45 lines
894 B
JavaScript
45 lines
894 B
JavaScript
function sequential(fn) {
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let sequenceState = {
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running: null,
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queue: []
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};
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function pump() {
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if (sequenceState.queue.length > 0) {
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const next = sequenceState.queue.shift();
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run(next.args, next.resolve, next.reject);
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} else {
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sequenceState.running = null;
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}
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}
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function run(args, resolve, reject) {
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sequenceState.running = fn(...args);
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sequenceState.running.then(
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val => {
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pump();
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resolve(val);
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},
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err => {
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pump();
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reject(err);
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}
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);
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}
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return (...args) => {
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if (!sequenceState.running) {
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return new Promise((resolve, reject) => {
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return run(args, resolve, reject);
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});
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} else {
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return new Promise((resolve, reject) => {
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sequenceState.queue.push({ resolve, reject, args });
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});
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}
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};
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}
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module.exports = { sequential };
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