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// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.// This module is browser compatible.
const NEWLINE_REGEXP = /\r\n|\r|\n/;const encoder = new TextEncoder();
/** * Represents a message in the Server-Sent Event (SSE) protocol. * * @see {@link https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events#fields} */export interface ServerSentEventMessage { /** Ignored by the client. */ comment?: string; /** A string identifying the type of event described. */ event?: string; /** The data field for the message. Split by new lines. */ data?: string; /** The event ID to set the {@linkcode EventSource} object's last event ID value. */ id?: string | number; /** The reconnection time. */ retry?: number;}
function assertHasNoNewline(value: string, varName: string) { if (value.match(NEWLINE_REGEXP) !== null) { throw new RangeError(`${varName} cannot contain a newline`); }}
/** * Converts a server-sent message object into a string for the client. * * @see {@link https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events#event_stream_format} */function stringify(message: ServerSentEventMessage): Uint8Array { const lines = []; if (message.comment) { assertHasNoNewline(message.comment, "`message.comment`"); lines.push(`:${message.comment}`); } if (message.event) { assertHasNoNewline(message.event, "`message.event`"); lines.push(`event:${message.event}`); } if (message.data) { message.data.split(NEWLINE_REGEXP).forEach((line) => lines.push(`data:${line}`) ); } if (message.id) { assertHasNoNewline(message.id.toString(), "`message.id`"); lines.push(`id:${message.id}`); } if (message.retry) lines.push(`retry:${message.retry}`); return encoder.encode(lines.join("\n") + "\n\n");}
/** * Transforms server-sent message objects into strings for the client. * * @see {@link https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events} * * @example * ```ts * import { * type ServerSentEventMessage, * ServerSentEventStream, * } from "https://deno.land/std@$STD_VERSION/http/server_sent_event_stream.ts"; * * const stream = ReadableStream.from<ServerSentEventMessage>([ * { data: "hello there" } * ]).pipeThrough(new ServerSentEventStream()); * new Response(stream, { * headers: { * "content-type": "text/event-stream", * "cache-control": "no-cache", * }, * }); * ``` */export class ServerSentEventStream extends TransformStream<ServerSentEventMessage, Uint8Array> { constructor() { super({ transform: (message, controller) => { controller.enqueue(stringify(message)); }, }); }}