1# Copyright 2015 Google Inc. All rights reserved.
2#
3# Licensed under the Apache License, Version 2.0 (the "License");
4# you may not use this file except in compliance with the License.
5# You may obtain a copy of the License at
6#
7#    http://www.apache.org/licenses/LICENSE-2.0
8#
9# Unless required by applicable law or agreed to in writing, software
10# distributed under the License is distributed on an "AS IS" BASIS,
11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12# See the License for the specific language governing permissions and
13# limitations under the License.
14
15import argparse
16
17
18class _Bailout(Exception):
19    pass
20
21
22class ArgumentParser(argparse.ArgumentParser):
23    SUPPRESS = argparse.SUPPRESS
24
25    def __init__(self, host, prog, desc, **kwargs):
26        kwargs['prog'] = prog
27        kwargs['description'] = desc
28        kwargs['formatter_class'] = argparse.RawDescriptionHelpFormatter
29        super(ArgumentParser, self).__init__(**kwargs)
30        self._host = host
31        self.exit_status = None
32        self.add_argument('-V', '--version', action='store_true',
33                          help='print the version and exit')
34
35    def parse_args(self, args=None, namespace=None):
36        try:
37            rargs = super(ArgumentParser, self).parse_args(args=args,
38                                                           namespace=namespace)
39        except _Bailout:
40            return None
41
42        return rargs
43
44    # Redefining built-in 'file' pylint: disable=W0622
45
46    def _print_message(self, msg, file=None):
47        self._host.print_(msg=msg, stream=file, end='\n')
48
49    def print_help(self, file=None):
50        self._print_message(msg=self.format_help(), file=file)
51
52    def error(self, message, bailout=True):  # pylint: disable=W0221
53        self.exit(2, '%s: error: %s\n' % (self.prog, message), bailout=bailout)
54
55    def exit(self, status=0, message=None,  # pylint: disable=W0221
56             bailout=True):
57        self.exit_status = status
58        if message:
59            self._print_message(message, file=self._host.stderr)
60        if bailout:
61            raise _Bailout()
62