4cd8b23032
Follow-up to the earlier enabling of classes/variables etc. Bug Related issues linked using fixes #number Integration tests added Errors have helpful link attached, see contributing.md Feature Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR. Related issues linked using fixes #number Integration tests added Documentation added Telemetry added. In case of a feature if it's used or not. Errors have helpful link attached, see contributing.md Documentation / Examples Make sure the linting passes by running pnpm lint The examples guidelines are followed from our contributing doc Co-authored-by: Steven <steven@ceriously.com>
309 lines
8.6 KiB
TypeScript
309 lines
8.6 KiB
TypeScript
import { nonNullable } from '../lib/non-nullable'
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export type ReactReadableStream = ReadableStream<Uint8Array> & {
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allReady?: Promise<void> | undefined
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}
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export function encodeText(input: string) {
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return new TextEncoder().encode(input)
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}
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export function decodeText(input?: Uint8Array, textDecoder?: TextDecoder) {
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return textDecoder
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? textDecoder.decode(input, { stream: true })
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: new TextDecoder().decode(input)
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}
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export function readableStreamTee<T = any>(
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readable: ReadableStream<T>
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): [ReadableStream<T>, ReadableStream<T>] {
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const transformStream = new TransformStream()
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const transformStream2 = new TransformStream()
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const writer = transformStream.writable.getWriter()
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const writer2 = transformStream2.writable.getWriter()
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const reader = readable.getReader()
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function read() {
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reader.read().then(({ done, value }) => {
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if (done) {
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writer.close()
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writer2.close()
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return
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}
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writer.write(value)
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writer2.write(value)
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read()
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})
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}
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read()
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return [transformStream.readable, transformStream2.readable]
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}
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export function chainStreams<T>(
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streams: ReadableStream<T>[]
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): ReadableStream<T> {
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const { readable, writable } = new TransformStream()
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let promise = Promise.resolve()
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for (let i = 0; i < streams.length; ++i) {
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promise = promise.then(() =>
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streams[i].pipeTo(writable, { preventClose: i + 1 < streams.length })
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)
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}
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return readable
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}
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export function streamFromArray(strings: string[]): ReadableStream<Uint8Array> {
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// Note: we use a TransformStream here instead of instantiating a ReadableStream
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// because the built-in ReadableStream polyfill runs strings through TextEncoder.
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const { readable, writable } = new TransformStream()
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const writer = writable.getWriter()
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strings.forEach((str) => writer.write(encodeText(str)))
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writer.close()
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return readable
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}
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export async function streamToString(
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stream: ReadableStream<Uint8Array>
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): Promise<string> {
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const reader = stream.getReader()
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const textDecoder = new TextDecoder()
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let bufferedString = ''
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while (true) {
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const { done, value } = await reader.read()
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if (done) {
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return bufferedString
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}
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bufferedString += decodeText(value, textDecoder)
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}
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}
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export function createBufferedTransformStream(
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transform: (v: string) => string | Promise<string> = (v) => v
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): TransformStream<Uint8Array, Uint8Array> {
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let bufferedString = ''
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let pendingFlush: Promise<void> | null = null
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const flushBuffer = (controller: TransformStreamDefaultController) => {
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if (!pendingFlush) {
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pendingFlush = new Promise((resolve) => {
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setTimeout(async () => {
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const buffered = await transform(bufferedString)
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controller.enqueue(encodeText(buffered))
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bufferedString = ''
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pendingFlush = null
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resolve()
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}, 0)
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})
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}
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return pendingFlush
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}
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const textDecoder = new TextDecoder()
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return new TransformStream({
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transform(chunk, controller) {
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bufferedString += decodeText(chunk, textDecoder)
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flushBuffer(controller)
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},
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flush() {
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if (pendingFlush) {
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return pendingFlush
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}
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},
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})
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}
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export function createFlushEffectStream(
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handleFlushEffect: () => string
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): TransformStream<Uint8Array, Uint8Array> {
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return new TransformStream({
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transform(chunk, controller) {
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const flushedChunk = encodeText(handleFlushEffect())
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controller.enqueue(flushedChunk)
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controller.enqueue(chunk)
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},
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})
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}
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export function renderToInitialStream({
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ReactDOMServer,
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element,
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streamOptions,
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}: {
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ReactDOMServer: any
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element: React.ReactElement
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streamOptions?: any
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}): Promise<ReactReadableStream> {
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return ReactDOMServer.renderToReadableStream(element, streamOptions)
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}
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export function createHeadInjectionTransformStream(
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inject: () => string
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): TransformStream<Uint8Array, Uint8Array> {
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let injected = false
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return new TransformStream({
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transform(chunk, controller) {
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const content = decodeText(chunk)
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let index
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if (!injected && (index = content.indexOf('</head')) !== -1) {
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injected = true
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const injectedContent =
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content.slice(0, index) + inject() + content.slice(index)
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controller.enqueue(encodeText(injectedContent))
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} else {
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controller.enqueue(chunk)
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}
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},
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})
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}
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// Suffix after main body content - scripts before </body>,
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// but wait for the major chunks to be enqueued.
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export function createDeferredSuffixStream(
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suffix: string
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): TransformStream<Uint8Array, Uint8Array> {
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let suffixFlushed = false
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let suffixFlushTask: Promise<void> | null = null
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return new TransformStream({
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transform(chunk, controller) {
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controller.enqueue(chunk)
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if (!suffixFlushed && suffix) {
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suffixFlushed = true
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suffixFlushTask = new Promise((res) => {
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// NOTE: streaming flush
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// Enqueue suffix part before the major chunks are enqueued so that
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// suffix won't be flushed too early to interrupt the data stream
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setTimeout(() => {
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controller.enqueue(encodeText(suffix))
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res()
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})
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})
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}
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},
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flush(controller) {
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if (suffixFlushTask) return suffixFlushTask
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if (!suffixFlushed && suffix) {
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suffixFlushed = true
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controller.enqueue(encodeText(suffix))
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}
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},
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})
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}
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export function createInlineDataStream(
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dataStream: ReadableStream<Uint8Array>
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): TransformStream<Uint8Array, Uint8Array> {
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let dataStreamFinished: Promise<void> | null = null
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return new TransformStream({
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transform(chunk, controller) {
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controller.enqueue(chunk)
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if (!dataStreamFinished) {
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const dataStreamReader = dataStream.getReader()
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// NOTE: streaming flush
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// We are buffering here for the inlined data stream because the
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// "shell" stream might be chunkenized again by the underlying stream
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// implementation, e.g. with a specific high-water mark. To ensure it's
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// the safe timing to pipe the data stream, this extra tick is
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// necessary.
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dataStreamFinished = new Promise((res) =>
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setTimeout(async () => {
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try {
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while (true) {
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const { done, value } = await dataStreamReader.read()
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if (done) {
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return res()
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}
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controller.enqueue(value)
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}
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} catch (err) {
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controller.error(err)
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}
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res()
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}, 0)
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)
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}
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},
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flush() {
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if (dataStreamFinished) {
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return dataStreamFinished
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}
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},
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})
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}
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export function createSuffixStream(
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suffix: string
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): TransformStream<Uint8Array, Uint8Array> {
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return new TransformStream({
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flush(controller) {
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if (suffix) {
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controller.enqueue(encodeText(suffix))
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}
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},
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})
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}
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export async function continueFromInitialStream(
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renderStream: ReactReadableStream,
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{
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suffix,
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dataStream,
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generateStaticHTML,
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flushEffectHandler,
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flushEffectsToHead,
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initialStylesheets,
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}: {
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suffix?: string
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dataStream?: ReadableStream<Uint8Array>
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generateStaticHTML: boolean
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flushEffectHandler?: () => string
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flushEffectsToHead: boolean
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initialStylesheets?: string[]
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}
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): Promise<ReadableStream<Uint8Array>> {
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const closeTag = '</body></html>'
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const suffixUnclosed = suffix ? suffix.split(closeTag)[0] : null
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if (generateStaticHTML) {
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await renderStream.allReady
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}
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const transforms: Array<TransformStream<Uint8Array, Uint8Array>> = [
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createBufferedTransformStream(),
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flushEffectHandler && !flushEffectsToHead
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? createFlushEffectStream(flushEffectHandler)
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: null,
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suffixUnclosed != null ? createDeferredSuffixStream(suffixUnclosed) : null,
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dataStream ? createInlineDataStream(dataStream) : null,
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suffixUnclosed != null ? createSuffixStream(closeTag) : null,
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createHeadInjectionTransformStream(() => {
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const inlineStyleLinks = (initialStylesheets || [])
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.map((href) => `<link rel="stylesheet" href="/_next/${href}">`)
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.join('')
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// TODO-APP: Inject flush effects to end of head in app layout rendering, to avoid
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// hydration errors. Remove this once it's ready to be handled by react itself.
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const flushEffectsContent =
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flushEffectHandler && flushEffectsToHead ? flushEffectHandler() : ''
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return inlineStyleLinks + flushEffectsContent
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}),
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].filter(nonNullable)
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return transforms.reduce(
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(readable, transform) => readable.pipeThrough(transform),
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renderStream
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)
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}
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