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# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""Discover and lookup command plugins.
"""
import inspect
import logging
import pkg_resources
LOG = logging.getLogger(__name__)
class EntryPointWrapper(object):
"""Wrap up a command class already imported to make it look like a plugin.
"""
def __init__(self, name, command_class):
self.name = name
self.command_class = command_class
def load(self, require=False):
return self.command_class
class CommandManager(object):
"""Discovers commands and handles lookup based on argv data.
:param namespace: String containing the setuptools entrypoint namespace
for the plugins to be loaded. For example,
``'cliff.formatter.list'``.
:param convert_underscores: Whether cliff should convert underscores to
spaces in entry_point commands.
"""
def __init__(self, namespace, convert_underscores=True):
self.commands = {}
self.namespace = namespace
self.convert_underscores = convert_underscores
self._load_commands()
def _load_commands(self):
# NOTE(jamielennox): kept for compatibility.
self.load_commands(self.namespace)
def load_commands(self, namespace):
"""Load all the commands from an entrypoint"""
for ep in pkg_resources.iter_entry_points(namespace):
LOG.debug('found command %r', ep.name)
cmd_name = (ep.name.replace('_', ' ')
if self.convert_underscores
else ep.name)
self.commands[cmd_name] = ep
return
def __iter__(self):
return iter(self.commands.items())
def add_command(self, name, command_class):
self.commands[name] = EntryPointWrapper(name, command_class)
def find_command(self, argv):
"""Given an argument list, find a command and
return the processor and any remaining arguments.
"""
start = self._get_last_possible_command_index(argv)
for i in range(start, 0, -1):
name = ' '.join(argv[:i])
search_args = argv[i:]
if name in self.commands:
cmd_ep = self.commands[name]
if hasattr(cmd_ep, 'resolve'):
cmd_factory = cmd_ep.resolve()
else:
# NOTE(dhellmann): Some fake classes don't take
# require as an argument. Yay?
arg_spec = inspect.getargspec(cmd_ep.load)
if 'require' in arg_spec[0]:
cmd_factory = cmd_ep.load(require=False)
else:
cmd_factory = cmd_ep.load()
return (cmd_factory, name, search_args)
else:
raise ValueError('Unknown command %r' %
(argv,))
def _get_last_possible_command_index(self, argv):
"""Returns the index after the last argument
in argv that can be a command word
"""
for i, arg in enumerate(argv):
if arg.startswith('-'):
return i
return len(argv)
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