python-mpd 1.0.0-1 / usr / lib / python2.7 / dist-packages / mpd / twisted.py

# python-mpd2: Python MPD client library
#
# Copyright (C) 2008-2010  J. Alexander Treuman <jat@spatialrift.net>
# Copyright (C) 2010  Jasper St. Pierre <jstpierre@mecheye.net>
# Copyright (C) 2010-2011  Oliver Mader <b52@reaktor42.de>
# Copyright (C) 2016  Robert Niederreiter <rnix@squarewave.at>
#
# python-mpd2 is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# python-mpd2 is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with python-mpd2.  If not, see <http://www.gnu.org/licenses/>.
#
# THIS MODULE IS EXPERIMENTAL. AS SOON AS IT IS CONSIDERED STABLE THIS NOTE
# WILL BE REMOVED. PLEASE REPORT INCONSISTENCIES, BUGS AND IMPROVEMENTS AT
# https://github.com/Mic92/python-mpd2/issues

from __future__ import absolute_import
from __future__ import unicode_literals
from mpd.base import CommandError
from mpd.base import CommandListError
from mpd.base import ERROR_PREFIX
from mpd.base import HELLO_PREFIX
from mpd.base import MPDClientBase
from mpd.base import NEXT
from mpd.base import SUCCESS
from mpd.base import escape
from mpd.base import logger
from mpd.base import mpd_command_provider
from mpd.base import mpd_commands
from twisted.internet import defer
from twisted.protocols import basic
import threading
import types


def lock(func):
    def wrapped(self, *args, **kwargs):
        with self._lock:
            return func(self, *args, **kwargs)
    return wrapped


def _create_command(wrapper, name, callback):
    def mpd_command(self, *args):
        def bound_callback(lines):
            return callback(self, lines)
        bound_callback.callback = callback
        return wrapper(self, name, args, bound_callback)
    return mpd_command


@mpd_command_provider
class MPDProtocol(basic.LineReceiver, MPDClientBase):
    delimiter = b'\n'

    def __init__(self, default_idle=True, idle_result=None):
        super(MPDProtocol, self).__init__(use_unicode=True)
        # flag whether client should idle by default
        self._default_idle = default_idle
        self.idle_result = idle_result
        self._reset()
        self._lock = threading.RLock()

    def _reset(self):
        super(MPDProtocol, self)._reset()
        self.mpd_version = None
        self._command_list = False
        self._command_list_results = []
        self._rcvd_lines = []
        self._state = []
        self._idle = False

    @classmethod
    def add_command(cls, name, callback):
        # ignore commands which are implemented on class directly
        if getattr(cls, name, None) is not None:
            return
        # create command and hook it on class
        func = _create_command(cls._execute, name, callback)
        escaped_name = name.replace(' ', '_')
        setattr(cls, escaped_name, func)

    @lock
    def lineReceived(self, line):
        line = line.decode('utf-8')
        command_list = self._state and isinstance(self._state[0], list)
        state_list = self._state[0] if command_list else self._state
        if line.startswith(HELLO_PREFIX):
            self.mpd_version = line[len(HELLO_PREFIX):].strip()
            # default state idle, enter idle
            if self._default_idle:
                self.idle().addCallback(self._dispatch_idle_result)
        elif line.startswith(ERROR_PREFIX):
            error = line[len(ERROR_PREFIX):].strip()
            if command_list:
                state_list[0].errback(CommandError(error))
                for state in state_list[1:-1]:
                    state.errback(
                        CommandListError('An earlier command failed.'))
                state_list[-1].errback(CommandListError(error))
                del self._state[0]
                del self._command_list_results[0]
            else:
                state_list.pop(0).errback(CommandError(error))
            self._continue_idle()
        elif line == SUCCESS or (command_list and line == NEXT):
            state_list.pop(0).callback(self._rcvd_lines[:])
            self._rcvd_lines = []
            if command_list and line == SUCCESS:
                del self._state[0]
            self._continue_idle()
        else:
            self._rcvd_lines.append(line)

    def _lookup_callback(self, parser):
        if hasattr(parser, 'callback'):
            return parser.callback
        return parser

    @lock
    def _execute(self, command, args, parser):
        # close or kill command in command list not allowed
        if self._command_list and self._lookup_callback(parser) is self.NOOP:
            msg = '{} not allowed in command list'.format(command)
            raise CommandListError(msg)
        # default state idle and currently in idle state, trigger noidle
        if self._default_idle and self._idle and command != 'idle':
            self.noidle().addCallback(self._dispatch_noidle_result)
        # write command to MPD
        self._write_command(command, args)
        # create command related deferred
        deferred = defer.Deferred()
        # extend pending result queue
        state = self._state[-1] if self._command_list else self._state
        state.append(deferred)
        # NOOP is for close and kill commands
        if self._lookup_callback(parser) is not self.NOOP:
            # attach command related result parser
            deferred.addCallback(parser)
            # command list, attach handler for collecting command list results
            if self._command_list:
                deferred.addCallback(self._parse_command_list_item)
        return deferred

    def _create_command(self, command, args=[]):
        # XXX: this function should be generalized in future. There exists
        #      almost identical code in ``MPDClient._write_command``, with the
        #      difference that it's using ``encode_str`` for text arguments.
        parts = [command]
        for arg in args:
            if type(arg) is tuple:
                if len(arg) == 0:
                    parts.append('":"')
                elif len(arg) == 1:
                    parts.append('"{}:"'.format(int(arg[0])))
                else:
                    parts.append('"{}:{}"'.format(int(arg[0]), int(arg[1])))
            else:
                parts.append('"{}"'.format(escape(arg)))
        return ' '.join(parts).encode('utf-8')

    def _write_command(self, command, args=[]):
        self.sendLine(self._create_command(command, args))

    def _parse_command_list_item(self, result):
        if isinstance(result, types.GeneratorType):
            result = list(result)
        self._command_list_results[0].append(result)
        return result

    def _parse_command_list_end(self, lines):
        return self._command_list_results.pop(0)

    @mpd_commands(
        *MPDClientBase._parse_nothing.mpd_commands)
    def _parse_nothing(self, lines):
        return None

    def _continue_idle(self):
        if self._default_idle and not self._idle and not self._state:
            self.idle().addCallback(self._dispatch_idle_result)

    def _do_dispatch(self, result):
        if self.idle_result:
            self.idle_result(result)
        else:
            res = list(result)
            msg = 'MPDProtocol: no idle callback defined: {}'.format(res)
            logger.warning(msg)

    def _dispatch_noidle_result(self, result):
        self._do_dispatch(result)

    def _dispatch_idle_result(self, result):
        self._idle = False
        self._do_dispatch(result)
        self._continue_idle()

    def idle(self):
        if self._idle:
            raise CommandError('Already in idle state')
        self._idle = True
        return self._execute('idle', [], self._parse_list)

    def noidle(self):
        if not self._idle:
            raise CommandError('Not in idle state')
        # delete first pending deferred, idle returns nothing when
        # noidle gets called
        self._state.pop(0)
        self._idle = False
        return self._execute('noidle', [], self._parse_list)

    def command_list_ok_begin(self):
        if self._command_list:
            raise CommandListError('Already in command list')
        if self._default_idle and self._idle:
            self.noidle().addCallback(self._dispatch_noidle_result)
        self._write_command('command_list_ok_begin')
        self._command_list = True
        self._command_list_results.append([])
        self._state.append([])

    def command_list_end(self):
        if not self._command_list:
            raise CommandListError('Not in command list')
        self._write_command('command_list_end')
        deferred = defer.Deferred()
        deferred.addCallback(self._parse_command_list_end)
        self._state[-1].append(deferred)
        self._command_list = False
        return deferred

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