1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
|
# vi: ts=4 expandtab
#
# Copyright (C) 2012 Yahoo! Inc.
#
# Author: Joshua Harlow <harlowja@yahoo-inc.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 3, as
# published by the Free Software Foundation.
#
# This program 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
from cloudinit import importer
from cloudinit import log as logging
from cloudinit import util
LOG = logging.getLogger(__name__)
class UnknownMerger(object):
# Named differently so auto-method finding
# doesn't pick this up if there is ever a type
# named "unknown"
def _handle_unknown(self, meth_wanted, value, merge_with):
return value
def merge(self, source, merge_with):
type_name = util.obj_name(source)
type_name = type_name.lower()
method_name = "_on_%s" % (type_name)
meth = None
args = [source, merge_with]
if hasattr(self, method_name):
meth = getattr(self, method_name)
if not meth:
meth = self._handle_unknown
args.insert(0, method_name)
return meth(*args)
class LookupMerger(UnknownMerger):
def __init__(self, lookups=None):
UnknownMerger.__init__(self)
if lookups is None:
self._lookups = []
else:
self._lookups = lookups
def _handle_unknown(self, meth_wanted, value, merge_with):
meth = None
for merger in self._lookups:
if hasattr(merger, meth_wanted):
# First one that has that method/attr gets to be
# the one that will be called
meth = getattr(merger, meth_wanted)
break
if not meth:
return UnknownMerger._handle_unknown(self, meth_wanted,
value, merge_with)
return meth(value, merge_with)
def _extract_merger_names(merge_how):
names = []
for m_name in merge_how.split("+"):
# Canonicalize the name (so that it can be found
# even when users alter it in various ways...
m_name = m_name.lower().strip()
m_name = m_name.replace(" ", "_")
m_name = m_name.replace("\t", "_")
m_name = m_name.replace("-", "_")
if not m_name:
continue
names.append(m_name)
return names
def construct(merge_how, default_classes=None):
mergers = []
merger_classes = []
root = LookupMerger(mergers)
for m_name in _extract_merger_names(merge_how):
merger_locs = importer.find_module(m_name,
[__name__],
['Merger'])
if not merger_locs:
msg = "Could not find merger named %s" % (m_name)
raise ImportError(msg)
else:
mod = importer.import_module(merger_locs[0])
cls = getattr(mod, 'Merger')
merger_classes.append(cls)
if not merger_classes and default_classes:
merger_classes = default_classes
for m_class in merger_classes:
mergers.append(m_class(root))
return root
|
