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Cargoify servo

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Jack Moffitt 2014-08-28 09:34:23 -06:00
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commit c6ab60dbfc
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# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.
from __future__ import unicode_literals
import argparse
import difflib
import sys
from operator import itemgetter
from .base import (
NoCommandError,
UnknownCommandError,
UnrecognizedArgumentError,
)
class CommandFormatter(argparse.HelpFormatter):
"""Custom formatter to format just a subcommand."""
def add_usage(self, *args):
pass
class CommandAction(argparse.Action):
"""An argparse action that handles mach commands.
This class is essentially a reimplementation of argparse's sub-parsers
feature. We first tried to use sub-parsers. However, they were missing
features like grouping of commands (http://bugs.python.org/issue14037).
The way this works involves light magic and a partial understanding of how
argparse works.
Arguments registered with an argparse.ArgumentParser have an action
associated with them. An action is essentially a class that when called
does something with the encountered argument(s). This class is one of those
action classes.
An instance of this class is created doing something like:
parser.add_argument('command', action=CommandAction, registrar=r)
Note that a mach.registrar.Registrar instance is passed in. The Registrar
holds information on all the mach commands that have been registered.
When this argument is registered with the ArgumentParser, an instance of
this class is instantiated. One of the subtle but important things it does
is tell the argument parser that it's interested in *all* of the remaining
program arguments. So, when the ArgumentParser calls this action, we will
receive the command name plus all of its arguments.
For more, read the docs in __call__.
"""
def __init__(self, option_strings, dest, required=True, default=None,
registrar=None, context=None):
# A proper API would have **kwargs here. However, since we are a little
# hacky, we intentionally omit it as a way of detecting potentially
# breaking changes with argparse's implementation.
#
# In a similar vein, default is passed in but is not needed, so we drop
# it.
argparse.Action.__init__(self, option_strings, dest, required=required,
help=argparse.SUPPRESS, nargs=argparse.REMAINDER)
self._mach_registrar = registrar
self._context = context
def __call__(self, parser, namespace, values, option_string=None):
"""This is called when the ArgumentParser has reached our arguments.
Since we always register ourselves with nargs=argparse.REMAINDER,
values should be a list of remaining arguments to parse. The first
argument should be the name of the command to invoke and all remaining
arguments are arguments for that command.
The gist of the flow is that we look at the command being invoked. If
it's *help*, we handle that specially (because argparse's default help
handler isn't satisfactory). Else, we create a new, independent
ArgumentParser instance for just the invoked command (based on the
information contained in the command registrar) and feed the arguments
into that parser. We then merge the results with the main
ArgumentParser.
"""
if namespace.help:
# -h or --help is in the global arguments.
self._handle_main_help(parser, namespace.verbose)
sys.exit(0)
elif values:
command = values[0].lower()
args = values[1:]
if command == 'help':
if args and args[0] not in ['-h', '--help']:
# Make sure args[0] is indeed a command.
self._handle_subcommand_help(parser, args[0])
else:
self._handle_main_help(parser, namespace.verbose)
sys.exit(0)
elif '-h' in args or '--help' in args:
# -h or --help is in the command arguments.
self._handle_subcommand_help(parser, command)
sys.exit(0)
else:
raise NoCommandError()
# Command suggestion
if command not in self._mach_registrar.command_handlers:
# We first try to look for a valid command that is very similar to the given command.
suggested_commands = difflib.get_close_matches(command, self._mach_registrar.command_handlers.keys(), cutoff=0.8)
# If we find more than one matching command, or no command at all, we give command suggestions instead
# (with a lower matching threshold). All commands that start with the given command (for instance: 'mochitest-plain',
# 'mochitest-chrome', etc. for 'mochitest-') are also included.
if len(suggested_commands) != 1:
suggested_commands = set(difflib.get_close_matches(command, self._mach_registrar.command_handlers.keys(), cutoff=0.5))
suggested_commands |= {cmd for cmd in self._mach_registrar.command_handlers if cmd.startswith(command)}
raise UnknownCommandError(command, 'run', suggested_commands)
sys.stderr.write("We're assuming the '%s' command is '%s' and we're executing it for you.\n\n" % (command, suggested_commands[0]))
command = suggested_commands[0]
handler = self._mach_registrar.command_handlers.get(command)
# FUTURE
# If we wanted to conditionally enable commands based on whether
# it's possible to run them given the current state of system, here
# would be a good place to hook that up.
# We create a new parser, populate it with the command's arguments,
# then feed all remaining arguments to it, merging the results
# with ourselves. This is essentially what argparse subparsers
# do.
parser_args = {
'add_help': False,
'usage': '%(prog)s [global arguments] ' + command +
' command arguments]',
}
if handler.allow_all_arguments:
parser_args['prefix_chars'] = '+'
if handler.parser:
subparser = handler.parser
else:
subparser = argparse.ArgumentParser(**parser_args)
for arg in handler.arguments:
subparser.add_argument(*arg[0], **arg[1])
# We define the command information on the main parser result so as to
# not interfere with arguments passed to the command.
setattr(namespace, 'mach_handler', handler)
setattr(namespace, 'command', command)
command_namespace, extra = subparser.parse_known_args(args)
setattr(namespace, 'command_args', command_namespace)
if extra:
raise UnrecognizedArgumentError(command, extra)
def _handle_main_help(self, parser, verbose):
# Since we don't need full sub-parser support for the main help output,
# we create groups in the ArgumentParser and populate each group with
# arguments corresponding to command names. This has the side-effect
# that argparse renders it nicely.
r = self._mach_registrar
disabled_commands = []
cats = [(k, v[2]) for k, v in r.categories.items()]
sorted_cats = sorted(cats, key=itemgetter(1), reverse=True)
for category, priority in sorted_cats:
group = None
for command in sorted(r.commands_by_category[category]):
handler = r.command_handlers[command]
# Instantiate a handler class to see if it should be filtered
# out for the current context or not. Condition functions can be
# applied to the command's decorator.
if handler.conditions:
if handler.pass_context:
instance = handler.cls(self._context)
else:
instance = handler.cls()
is_filtered = False
for c in handler.conditions:
if not c(instance):
is_filtered = True
break
if is_filtered:
description = handler.description
disabled_command = {'command': command, 'description': description}
disabled_commands.append(disabled_command)
continue
if group is None:
title, description, _priority = r.categories[category]
group = parser.add_argument_group(title, description)
description = handler.description
group.add_argument(command, help=description,
action='store_true')
if disabled_commands and 'disabled' in r.categories:
title, description, _priority = r.categories['disabled']
group = parser.add_argument_group(title, description)
if verbose == True:
for c in disabled_commands:
group.add_argument(c['command'], help=c['description'],
action='store_true')
parser.print_help()
def _handle_subcommand_help(self, parser, command):
handler = self._mach_registrar.command_handlers.get(command)
if not handler:
raise UnknownCommandError(command, 'query')
# This code is worth explaining. Because we are doing funky things with
# argument registration to allow the same option in both global and
# command arguments, we can't simply put all arguments on the same
# parser instance because argparse would complain. We can't register an
# argparse subparser here because it won't properly show help for
# global arguments. So, we employ a strategy similar to command
# execution where we construct a 2nd, independent ArgumentParser for
# just the command data then supplement the main help's output with
# this 2nd parser's. We use a custom formatter class to ignore some of
# the help output.
parser_args = {
'formatter_class': CommandFormatter,
'add_help': False,
}
if handler.allow_all_arguments:
parser_args['prefix_chars'] = '+'
if handler.parser:
c_parser = handler.parser
c_parser.formatter_class = NoUsageFormatter
# Accessing _action_groups is a bit shady. We are highly dependent
# on the argparse implementation not changing. We fail fast to
# detect upstream changes so we can intelligently react to them.
group = c_parser._action_groups[1]
# By default argparse adds two groups called "positional arguments"
# and "optional arguments". We want to rename these to reflect standard
# mach terminology.
c_parser._action_groups[0].title = 'Command Parameters'
c_parser._action_groups[1].title = 'Command Arguments'
if not handler.description:
handler.description = c_parser.description
c_parser.description = None
else:
c_parser = argparse.ArgumentParser(**parser_args)
group = c_parser.add_argument_group('Command Arguments')
for arg in handler.arguments:
group.add_argument(*arg[0], **arg[1])
# This will print the description of the command below the usage.
description = handler.description
if description:
parser.description = description
parser.usage = '%(prog)s [global arguments] ' + command + \
' [command arguments]'
parser.print_help()
print('')
c_parser.print_help()
class NoUsageFormatter(argparse.HelpFormatter):
def _format_usage(self, *args, **kwargs):
return ""