buffering/index.js

"use strict";

var Transform = require("stream").Transform,
    util = require("util");

function BufferingStream(options) {
    Transform.call(this, options);
    
    this._neededLength = null;
    this._buffer = new Buffer([]);
}

util.inherits(BufferingStream, Transform);

BufferingStream.prototype._transform = function(chunk, encoding, callback) {

    if(!Buffer.isBuffer(chunk)) {
        chunk = new Buffer(chunk, encoding);
    };
    
    this._buffer = Buffer.concat([this._buffer, chunk]);
    this._tryRead();
    
    callback();
    
};

BufferingStream.prototype.buffer = function(length) {
    this._neededLength = length;
    this._tryRead();
};

BufferingStream.prototype._tryRead = function() {
    
    // Only read if we need to
    if(this._neededLength == null) return;
    var neededLength = this._neededLength;
    
    // Don't read if we don't have enough data
    if(this._buffer.length < this._neededLength) return;
    var buf = this._buffer;
    
    var data = buf.slice(0, neededLength);
    this._buffer = buf.slice(neededLength);
    
    // Reset job
    this._neededLength = null;
    
    // Send data event
    this.push(data);
    
};

module.exports = BufferingStream;