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