"""functools.py - Tools for working with functions and callable objects

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"""

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# Python module wrapper for _functools C module

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# to allow utilities written in Python to be added

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# to the functools module.

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# Written by Nick Coghlan <ncoghlan at gmail.com>

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# Copyright (C) 2006 Python Software Foundation.

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# See C source code for _functools credits/copyright

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from _functools import partial, reduce

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# update_wrapper() and wraps() are tools to help write

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# wrapper functions that can handle naive introspection

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WRAPPER_ASSIGNMENTS = ('__module__', '__name__', '__doc__')

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WRAPPER_UPDATES = ('__dict__',)

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def update_wrapper(wrapper,

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wrapped,

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assigned = WRAPPER_ASSIGNMENTS,

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updated = WRAPPER_UPDATES):

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"""Update a wrapper function to look like the wrapped function

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wrapper is the function to be updated

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wrapped is the original function

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assigned is a tuple naming the attributes assigned directly

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from the wrapped function to the wrapper function (defaults to

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functools.WRAPPER_ASSIGNMENTS)

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updated is a tuple naming the attributes of the wrapper that

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are updated with the corresponding attribute from the wrapped

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function (defaults to functools.WRAPPER_UPDATES)

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"""

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for attr in assigned:

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setattr(wrapper, attr, getattr(wrapped, attr))

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for attr in updated:

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getattr(wrapper, attr).update(getattr(wrapped, attr, {}))

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# Return the wrapper so this can be used as a decorator via partial()

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return wrapper

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def wraps(wrapped,

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assigned = WRAPPER_ASSIGNMENTS,

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updated = WRAPPER_UPDATES):

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"""Decorator factory to apply update_wrapper() to a wrapper function

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Returns a decorator that invokes update_wrapper() with the decorated

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function as the wrapper argument and the arguments to wraps() as the

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remaining arguments. Default arguments are as for update_wrapper().

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This is a convenience function to simplify applying partial() to

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update_wrapper().

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"""

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return partial(update_wrapper, wrapped=wrapped,

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assigned=assigned, updated=updated)

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def total_ordering(cls):

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"""Class decorator that fills in missing ordering methods"""

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convert = {

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'__lt__': [('__gt__', lambda self, other: not (self < other or self == other)),

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('__le__', lambda self, other: self < other or self == other),

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('__ne__', lambda self, other: not self == other),

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('__ge__', lambda self, other: not self < other)],

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'__le__': [('__ge__', lambda self, other: not self <= other or self == other),

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('__lt__', lambda self, other: self <= other and not self == other),

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('__ne__', lambda self, other: not self == other),

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('__gt__', lambda self, other: not self <= other)],

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'__gt__': [('__lt__', lambda self, other: not (self > other or self == other)),

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('__ge__', lambda self, other: self > other or self == other),

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('__ne__', lambda self, other: not self == other),

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('__le__', lambda self, other: not self > other)],

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'__ge__': [('__le__', lambda self, other: (not self >= other) or self == other),

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('__gt__', lambda self, other: self >= other and not self == other),

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('__ne__', lambda self, other: not self == other),

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('__lt__', lambda self, other: not self >= other)]

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}

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defined_methods = set(dir(cls))

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roots = defined_methods & set(convert)

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if not roots:

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raise ValueError('must define at least one ordering operation: < > <= >=')

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root = max(roots) # prefer __lt__ to __le__ to __gt__ to __ge__

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for opname, opfunc in convert[root]:

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if opname not in defined_methods:

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opfunc.__name__ = opname

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opfunc.__doc__ = getattr(int, opname).__doc__

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setattr(cls, opname, opfunc)

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return cls

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def cmp_to_key(mycmp):

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"""Convert a cmp= function into a key= function"""

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class K(object):

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__slots__ = ['obj']

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def __init__(self, obj, *args):

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self.obj = obj

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def __lt__(self, other):

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return mycmp(self.obj, other.obj) < 0

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def __gt__(self, other):

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return mycmp(self.obj, other.obj) > 0

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def __eq__(self, other):

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return mycmp(self.obj, other.obj) == 0

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def __le__(self, other):

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return mycmp(self.obj, other.obj) <= 0

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def __ge__(self, other):

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return mycmp(self.obj, other.obj) >= 0

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def __ne__(self, other):

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return mycmp(self.obj, other.obj) != 0

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def __hash__(self):

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raise TypeError('hash not implemented')

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return K

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