1#!/usr/bin/env python3
2#
3#   Copyright 2018 - The Android Open Source Project
4#
5#   Licensed under the Apache License, Version 2.0 (the "License");
6#   you may not use this file except in compliance with the License.
7#   You may obtain a copy of the License at
8#
9#       http://www.apache.org/licenses/LICENSE-2.0
10#
11#   Unless required by applicable law or agreed to in writing, software
12#   distributed under the License is distributed on an "AS IS" BASIS,
13#   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14#   See the License for the specific language governing permissions and
15#   limitations under the License.
16
17
18class EventSubscription(object):
19    """A class that defines the way a function is subscribed to an event.
20
21    Attributes:
22        event_type: The type of the event.
23        _func: The subscribed function.
24        _event_filter: A lambda that returns True if an event should be passed
25                       to the subscribed function.
26        order: The order value in which this subscription should be called.
27    """
28    def __init__(self, event_type, func, event_filter=None, order=0):
29        self._event_type = event_type
30        self._func = func
31        self._event_filter = event_filter
32        self.order = order
33
34    @property
35    def event_type(self):
36        return self._event_type
37
38    def deliver(self, event):
39        """Delivers an event to the subscriber.
40
41        This function will not deliver the event if the event filter rejects the
42        event.
43
44        Args:
45            event: The event to send to the subscriber.
46        """
47        if self._event_filter and not self._event_filter(event):
48            return
49        self._func(event)
50