Can't use PullParser to parse several valid messages in a row

[DmitryPogrebnoy]

I have the following use case:

require 'socket'
require 'rexml/parsers/pullparser'

# Server setup for demonstration purposes
server = TCPServer.new 2000
Thread.new do
  client = server.accept
  client.puts "<message>First valid and complete message</message>"
  sleep 1
  client.puts "<message>Second valid and complete message</message>"
  sleep 1
  client.puts "<message>Third valid and complete message</message>"
  client.close
end

# Client setup
socket = TCPSocket.new 'localhost', 2000

# REXML PullParser using socket
parser = REXML::Parsers::PullParser.new(socket)

begin
  while parser.has_next?
    event = parser.pull
    if event.start_element? and event[0] == 'message'
      text = parser.pull
      if text.text?
        puts "Received message: #{text[0]}"
      end
    end
  end
ensure
  socket.close
end

# Closing the server in this demonstration
server.close

Here I have a socket, and I pull messages from the server and parse it. Every message is valid and complete xml.
Before the release https://github.com/ruby/rexml/releases/tag/v3.3.2 this use case worked like a charm. After that it doesn't work with exception

'REXML::Parsers::BaseParser#pull_event': Malformed XML: Extra tag at the end of the document (got '<message') (REXML::ParseException)

This is a side effect after this changes - #161
It seems there is no proper solution for this use case now, and I can't use the actual version of this gem.

Possible solutions could be as follows:

1. Addition parameter or flag to ignore the error above.
2. Add a special call to refresh the parser after each pull event.

[kou]

Adding PullParser#reset and users can call it explicitly is acceptable.
Do you want to work on this?

[DmitryPogrebnoy]

I'll be ready to take it on in one week. If that's okay, no problem.

[kou]

No problem. We aren't in a hurry.

[DmitryPogrebnoy]

@kou Here is a PR #220. Please take a look.