var Transform = require('readable-stream').Transform , inherits = require('util').inherits function DestroyableTransform(opts) { Transform.call(this, opts) this._destroyed = false } inherits(DestroyableTransform, Transform) DestroyableTransform.prototype.destroy = function(err) { if (this._destroyed) return this._destroyed = true var self = this process.nextTick(function() { if (err) self.emit('error', err) self.emit('close') }) } // a noop _transform function function noop (chunk, enc, callback) { callback(null, chunk) } // 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 function (options, transform, flush) { if (typeof options == 'function') { flush = transform transform = options options = {} } if (typeof transform != 'function') transform = noop if (typeof flush != 'function') flush = null return construct(options, transform, flush) } } // main export, just make me a transform stream! module.exports = through2(function (options, transform, flush) { var t2 = new DestroyableTransform(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 module.exports.ctor = through2(function (options, transform, flush) { function Through2 (override) { if (!(this instanceof Through2)) return new Through2(override) this.options = Object.assign({}, options, override) DestroyableTransform.call(this, this.options) } inherits(Through2, DestroyableTransform) Through2.prototype._transform = transform if (flush) Through2.prototype._flush = flush return Through2 }) module.exports.obj = through2(function (options, transform, flush) { var t2 = new DestroyableTransform(Object.assign({ objectMode: true, highWaterMark: 16 }, options)) t2._transform = transform if (flush) t2._flush = flush return t2 })