vscode-extension-samples/source-control-sample/src/fiddleDocumentContentProvider.ts

import { CancellationToken, ProviderResult, TextDocumentContentProvider, Event, Uri, EventEmitter, Disposable } from "vscode";
import { toExtension, JSFIDDLE_SCHEME, Fiddle } from "./fiddleRepository";
import { basename } from "path";

/**
 * Provides the content of the JS Fiddle documents as fetched from the server i.e.  without the local edits.
 * This is used for the source control diff.
 */
export class JSFiddleDocumentContentProvider implements TextDocumentContentProvider, Disposable {
	private _onDidChange = new EventEmitter<Uri>();
	private fiddles = new Map<string, Fiddle>(); // this assumes each fiddle is only open once per workspace

	get onDidChange(): Event<Uri> {
		return this._onDidChange.event;
	}

	dispose(): void {
		this._onDidChange.dispose();
	}

	updated(newFiddle: Fiddle): void {
		this.fiddles.set(newFiddle.slug, newFiddle);

		// let's assume all 3 documents actually changed and notify the quick-diff
		this._onDidChange.fire(Uri.parse(`${JSFIDDLE_SCHEME}:${newFiddle.slug}.html`));
		this._onDidChange.fire(Uri.parse(`${JSFIDDLE_SCHEME}:${newFiddle.slug}.css`));
		this._onDidChange.fire(Uri.parse(`${JSFIDDLE_SCHEME}:${newFiddle.slug}.js`));
	}

	provideTextDocumentContent(uri: Uri, token: CancellationToken): ProviderResult<string> {
		if (token.isCancellationRequested) { return "Canceled"; }

		let fiddleSlug = basename(uri.fsPath);
		// strip off the file extension
		fiddleSlug = fiddleSlug.split('.').slice(0, -1).join('.');
		const fiddlePart = toExtension(uri);

		const fiddle = this.fiddles.get(fiddleSlug);
		if (!fiddle) { return "Resource not found: " + uri.toString(); }

		return fiddle.data[fiddlePart];
	}
}