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  $   ˆl–Ãa¾”d*j"TÚzã@¸Ø”Å£Â„YÁÀ¿ ,9    # -*- Mode: Python; tab-width: 4 -*-
#       Id: asynchat.py,v 2.26 2000/09/07 22:29:26 rushing Exp
#       Author: Sam Rushing <rushing@nightmare.com>

# ======================================================================
# Copyright 1996 by Sam Rushing
#
#                         All Rights Reserved
#
# Permission to use, copy, modify, and distribute this software and
# its documentation for any purpose and without fee is hereby
# granted, provided that the above copyright notice appear in all
# copies and that both that copyright notice and this permission
# notice appear in supporting documentation, and that the name of Sam
# Rushing not be used in advertising or publicity pertaining to
# distribution of the software without specific, written prior
# permission.
#
# SAM RUSHING DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
# INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN
# NO EVENT SHALL SAM RUSHING BE LIABLE FOR ANY SPECIAL, INDIRECT OR
# CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
# OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
# NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
# CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
# ======================================================================

r"""A class supporting chat-style (command/response) protocols.

This class adds support for 'chat' style protocols - where one side
sends a 'command', and the other sends a response (examples would be
the common internet protocols - smtp, nntp, ftp, etc..).

The handle_read() method looks at the input stream for the current
'terminator' (usually '\r\n' for single-line responses, '\r\n.\r\n'
for multi-line output), calling self.found_terminator() on its
receipt.

for example:
Say you build an async nntp client using this class.  At the start
of the connection, you'll have self.terminator set to '\r\n', in
order to process the single-line greeting.  Just before issuing a
'LIST' command you'll set it to '\r\n.\r\n'.  The output of the LIST
command will be accumulated (using your own 'collect_incoming_data'
method) up to the terminator, and then control will be returned to
you - by calling your self.found_terminator() method.
"""
import asyncore
from collections import deque


class async_chat(asyncore.dispatcher):
    """This is an abstract class.  You must derive from this class, and add
    the two methods collect_incoming_data() and found_terminator()"""

    # these are overridable defaults

    ac_in_buffer_size = 65536
    ac_out_buffer_size = 65536

    # we don't want to enable the use of encoding by default, because that is a
    # sign of an application bug that we don't want to pass silently

    use_encoding = 0
    encoding = 'latin-1'

    def __init__(self, sock=None, map=None):
        # for string terminator matching
        self.ac_in_buffer = b''

        # we use a list here rather than io.BytesIO for a few reasons...
        # del lst[:] is faster than bio.truncate(0)
        # lst = [] is faster than bio.truncate(0)
        self.incoming = []

        # we toss the use of the "simple producer" and replace it with
        # a pure deque, which the original fifo was a wrapping of
        self.producer_fifo = deque()
        asyncore.dispatcher.__init__(self, sock, map)

    def collect_incoming_data(self, data):
        raise NotImplementedError("must be implemented in subclass")

    def _collect_incoming_data(self, data):
        self.incoming.append(data)

    def _get_data(self):
        d = b''.join(self.incoming)
        del self.incoming[:]
        return d

    def found_terminator(self):
        raise NotImplementedError("must be implemented in subclass")

    def set_terminator(self, term):
        """Set the input delimiter.

        Can be a fixed string of any length, an integer, or None.
        """
        if isinstance(term, str) and self.use_encoding:
            term = bytes(term, self.encoding)
        elif isinstance(term, int) and term < 0: