<()> {
+    let subscriber = tracing_subscriber::FmtSubscriber::builder()
+        .with_max_level(Level::DEBUG)
+        .finish();
+
+    tracing::subscriber::set_global_default(subscriber)?;
+
+    let (connection, io_threads) = Connection::listen("127.0.0.1:4000")?;
+
+    let server_capabilities = serde_json::to_value(ServerCapabilities {
+        definition_provider: Some(OneOf::Left(true)),
+        ..Default::default()
+    })
+    .unwrap();
+    let initialization_params = match connection.initialize(server_capabilities) {
+        Ok(it) => it,
+        Err(e) => {
+            if e.channel_is_disconnected() {
+                io_threads.join()?;
+            }
+            return Err(e.into());
+        }
+    };
+    main_loop(connection, initialization_params)?;
+    io_threads.join()?;
+
+    info!("Shutting down server.c");
+    Ok(())
+}
+
+fn main_loop(connection: Connection, params: serde_json::Value) -> anyhow::Result<()> {
+    let _params: InitializeParams = serde_json::from_value(params).unwrap();
+    info!("Starting example main loop");
+    for msg in &connection.receiver {
+        info!("Got msg: {msg:?}");
+        match msg {
+            Message::Request(req) => {
+                if connection.handle_shutdown(&req)? {
+                    return Ok(());
+                }
+                info!("Got request: {req:?}");
+                match cast::<GotoDefinition>(req) {
+                    Ok((id, params)) => {
+                        info!("Got gotoDefinition request #{id}: {params:?}");
+                        let result = Some(GotoDefinitionResponse::Array(vec![Location {
+                            uri: params.text_document_position_params.text_document.uri,
+                            range: lsp_types::Range {
+                                start: Position {
+                                    line: 0,
+                                    character: 0,
+                                },
+                                end: Position {
+                                    line: 0,
+                                    character: 0,
+                                },
+                            },
+                        }]));
+                        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) => {
+                info!("Got response: {resp:?}");
+            }
+            Message::Notification(not) => {
+                info!("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)
+}

nvim.lua

@@ -0,0 +1,5 @@
+vim.lsp.start({
+  name = "example",
+  cmd = vim.lsp.rpc.connect("127.0.0.1", 4000),
+  root_dir = "."
+})