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'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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