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# Copyright 2011 Canonical Ltd.
#
# This file is part of u1db.
#
# u1db is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License version 3
# as published by the Free Software Foundation.
#
# u1db 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 u1db. If not, see <http://www.gnu.org/licenses/>.
"""Command infrastructure for u1db"""
import argparse
import inspect
class CommandGroup(object):
"""A collection of commands."""
def __init__(self, description=None):
self.commands = {}
self.description = description
def register(self, cmd):
"""Register a new command to be incorporated with this group."""
self.commands[cmd.name] = cmd
def make_argparser(self):
"""Create an argparse.ArgumentParser"""
parser = argparse.ArgumentParser(description=self.description)
subs = parser.add_subparsers(title='commands')
for name, cmd in sorted(self.commands.iteritems()):
sub = subs.add_parser(name, help=cmd.__doc__)
sub.set_defaults(subcommand=cmd)
cmd._populate_subparser(sub)
return parser
def run_argv(self, argv, stdin, stdout, stderr):
"""Run a command, from a sys.argv[1:] style input."""
parser = self.make_argparser()
args = parser.parse_args(argv)
cmd = args.subcommand(stdin, stdout, stderr)
params, _, _, _ = inspect.getargspec(cmd.run)
vals = []
for param in params[1:]:
vals.append(getattr(args, param))
return cmd.run(*vals)
class Command(object):
"""Definition of a Command that can be run.
:cvar name: The name of the command, so that you can run
'u1db-client <name>'.
"""
name = None
def __init__(self, stdin, stdout, stderr):
self.stdin = stdin
self.stdout = stdout
self.stderr = stderr
@classmethod
def _populate_subparser(cls, parser):
"""Child classes should override this to provide their arguments."""
raise NotImplementedError(cls._populate_subparser)
def run(self, *args):
"""This is where the magic happens.
Subclasses should implement this, requesting their specific arguments.
"""
raise NotImplementedError(self.run)
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