/**
 * Copyright 2019 Google Inc. All Rights Reserved.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *     http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */ /**
 * Symbol indicating the end of a stream. Used with `external`.
 */ export const EOF = Symbol ( ) ; export type NextFunc < T > = ( v : T | typeof EOF ) => void ; typeparam export function external < T > ( ) { let next ; const observable = new ReadableStream < T > ( { async start ( controller ) { next = ( v ) => { if ( v === EOF ) { return controller . close ( ) ; } controller . enqueue ( v ) ; } ; } } , { highWaterMark : 0 } ) ; return { observable , next : next ! } ; }