add prompt snippets support

src/vs/base/common/codecs/asyncDecoder.ts

@@ -0,0 +1,85 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import { Disposable } from '../lifecycle.js';
+import { BaseDecoder } from './baseDecoder.js';
+
+/**
+ * Asynchronous interator wrapper for a decoder.
+ */
+export class AsyncDecoder<T extends NonNullable<unknown>, K extends NonNullable<unknown> = NonNullable<unknown>> extends Disposable {
+	// Buffer of messages that have been decoded but not yet consumed.
+	private readonly messages: T[] = [];
+
+	/**
+	 * A transient promise that is resolved when a new event
+	 * is received. Used in the situation when there is no new
+	 * data avaialble and decoder stream did not finish yet,
+	 * hence we need to wait until new event is received.
+	 */
+	private resolveOnNewEvent?: (value: void) => void;
+
+	/**
+	 * @param decoder The decoder instance to wrap.
+	 *
+	 * Note! Assumes ownership of the `decoder` object, hence will `dipose`
+	 * 		 it when the decoder stream is ended.
+	 */
+	constructor(
+		private readonly decoder: BaseDecoder<T, K>,
+	) {
+		super();
+
+		this._register(decoder);
+	}
+
+	/**
+	 * Async iterator implementation.
+	 */
+	async *[Symbol.asyncIterator](): AsyncIterator<T | null> {
+		// callback is called when `data` or `end` event is received
+		const callback = (data?: T) => {
+			if (data !== undefined) {
+				this.messages.push(data);
+			} else {
+				this.decoder.removeListener('data', callback);
+				this.decoder.removeListener('end', callback);
+			}
+
+			// is the promise resolve callback is present,
+			// then call it and remove the reference
+			if (this.resolveOnNewEvent) {
+				this.resolveOnNewEvent();
+				delete this.resolveOnNewEvent;
+			}
+		};
+		this.decoder.on('data', callback);
+		this.decoder.on('end', callback);
+
+		// start flowing the decoder stream
+		this.decoder.start();
+
+		while (true) {
+			const maybeMessage = this.messages.shift();
+			if (maybeMessage !== undefined) {
+				yield maybeMessage;
+				continue;
+			}
+
+			// if no data available and stream ended, we're done
+			if (this.decoder.isEnded) {
+				this.dispose();
+
+				return null;
+			}
+
+			// stream isn't ended so wait for the new
+			// `data` or `end` event to be received
+			await new Promise((resolve) => {
+				this.resolveOnNewEvent = resolve;
+			});
+		}
+	}
+}