Register command to show references (hashicorp#686)

src/clientHandler.ts

@@ -20,6 +20,7 @@ import {
 	sortedWorkspaceFolders
 } from './vscodeUtils';
 import TelemetryReporter from 'vscode-extension-telemetry';
+import { ShowReferencesFeature } from './showReferences';
 import { ServerPath, CUSTOM_BIN_PATH_OPTION_NAME } from './serverPath';
 
 export interface TerraformLanguageClient {
@@ -177,6 +178,8 @@ export class ClientHandler {
 			clientOptions
 		);
 
+		client.registerFeature(new ShowReferencesFeature(client));
+
 		client.onDidChangeState((event) => {
 			if (event.newState === State.Stopped) {
 				clients.delete(location);

src/showReferences.ts

@@ -0,0 +1,65 @@
+import * as vscode from 'vscode';
+import {
+	ClientCapabilities,
+	ServerCapabilities,
+	StaticFeature,
+	ReferencesRequest,
+	ReferenceContext, 
+	BaseLanguageClient
+} from 'vscode-languageclient';
+
+type Position = {
+	line: number;
+	character: number;
+}
+
+type RefContext = {
+	includeDeclaration: boolean;
+}
+
+const CLIENT_CMD_ID = 'client.showReferences';
+const VSCODE_SHOW_REFERENCES = 'editor.action.showReferences'
+
+export class ShowReferencesFeature implements StaticFeature {
+	private registeredCommands: vscode.Disposable[] = [];
+
+	constructor(private _client: BaseLanguageClient) {
+	}
+
+	public fillClientCapabilities(capabilities: ClientCapabilities): void {
+		if (!capabilities['experimental']) {
+			capabilities['experimental'] = {};
+		}
+		capabilities['experimental']['showReferencesCommandId'] = CLIENT_CMD_ID;
+	}
+
+	public initialize(capabilities: ServerCapabilities): void {
+		if ( !capabilities.experimental?.referenceCountCodeLens ) {
+			return
+		}
+
+		const showRefs = vscode.commands.registerCommand(CLIENT_CMD_ID, async (pos: Position, refCtx: RefContext) => {
+			const client = this._client;
+
+			const doc = vscode.window.activeTextEditor.document;
+
+			const position = new vscode.Position(pos.line, pos.character);
+			const context: ReferenceContext = {includeDeclaration: refCtx.includeDeclaration}
+
+			const provider: vscode.ReferenceProvider = client.getFeature(ReferencesRequest.method).getProvider(doc);
+			const tokenSource: vscode.CancellationTokenSource = new vscode.CancellationTokenSource();
+
+			const locations = await provider.provideReferences(doc, position, context, tokenSource.token);
+
+			await vscode.commands.executeCommand(VSCODE_SHOW_REFERENCES, doc.uri, position, locations);
+		})
+		this.registeredCommands.push(showRefs);
+	}
+
+	public dispose(): void {
+		this.registeredCommands.forEach(function(cmd, index, commands) {
+			cmd.dispose();
+			commands.splice(index, 1);
+		})
+	}
+}