bendns' repos / rust-analyzer
Unnamed repository; edit this file 'description' to name the repository.
Diffstat (limited to 'lib/lsp-server/examples/minimal_lsp.rs')
-rw-r--r--lib/lsp-server/examples/minimal_lsp.rs335
1 files changed, 335 insertions, 0 deletions
diff --git a/lib/lsp-server/examples/minimal_lsp.rs b/lib/lsp-server/examples/minimal_lsp.rs
new file mode 100644
index 0000000000..5eef999e06
--- /dev/null
+++ b/lib/lsp-server/examples/minimal_lsp.rs
@@ -0,0 +1,335 @@
+//! Minimal Language‑Server‑Protocol example: **`minimal_lsp.rs`**
+//! =============================================================
+//!
+//! | ↔ / ← | LSP method | What the implementation does |
+//! |-------|------------|------------------------------|
+//! | ↔ | `initialize` / `initialized` | capability handshake |
+//! | ← | `textDocument/publishDiagnostics` | pushes a dummy info diagnostic whenever the buffer changes |
+//! | ← | `textDocument/definition` | echoes an empty location array so the jump works |
+//! | ← | `textDocument/completion` | offers one hard‑coded item `HelloFromLSP` |
+//! | ← | `textDocument/hover` | shows *Hello from minimal_lsp* markdown |
+//! | ← | `textDocument/formatting` | pipes the doc through **rustfmt** and returns a full‑file edit |
+//!
+//! ### Quick start
+//! ```bash
+//! cd rust-analyzer/lib/lsp-server
+//! cargo run --example minimal_lsp
+//! ```
+//!
+//! ### Minimal manual session (all nine packets)
+//! ```no_run
+//! # 1. initialize - server replies with capabilities
+//! Content-Length: 85
+
+//! {"jsonrpc":"2.0","id":1,"method":"initialize","params":{"capabilities":{}}}
+//!
+//! # 2. initialized - no response expected
+//! Content-Length: 59
+
+//! {"jsonrpc":"2.0","method":"initialized","params":{}}
+//!
+//! # 3. didOpen - provide initial buffer text
+//! Content-Length: 173
+
+//! {"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"file:///tmp/foo.rs","languageId":"rust","version":1,"text":"fn main( ){println!(\"hi\") }"}}}
+//!
+//! # 4. completion - expect HelloFromLSP
+//! Content-Length: 139
+
+//! {"jsonrpc":"2.0","id":2,"method":"textDocument/completion","params":{"textDocument":{"uri":"file:///tmp/foo.rs"},"position":{"line":0,"character":0}}}
+//!
+//! # 5. hover - expect markdown greeting
+//! Content-Length: 135
+
+//! {"jsonrpc":"2.0","id":3,"method":"textDocument/hover","params":{"textDocument":{"uri":"file:///tmp/foo.rs"},"position":{"line":0,"character":0}}}
+//!
+//! # 6. goto-definition - dummy empty array
+//! Content-Length: 139
+
+//! {"jsonrpc":"2.0","id":4,"method":"textDocument/definition","params":{"textDocument":{"uri":"file:///tmp/foo.rs"},"position":{"line":0,"character":0}}}
+//!
+//! # 7. formatting - rustfmt full document
+//! Content-Length: 157
+
+//! {"jsonrpc":"2.0","id":5,"method":"textDocument/formatting","params":{"textDocument":{"uri":"file:///tmp/foo.rs"},"options":{"tabSize":4,"insertSpaces":true}}}
+//!
+//! # 8. shutdown request - server acks and prepares to exit
+//! Content-Length: 67
+
+//! {"jsonrpc":"2.0","id":6,"method":"shutdown","params":null}
+//!
+//! # 9. exit notification - terminates the server
+//! Content-Length: 54
+
+//! {"jsonrpc":"2.0","method":"exit","params":null}
+//! ```
+//!
+
+use std::{error::Error, io::Write};
+
+use rustc_hash::FxHashMap; // fast hash map
+use std::process::Stdio;
+use toolchain::command; // clippy-approved wrapper
+
+#[allow(clippy::print_stderr, clippy::disallowed_types, clippy::disallowed_methods)]
+use anyhow::{Context, Result, anyhow, bail};
+use lsp_server::{Connection, Message, Request as ServerRequest, RequestId, Response};
+use lsp_types::notification::Notification as _; // for METHOD consts
+use lsp_types::request::Request as _;
+use lsp_types::{
+ CompletionItem,
+ CompletionItemKind,
+ // capability helpers
+ CompletionOptions,
+ CompletionResponse,
+ Diagnostic,
+ DiagnosticSeverity,
+ DidChangeTextDocumentParams,
+ DidOpenTextDocumentParams,
+ DocumentFormattingParams,
+ Hover,
+ HoverContents,
+ HoverProviderCapability,
+ // core
+ InitializeParams,
+ MarkedString,
+ OneOf,
+ Position,
+ PublishDiagnosticsParams,
+ Range,
+ ServerCapabilities,
+ TextDocumentSyncCapability,
+ TextDocumentSyncKind,
+ TextEdit,
+ Url,
+ // notifications
+ notification::{DidChangeTextDocument, DidOpenTextDocument, PublishDiagnostics},
+ // requests
+ request::{Completion, Formatting, GotoDefinition, HoverRequest},
+}; // for METHOD consts
+
+// =====================================================================
+// main
+// =====================================================================
+
+#[allow(clippy::print_stderr)]
+fn main() -> std::result::Result<(), Box<dyn Error + Sync + Send>> {
+ log::error!("starting minimal_lsp");
+
+ // transport
+ let (connection, io_thread) = Connection::stdio();
+
+ // advertised capabilities
+ let caps = ServerCapabilities {
+ text_document_sync: Some(TextDocumentSyncCapability::Kind(TextDocumentSyncKind::FULL)),
+ completion_provider: Some(CompletionOptions::default()),
+ definition_provider: Some(OneOf::Left(true)),
+ hover_provider: Some(HoverProviderCapability::Simple(true)),
+ document_formatting_provider: Some(OneOf::Left(true)),
+ ..Default::default()
+ };
+ let init_value = serde_json::json!({
+ "capabilities": caps,
+ "offsetEncoding": ["utf-8"],
+ });
+
+ let init_params = connection.initialize(init_value)?;
+ main_loop(connection, init_params)?;
+ io_thread.join()?;
+ log::error!("shutting down server");
+ Ok(())
+}
+
+// =====================================================================
+// event loop
+// =====================================================================
+
+fn main_loop(
+ connection: Connection,
+ params: serde_json::Value,
+) -> std::result::Result<(), Box<dyn Error + Sync + Send>> {
+ let _init: InitializeParams = serde_json::from_value(params)?;
+ let mut docs: FxHashMap<Url, String> = FxHashMap::default();
+
+ for msg in &connection.receiver {
+ match msg {
+ Message::Request(req) => {
+ if connection.handle_shutdown(&req)? {
+ break;
+ }
+ if let Err(err) = handle_request(&connection, &req, &mut docs) {
+ log::error!("[lsp] request {} failed: {err}", &req.method);
+ }
+ }
+ Message::Notification(note) => {
+ if let Err(err) = handle_notification(&connection, &note, &mut docs) {
+ log::error!("[lsp] notification {} failed: {err}", note.method);
+ }
+ }
+ Message::Response(resp) => log::error!("[lsp] response: {resp:?}"),
+ }
+ }
+ Ok(())
+}
+
+// =====================================================================
+// notifications
+// =====================================================================
+
+fn handle_notification(
+ conn: &Connection,
+ note: &lsp_server::Notification,
+ docs: &mut FxHashMap<Url, String>,
+) -> Result<()> {
+ match note.method.as_str() {
+ DidOpenTextDocument::METHOD => {
+ let p: DidOpenTextDocumentParams = serde_json::from_value(note.params.clone())?;
+ let uri = p.text_document.uri;
+ docs.insert(uri.clone(), p.text_document.text);
+ publish_dummy_diag(conn, &uri)?;
+ }
+ DidChangeTextDocument::METHOD => {
+ let p: DidChangeTextDocumentParams = serde_json::from_value(note.params.clone())?;
+ if let Some(change) = p.content_changes.into_iter().next() {
+ let uri = p.text_document.uri;
+ docs.insert(uri.clone(), change.text);
+ publish_dummy_diag(conn, &uri)?;
+ }
+ }
+ _ => {}
+ }
+ Ok(())
+}
+
+// =====================================================================
+// requests
+// =====================================================================
+
+fn handle_request(
+ conn: &Connection,
+ req: &ServerRequest,
+ docs: &mut FxHashMap<Url, String>,
+) -> Result<()> {
+ match req.method.as_str() {
+ GotoDefinition::METHOD => {
+ send_ok(conn, req.id.clone(), &lsp_types::GotoDefinitionResponse::Array(Vec::new()))?;
+ }
+ Completion::METHOD => {
+ let item = CompletionItem {
+ label: "HelloFromLSP".into(),
+ kind: Some(CompletionItemKind::FUNCTION),
+ detail: Some("dummy completion".into()),
+ ..Default::default()
+ };
+ send_ok(conn, req.id.clone(), &CompletionResponse::Array(vec![item]))?;
+ }
+ HoverRequest::METHOD => {
+ let hover = Hover {
+ contents: HoverContents::Scalar(MarkedString::String(
+ "Hello from *minimal_lsp*".into(),
+ )),
+ range: None,
+ };
+ send_ok(conn, req.id.clone(), &hover)?;
+ }
+ Formatting::METHOD => {
+ let p: DocumentFormattingParams = serde_json::from_value(req.params.clone())?;
+ let uri = p.text_document.uri;
+ let text = docs
+ .get(&uri)
+ .ok_or_else(|| anyhow!("document not in cache – did you send DidOpen?"))?;
+ let formatted = run_rustfmt(text)?;
+ let edit = TextEdit { range: full_range(text), new_text: formatted };
+ send_ok(conn, req.id.clone(), &vec![edit])?;
+ }
+ _ => send_err(
+ conn,
+ req.id.clone(),
+ lsp_server::ErrorCode::MethodNotFound,
+ "unhandled method",
+ )?,
+ }
+ Ok(())
+}
+
+// =====================================================================
+// diagnostics
+// =====================================================================
+fn publish_dummy_diag(conn: &Connection, uri: &Url) -> Result<()> {
+ let diag = Diagnostic {
+ range: Range::new(Position::new(0, 0), Position::new(0, 1)),
+ severity: Some(DiagnosticSeverity::INFORMATION),
+ code: None,
+ code_description: None,
+ source: Some("minimal_lsp".into()),
+ message: "dummy diagnostic".into(),
+ related_information: None,
+ tags: None,
+ data: None,
+ };
+ let params =
+ PublishDiagnosticsParams { uri: uri.clone(), diagnostics: vec![diag], version: None };
+ conn.sender.send(Message::Notification(lsp_server::Notification::new(
+ PublishDiagnostics::METHOD.to_owned(),
+ params,
+ )))?;
+ Ok(())
+}
+
+// =====================================================================
+// helpers
+// =====================================================================
+
+fn run_rustfmt(input: &str) -> Result<String> {
+ let cwd = std::env::current_dir().expect("can't determine CWD");
+ let mut child = command("rustfmt", &cwd, &FxHashMap::default())
+ .arg("--emit")
+ .arg("stdout")
+ .stdin(Stdio::piped())
+ .stdout(Stdio::piped())
+ .stderr(Stdio::piped())
+ .spawn()
+ .context("failed to spawn rustfmt – is it installed?")?;
+
+ let Some(stdin) = child.stdin.as_mut() else {
+ bail!("stdin unavailable");
+ };
+ stdin.write_all(input.as_bytes())?;
+ let output = child.wait_with_output()?;
+ if !output.status.success() {
+ let stderr = String::from_utf8_lossy(&output.stderr);
+ bail!("rustfmt failed: {stderr}");
+ }
+ Ok(String::from_utf8(output.stdout)?)
+}
+
+fn full_range(text: &str) -> Range {
+ let last_line_idx = text.lines().count().saturating_sub(1) as u32;
+ let last_col = text.lines().last().map_or(0, |l| l.chars().count()) as u32;
+ Range::new(Position::new(0, 0), Position::new(last_line_idx, last_col))
+}
+
+fn send_ok<T: serde::Serialize>(conn: &Connection, id: RequestId, result: &T) -> Result<()> {
+ let resp = Response { id, result: Some(serde_json::to_value(result)?), error: None };
+ conn.sender.send(Message::Response(resp))?;
+ Ok(())
+}
+
+fn send_err(
+ conn: &Connection,
+ id: RequestId,
+ code: lsp_server::ErrorCode,
+ msg: &str,
+) -> Result<()> {
+ let resp = Response {
+ id,
+ result: None,
+ error: Some(lsp_server::ResponseError {
+ code: code as i32,
+ message: msg.into(),
+ data: None,
+ }),
+ };
+ conn.sender.send(Message::Response(resp))?;
+ Ok(())
+}