LendAndRegret/node_modules/@simple-libs/stream-utils/dist/index.js
2026-05-02 17:27:43 +08:00

116 lines
6.7 KiB
JavaScript

import { Readable } from 'stream';
/**
* Get all items from an async iterable and return them as an array.
* @param iterable
* @returns A promise that resolves to an array of items.
*/
export async function toArray(iterable) {
const result = [];
for await (const item of iterable) {
result.push(item);
}
return result;
}
/**
* Concatenate all buffers from an async iterable into a single Buffer.
* @param iterable
* @returns A promise that resolves to a single Buffer containing all concatenated buffers.
*/
export async function concatBufferStream(iterable) {
return Buffer.concat(await toArray(iterable));
}
/**
* Concatenate all strings from an async iterable into a single string.
* @param iterable
* @returns A promise that resolves to a single string containing all concatenated strings.
*/
export async function concatStringStream(iterable) {
return (await toArray(iterable)).join('');
}
/**
* Get the first item from an async iterable.
* @param stream
* @returns A promise that resolves to the first item, or null if the iterable is empty.
*/
export async function firstFromStream(stream) {
for await (const tag of stream) {
return tag;
}
return null;
}
/**
* Merges multiple Readable streams into a single Readable stream.
* Each chunk will be an object containing the source stream name and the chunk data.
* @param streams - An object where keys are stream names and values are Readable streams.
* @returns A merged Readable stream.
*/
export function mergeReadables(streams) {
const mergedStream = new Readable({
objectMode: true,
read() { }
});
let ended = 0;
Object.entries(streams).forEach(([name, stream], _i, entries) => {
stream
.on('data', (chunk) => mergedStream.push({
source: name,
chunk
}))
.on('end', () => {
ended += 1;
if (ended === entries.length) {
mergedStream.push(null);
}
})
.on('error', err => mergedStream.destroy(err));
});
return mergedStream;
}
/**
* Split stream by separator.
* @param stream
* @param separator
* @yields String chunks.
*/
export async function* splitStream(stream, separator) {
let chunk;
let payload;
let buffer = '';
for await (chunk of stream) {
buffer += chunk.toString();
if (buffer.includes(separator)) {
payload = buffer.split(separator);
buffer = payload.pop() || '';
yield* payload;
}
}
if (buffer) {
yield buffer;
}
}
/**
* Parse JSON objects from a stream, separated by a delimiter (default is newline).
* @param stream
* @param delimiter
* @yields Parsed JSON objects of type T.
*/
export async function* parseJsonStream(stream, delimiter = /\r?\n/) {
let chunk;
let payload;
let buffer = '';
let json;
for await (chunk of stream) {
buffer += chunk.toString();
if (delimiter.test(buffer)) {
payload = buffer.split(delimiter);
buffer = payload.pop() || '';
for (json of payload) {
yield JSON.parse(json);
}
}
}
if (buffer) {
yield JSON.parse(buffer);
}
}
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