Support functions in View() (#8262)

Addresses #2945.
Companion PR for posit-dev/ark#848.

The main change needed on the frontend side is to detect non-file
schemes in the `OpenEditor` event handler of the UI comm. This way we
preserve `ark:` URIs, which allows Ark to request the frontend to open
documents via its own vdoc provider.

I also improved vdoc provider errors to be more user friendly. The error
is mentioned in the virtual editor and the error message is logged.


### Release Notes

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#### New Features

- `View()` now supports function objects (#2945). It
takes you directly to the original source, if the function has source
references, or to a virtual document containing the deparsed function
code otherwise.

- Functions are now also viewable from the Variables pane. Click on the
"view" button on the right hand side of a variable entry to view its
source definition in an editor.


#### Bug Fixes

- N/A


### QA Notes

See companion PR: posit-dev/ark#848.

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@:variables

Author: lionel-

extensions/positron-r/package.json

@@ -815,7 +815,7 @@
   },
   "positron": {
     "binaryDependencies": {
-      "ark": "0.1.193"
+      "ark": "0.1.194"
     },
     "minimumRVersion": "4.2.0",
     "minimumRenvVersion": "1.0.9"

extensions/positron-r/src/virtual-documents.ts

@@ -6,6 +6,7 @@
 import * as vscode from 'vscode';
 import { RequestType } from 'vscode-languageclient';
 import { LanguageClient } from 'vscode-languageclient/node';
+import { LOGGER } from './extension';
 
 interface VirtualDocumentParams {
 	path: string;
@@ -27,6 +28,11 @@ export class VirtualDocumentProvider implements vscode.TextDocumentContentProvid
 			path: uri.path,
 		};
 
-		return await this._client.sendRequest(VIRTUAL_DOCUMENT_REQUEST_TYPE, params, token);
+		try {
+		  return await this._client.sendRequest(VIRTUAL_DOCUMENT_REQUEST_TYPE, params, token);
+		} catch (err) {
+      LOGGER.warn(`Failed to provide document for URI '${uri}': ${err}`);
+      return 'Error: This document does not exist';
+		}
 	}
 }

positron/comms/variables-backend-openrpc.json

@@ -186,7 +186,8 @@
 				"schema": {
 					"description": "The ID of the viewer that was opened.",
 					"type": "string"
-				}
+				},
+				"required": false
 			}
 		}
 	],

src/vs/workbench/api/browser/positron/mainThreadLanguageRuntime.ts

@@ -230,8 +230,15 @@ class ExtHostLanguageRuntimeSessionAdapter extends Disposable implements ILangua
 			} else if (ev.name === UiFrontendEvent.OpenEditor) {
 				// Open an editor
 				const ed = ev.data as OpenEditorEvent;
+
+				let file = URI.parse(ed.file);
+				if (!file.scheme) {
+					// If the URI doesn't have a scheme, assume it's a file URI
+					file = URI.file(ed.file);
+				}
+
 				const editor: ITextResourceEditorInput = {
-					resource: URI.file(ed.file),
+					resource: file,
 					options: { selection: { startLineNumber: ed.line, startColumn: ed.column } }
 				};
 				this._editorService.openEditor(editor);

src/vs/workbench/api/common/positron/extHostMethods.ts

@@ -281,14 +281,14 @@ export class ExtHostMethods implements extHostProtocol.ExtHostMethodsShape {
 	}
 
 	async createDocument(contents: string, languageId: string): Promise<null> {
-
 		const uri = await this.documents.createDocumentData({
-			content: contents, language: languageId
+			content: contents,
+			language: languageId,
 		});
+		const documentData = await this.documents.ensureDocumentData(uri);
+
 		const opts: TextEditorOpenOptions = { preview: true };
-		this.documents.ensureDocumentData(uri).then(documentData => {
-			this.editors.showTextDocument(documentData.document, opts);
-		});
+		await this.editors.showTextDocument(documentData.document, opts);
 
 		// TODO: Return a document ID
 		return null;

src/vs/workbench/contrib/positronVariables/browser/components/variableItem.tsx

@@ -137,7 +137,11 @@ export const VariableItem = (props: VariableItemProps) => {
 				));
 			}
 
-			// If a binding was returned, save the binding between the viewer and the variable item.
+			// If a binding was returned, save the binding between the viewer and the
+			// variable item. Note that it's valid for backends to not return any ID
+			// if no comm was open. This happens with Ark when the user views a
+			// function object: a virtual document is opened in an editor but is not
+			// managed by a comm.
 			if (viewerId) {
 				explorerService.setInstanceForVar(viewerId, item.id);
 			}

src/vs/workbench/services/languageRuntime/common/languageRuntimeVariablesClient.ts

@@ -76,9 +76,9 @@ export class PositronVariable {
 	/**
 	 * Requests that the language runtime open a viewer for this variable.
 	 *
-	 * @returns The ID of the viewer that was opened.
+	 * @returns The ID of the viewer that was opened, if any.
 	 */
-	async view(): Promise<string> {
+	async view(): Promise<string | undefined> {
 		const path = this.parentKeys.concat(this.data.access_key);
 		return this._comm.view(path);
 	}
@@ -268,4 +268,3 @@ export class VariablesClientInstance extends Disposable {
 		}));
 	}
 }
-

src/vs/workbench/services/languageRuntime/common/positronVariablesComm.ts

@@ -415,7 +415,7 @@ export class PositronVariablesComm extends PositronBaseComm {
 	 *
 	 * @returns The ID of the viewer that was opened.
 	 */
-	view(path: Array<string>): Promise<string> {
+	view(path: Array<string>): Promise<string | undefined> {
 		return super.performRpc('view', ['path'], [path]);
 	}
 

src/vs/workbench/services/positronVariables/common/classes/variableItem.ts

@@ -324,7 +324,7 @@ export class VariableItem implements IVariableItem {
 	/**
 	 * Requests that a viewer be opened for this variable.
 	 */
-	async view(): Promise<string> {
+	async view(): Promise<string | undefined> {
 		return this._variable.view();
 	}
 

src/vs/workbench/services/positronVariables/common/interfaces/variableItem.ts

@@ -85,5 +85,5 @@ export interface IVariableItem {
 	/**
 	 * Requests that a data viewer be opened for this variable.
 	 */
-	view(): Promise<string>;
+	view(): Promise<string | undefined>;
 }