fix: ensure server commands can be executed

This brings back the ability to execute commands provided by the
language server in the `vscode-playground` extension.

Instead of encoding all the commands in the `package.json` file, the
extension inspects the `ServerCapabilities` of the `initialize` response
to determine which commands a server provides. It then presents a quick
pick list of commands the user can choose to run.

This should mean commands (that don't take any arguments at least) now
"just work" with the playground extension

examples/servers/json_server.py

@@ -41,7 +41,7 @@ class JsonLanguageServer(LanguageServer):
     CMD_SHOW_CONFIGURATION_THREAD = "showConfigurationThread"
     CMD_UNREGISTER_COMPLETIONS = "unregisterCompletions"
 
-    CONFIGURATION_SECTION = "jsonServer"
+    CONFIGURATION_SECTION = "pygls.jsonServer"
 
     def __init__(self, *args):
         super().__init__(*args)

examples/vscode-playground/package.json

@@ -33,6 +33,17 @@
       }
     ],
     "configuration": [
+      {
+        "type": "object",
+        "title": "Json Server Configuration",
+        "properties": {
+          "pygls.jsonServer.exampleConfiguration": {
+            "scope": "resource",
+            "type": "string",
+            "default": "You can override this message"
+          }
+        }
+      },
       {
         "type": "object",
         "title": "Server Configuration",

examples/vscode-playground/src/extension.ts

@@ -30,7 +30,6 @@ const MIN_PYTHON = semver.parse("3.7.9")
 
 // Some other nice to haves.
 // TODO: Check selected env satisfies pygls' requirements - if not offer to run the select env command.
-// TODO: Inspect ServerCapabilities and present a quick pick list of runnable commands.
 // TODO: Start a debug session for the currently configured server.
 // TODO: TCP Transport
 // TODO: WS Transport
@@ -62,6 +61,13 @@ export async function activate(context: vscode.ExtensionContext) {
         })
     )
 
+    // Execute command... command
+    context.subscriptions.push(
+        vscode.commands.registerCommand("pygls.server.executeCommand", async () => {
+            await executeServerCommand()
+        })
+    )
+
     // Restart the language server if the user switches Python envs...
     context.subscriptions.push(
         python.environments.onDidChangeActiveEnvironmentPath(async () => {
@@ -213,6 +219,35 @@ function startLangServerTCP(addr: number): LanguageClient {
     );
 }
 
+/**
+ * Execute a command provided by the language server.
+ */
+async function executeServerCommand() {
+    if (!client || client.state !== State.Running) {
+        await vscode.window.showErrorMessage("There is no language server running.")
+        return
+    }
+
+    const knownCommands = client.initializeResult.capabilities.executeCommandProvider?.commands
+    if (!knownCommands || knownCommands.length === 0) {
+        const info = client.initializeResult.serverInfo
+        const name = info?.name || "Server"
+        const version = info?.version || ""
+
+        await vscode.window.showInformationMessage(`${name} ${version} does not implement any commands.`)
+        return
+    }
+
+    const commandName = await vscode.window.showQuickPick(knownCommands, { canPickMany: false })
+    if (!commandName) {
+        return
+    }
+    logger.info(`executing command: '${commandName}'`)
+
+    const result = await vscode.commands.executeCommand(commandName /* if your command accepts arguments you can pass them here */)
+    logger.info(`${commandName} result: ${JSON.stringify(result, undefined, 2)}`)
+}
+
 /**
  * If the user has explicitly provided a src directory use that.
  * Otherwise, fallback to the examples/servers directory.