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@fxsjy
Created Aug 8, 2012
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QBuffer: A little buffer tool for Node.JS
var QBuffer = exports.QBuffer= function(){
this.list = []
this.length = 0
}
QBuffer.prototype.append=function(chunk){
this.list.push(chunk)
this.length += chunk.length
}
QBuffer.prototype.read=function(N){
var M = (N<this.length)? N: this.length
var result = new Buffer(M)
var read_count = 0
while(this.list.length>0){
if(read_count == M) break;
var chunk = this.list[0]
if(chunk.length <= M - read_count){
chunk.copy(result,read_count,0,chunk.length)
read_count += chunk.length
this.list.shift()
}else{
need_count = M - read_count
chunk.copy(result,read_count,0,need_count)
this.list[0] = this.list[0].slice(need_count)
break;
}
}
this.length -= M
return result
}
QBuffer.prototype.search=function(niddle){
if(typeof niddle == 'string')
niddle = new Buffer(niddle)
var i=0
var j=0
var k=0
var last_i=0
var last_j=0
var found=false
var offset = 0
while(true){
if(i>=this.list.length)break;
if(j>=this.list[i].length)break;
var c = this.list[i][j]
if(c == niddle[k]){
if(j<this.list[i].length-1)
j++
else{
i++
j=0
}
k++
if(k==niddle.length){
found = true
break
}
}else{
k = 0
i = last_i
j = last_j
if(j<this.list[i].length-1)
j++
else{
i++
j=0
}
last_i = i
last_j = j
offset++
}
}
if(found)
return offset
else
return -1
}
QBuffer.prototype.readUntil=function(niddle){
if(typeof niddle == 'string')
niddle = new Buffer(niddle)
var offset = this.search(niddle)
if(offset!=-1)
return this.read(offset)
else
return new Buffer(0)
}
QBuffer.prototype.readUntilOrEnd=function(niddle){
if(typeof niddle == 'string')
niddle = new Buffer(niddle)
var offset = this.search(niddle)
if(offset!=-1)
return this.read(offset)
else
return this.read(this.length)
}
@fxsjy
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fxsjy commented Aug 8, 2012

var QBuffer = require('./qbuffer').QBuffer
var fs = require('fs')
var buf = new QBuffer()
var myfile=fs.createReadStream("hugefile.txt")
myfile.on('data',function(data){
buf.append(data)
var line = null
line = buf.readUntil("\r\n")
if(line.length>0){
console.log(line.toString())
buf.read(2) //skip two bytes of CRLF
}
})
myfile.on('end',function(){
while(buf.length>0){
console.log(buf.readUntilOrEnd("\r\n").toString())
buf.read(2) //skip two bytes of CRLF
}
})

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