forked from nodejs/node
/
operators.js
152 lines (125 loc) · 2.79 KB
/
operators.js
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'use strict';
const { AbortController } = require('internal/abort_controller');
const {
codes: {
ERR_INVALID_ARG_TYPE,
},
AbortError,
} = require('internal/errors');
const { validateInteger } = require('internal/validators');
const {
MathFloor,
Promise,
PromiseReject,
PromisePrototypeCatch,
Symbol,
} = primordials;
const kEmpty = Symbol('kEmpty');
const kEof = Symbol('kEof');
async function * map(fn, options) {
if (typeof fn !== 'function') {
throw new ERR_INVALID_ARG_TYPE(
'fn', ['Function', 'AsyncFunction'], this);
}
if (options != null && typeof options !== 'object') {
throw new ERR_INVALID_ARG_TYPE('options', ['Object']);
}
let concurrency = 1;
if (options?.concurrency != null) {
concurrency = MathFloor(options.concurrency);
}
validateInteger(concurrency, 'concurrency', 1);
const ac = new AbortController();
const stream = this;
const queue = [];
const signal = ac.signal;
const signalOpt = { signal };
const abort = () => ac.abort();
options?.signal?.addEventListener('abort', abort);
let next;
let resume;
let done = false;
function onDone() {
done = true;
}
async function pump() {
try {
for await (let val of stream) {
if (done) {
return;
}
if (signal.aborted) {
throw new AbortError();
}
try {
val = fn(val, signalOpt);
} catch (err) {
val = PromiseReject(err);
}
if (val === kEmpty) {
continue;
}
if (typeof val?.catch === 'function') {
val.catch(onDone);
}
queue.push(val);
if (next) {
next();
next = null;
}
if (!done && queue.length && queue.length >= concurrency) {
await new Promise((resolve) => {
resume = resolve;
});
}
}
queue.push(kEof);
} catch (err) {
const val = PromiseReject(err);
PromisePrototypeCatch(val, onDone);
queue.push(val);
} finally {
done = true;
if (next) {
next();
next = null;
}
options?.signal?.removeEventListener('abort', abort);
}
}
pump();
try {
while (true) {
while (queue.length > 0) {
const val = await queue[0];
if (val === kEof) {
return;
}
if (signal.aborted) {
throw new AbortError();
}
if (val !== kEmpty) {
yield val;
}
queue.shift();
if (resume) {
resume();
resume = null;
}
}
await new Promise((resolve) => {
next = resolve;
});
}
} finally {
ac.abort();
done = true;
if (resume) {
resume();
resume = null;
}
}
}
module.exports = {
map,
};