feat(lsp): define and read configuration values

Create a sample configuration in the editor plugin and read it from the
LSP side (as well as reloading it on changes).

crates/stef-lsp/Cargo.toml

@@ -13,6 +13,8 @@ license.workspace = true
 clap.workspace = true
 directories = "5.0.1"
 ouroboros = "0.18.0"
+serde = { version = "1.0.193", features = ["derive"] }
+serde_json = "1.0.108"
 stef-compiler = { path = "../stef-compiler" }
 stef-parser = { path = "../stef-parser" }
 tokio = { version = "1.34.0", features = ["fs", "io-std", "io-util", "macros", "rt-multi-thread"] }

crates/stef-lsp/src/config.rs

@@ -0,0 +1,7 @@
+use serde::Deserialize;
+
+#[derive(Debug, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct Global {
+    pub max_number_of_problems: u32,
+}

crates/stef-lsp/src/main.rs

@@ -10,9 +10,10 @@ use tower_lsp::{
     async_trait,
     jsonrpc::Result,
     lsp_types::{
-        Diagnostic, DidChangeTextDocumentParams, DidOpenTextDocumentParams, InitializeParams,
-        InitializeResult, InitializedParams, MessageType, ServerCapabilities, ServerInfo,
-        TextDocumentSyncCapability, TextDocumentSyncKind, Url,
+        ConfigurationItem, Diagnostic, DidChangeConfigurationParams, DidChangeTextDocumentParams,
+        DidOpenTextDocumentParams, InitializeParams, InitializeResult, InitializedParams,
+        MessageType, Registration, ServerCapabilities, ServerInfo, TextDocumentSyncCapability,
+        TextDocumentSyncKind, Url,
     },
     Client, LanguageServer, LspService, Server,
 };
@@ -23,6 +24,7 @@ use self::cli::Cli;
 
 mod cli;
 mod compile;
+mod config;
 mod utf16;
 
 #[derive(Debug)]
@@ -59,6 +61,38 @@ impl LanguageServer for Backend {
     }
 
     async fn initialized(&self, _params: InitializedParams) {
+        let settings = self
+            .client
+            .configuration(vec![ConfigurationItem {
+                scope_uri: None,
+                section: Some("stef-lsp".to_owned()),
+            }])
+            .await
+            .unwrap()
+            .remove(0);
+
+        let settings = serde_json::from_value::<config::Global>(settings).unwrap();
+
+        self.client
+            .log_message(
+                MessageType::INFO,
+                format!("current settings: {settings:#?}"),
+            )
+            .await;
+
+        self.client
+            .register_capability(vec![Registration {
+                id: "1".to_owned(),
+                method: "workspace/didChangeConfiguration".to_owned(),
+                register_options: None,
+            }])
+            .await
+            .unwrap();
+
+        self.client
+            .log_message(MessageType::INFO, "server initialized!")
+            .await;
+
         debug!("initialized");
     }
 
@@ -119,6 +153,27 @@ impl LanguageServer for Backend {
             .await
             .insert(params.text_document.uri, file);
     }
+
+    async fn did_change_configuration(&self, _: DidChangeConfigurationParams) {
+        let settings = self
+            .client
+            .configuration(vec![ConfigurationItem {
+                scope_uri: None,
+                section: Some("stef-lsp".to_owned()),
+            }])
+            .await
+            .unwrap()
+            .remove(0);
+
+        let settings = serde_json::from_value::<config::Global>(settings).unwrap();
+
+        self.client
+            .log_message(
+                MessageType::INFO,
+                format!("updated settings: {settings:#?}"),
+            )
+            .await;
+    }
 }
 
 #[tokio::main]

vscode-extension/package.json

@@ -36,7 +36,18 @@
         "scopeName": "source.stef",
         "path": "./syntaxes/stef.tmLanguage.json"
       }
-    ]
+    ],
+    "configuration": {
+      "title": "STEF",
+      "properties": {
+        "stef-lsp.maxNumberOfProblems": {
+          "scope": "resource",
+          "type": "number",
+          "default": 100,
+          "description": "Controls the maximum number of problems produced by the server."
+        }
+      }
+    }
   },
   "vsce": {
     "dependencies": false