99 lines
3.1 KiB
Python
99 lines
3.1 KiB
Python
"""Application base class for displaying data.
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"""
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import abc
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try:
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from itertools import compress
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except ImportError:
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# for py26 compat
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from itertools import izip
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def compress(data, selectors):
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return (d for d, s in izip(data, selectors) if s)
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import logging
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import six
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import stevedore
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from .command import Command
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LOG = logging.getLogger(__name__)
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@six.add_metaclass(abc.ABCMeta)
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class DisplayCommandBase(Command):
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"""Command base class for displaying data about a single object.
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"""
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def __init__(self, app, app_args, cmd_name=None):
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super(DisplayCommandBase, self).__init__(app, app_args,
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cmd_name=cmd_name)
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self._formatter_plugins = self._load_formatter_plugins()
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@abc.abstractproperty
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def formatter_namespace(self):
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"String specifying the namespace to use for loading formatter plugins."
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@abc.abstractproperty
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def formatter_default(self):
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"String specifying the name of the default formatter."
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def _load_formatter_plugins(self):
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# Here so tests can override
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return stevedore.ExtensionManager(
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self.formatter_namespace,
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invoke_on_load=True,
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)
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def get_parser(self, prog_name):
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parser = super(DisplayCommandBase, self).get_parser(prog_name)
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formatter_group = parser.add_argument_group(
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title='output formatters',
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description='output formatter options',
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)
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formatter_choices = sorted(self._formatter_plugins.names())
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formatter_default = self.formatter_default
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if formatter_default not in formatter_choices:
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formatter_default = formatter_choices[0]
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formatter_group.add_argument(
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'-f', '--format',
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dest='formatter',
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action='store',
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choices=formatter_choices,
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default=formatter_default,
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help='the output format, defaults to %s' % formatter_default,
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)
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formatter_group.add_argument(
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'-c', '--column',
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action='append',
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default=[],
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dest='columns',
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metavar='COLUMN',
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help='specify the column(s) to include, can be repeated',
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)
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for formatter in self._formatter_plugins:
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formatter.obj.add_argument_group(parser)
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return parser
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@abc.abstractmethod
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def produce_output(self, parsed_args, column_names, data):
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"""Use the formatter to generate the output.
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:param parsed_args: argparse.Namespace instance with argument values
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:param column_names: sequence of strings containing names
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of output columns
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:param data: iterable with values matching the column names
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"""
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def run(self, parsed_args):
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self.formatter = self._formatter_plugins[parsed_args.formatter].obj
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column_names, data = self.take_action(parsed_args)
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self.produce_output(parsed_args, column_names, data)
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return 0
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@staticmethod
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def _compress_iterable(iterable, selectors):
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return compress(iterable, selectors)
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