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/**
* Original sources:
* - https://github.com/kmalakoff/response-iterator/blob/master/src/index.ts
* - https://github.com/apollographql/apollo-client/blob/main/src/utilities/common/responseIterator.ts
*/
import type { ReadableStreamDefaultReadResult } from 'node:stream/web';
import { Readable as NodeReadableStream } from 'stream';
interface NodeStreamIterator<T> {
next(): Promise<IteratorResult<T, boolean | undefined>>;
[Symbol.asyncIterator]?(): AsyncIterator<T>;
}
interface PromiseIterator<T> {
next(): Promise<IteratorResult<T, ArrayBuffer | undefined>>;
[Symbol.asyncIterator]?(): AsyncIterator<T>;
}
interface ReaderIterator<T> {
next(): Promise<ReadableStreamDefaultReadResult<T>>;
[Symbol.asyncIterator]?(): AsyncIterator<T>;
}
const canUseSymbol = typeof Symbol === 'function' && typeof Symbol.for === 'function';
const canUseAsyncIteratorSymbol = canUseSymbol && Symbol.asyncIterator;
function isBuffer(value: any): value is Buffer {
return (
value?.constructor != null &&
typeof value.constructor.isBuffer === 'function' &&
value.constructor.isBuffer(value)
);
}
function isNodeResponse(value: any): value is Response {
return !!(value as Response).body;
}
function isReadableStream(value: any): value is ReadableStream<any> {
return !!(value as ReadableStream<any>).getReader;
}
function isAsyncIterableIterator(value: any): value is AsyncIterableIterator<any> {
return !!(
canUseAsyncIteratorSymbol && (value as AsyncIterableIterator<any>)[Symbol.asyncIterator]
);
}
function isStreamableBlob(value: any): value is Blob {
return !!(value as Blob).stream;
}
function isBlob(value: any): value is Blob {
return !!(value as Blob).arrayBuffer;
}
function isNodeReadableStream(value: any): value is NodeReadableStream {
return !!(value as NodeReadableStream).pipe;
}
function readerIterator<T>(reader: ReadableStreamDefaultReader<T>): AsyncIterableIterator<T> {
const iterator: ReaderIterator<T> = {
//@ts-expect-error
next() {
return reader.read();
},
};
if (canUseAsyncIteratorSymbol) {
iterator[Symbol.asyncIterator] = function (): AsyncIterator<T> {
//@ts-expect-error
return this;
};
}
return iterator as AsyncIterableIterator<T>;
}
function promiseIterator<T = ArrayBuffer>(promise: Promise<ArrayBuffer>): AsyncIterableIterator<T> {
let resolved = false;
const iterator: PromiseIterator<T> = {
next(): Promise<IteratorResult<T, ArrayBuffer | undefined>> {
if (resolved)
return Promise.resolve({
value: undefined,
done: true,
});
resolved = true;
return new Promise(function (resolve, reject) {
promise
.then(function (value) {
resolve({ value: value as unknown as T, done: false });
})
.catch(reject);
});
},
};
if (canUseAsyncIteratorSymbol) {
iterator[Symbol.asyncIterator] = function (): AsyncIterator<T> {
return this;
};
}
return iterator as AsyncIterableIterator<T>;
}
function nodeStreamIterator<T>(stream: NodeReadableStream): AsyncIterableIterator<T> {
let cleanup: (() => void) | null = null;
let error: Error | null = null;
let done = false;
const data: unknown[] = [];
const waiting: [
(
value:
| IteratorResult<T, boolean | undefined>
| PromiseLike<IteratorResult<T, boolean | undefined>>
) => void,
(reason?: any) => void,
][] = [];
function onData(chunk: any) {
if (error) return;
if (waiting.length) {
const shiftedArr = waiting.shift();
if (Array.isArray(shiftedArr) && shiftedArr[0]) {
return shiftedArr[0]({ value: chunk, done: false });
}
}
data.push(chunk);
}
function onError(err: Error) {
error = err;
const all = waiting.slice();
all.forEach(function (pair) {
pair[1](err);
});
!cleanup || cleanup();
}
function onEnd() {
done = true;
const all = waiting.slice();
all.forEach(function (pair) {
pair[0]({ value: undefined, done: true });
});
!cleanup || cleanup();
}
cleanup = function () {
cleanup = null;
stream.removeListener('data', onData);
stream.removeListener('error', onError);
stream.removeListener('end', onEnd);
stream.removeListener('finish', onEnd);
stream.removeListener('close', onEnd);
};
stream.on('data', onData);
stream.on('error', onError);
stream.on('end', onEnd);
stream.on('finish', onEnd);
stream.on('close', onEnd);
function getNext(): Promise<IteratorResult<T, boolean | undefined>> {
return new Promise(function (resolve, reject) {
if (error) return reject(error);
if (data.length) return resolve({ value: data.shift() as T, done: false });
if (done) return resolve({ value: undefined, done: true });
waiting.push([resolve, reject]);
});
}
const iterator: NodeStreamIterator<T> = {
next(): Promise<IteratorResult<T, boolean | undefined>> {
return getNext();
},
};
if (canUseAsyncIteratorSymbol) {
iterator[Symbol.asyncIterator] = function (): AsyncIterator<T> {
return this;
};
}
return iterator as AsyncIterableIterator<T>;
}
function asyncIterator<T>(source: AsyncIterableIterator<T>): AsyncIterableIterator<T> {
const iterator = source[Symbol.asyncIterator]();
return {
next(): Promise<IteratorResult<T, boolean>> {
return iterator.next();
},
[Symbol.asyncIterator](): AsyncIterableIterator<T> {
return this;
},
};
}
export function responseIterator<T>(response: Response | Buffer): AsyncIterableIterator<T> {
let body: unknown = response;
if (isNodeResponse(response)) body = response.body;
if (isBuffer(body)) body = NodeReadableStream.from(body);
if (isAsyncIterableIterator(body)) return asyncIterator<T>(body);
if (isReadableStream(body)) return readerIterator<T>(body.getReader());
// this errors without casting to ReadableStream<T>
// because Blob.stream() returns a NodeJS ReadableStream
if (isStreamableBlob(body)) {
return readerIterator<T>((body.stream() as unknown as ReadableStream<T>).getReader());
}
if (isBlob(body)) return promiseIterator<T>(body.arrayBuffer());
if (isNodeReadableStream(body)) return nodeStreamIterator<T>(body);
throw new Error('Unknown body type for responseIterator. Please pass a streamable response.');
}
|
