gistfile1.txt

var combine = require('stream-combiner');
var split = require('split');
var through = require('through');
var zlib = require('zlib');


module.exports = function () {
  var genreInfo;

  function write(buf) {
    if (buf.length === 0) {
      return;
    }

    buf = JSON.parse(buf);
    if (buf.type === 'genre') {
      if (genreInfo) {
        this.queue(JSON.stringify(genreInfo) + '\n');
      }

      genreInfo = {
        name: buf.name,
        books: []
      };
    }
    else {
      genreInfo.books.push(buf.name);
    }
  }

  function end() {
    this.queue(JSON.stringify(genreInfo) + '\n');
    this.queue(null);
  }

  return combine(
    split(),
    through(write, end),
    zlib.createGzip()
  );
};


//concat stream takes the whole content as a buffer
var  concat = require('concat-stream');

//pipes it into concat with a callback function that you can then do stuff to.
//the function takes an object then you can call methods on that object
process.stdin.pipe(concat(function(src){
  var s = src.toString().split('').reverse().join('');
  console.log(s);
}));


var spawn = require('child_process').spawn;
var duplexer = require('duplexer');

module.exports = function (cmd, args) {
  var proc = spawn(cmd, args);
  return duplexer(proc.stdin, proc.stdout);
};


var trumpet = require('trumpet');
var through = require('through');
var tr = trumpet();

var loud = tr.select('.loud').createStream();
loud.pipe(through(function (buf) {
  this.queue(buf.toString().toUpperCase());
})).pipe(loud);

process.stdin.pipe(tr).pipe(process.stdout);


var http = require('http');
var through = require('through');

var server = http.createServer(function (req, res) {
  if (req.method === 'POST') {
    req.pipe(through(function (buf) {
      this.queue(buf.toString().toUpperCase());
    })).pipe(res);
  }
  else res.end('send me a POST\n');
});
server.listen(parseInt(process.argv[2]));


var tar = require('tar');
var parser = tar.Parse();
var crypto = require('crypto');
var through = require('through');

var gunzipStream = require('zlib').createGunzip();
var cypherStream = crypto.createDecipher(process.argv[2], process.argv[3]);

parser.on('entry', function (e) {
  var md5Stream = crypto.createHash('md5', { encoding: 'hex' });

  if (e.type !== 'File') {
    return;
  }

  e.pipe(md5Stream).pipe(through(function (buf) {
    this.queue(buf.toString());
  }, function () {
    this.queue(" " + e.path + "\n");
    this.queue(null);
  })).pipe(process.stdout);
});

process.stdin.pipe(cypherStream).pipe(gunzipStream).pipe(parser);


//this will pipe data from one thing to another and then you can transform it to a string and then do stuff to it.
var through = require('through');

var tr = through(
  function write(data){
    this.queue(data.toString().toUpperCase());
  }
);

process.stdin.pipe(tr).pipe(process.stdout);