var assert = require('assert')
|
|
var Reader = module.exports = function(options) {
|
//TODO - remove for version 1.0
|
if(typeof options == 'number') {
|
options = { headerSize: options }
|
}
|
options = options || {}
|
this.offset = 0
|
this.lastChunk = false
|
this.chunk = null
|
this.chunkLength = 0
|
this.headerSize = options.headerSize || 0
|
this.lengthPadding = options.lengthPadding || 0
|
this.header = null
|
assert(this.headerSize < 2, 'pre-length header of more than 1 byte length not currently supported')
|
}
|
|
Reader.prototype.addChunk = function(chunk) {
|
if (!this.chunk || this.offset === this.chunkLength) {
|
this.chunk = chunk
|
this.chunkLength = chunk.length
|
this.offset = 0
|
return
|
}
|
|
var newChunkLength = chunk.length
|
var newLength = this.chunkLength + newChunkLength
|
|
if (newLength > this.chunk.length) {
|
var newBufferLength = this.chunk.length * 2
|
while (newLength >= newBufferLength) {
|
newBufferLength *= 2
|
}
|
var newBuffer = Buffer.alloc(newBufferLength)
|
this.chunk.copy(newBuffer)
|
this.chunk = newBuffer
|
}
|
chunk.copy(this.chunk, this.chunkLength)
|
this.chunkLength = newLength
|
}
|
|
Reader.prototype.read = function() {
|
if(this.chunkLength < (this.headerSize + 4 + this.offset)) {
|
return false
|
}
|
|
if(this.headerSize) {
|
this.header = this.chunk[this.offset]
|
}
|
|
//read length of next item
|
var length = this.chunk.readUInt32BE(this.offset + this.headerSize) + this.lengthPadding
|
|
//next item spans more chunks than we have
|
var remaining = this.chunkLength - (this.offset + 4 + this.headerSize)
|
if(length > remaining) {
|
return false
|
}
|
|
this.offset += (this.headerSize + 4)
|
var result = this.chunk.slice(this.offset, this.offset + length)
|
this.offset += length
|
return result
|
}
|
