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