ranged-stream/index.js

node-ranged-stream ==================

var Transform = require('stream').Transform;
var util = require('util');


function RangeStream(opt) {
  Transform.call(this, opt);
  this.data = '';
  this._start = opt.start || 0;
  this._end = (opt.end != undefined ) ? opt.end  : -1;  
  this._current = 0;
};
util.inherits(RangeStream, Transform);

RangeStream.prototype._transform = function(data, encoding, callback) {
  if (this._end > -1 && this._current > this._end  ) {
    //should we emit end  ?
    callback();
    return;
  } else if (this._start > this._current) {
    if ( this._start > this._current + data.length) {
      this._current += data.length;
      callback();
      return;
    }
    data = data.slice( this._start - this._current );
    this._current += this._start;
  }

  if (this._end > -1 && (this._current + data.length) >= this._end) {
    data = data.slice(0, this._end - this._current +1 ) ; // _end is index, not length
  }
  this._current += data.length;
  this.push(data);
  callback();
}

RangeStream.prototype._flush = function(callback) {
  callback();
}

module.exports = RangeStream;