1# Copyright (c) 2012 Ian C. Good
2#
3# Permission is hereby granted, free of charge, to any person obtaining a copy
4# of this software and associated documentation files (the "Software"), to deal
5# in the Software without restriction, including without limitation the rights
6# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
7# copies of the Software, and to permit persons to whom the Software is
8# furnished to do so, subject to the following conditions:
9#
10# The above copyright notice and this permission notice shall be included in
11# all copies or substantial portions of the Software.
12#
13# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
14# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
15# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
16# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
17# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
18# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
19# THE SOFTWARE.
20#
21
22"""Implements a simple forwarding policy, to transform or replace
23recipients.
24
25"""
26
27from __future__ import absolute_import
28
29import re
30
31from . import QueuePolicy
32
33__all__ = ['Forward']
34
35
36class Forward(QueuePolicy):
37    """Each |Envelope| recipient is run through :func:`re.sub()` to see if it
38    is modified. If a recipient matches a mapping rule, no further mapping
39    rules are processed. Mapping rules are checked in the order that they were
40    added.
41
42    """
43
44    def __init__(self):
45        self.mapping = []
46
47    def add_mapping(self, pattern, repl, count=0):
48        """Adds a mapping rule.
49
50        :param pattern: Pattern to check recipient against.
51        :type pattern: :py:obj:`str` or :class:`re.RegexObject`
52        :param repl: Replacement for ``pattern`` matches, as described by
53                     :func:`re.sub()`.
54        :type repl: :py:obj:`str` or function
55        :param count: Max number of replacements per recipient string.
56
57        """
58        self.mapping.append((re.compile(pattern), repl, count))
59
60    def apply(self, envelope):
61        n_rcpt = len(envelope.recipients)
62        for i in range(n_rcpt):
63            old_rcpt = envelope.recipients[i]
64            for pattern, repl, count in self.mapping:
65                new_rcpt, changes = re.subn(pattern, repl, old_rcpt, count)
66                if new_rcpt and changes > 0:
67                    envelope.recipients[i] = new_rcpt
68                    break
69
70
71# vim:et:fdm=marker:sts=4:sw=4:ts=4
72