66 lines
1.9 KiB
JavaScript
66 lines
1.9 KiB
JavaScript
import {isReadableStream} from 'is-stream';
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import {asyncIterator} from '@sec-ant/readable-stream/ponyfill';
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export const getAsyncIterable = stream => {
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if (isReadableStream(stream, {checkOpen: false}) && nodeImports.on !== undefined) {
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return getStreamIterable(stream);
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}
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if (typeof stream?.[Symbol.asyncIterator] === 'function') {
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return stream;
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}
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// `ReadableStream[Symbol.asyncIterator]` support is missing in multiple browsers, so we ponyfill it
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if (toString.call(stream) === '[object ReadableStream]') {
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return asyncIterator.call(stream);
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}
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throw new TypeError('The first argument must be a Readable, a ReadableStream, or an async iterable.');
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};
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const {toString} = Object.prototype;
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// The default iterable for Node.js streams does not allow for multiple readers at once, so we re-implement it
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const getStreamIterable = async function * (stream) {
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const controller = new AbortController();
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const state = {};
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handleStreamEnd(stream, controller, state);
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try {
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for await (const [chunk] of nodeImports.on(stream, 'data', {signal: controller.signal})) {
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yield chunk;
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}
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} catch (error) {
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// Stream failure, for example due to `stream.destroy(error)`
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if (state.error !== undefined) {
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throw state.error;
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// `error` event directly emitted on stream
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} else if (!controller.signal.aborted) {
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throw error;
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// Otherwise, stream completed successfully
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}
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// The `finally` block also runs when the caller throws, for example due to the `maxBuffer` option
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} finally {
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stream.destroy();
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}
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};
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const handleStreamEnd = async (stream, controller, state) => {
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try {
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await nodeImports.finished(stream, {
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cleanup: true,
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readable: true,
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writable: false,
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error: false,
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});
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} catch (error) {
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state.error = error;
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} finally {
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controller.abort();
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}
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};
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// Loaded by the Node entrypoint, but not by the browser one.
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// This prevents using dynamic imports.
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export const nodeImports = {};
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