aaac7fed
 liuqimichale
add
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var Transform = require('readable-stream').Transform
, inherits = require('util').inherits
, xtend = require('xtend')
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 = xtend(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(xtend({ objectMode: true, highWaterMark: 16 }, options))
t2._transform = transform
if (flush)
t2._flush = flush
return t2
})
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