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# -*- coding: UTF-8 -*-
# Copyright 2016 Red Hat, Inc.
# Part of clufter project
# Licensed under GPLv2+ (a copy included | http://gnu.org/licenses/gpl-2.0.txt)
"""Various little+independent helpers"""
__author__ = "Jan Pokorný <jpokorny @at@ Red Hat .dot. com>"
from itertools import takewhile
# inspired by http://stackoverflow.com/a/4374075
immutable = lambda x: isinstance(x, (basestring, int, long, bool, float, tuple))
tuplist = lambda x: isinstance(x, (tuple, list, set))
# turn args into tuple unless single tuplist arg
args2sgpl = \
lambda x=(), *y: x if not y and tuplist(x) else (x, ) + y
arg2wrapped = \
lambda x=(), *y: \
x if not y and isinstance(x, tuple) else (x, ) + y
args2unwrapped = \
lambda x=None, *y: x if not y else (x, ) + y
# turn args into tuple unconditionally
args2tuple = lambda *args: args
any2iter = \
lambda x: \
x if hasattr(x, 'next') and hasattr(x.next, '__call__') \
else iter(args2sgpl(x, None))
head_tail = \
lambda x=None, *y, **kwargs: \
(x, args2sgpl(*y)) if not tuplist(x) or kwargs.get('stop', 0) \
else (head_tail(stop=1, *tuple(x) + y))
nonetype = type(None)
identity = lambda x: x
#
# easily mangle with dicts/sets (eventually lists), returning dicts
#
filterdict_map = \
lambda fn, src, *which, **update: \
dict((x, fn(x)) for x in which if x in src, **update)
# .copy() so as to allow for in-situ manipulations like .pop() without
# affecting the running iteration
filterdict_invmap = \
lambda fn, src, *which, **update: \
dict((x, fn(x)) for x in src.copy() if x not in which, **update)
#
filterdict_keep = \
lambda src, *which, **update: \
filterdict_map(
lambda x, fn=update.pop('_fn_', identity): fn(src[x]),
src, *which, **update
)
filterdict_invkeep = \
lambda src, *which, **update: \
filterdict_invmap(
lambda x, fn=update.pop('_fn_', identity): fn(src[x]),
src, *which, **update
)
#
filterdict_pop = \
lambda src, *which, **update: \
filterdict_map(
lambda x, fn=update.pop('_fn_', identity): fn(src.pop(x)),
src, *which, **update
)
filterdict_invpop = \
lambda src, *which, **update: \
filterdict_invmap(
lambda x, fn=update.pop('_fn_', identity): fn(src.pop(x)),
src, *which, **update
)
# following supposes that remove() returns None (as is the case with set/list)
filterdict_remove = \
lambda src, *which, **update: \
filterdict_map(
lambda x, fn=update.pop('_fn_', identity): fn(src.remove(x) or x),
src, *which, **update
)
filterdict_invremove = \
lambda src, *which, **update: \
filterdict_invmap(
lambda x, fn=update.pop('_fn_', identity): fn(src.remove(x) or x),
src, *which, **update
)
#
# introspection related
#
def isinstanceexcept(subj, obj, *exc):
return isinstance(subj, obj) and not isinstance(subj, exc)
def isinstanceupto(subj, obj, *exc):
return isinstance(subj,
tuple(takewhile(lambda x: x not in exc, obj.__mro__)))
def areinstances(obj1, obj2):
return isinstance(obj1, obj2.__class__) or isinstance(obj2, obj1.__class__)
def popattr(obj, what, *args):
assert len(args) < 2
ret = getattr(obj, what, *args)
try:
delattr(obj, what)
except AttributeError:
if args:
ret = args[0]
else:
raise
return ret
def iterattrs(obj, skip_private=True):
"""Iterate through (unbound) attributes of obj, skipping private or not"""
if skip_private:
return ((n, v) for n, v in obj.__dict__.iteritems()
if not n.startswith('__'))
return obj.__dict__.iteritems()
def func_defaults_varnames(func, skip=0):
"""Using introspection, get arg defaults (dict) + all arg names (tuple)
Parameters:
skip how many initial arguments to skip
"""
code = func.func_code
func_varnames = code.co_varnames[skip:code.co_argcount]
func_defaults = dict(zip(
reversed(func_varnames),
reversed(func.func_defaults)
))
return func_defaults, func_varnames
#
# decorators
#
def selfaware(func):
"""Decorator suitable for recursive staticmethod"""
def selfaware_inner(*args, **kwargs):
return func(selfaware(func), *args, **kwargs)
map(lambda a: setattr(selfaware_inner, a, getattr(func, a)),
('__doc__', '__name__'))
return selfaware_inner
# Inspired by http://stackoverflow.com/a/1383402
class classproperty(property):
def __init__(self, fnc):
property.__init__(self, classmethod(fnc))
def __get__(self, this, owner):
return self.fget.__get__(None, owner)()
class hybridproperty(property):
def __init__(self, fnc):
property.__init__(self, classmethod(fnc))
def __get__(self, this, owner):
return self.fget.__get__(None, this if this else owner)()
class hybridmethod(property):
def __init__(self, fnc):
property.__init__(self, classmethod(fnc))
def __get__(self, this, owner):
return self.fget.__get__(None, this if this else owner)
# inspired from speaklater: http://pypi.python.org/pypi/speaklater
class lazystring(object):
"""Mimic string that in fact is on-off constructed on-demand
Note: only direct use, str methods and '+' operator supported.
"""
def __init__(self, fnc, cache=True):
self._fnc = fnc
self._cache = cache
@property
def content(self):
ret = self._cache
if ret is False or ret is True:
ret = self._fnc()
if ret is True:
self._cache = ret
return ret
def __str__(self): return str(self.content)
def __repr__(self): return repr(self.content)
def __getattr__(self, what): return getattr(self.content, what)
def __add__(self, other): return self.content + other
def __radd__(self, other): return other + self.content
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