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# Copyright 2014-2015 Canonical Limited.
#
# This file is part of charm-helpers.
#
# charm-helpers 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.
#
# charm-helpers 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 charm-helpers. If not, see <http://www.gnu.org/licenses/>.
import inspect
import argparse
import sys
from six.moves import zip
import charmhelpers.core.unitdata
class OutputFormatter(object):
def __init__(self, outfile=sys.stdout):
self.formats = (
"raw",
"json",
"py",
"yaml",
"csv",
"tab",
)
self.outfile = outfile
def add_arguments(self, argument_parser):
formatgroup = argument_parser.add_mutually_exclusive_group()
choices = self.supported_formats
formatgroup.add_argument("--format", metavar='FMT',
help="Select output format for returned data, "
"where FMT is one of: {}".format(choices),
choices=choices, default='raw')
for fmt in self.formats:
fmtfunc = getattr(self, fmt)
formatgroup.add_argument("-{}".format(fmt[0]),
"--{}".format(fmt), action='store_const',
const=fmt, dest='format',
help=fmtfunc.__doc__)
@property
def supported_formats(self):
return self.formats
def raw(self, output):
"""Output data as raw string (default)"""
if isinstance(output, (list, tuple)):
output = '\n'.join(map(str, output))
self.outfile.write(str(output))
def py(self, output):
"""Output data as a nicely-formatted python data structure"""
import pprint
pprint.pprint(output, stream=self.outfile)
def json(self, output):
"""Output data in JSON format"""
import json
json.dump(output, self.outfile)
def yaml(self, output):
"""Output data in YAML format"""
import yaml
yaml.safe_dump(output, self.outfile)
def csv(self, output):
"""Output data as excel-compatible CSV"""
import csv
csvwriter = csv.writer(self.outfile)
csvwriter.writerows(output)
def tab(self, output):
"""Output data in excel-compatible tab-delimited format"""
import csv
csvwriter = csv.writer(self.outfile, dialect=csv.excel_tab)
csvwriter.writerows(output)
def format_output(self, output, fmt='raw'):
fmtfunc = getattr(self, fmt)
fmtfunc(output)
class CommandLine(object):
argument_parser = None
subparsers = None
formatter = None
exit_code = 0
def __init__(self):
if not self.argument_parser:
self.argument_parser = argparse.ArgumentParser(description='Perform common charm tasks')
if not self.formatter:
self.formatter = OutputFormatter()
self.formatter.add_arguments(self.argument_parser)
if not self.subparsers:
self.subparsers = self.argument_parser.add_subparsers(help='Commands')
def subcommand(self, command_name=None):
"""
Decorate a function as a subcommand. Use its arguments as the
command-line arguments"""
def wrapper(decorated):
cmd_name = command_name or decorated.__name__
subparser = self.subparsers.add_parser(cmd_name,
description=decorated.__doc__)
for args, kwargs in describe_arguments(decorated):
subparser.add_argument(*args, **kwargs)
subparser.set_defaults(func=decorated)
return decorated
return wrapper
def test_command(self, decorated):
"""
Subcommand is a boolean test function, so bool return values should be
converted to a 0/1 exit code.
"""
decorated._cli_test_command = True
return decorated
def no_output(self, decorated):
"""
Subcommand is not expected to return a value, so don't print a spurious None.
"""
decorated._cli_no_output = True
return decorated
def subcommand_builder(self, command_name, description=None):
"""
Decorate a function that builds a subcommand. Builders should accept a
single argument (the subparser instance) and return the function to be
run as the command."""
def wrapper(decorated):
subparser = self.subparsers.add_parser(command_name)
func = decorated(subparser)
subparser.set_defaults(func=func)
subparser.description = description or func.__doc__
return wrapper
def run(self):
"Run cli, processing arguments and executing subcommands."
arguments = self.argument_parser.parse_args()
argspec = inspect.getargspec(arguments.func)
vargs = []
for arg in argspec.args:
vargs.append(getattr(arguments, arg))
if argspec.varargs:
vargs.extend(getattr(arguments, argspec.varargs))
output = arguments.func(*vargs)
if getattr(arguments.func, '_cli_test_command', False):
self.exit_code = 0 if output else 1
output = ''
if getattr(arguments.func, '_cli_no_output', False):
output = ''
self.formatter.format_output(output, arguments.format)
if charmhelpers.core.unitdata._KV:
charmhelpers.core.unitdata._KV.flush()
cmdline = CommandLine()
def describe_arguments(func):
"""
Analyze a function's signature and return a data structure suitable for
passing in as arguments to an argparse parser's add_argument() method."""
argspec = inspect.getargspec(func)
# we should probably raise an exception somewhere if func includes **kwargs
if argspec.defaults:
positional_args = argspec.args[:-len(argspec.defaults)]
keyword_names = argspec.args[-len(argspec.defaults):]
for arg, default in zip(keyword_names, argspec.defaults):
yield ('--{}'.format(arg),), {'default': default}
else:
positional_args = argspec.args
for arg in positional_args:
yield (arg,), {}
if argspec.varargs:
yield (argspec.varargs,), {'nargs': '*'}
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