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import functools
import threading
import collections
def map0(func, value):
return func(value) if value is not None else value
def single(x):
if len(x) != 1:
raise Exception('Length of {} is not equal to 1'.format(x))
return x[0]
class _Result(object):
pass
def lazy(func):
result = _Result()
@functools.wraps(func)
def wrapper(*args):
try:
return result.result
except AttributeError:
result.result = func(*args)
return result.result
return wrapper
def lazy_property(fn):
attr_name = '_lazy_' + fn.__name__
@property
def _lazy_property(self):
if not hasattr(self, attr_name):
setattr(self, attr_name, fn(self))
return getattr(self, attr_name)
return _lazy_property
class classproperty(object):
def __init__(self, func):
self.func = func
def __get__(self, _, owner):
return self.func(owner)
class lazy_classproperty(object):
def __init__(self, func):
self.func = func
def __get__(self, _, owner):
attr_name = '_lazy_' + self.func.__name__
if not hasattr(owner, attr_name):
setattr(owner, attr_name, self.func(owner))
return getattr(owner, attr_name)
def memoize(limit=0, thread_local=False):
assert limit >= 0
def decorator(func):
memory = {}
lock = threading.Lock()
if limit:
keys = collections.deque()
def get(args):
try:
return memory[args]
except KeyError:
with lock:
if args not in memory:
fargs = args[-1]
memory[args] = func(*fargs)
keys.append(args)
if len(keys) > limit:
del memory[keys.popleft()]
return memory[args]
else:
def get(args):
if args not in memory:
with lock:
if args not in memory:
fargs = args[-1]
memory[args] = func(*fargs)
return memory[args]
if thread_local:
@functools.wraps(func)
def wrapper(*args):
th = threading.current_thread()
return get((th.ident, th.name, args))
else:
@functools.wraps(func)
def wrapper(*args):
return get(('', '', args))
return wrapper
return decorator
# XXX: add test
def compose(*functions):
def compose2(f, g):
return lambda x: f(g(x))
return functools.reduce(compose2, functions, lambda x: x)
class Singleton(type):
_instances = {}
def __call__(cls, *args, **kwargs):
if cls not in cls._instances:
cls._instances[cls] = super(Singleton, cls).__call__(*args, **kwargs)
return cls._instances[cls]
def stable_uniq(it):
seen = set()
res = []
for e in it:
if e not in seen:
res.append(e)
seen.add(e)
return res
def first(it):
for d in it:
if d:
return d
def split(data, func):
l, r = [], []
for e in data:
if func(e):
l.append(e)
else:
r.append(e)
return l, r
def flatten_dict(dd, separator='.', prefix=''):
return (
{
prefix + separator + k if prefix else k: v
for kk, vv in dd.items()
for k, v in flatten_dict(vv, separator, kk).items()
}
if isinstance(dd, dict)
else {prefix: dd}
)
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