#!/usr/bin/env ruby

class BufferedString

  class Buffer < String

    def initialize
      @eof = false
      super
    end

    def eof?
      @eof
    end

    def close!
      @eof = true
    end

  end

  def initialize
    @buf = Buffer.new
    @pos = 0
  end

  def initialize_copy( from )
    @buf = from.instance_eval { @buf }
    @pos = 0
  end

  def read
    rval = @buf[ @pos..-1 ]
    @pos += ( @buf.length - @pos )
    return rval
  end

  def close!
    @buf.close!
  end

  def eof?
    @buf.eof? and @pos >= @buf.length
  end

  def seek(pos) ; @pos = pos ; end

  def write( string )
    @buf.insert(@pos,string)
  end

  def method_missing(name,*args,&block)
    @buf.send(name,*args,&block)
  end

end

io = BufferedString.new
ioread = io.dup
writer = Thread.new do
  io << "xxx" while ( io.length < 1000 )
  io.close!
end
reader = Thread.new do
  p ioread.read until ioread.eof?
end
sleep 1 while [ reader, writer ].find { |thread| thread.alive? }

io = BufferedString.new
ioread = io.dup
io << "dan"
io.seek(0)
io.write("hello ")
p ioread.read