205 lines
8.2 KiB
Python
205 lines
8.2 KiB
Python
"""functools.py - Tools for working with functions and callable objects
|
|
"""
|
|
# Python module wrapper for _functools C module
|
|
# to allow utilities written in Python to be added
|
|
# to the functools module.
|
|
# Written by Nick Coghlan <ncoghlan at gmail.com>
|
|
# and Raymond Hettinger <python at rcn.com>
|
|
# Copyright (C) 2006-2010 Python Software Foundation.
|
|
# See C source code for _functools credits/copyright
|
|
|
|
__all__ = ['update_wrapper', 'wraps', 'WRAPPER_ASSIGNMENTS', 'WRAPPER_UPDATES',
|
|
'total_ordering', 'cmp_to_key', 'lru_cache', 'reduce', 'partial']
|
|
|
|
from _functools import partial, reduce
|
|
from collections import OrderedDict, namedtuple
|
|
try:
|
|
from _thread import allocate_lock as Lock
|
|
except:
|
|
from _dummy_thread import allocate_lock as Lock
|
|
|
|
# update_wrapper() and wraps() are tools to help write
|
|
# wrapper functions that can handle naive introspection
|
|
|
|
WRAPPER_ASSIGNMENTS = ('__module__', '__name__', '__doc__', '__annotations__')
|
|
WRAPPER_UPDATES = ('__dict__',)
|
|
def update_wrapper(wrapper,
|
|
wrapped,
|
|
assigned = WRAPPER_ASSIGNMENTS,
|
|
updated = WRAPPER_UPDATES):
|
|
"""Update a wrapper function to look like the wrapped function
|
|
|
|
wrapper is the function to be updated
|
|
wrapped is the original function
|
|
assigned is a tuple naming the attributes assigned directly
|
|
from the wrapped function to the wrapper function (defaults to
|
|
functools.WRAPPER_ASSIGNMENTS)
|
|
updated is a tuple naming the attributes of the wrapper that
|
|
are updated with the corresponding attribute from the wrapped
|
|
function (defaults to functools.WRAPPER_UPDATES)
|
|
"""
|
|
wrapper.__wrapped__ = wrapped
|
|
for attr in assigned:
|
|
try:
|
|
value = getattr(wrapped, attr)
|
|
except AttributeError:
|
|
pass
|
|
else:
|
|
setattr(wrapper, attr, value)
|
|
for attr in updated:
|
|
getattr(wrapper, attr).update(getattr(wrapped, attr, {}))
|
|
# Return the wrapper so this can be used as a decorator via partial()
|
|
return wrapper
|
|
|
|
def wraps(wrapped,
|
|
assigned = WRAPPER_ASSIGNMENTS,
|
|
updated = WRAPPER_UPDATES):
|
|
"""Decorator factory to apply update_wrapper() to a wrapper function
|
|
|
|
Returns a decorator that invokes update_wrapper() with the decorated
|
|
function as the wrapper argument and the arguments to wraps() as the
|
|
remaining arguments. Default arguments are as for update_wrapper().
|
|
This is a convenience function to simplify applying partial() to
|
|
update_wrapper().
|
|
"""
|
|
return partial(update_wrapper, wrapped=wrapped,
|
|
assigned=assigned, updated=updated)
|
|
|
|
def total_ordering(cls):
|
|
"""Class decorator that fills in missing ordering methods"""
|
|
convert = {
|
|
'__lt__': [('__gt__', lambda self, other: not (self < other or self == other)),
|
|
('__le__', lambda self, other: self < other or self == other),
|
|
('__ge__', lambda self, other: not self < other)],
|
|
'__le__': [('__ge__', lambda self, other: not self <= other or self == other),
|
|
('__lt__', lambda self, other: self <= other and not self == other),
|
|
('__gt__', lambda self, other: not self <= other)],
|
|
'__gt__': [('__lt__', lambda self, other: not (self > other or self == other)),
|
|
('__ge__', lambda self, other: self > other or self == other),
|
|
('__le__', lambda self, other: not self > other)],
|
|
'__ge__': [('__le__', lambda self, other: (not self >= other) or self == other),
|
|
('__gt__', lambda self, other: self >= other and not self == other),
|
|
('__lt__', lambda self, other: not self >= other)]
|
|
}
|
|
# Find user-defined comparisons (not those inherited from object).
|
|
roots = [op for op in convert if getattr(cls, op, None) is not getattr(object, op, None)]
|
|
if not roots:
|
|
raise ValueError('must define at least one ordering operation: < > <= >=')
|
|
root = max(roots) # prefer __lt__ to __le__ to __gt__ to __ge__
|
|
for opname, opfunc in convert[root]:
|
|
if opname not in roots:
|
|
opfunc.__name__ = opname
|
|
opfunc.__doc__ = getattr(int, opname).__doc__
|
|
setattr(cls, opname, opfunc)
|
|
return cls
|
|
|
|
def cmp_to_key(mycmp):
|
|
"""Convert a cmp= function into a key= function"""
|
|
class K(object):
|
|
def __init__(self, obj, *args):
|
|
self.obj = obj
|
|
def __lt__(self, other):
|
|
return mycmp(self.obj, other.obj) < 0
|
|
def __gt__(self, other):
|
|
return mycmp(self.obj, other.obj) > 0
|
|
def __eq__(self, other):
|
|
return mycmp(self.obj, other.obj) == 0
|
|
def __le__(self, other):
|
|
return mycmp(self.obj, other.obj) <= 0
|
|
def __ge__(self, other):
|
|
return mycmp(self.obj, other.obj) >= 0
|
|
def __ne__(self, other):
|
|
return mycmp(self.obj, other.obj) != 0
|
|
def __hash__(self):
|
|
raise TypeError('hash not implemented')
|
|
return K
|
|
|
|
_CacheInfo = namedtuple("CacheInfo", "hits misses maxsize currsize")
|
|
|
|
def lru_cache(maxsize=100):
|
|
"""Least-recently-used cache decorator.
|
|
|
|
If *maxsize* is set to None, the LRU features are disabled and the cache
|
|
can grow without bound.
|
|
|
|
Arguments to the cached function must be hashable.
|
|
|
|
View the cache statistics named tuple (hits, misses, maxsize, currsize) with
|
|
f.cache_info(). Clear the cache and statistics with f.cache_clear().
|
|
Access the underlying function with f.__wrapped__.
|
|
|
|
See: http://en.wikipedia.org/wiki/Cache_algorithms#Least_Recently_Used
|
|
|
|
"""
|
|
# Users should only access the lru_cache through its public API:
|
|
# cache_info, cache_clear, and f.__wrapped__
|
|
# The internals of the lru_cache are encapsulated for thread safety and
|
|
# to allow the implementation to change (including a possible C version).
|
|
|
|
def decorating_function(user_function,
|
|
tuple=tuple, sorted=sorted, len=len, KeyError=KeyError):
|
|
|
|
hits = misses = 0
|
|
kwd_mark = (object(),) # separates positional and keyword args
|
|
lock = Lock() # needed because ordereddicts aren't threadsafe
|
|
|
|
if maxsize is None:
|
|
cache = dict() # simple cache without ordering or size limit
|
|
|
|
@wraps(user_function)
|
|
def wrapper(*args, **kwds):
|
|
nonlocal hits, misses
|
|
key = args
|
|
if kwds:
|
|
key += kwd_mark + tuple(sorted(kwds.items()))
|
|
try:
|
|
result = cache[key]
|
|
hits += 1
|
|
except KeyError:
|
|
result = user_function(*args, **kwds)
|
|
cache[key] = result
|
|
misses += 1
|
|
return result
|
|
else:
|
|
cache = OrderedDict() # ordered least recent to most recent
|
|
cache_popitem = cache.popitem
|
|
cache_renew = cache.move_to_end
|
|
|
|
@wraps(user_function)
|
|
def wrapper(*args, **kwds):
|
|
nonlocal hits, misses
|
|
key = args
|
|
if kwds:
|
|
key += kwd_mark + tuple(sorted(kwds.items()))
|
|
try:
|
|
with lock:
|
|
result = cache[key]
|
|
cache_renew(key) # record recent use of this key
|
|
hits += 1
|
|
except KeyError:
|
|
result = user_function(*args, **kwds)
|
|
with lock:
|
|
cache[key] = result # record recent use of this key
|
|
misses += 1
|
|
if len(cache) > maxsize:
|
|
cache_popitem(0) # purge least recently used cache entry
|
|
return result
|
|
|
|
def cache_info():
|
|
"""Report cache statistics"""
|
|
with lock:
|
|
return _CacheInfo(hits, misses, maxsize, len(cache))
|
|
|
|
def cache_clear():
|
|
"""Clear the cache and cache statistics"""
|
|
nonlocal hits, misses
|
|
with lock:
|
|
cache.clear()
|
|
hits = misses = 0
|
|
|
|
wrapper.cache_info = cache_info
|
|
wrapper.cache_clear = cache_clear
|
|
return wrapper
|
|
|
|
return decorating_function
|