Add option to use Go language server for certain features

package.json

@@ -37,7 +37,8 @@
     "json-rpc2": "^1.0.2",
     "vscode-debugadapter": "^1.11.0",
     "vscode-debugprotocol": "^1.11.0",
-    "vscode-extension-telemetry": "0.0.5"
+    "vscode-extension-telemetry": "0.0.5",
+    "vscode-languageclient": "^2.5.0"
   },
   "devDependencies": {
     "@types/fs-extra": "0.0.35",
@@ -388,6 +389,11 @@
           "type": "string",
           "default": "",
           "description": "Location to install the Go tools that the extension depends on if you don't want them in your GOPATH."
+        },
+        "go.useLanguageServer": {
+          "type": "boolean",
+          "default": false,
+          "description": "Use Go language server from Sourcegraph for Hover, Definition, Find All References, Signature Help, File Outline and Workspace Symbol features"
         }
       }
     }

src/goInstallTools.ts

@@ -52,6 +52,10 @@ function getTools(goVersion: SemVersion): { [key: string]: string } {
 		tools['gometalinter'] = 'github.com/alecthomas/gometalinter';
 	}
 
+	if (goConfig['useLanguageServer']) {
+		tools['langserver-go'] = 'github.com/sourcegraph/go-langserver/langserver/cmd/langserver-go';
+	}
+
 	return tools;
 }
 
@@ -179,6 +183,9 @@ function installTools(goVersion: SemVersion, missing?: string[]) {
 		outputChannel.appendLine(''); // Blank line for spacing
 		let failures = res.filter(x => x != null);
 		if (failures.length === 0) {
+			if (missing.indexOf('langserver-go') > -1) {
+				outputChannel.appendLine('Reload VS Code window to use the Go language server');
+			}
 			outputChannel.appendLine('All tools successfully installed. You\'re ready to Go :).');
 			return;
 		}
@@ -249,7 +256,20 @@ function getMissingTools(goVersion: SemVersion): Promise<string[]> {
 	});
 }
 
-
+// If langserver needs to be used, but is not installed, this will prompt user to install and Reload
+// If langserver needs to be used, and is installed, this will return true
+// Returns false in all other cases
+export function checkLanguageServer(): boolean {
+	let latestGoConfig = vscode.workspace.getConfiguration('go');
+	if (!latestGoConfig['useLanguageServer']) return false;
+
+	let langServerAvailable = getBinPath('langserver-go') !== 'langserver-go';
+	if (!langServerAvailable) {
+		promptForMissingTool('langserver-go');
+		vscode.window.showInformationMessage('Reload VS Code window after installing the Go language server');
+	}
+	return langServerAvailable;
+}
 
 
 

src/goMain.ts

@@ -27,22 +27,47 @@ import { coverageCurrentPackage, getCodeCoverage, removeCodeCoverage } from './g
 import { testAtCursor, testCurrentPackage, testCurrentFile, testPrevious } from './goTest';
 import * as goGenerateTests from './goGenerateTests';
 import { addImport } from './goImport';
-import { installAllTools } from './goInstallTools';
-import { isGoPathSet } from './util';
+import { installAllTools, checkLanguageServer } from './goInstallTools';
+import { isGoPathSet, getBinPath } from './util';
+import { LanguageClient } from 'vscode-languageclient';
 
 let diagnosticCollection: vscode.DiagnosticCollection;
+let useLangServer: boolean;
 
 export function activate(ctx: vscode.ExtensionContext): void {
+	let useLangServer = vscode.workspace.getConfiguration('go')['useLanguageServer'];
+	if (checkLanguageServer()) {
+		const c = new LanguageClient(
+			'langserver-go',
+			{
+				command: getBinPath('langserver-go'),
+				args: [
+					'-mode=stdio'
+				],
+			},
+			{
+				documentSelector: ['go'],
+				uriConverters: {
+					// Apply file:/// scheme to all file paths.
+					code2Protocol: (uri: vscode.Uri): string => (uri.scheme ? uri : uri.with({ scheme: 'file' })).toString(),
+					protocol2Code: (uri: string) => vscode.Uri.parse(uri),
+				},
+			}
+		);
+
+		ctx.subscriptions.push(c.start());
+	} else {
+		ctx.subscriptions.push(vscode.languages.registerHoverProvider(GO_MODE, new GoHoverProvider()));
+		ctx.subscriptions.push(vscode.languages.registerDefinitionProvider(GO_MODE, new GoDefinitionProvider()));
+		ctx.subscriptions.push(vscode.languages.registerReferenceProvider(GO_MODE, new GoReferenceProvider()));
+		ctx.subscriptions.push(vscode.languages.registerDocumentSymbolProvider(GO_MODE, new GoDocumentSymbolProvider()));
+		ctx.subscriptions.push(vscode.languages.registerWorkspaceSymbolProvider(new GoWorkspaceSymbolProvider()));
+		ctx.subscriptions.push(vscode.languages.registerSignatureHelpProvider(GO_MODE, new GoSignatureHelpProvider(), '(', ','));
+	}
 
-	ctx.subscriptions.push(vscode.languages.registerHoverProvider(GO_MODE, new GoHoverProvider()));
 	ctx.subscriptions.push(vscode.languages.registerCompletionItemProvider(GO_MODE, new GoCompletionItemProvider(), '.', '\"'));
-	ctx.subscriptions.push(vscode.languages.registerDefinitionProvider(GO_MODE, new GoDefinitionProvider()));
-	ctx.subscriptions.push(vscode.languages.registerReferenceProvider(GO_MODE, new GoReferenceProvider()));
 	ctx.subscriptions.push(vscode.languages.registerDocumentFormattingEditProvider(GO_MODE, new GoDocumentFormattingEditProvider()));
-	ctx.subscriptions.push(vscode.languages.registerDocumentSymbolProvider(GO_MODE, new GoDocumentSymbolProvider()));
-	ctx.subscriptions.push(vscode.languages.registerWorkspaceSymbolProvider(new GoWorkspaceSymbolProvider()));
 	ctx.subscriptions.push(vscode.languages.registerRenameProvider(GO_MODE, new GoRenameProvider()));
-	ctx.subscriptions.push(vscode.languages.registerSignatureHelpProvider(GO_MODE, new GoSignatureHelpProvider(), '(', ','));
 	ctx.subscriptions.push(vscode.languages.registerCodeActionsProvider(GO_MODE, new GoCodeActionProvider()));
 
 	diagnosticCollection = vscode.languages.createDiagnosticCollection('go');
@@ -92,6 +117,12 @@ export function activate(ctx: vscode.ExtensionContext): void {
 
 	ctx.subscriptions.push(vscode.workspace.onDidChangeConfiguration(() => {
 		updateGoPathGoRootFromConfig();
+		let updatedGoConfig = vscode.workspace.getConfiguration('go');
+		// If there was a change in "useLanguageServer" setting, then ask the user to reload VS Code.
+		if (useLangServer !== updatedGoConfig['useLanguageServer'] && (!updatedGoConfig['useLanguageServer'] || checkLanguageServer())) {
+			vscode.window.showInformationMessage('Reload VS Code window for the change in usage of language server to take effect');
+		}
+		useLangServer = updatedGoConfig['useLanguageServer'];
 	}));
 
 	ctx.subscriptions.push(vscode.commands.registerCommand('go.test.generate.package', () => {
@@ -213,3 +244,4 @@ function startBuildOnSaveWatcher(subscriptions: vscode.Disposable[]) {
 	}, null, subscriptions);
 
 }
+