codekingpro/portable-devtools

1"""Key functions for memoizing decorators."""2 3__all__ = ("hashkey", "methodkey", "typedkey")4 5 6class _HashedTuple(tuple):7    """A tuple that ensures that hash() will be called no more than once8    per element, since cache decorators will hash the key multiple9    times on a cache miss.  See also _HashedSeq in the standard10    library functools implementation.11 12    """13 14    __hashvalue = None15 16    def __hash__(self, hash=tuple.__hash__):17        hashvalue = self.__hashvalue18        if hashvalue is None:19            self.__hashvalue = hashvalue = hash(self)20        return hashvalue21 22    def __add__(self, other, add=tuple.__add__):23        return _HashedTuple(add(self, other))24 25    def __radd__(self, other, add=tuple.__add__):26        return _HashedTuple(add(other, self))27 28    def __getstate__(self):29        return {}30 31 32# used for separating keyword arguments; we do not use an object33# instance here so identity is preserved when pickling/unpickling34_kwmark = (_HashedTuple,)35 36 37def hashkey(*args, **kwargs):38    """Return a cache key for the specified hashable arguments."""39 40    if kwargs:41        return _HashedTuple(args + sum(sorted(kwargs.items()), _kwmark))42    else:43        return _HashedTuple(args)44 45 46def methodkey(self, *args, **kwargs):47    """Return a cache key for use with cached methods."""48    return hashkey(*args, **kwargs)49 50 51def typedkey(*args, **kwargs):52    """Return a typed cache key for the specified hashable arguments."""53 54    key = hashkey(*args, **kwargs)55    key += tuple(type(v) for v in args)56    key += tuple(type(v) for _, v in sorted(kwargs.items()))57    return key58