80 lines
1.5 KiB
JavaScript
80 lines
1.5 KiB
JavaScript
'use strict';
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const from = require('from2');
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const pIsPromise = require('p-is-promise');
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module.exports = x => {
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if (Array.isArray(x)) {
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x = x.slice();
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}
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let promise;
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let iterator;
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prepare(x);
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function prepare(value) {
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x = value;
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promise = pIsPromise(x) ? x : null;
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// we don't iterate on strings and buffers since slicing them is ~7x faster
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const shouldIterate = !promise && x[Symbol.iterator] && typeof x !== 'string' && !Buffer.isBuffer(x);
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iterator = shouldIterate ? x[Symbol.iterator]() : null;
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}
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return from(function reader(size, cb) {
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if (promise) {
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promise.then(prepare).then(() => reader.call(this, size, cb), cb);
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return;
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}
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if (iterator) {
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const obj = iterator.next();
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setImmediate(cb, null, obj.done ? null : obj.value);
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return;
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}
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if (x.length === 0) {
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setImmediate(cb, null, null);
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return;
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}
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const chunk = x.slice(0, size);
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x = x.slice(size);
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setImmediate(cb, null, chunk);
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});
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};
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module.exports.obj = x => {
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if (Array.isArray(x)) {
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x = x.slice();
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}
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let promise;
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let iterator;
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prepare(x);
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function prepare(value) {
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x = value;
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promise = pIsPromise(x) ? x : null;
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iterator = !promise && x[Symbol.iterator] ? x[Symbol.iterator]() : null;
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}
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return from.obj(function reader(size, cb) {
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if (promise) {
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promise.then(prepare).then(() => reader.call(this, size, cb), cb);
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return;
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}
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if (iterator) {
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const obj = iterator.next();
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setImmediate(cb, null, obj.done ? null : obj.value);
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return;
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}
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this.push(x);
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setImmediate(cb, null, null);
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});
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};
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