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var util = require('util')
var Stream = require('stream')
var StringDecoder = require('string_decoder').StringDecoder
module.exports = StringStream
module.exports.AlignedStringDecoder = AlignedStringDecoder
function StringStream(from, to) {
if (!(this instanceof StringStream)) return new StringStream(from, to)
Stream.call(this)
if (from == null) from = 'utf8'
this.readable = this.writable = true
this.paused = false
this.toEncoding = (to == null ? from : to)
this.fromEncoding = (to == null ? '' : from)
this.decoder = new AlignedStringDecoder(this.toEncoding)
}
util.inherits(StringStream, Stream)
StringStream.prototype.write = function(data) {
if (!this.writable) {
var err = new Error('stream not writable')
err.code = 'EPIPE'
this.emit('error', err)
return false
}
if (this.fromEncoding) {
if (Buffer.isBuffer(data) || typeof data === 'number') data = data.toString()
data = new Buffer(data, this.fromEncoding)
}
var string = this.decoder.write(data)
if (string.length) this.emit('data', string)
return !this.paused
}
StringStream.prototype.flush = function() {
if (this.decoder.flush) {
var string = this.decoder.flush()
if (string.length) this.emit('data', string)
}
}
StringStream.prototype.end = function() {
if (!this.writable && !this.readable) return
this.flush()
this.emit('end')
this.writable = this.readable = false
this.destroy()
}
StringStream.prototype.destroy = function() {
this.decoder = null
this.writable = this.readable = false
this.emit('close')
}
StringStream.prototype.pause = function() {
this.paused = true
}
StringStream.prototype.resume = function () {
if (this.paused) this.emit('drain')
this.paused = false
}
function AlignedStringDecoder(encoding) {
StringDecoder.call(this, encoding)
switch (this.encoding) {
case 'base64':
this.write = alignedWrite
this.alignedBuffer = new Buffer(3)
this.alignedBytes = 0
break
}
}
util.inherits(AlignedStringDecoder, StringDecoder)
AlignedStringDecoder.prototype.flush = function() {
if (!this.alignedBuffer || !this.alignedBytes) return ''
var leftover = this.alignedBuffer.toString(this.encoding, 0, this.alignedBytes)
this.alignedBytes = 0
return leftover
}
function alignedWrite(buffer) {
var rem = (this.alignedBytes + buffer.length) % this.alignedBuffer.length
if (!rem && !this.alignedBytes) return buffer.toString(this.encoding)
var returnBuffer = new Buffer(this.alignedBytes + buffer.length - rem)
this.alignedBuffer.copy(returnBuffer, 0, 0, this.alignedBytes)
buffer.copy(returnBuffer, this.alignedBytes, 0, buffer.length - rem)
buffer.copy(this.alignedBuffer, 0, buffer.length - rem, buffer.length)
this.alignedBytes = rem
return returnBuffer.toString(this.encoding)
}
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