feat: make r.lsp.multiServer accept auto, true, or false

- Updates configuration to allow 'auto', true, or false.
- 'auto' uses single server mode for languageserver >= 0.3.18, and multi-server otherwise.
- Introduces compareVersions utility to avoid external dependency.
- Backward compatible with existing boolean settings.

Author: randy3k

package.json

@@ -1388,9 +1388,10 @@
           "description": "Use STDIO connection instead of TCP. (Unix/macOS users only)"
         },
         "r.lsp.multiServer": {
-          "type": "boolean",
-          "default": false,
-          "markdownDescription": "Use multiple language servers for [multi-root workspaces](https://code.visualstudio.com/docs/editor/multi-root-workspaces). If disabled, only one language server will be used to handle all requests from all workspaces and files. Disabling this is recommended if you have the R `languageserver` package version >= 0.3.18 installed."
+          "type": ["string", "boolean"],
+          "enum": ["auto", true, false],
+          "default": "auto",
+          "markdownDescription": "Use multiple language servers for [multi-root workspaces](https://code.visualstudio.com/docs/editor/multi-root-workspaces). When set to `auto`, it will use a single server if the R `languageserver` package version is >= 0.3.18, and multiple servers otherwise. Disabling this (or using `auto` with a recent version) is recommended for better performance."
         },
         "r.rmarkdown.codeLensCommands": {
           "type": "array",

src/languageService.ts

@@ -4,7 +4,7 @@ import * as net from 'net';
 import { URL } from 'url';
 import { LanguageClient, LanguageClientOptions, StreamInfo, DocumentFilter, ErrorAction, CloseAction, RevealOutputChannelOn } from 'vscode-languageclient/node';
 import { Disposable, workspace, Uri, TextDocument, WorkspaceConfiguration, OutputChannel, window, WorkspaceFolder } from 'vscode';
-import { DisposableProcess, getRLibPaths, getRpath, promptToInstallRPackage, spawn, substituteVariables } from './util';
+import { DisposableProcess, getRLibPaths, getRpath, promptToInstallRPackage, spawn, substituteVariables, getRPackageVersion, compareVersions } from './util';
 import { extensionContext } from './extension';
 import { CommonOptions } from 'child_process';
 
@@ -309,7 +309,23 @@ export class LanguageService implements Disposable {
     }
 
     private async startLanguageService(): Promise<void> {
-        if (this.config.get<boolean>('lsp.multiServer')) {
+        let useMultiServer = false;
+        const multiServerConfig = this.config.get<string | boolean>('lsp.multiServer');
+
+        if (multiServerConfig === 'auto') {
+            const version = await getRPackageVersion('languageserver');
+            if (version && compareVersions(version, '0.3.18') < 0) {
+                console.log(`languageserver version is ${version}, using multi-server.`);
+                useMultiServer = true;
+            } else {
+                console.log(`languageserver version is ${version || 'unknown'}, using single-server.`);
+                useMultiServer = false;
+            }
+        } else if (multiServerConfig === true || multiServerConfig === 'true') {
+            useMultiServer = true;
+        }
+
+        if (useMultiServer) {
             this.startMultiLanguageService();
         } else {
             const documentSelector: DocumentFilter[] = [

src/util.ts

@@ -328,6 +328,27 @@ export async function getCranUrl(path: string = '', cwd?: string | URL): Promise
     return url;
 }
 
+export async function getRVersion(cwd?: string | URL): Promise<string | undefined> {
+    return await executeRCommand('cat(as.character(getRversion()))', cwd);
+}
+
+export async function getRPackageVersion(name: string, cwd?: string | URL): Promise<string | undefined> {
+    return await executeRCommand(`cat(as.character(utils::packageVersion('${name}')))`, cwd);
+}
+
+export function compareVersions(v1: string, v2: string): number {
+    const parts1 = v1.split('.').map(Number);
+    const parts2 = v2.split('.').map(Number);
+    const len = Math.max(parts1.length, parts2.length);
+    for (let i = 0; i < len; i++) {
+        const num1 = parts1[i] || 0;
+        const num2 = parts2[i] || 0;
+        if (num1 > num2) return 1;
+        if (num1 < num2) return -1;
+    }
+    return 0;
+}
+
 export function getRLibPaths(): string | undefined {
     return config().get<string[]>('libPaths')?.map(substituteVariables).join('\n');
 }