Export client from activation as API for use in other extensions

api/README.md

@@ -0,0 +1,38 @@
+# VS Code clangd Extension API
+
+The VS Code clangd extension exposes an API that other extensions can consume:
+
+```typescript
+import * as vscode from 'vscode';
+import type { ClangdExtension, ASTParams, ASTNode } from '@clangd/vscode-clangd';
+
+const CLANGD_EXTENSION = 'llvm-vs-code-extensions.vscode-clangd';
+const CLANGD_API_VERSION = 1;
+
+const ASTRequestMethod = 'textDocument/ast';
+
+const provideHover = async (document: vscode.TextDocument, position: vscode.Position, _token: vscode.CancellationToken): Promise<vscode.Hover | undefined> => {
+
+    const clangdExtension = vscode.extensions.getExtension<ClangdExtension>(CLANGD_EXTENSION);
+
+    if (clangdExtension) {
+        const api = (await clangdExtension.activate()).getApi(CLANGD_API_VERSION);
+
+        const textDocument = api.languageClient.code2ProtocolConverter.asTextDocumentIdentifier(document);
+        const range = api.languageClient.code2ProtocolConverter.asRange(new vscode.Range(position, position));
+        const params: ASTParams = { textDocument, range };
+
+        const ast: ASTNode | undefined = await api.languageClient.sendRequest(ASTRequestMethod, params);
+
+        if (!ast) {
+            return undefined;
+        }
+
+        return {
+            contents: [ast.kind]
+        };
+    }
+};
+
+vscode.languages.registerHoverProvider(['c', 'cpp'], { provideHover });
+```

api/package.json

@@ -0,0 +1,15 @@
+{
+    "name": "@clangd/vscode-clangd",
+    "version": "0.0.0",
+    "description": "API for the llvm-vs-code-extensions.vscode-clangd VS Code extension",
+    "types": "vscode-clangd.d.ts",
+    "publishConfig": {
+        "registry": "https://npm.pkg.github.com"
+    },
+    "repository": "https://github.com/clangd/vscode-clangd",
+    "license": "MIT",
+    "homepage": "https://github.com/clangd/vscode-clangd/blob/master/api/README.md",
+    "dependencies": {
+        "vscode-languageclient": "8.0.2"
+    }
+}

api/vscode-clangd.d.ts

@@ -0,0 +1,36 @@
+import {BaseLanguageClient} from 'vscode-languageclient';
+import * as vscodelc from 'vscode-languageclient/node';
+
+export interface ClangdApiV1 {
+  // vscode-clangd's language client which can be used to send requests to the
+  // clangd language server
+  // Standard requests:
+  // https://microsoft.github.io/language-server-protocol/specifications/specification-current
+  // clangd custom requests:
+  // https://clangd.llvm.org/extensions
+  languageClient: BaseLanguageClient
+}
+
+export interface ClangdExtension {
+  getApi(version: 1): ClangdApiV1;
+}
+
+// clangd custom request types
+// (type declarations for other requests may be added later)
+
+// textDocument/ast wire format
+// Send: position
+export interface ASTParams {
+  textDocument: vscodelc.TextDocumentIdentifier;
+  range: vscodelc.Range;
+}
+
+// Receive: tree of ASTNode
+export interface ASTNode {
+  role: string;    // e.g. expression
+  kind: string;    // e.g. BinaryOperator
+  detail?: string; // e.g. ||
+  arcana?: string; // e.g. BinaryOperator <0x12345> <col:12, col:1> 'bool' '||'
+  children?: Array<ASTNode>;
+  range?: vscodelc.Range;
+}

src/api.ts

@@ -0,0 +1,16 @@
+import {BaseLanguageClient} from 'vscode-languageclient';
+
+import {ClangdApiV1, ClangdExtension} from '../api/vscode-clangd';
+
+export class ClangdExtensionImpl implements ClangdExtension {
+  constructor(private readonly client: BaseLanguageClient) {}
+
+  public getApi(version: 1): ClangdApiV1;
+  public getApi(version: number): unknown {
+    if (version === 1) {
+      return {languageClient: this.client};
+    }
+
+    throw new Error(`No API version ${version} found`);
+  }
+}

src/ast.ts

@@ -4,27 +4,17 @@ import * as vscode from 'vscode';
 import * as vscodelc from 'vscode-languageclient/node';
 
 import {ClangdContext} from './clangd-context';
+import type {ASTParams, ASTNode} from '../api/vscode-clangd';
+
+const ASTRequestMethod = 'textDocument/ast';
 
 export function activate(context: ClangdContext) {
   const feature = new ASTFeature(context);
   context.client.registerFeature(feature);
 }
 
-// The wire format: we send a position, and get back a tree of ASTNode.
-interface ASTParams {
-  textDocument: vscodelc.TextDocumentIdentifier;
-  range: vscodelc.Range;
-}
-interface ASTNode {
-  role: string;    // e.g. expression
-  kind: string;    // e.g. BinaryOperator
-  detail?: string; // e.g. ||
-  arcana?: string; // e.g. BinaryOperator <0x12345> <col:12, col:1> 'bool' '||'
-  children?: Array<ASTNode>;
-  range?: vscodelc.Range;
-}
 const ASTRequestType =
-    new vscodelc.RequestType<ASTParams, ASTNode|null, void>('textDocument/ast');
+    new vscodelc.RequestType<ASTParams, ASTNode|null, void>(ASTRequestMethod);
 
 class ASTFeature implements vscodelc.StaticFeature {
   constructor(private context: ClangdContext) {

src/extension.ts

@@ -1,12 +1,16 @@
 import * as vscode from 'vscode';
 
+import {ClangdExtension} from '../api/vscode-clangd';
+
+import {ClangdExtensionImpl} from './api';
 import {ClangdContext} from './clangd-context';
 
 /**
  *  This method is called when the extension is activated. The extension is
  *  activated the very first time a command is executed.
  */
-export async function activate(context: vscode.ExtensionContext) {
+export async function activate(context: vscode.ExtensionContext):
+    Promise<ClangdExtension> {
   const outputChannel = vscode.window.createOutputChannel('clangd');
   context.subscriptions.push(outputChannel);
 
@@ -67,4 +71,6 @@ export async function activate(context: vscode.ExtensionContext) {
       }
     }, 5000);
   }
+
+  return new ClangdExtensionImpl(clangdContext.client);
 }