84 lines
1.8 KiB
JavaScript
84 lines
1.8 KiB
JavaScript
const { Transform } = require('readable-stream')
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function inherits (fn, sup) {
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fn.super_ = sup
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fn.prototype = Object.create(sup.prototype, {
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constructor: { value: fn, enumerable: false, writable: true, configurable: true }
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})
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}
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// create a new export function, used by both the main export and
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// the .ctor export, contains common logic for dealing with arguments
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function through2 (construct) {
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return (options, transform, flush) => {
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if (typeof options === 'function') {
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flush = transform
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transform = options
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options = {}
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}
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if (typeof transform !== 'function') {
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// noop
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transform = (chunk, enc, cb) => cb(null, chunk)
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}
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if (typeof flush !== 'function') {
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flush = null
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}
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return construct(options, transform, flush)
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}
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}
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// main export, just make me a transform stream!
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const make = through2((options, transform, flush) => {
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const t2 = new Transform(options)
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t2._transform = transform
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if (flush) {
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t2._flush = flush
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}
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return t2
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})
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// make me a reusable prototype that I can `new`, or implicitly `new`
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// with a constructor call
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const ctor = through2((options, transform, flush) => {
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function Through2 (override) {
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if (!(this instanceof Through2)) {
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return new Through2(override)
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}
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this.options = Object.assign({}, options, override)
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Transform.call(this, this.options)
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this._transform = transform
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if (flush) {
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this._flush = flush
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}
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}
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inherits(Through2, Transform)
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return Through2
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})
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const obj = through2(function (options, transform, flush) {
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const t2 = new Transform(Object.assign({ objectMode: true, highWaterMark: 16 }, options))
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t2._transform = transform
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if (flush) {
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t2._flush = flush
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}
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return t2
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})
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module.exports = make
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module.exports.ctor = ctor
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module.exports.obj = obj
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