event based twitter stream client

evented.rb

require 'socket'
require 'psych'

###
# Event based Twitter stream client.  Yields tweets as they happen from the
# "sample" stream.  Requires Ruby 1.9.2.
#
# Example:
#
#   sc = StreamClient.new($username, $password)
#   sc.each do |tweet|
#     puts tweet['text']
#   end
#
# See http://tenderlovemaking.com/2010/04/17/event-based-json-and-yaml-parsing/
class StreamClient
  class Listener < Psych::TreeBuilder
    def initialize block
      @block = block
      super()
    end

    def end_document implicit_end
      super
      @block.call @last.children.pop.to_ruby
    end
  end

  def initialize user, pass
    @ba = ["#{user}:#{pass}"].pack('m').chomp
  end

  def each &block
    socket = TCPSocket.new 'stream.twitter.com', 80
    socket.write "GET /1/statuses/sample.json HTTP/1.1\r\n"
    socket.write "Host: stream.twitter.com\r\n"
    socket.write "Authorization: Basic #{@ba}\r\n"
    socket.write "\r\n"

    # Read the headers
    while((line = socket.readline) != "\r\n"); puts line if $DEBUG; end

    reader, writer = IO.pipe
    producer = Thread.new(socket, writer) do |s, io|
      loop do
        io.write "---\n"
        io.write s.read s.readline.strip.to_i 16
        io.write "...\n"
        s.read 2 # strip the blank line
      end
    end

    parser = Psych::Parser.new Listener.new block
    parser.parse reader

    producer.join
  end
end

sc = StreamClient.new(ARGV[0], ARGV[1])
sc.each do |tweet|
  p tweet
end