Serialize saveables to disk for "Save As"

packages/core/src/browser/saveable.ts

@@ -22,6 +22,7 @@ import { Key } from './keyboard/keys';
 import { AbstractDialog } from './dialogs';
 import { nls } from '../common/nls';
 import { DisposableCollection, isObject } from '../common';
+import { BinaryBuffer } from '../common/buffer';
 
 export type AutoSaveMode = 'off' | 'afterDelay' | 'onFocusChange' | 'onWindowChange';
 
@@ -53,6 +54,10 @@ export interface Saveable {
      * Applies the given snapshot to the dirty state.
      */
     applySnapshot?(snapshot: object): void;
+    /**
+     * Serializes the full state of the saveable item to a binary buffer.
+     */
+    serialize?(): Promise<BinaryBuffer>;
 }
 
 export interface SaveableSource {
@@ -79,6 +84,7 @@ export class DelegatingSaveable implements Saveable {
     revert?(options?: Saveable.RevertOptions): Promise<void>;
     createSnapshot?(): Saveable.Snapshot;
     applySnapshot?(snapshot: object): void;
+    serialize?(): Promise<BinaryBuffer>;
 
     protected _delegate?: Saveable;
     protected toDispose = new DisposableCollection();
@@ -101,6 +107,7 @@ export class DelegatingSaveable implements Saveable {
         this.revert = delegate.revert?.bind(delegate);
         this.createSnapshot = delegate.createSnapshot?.bind(delegate);
         this.applySnapshot = delegate.applySnapshot?.bind(delegate);
+        this.serialize = delegate.serialize?.bind(delegate);
     }
 
 }
@@ -115,7 +122,8 @@ export namespace Saveable {
     }
 
     /**
-     * A snapshot of a saveable item. Contains the full content of the saveable file in a string serializable format.
+     * A snapshot of a saveable item.
+     * Applying a snapshot of a saveable on another (of the same type) using the `applySnapshot` should yield the state of the original saveable.
      */
     export type Snapshot = { value: string } | { read(): string | null };
     export namespace Snapshot {

packages/filesystem/src/browser/filesystem-saveable-service.ts

@@ -21,6 +21,7 @@ import { SaveableService } from '@theia/core/lib/browser/saveable-service';
 import URI from '@theia/core/lib/common/uri';
 import { FileService } from './file-service';
 import { FileDialogService } from './file-dialog';
+import { BinaryBuffer } from '@theia/core/lib/common/buffer';
 
 @injectable()
 export class FilesystemSaveableService extends SaveableService {
@@ -39,13 +40,13 @@ export class FilesystemSaveableService extends SaveableService {
     /**
      * This method ensures a few things about `widget`:
      * - `widget.getResourceUri()` actually returns a URI.
-     * - `widget.saveable.createSnapshot` is defined.
+     * - `widget.saveable.createSnapshot` or `widget.saveable.serialize` is defined.
      * - `widget.saveable.revert` is defined.
      */
     override canSaveAs(widget: Widget | undefined): widget is Widget & SaveableSource & Navigatable {
         return widget !== undefined
             && Saveable.isSource(widget)
-            && typeof widget.saveable.createSnapshot === 'function'
+            && (typeof widget.saveable.createSnapshot === 'function' || typeof widget.saveable.serialize === 'function')
             && typeof widget.saveable.revert === 'function'
             && Navigatable.is(widget)
             && widget.getResourceUri() !== undefined;
@@ -96,14 +97,23 @@ export class FilesystemSaveableService extends SaveableService {
      */
     protected async saveSnapshot(sourceWidget: Widget & SaveableSource & Navigatable, target: URI, overwrite: boolean): Promise<void> {
         const saveable = sourceWidget.saveable;
-        const snapshot = saveable.createSnapshot!();
-        const content = Saveable.Snapshot.read(snapshot) ?? '';
+        let buffer: BinaryBuffer;
+        if (saveable.serialize) {
+            buffer = await saveable.serialize();
+        } else if (saveable.createSnapshot) {
+            const snapshot = saveable.createSnapshot();
+            const content = Saveable.Snapshot.read(snapshot) ?? '';
+            buffer = BinaryBuffer.fromString(content);
+        } else {
+            throw new Error('Cannot save the widget as the saveable does not provide a snapshot or a serialize method.');
+        }
+
         if (await this.fileService.exists(target)) {
             // Do not fire the `onDidCreate` event as the file already exists.
-            await this.fileService.write(target, content);
+            await this.fileService.writeFile(target, buffer);
         } else {
             // Ensure to actually call `create` as that fires the `onDidCreate` event.
-            await this.fileService.create(target, content, { overwrite });
+            await this.fileService.createFile(target, buffer, { overwrite });
         }
         await saveable.revert!();
         await open(this.openerService, target, { widgetOptions: { ref: sourceWidget, mode: 'tab-replace' } });

packages/monaco/src/browser/monaco-editor-model.ts

@@ -33,6 +33,7 @@ import { IModelService } from '@theia/monaco-editor-core/esm/vs/editor/common/se
 import { createTextBufferFactoryFromStream } from '@theia/monaco-editor-core/esm/vs/editor/common/model/textModel';
 import { editorGeneratedPreferenceProperties } from '@theia/editor/lib/browser/editor-generated-preference-schema';
 import { MarkdownString } from '@theia/core/lib/common/markdown-rendering';
+import { BinaryBuffer } from '@theia/core/lib/common/buffer';
 
 export {
     TextDocumentSaveReason
@@ -655,6 +656,10 @@ export class MonacoEditorModel implements IResolvedTextEditorModel, TextEditorDo
         this.model.setValue(value);
     }
 
+    async serialize(): Promise<BinaryBuffer> {
+        return BinaryBuffer.fromString(this.model.getValue());
+    }
+
     protected trace(loggable: Loggable): void {
         if (this.logger) {
             this.logger.debug((log: Log) =>

packages/notebook/src/browser/view-model/notebook-model.ts

@@ -34,6 +34,7 @@ import { inject, injectable, interfaces, postConstruct } from '@theia/core/share
 import { UndoRedoService } from '@theia/editor/lib/browser/undo-redo-service';
 import { MarkdownString } from '@theia/core/lib/common/markdown-rendering';
 import type { NotebookModelResolverService } from '../service/notebook-model-resolver-service';
+import { BinaryBuffer } from '@theia/core/lib/common/buffer';
 
 export const NotebookModelFactory = Symbol('NotebookModelFactory');
 
@@ -176,8 +177,7 @@ export class NotebookModel implements Saveable, Disposable {
         this.dirtyCells = [];
         this.dirty = false;
 
-        const data = this.getData();
-        const serializedNotebook = await this.props.serializer.fromNotebook(data);
+        const serializedNotebook = await this.serialize();
         this.fileService.writeFile(this.uri, serializedNotebook);
 
         this.onDidSaveNotebookEmitter.fire();
@@ -189,6 +189,10 @@ export class NotebookModel implements Saveable, Disposable {
         };
     }
 
+    serialize(): Promise<BinaryBuffer> {
+        return this.props.serializer.fromNotebook(this.getData());
+    }
+
     async applySnapshot(snapshot: Saveable.Snapshot): Promise<void> {
         const rawData = Saveable.Snapshot.read(snapshot);
         if (!rawData) {