Add Positron help topic provider

apps/vscode/src/@types/hooks.d.ts

@@ -25,6 +25,10 @@ declare module 'positron' {
 			selector: vscode.DocumentSelector,
 			provider: StatementRangeProvider
 		): vscode.Disposable;
+		registerHelpTopicProvider(
+			selector: vscode.DocumentSelector,
+			provider: HelpTopicProvider
+		): vscode.Disposable;
 	}
 
 	export interface StatementRangeProvider {
@@ -35,6 +39,14 @@ declare module 'positron' {
 		): vscode.ProviderResult<StatementRange>;
 	}
 
+	export interface HelpTopicProvider {
+		provideHelpTopic(
+			document: vscode.TextDocument,
+			position: vscode.Position,
+			token: vscode.CancellationToken
+		): vscode.ProviderResult<string>;
+	}
+
 	export interface StatementRange {
 		readonly range: vscode.Range;
 		readonly code?: string;

apps/vscode/src/host/hooks.ts

@@ -16,7 +16,7 @@
 import * as vscode from 'vscode';
 import * as hooks from 'positron';
 
-import { ExtensionHost, HostWebviewPanel, HostStatementRangeProvider } from '.';
+import { ExtensionHost, HostWebviewPanel, HostStatementRangeProvider, HostHelpTopicProvider } from '.';
 import { CellExecutor, cellExecutorForLanguage, executableLanguages, isKnitrDocument, pythonWithReticulate } from './executors';
 import { ExecuteQueue } from './execute-queue';
 import { MarkdownEngine } from '../markdown/engine';
@@ -99,6 +99,15 @@ export function hooksExtensionHost(): ExtensionHost {
       return new vscode.Disposable(() => { });
     },
 
+    registerHelpTopicProvider: (engine: MarkdownEngine): vscode.Disposable => {
+      const hooks = hooksApi();
+      if (hooks) {
+        return hooks.languages.registerHelpTopicProvider('quarto',
+          new EmbeddedHelpTopicProvider(engine));
+      }
+      return new vscode.Disposable(() => { });
+    },
+
     createPreviewPanel: (
       viewType: string,
       title: string,
@@ -186,3 +195,39 @@ async function getStatementRange(
   );
   return { range: unadjustedRange(language, result.range), code: result.code };
 }
+
+class EmbeddedHelpTopicProvider implements HostHelpTopicProvider {
+  private readonly _engine: MarkdownEngine;
+
+  constructor(
+    readonly engine: MarkdownEngine,
+  ) {
+    this._engine = engine;
+  }
+
+  async provideHelpTopic(
+    document: vscode.TextDocument,
+    position: vscode.Position,
+    token: vscode.CancellationToken): Promise<string | undefined> {
+    const vdoc = await virtualDoc(document, position, this._engine);
+    if (vdoc) {
+      const vdocUri = await virtualDocUri(vdoc, document.uri, "helpTopic");
+      try {
+        return await vscode.commands.executeCommand<string>(
+          "positron.executeHelpTopicProvider",
+          vdocUri.uri,
+          adjustedPosition(vdoc.language, position),
+          vdoc.language
+        );
+      } catch (error) {
+        return undefined;
+      } finally {
+        if (vdocUri.cleanup) {
+          await vdocUri.cleanup();
+        }
+      }
+    } else {
+      return undefined;
+    }
+  };
+}

apps/vscode/src/host/index.ts

@@ -47,6 +47,14 @@ export interface HostStatementRange {
   readonly code?: string;
 }
 
+export interface HostHelpTopicProvider {
+  provideHelpTopic(
+    document: vscode.TextDocument,
+    position: vscode.Position,
+    token: vscode.CancellationToken
+  ): vscode.ProviderResult<string>;
+}
+
 export interface ExtensionHost {
 
   // code execution
@@ -63,6 +71,11 @@ export interface ExtensionHost {
     engine: MarkdownEngine,
   ): vscode.Disposable;
 
+  // help topic provider
+  registerHelpTopicProvider(
+    engine: MarkdownEngine,
+  ): vscode.Disposable;
+
   // preview
   createPreviewPanel(
     viewType: string,
@@ -99,10 +112,13 @@ function defaultExtensionHost(): ExtensionHost {
       return languages.filter(language => knitr || !visualMode || (language !== "python"));
     },
     cellExecutorForLanguage,
-    // in the default extension host, this is a noop:
+    // in the default extension host, both of these are just a noop:
     registerStatementRangeProvider: (engine: MarkdownEngine): vscode.Disposable => {
       return new vscode.Disposable(() => { });
     },
+    registerHelpTopicProvider: (engine: MarkdownEngine): vscode.Disposable => {
+      return new vscode.Disposable(() => { });
+    },
     createPreviewPanel,
   };
 }

apps/vscode/src/lsp/client.ts

@@ -110,6 +110,7 @@ export async function activateLsp(
     middleware.provideSignatureHelp = embeddedSignatureHelpProvider(engine);
   }
   extensionHost().registerStatementRangeProvider(engine);
+  extensionHost().registerHelpTopicProvider(engine);
 
   // create client options
   const initializationOptions: LspInitializationOptions = {

apps/vscode/src/vdoc/vdoc.ts

@@ -117,7 +117,8 @@ export type VirtualDocAction =
   "signature" |
   "definition" |
   "format" |
-  "statementRange";
+  "statementRange" |
+  "helpTopic";
 
 export type VirtualDocUri = { uri: Uri, cleanup?: () => Promise<void> };