qutebrowser/qutebrowser/commands/utils.py
2014-06-19 09:04:37 +02:00

224 lines
7.7 KiB
Python

# vim: ft=python fileencoding=utf-8 sts=4 sw=4 et:
# Copyright 2014 Florian Bruhin (The Compiler) <mail@qutebrowser.org>
#
# This file is part of qutebrowser.
#
# qutebrowser is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# qutebrowser 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with qutebrowser. If not, see <http://www.gnu.org/licenses/>.
"""Contains various command utils and a global command dict.
Module attributes:
cmd_dict: A mapping from command-strings to command objects.
"""
import inspect
from collections import Iterable
import qutebrowser.utils.misc as utils
from qutebrowser.commands.command import Command
from qutebrowser.commands.exceptions import CommandError
cmd_dict = {}
def check_overflow(arg, ctype):
"""Check if the given argument is in bounds for the given type.
Args:
arg: The argument to check
ctype: The C/Qt type to check as a string.
Raise:
CommandError if the argument is out of bounds.
ValueError if the given ctype is unknown.
"""
# FIXME we somehow should have nicer exceptions...
try:
utils.check_overflow(arg, ctype)
except OverflowError:
raise CommandError("Numeric argument is too large for internal {} "
"representation.".format(ctype))
def arg_or_count(arg, count, default=None, countzero=None):
"""Get a value based on an argument and count given to a command.
If both arg and count are set, ValueError is raised.
If only arg/count is set, it is used.
If none is set, a default is returned or ValueError is raised.
Args:
arg: The argument given to a command.
count: The count given to a command.
countzero: Special value if count is 0.
Return:
The value to use.
Raise:
ValueError: If nothing was set or the value couldn't be converted to
an integer.
"""
if count is not None and arg is not None:
raise ValueError("Both count and argument given!")
elif arg is not None:
try:
return int(arg)
except ValueError:
raise ValueError("Invalid number: {}".format(arg))
elif count is not None:
if countzero is not None and count == 0:
return countzero
else:
return int(count)
elif default is not None:
return int(default)
else:
raise ValueError("Either count or argument have to be set!")
class register: # pylint: disable=invalid-name
"""Decorator to register a new command handler.
This could also be a function, but as a class (with a "wrong" name) it's
much cleaner to implement.
Attributes:
instance: The instance to be used as "self", as a dotted string.
name: The name (as string) or names (as list) of the command.
nargs: A (minargs, maxargs) tuple of valid argument counts, or an int.
split: Whether to split the arguments.
hide: Whether to hide the command or not.
completion: Which completion to use for arguments, as a list of
strings.
modes/not_modes: List of modes to use/not use.
needs_js: If javascript is needed for this command.
debug: Whether this is a debugging command (only shown with --debug).
"""
def __init__(self, instance=None, name=None, nargs=None, split=True,
hide=False, completion=None, modes=None, not_modes=None,
needs_js=False, debug=False):
"""Save decorator arguments.
Gets called on parse-time with the decorator arguments.
Args:
See class attributes.
"""
# pylint: disable=too-many-arguments
if modes is not None and not_modes is not None:
raise ValueError("Only modes or not_modes can be given!")
self.name = name
self.split = split
self.hide = hide
self.nargs = nargs
self.instance = instance
self.completion = completion
self.modes = modes
self.not_modes = not_modes
self.needs_js = needs_js
self.debug = debug
def __call__(self, func):
"""Register the command before running the function.
Gets called when a function should be decorated.
Doesn't actually decorate anything, but creates a Command object and
registers it in the cmd_dict.
Args:
func: The function to be decorated.
Return:
The original function (unmodified).
"""
# pylint: disable=no-member
names = []
if self.name is None:
name = func.__name__.lower().replace('_', '-')
else:
name = self.name
if isinstance(name, str):
mainname = name
names.append(name)
else:
mainname = name[0]
names += name
if mainname in cmd_dict:
raise ValueError("{} is already registered!".format(name))
argspec = inspect.getfullargspec(func)
if 'self' in argspec.args and self.instance is None:
raise ValueError("{} is a class method, but instance was not "
"given!".format(mainname))
count, nargs = self._get_nargs_count(argspec)
if func.__doc__ is not None:
desc = func.__doc__.splitlines()[0].strip()
else:
desc = ""
cmd = Command(name=mainname, split=self.split,
hide=self.hide, nargs=nargs, count=count, desc=desc,
instance=self.instance, handler=func,
completion=self.completion, modes=self.modes,
not_modes=self.not_modes, needs_js=self.needs_js,
debug=self.debug)
for name in names:
cmd_dict[name] = cmd
return func
def _get_nargs_count(self, spec):
"""Get the number of command-arguments and count-support for a func.
Args:
spec: A FullArgSpec as returned by inspect.
Return:
A (count, (minargs, maxargs)) tuple, with maxargs=None if there are
infinite args. count is True if the function supports count, else
False.
Mapping from old nargs format to (minargs, maxargs):
? (0, 1)
N (N, N)
+ (1, None)
* (0, None)
"""
# pylint: disable=unpacking-non-sequence
# pylint: disable=no-member
count = 'count' in spec.args
# we assume count always has a default (and it should!)
if self.nargs is not None:
# If nargs is overriden, use that.
if isinstance(self.nargs, Iterable):
# Iterable (min, max)
minargs, maxargs = self.nargs
else:
# Single int
minargs, maxargs = self.nargs, self.nargs
else:
defaultcount = (len(spec.defaults) if spec.defaults is not None
else 0)
argcount = len(spec.args)
if 'self' in spec.args:
argcount -= 1
minargs = argcount - defaultcount
if spec.varargs is not None:
maxargs = None
else:
maxargs = argcount - int(count) # -1 if count is defined
return (count, (minargs, maxargs))