forked from LBRYCommunity/lbry-sdk
25 lines
889 B
Python
25 lines
889 B
Python
from lbrynet.dht import constants
|
|
|
|
|
|
class Distance:
|
|
"""Calculate the XOR result between two string variables.
|
|
|
|
Frequently we re-use one of the points so as an optimization
|
|
we pre-calculate the value of that point.
|
|
"""
|
|
|
|
def __init__(self, key: bytes):
|
|
if len(key) != constants.hash_length:
|
|
raise ValueError(f"invalid key length: {len(key)}")
|
|
self.key = key
|
|
self.val_key_one = int.from_bytes(key, 'big')
|
|
|
|
def __call__(self, key_two: bytes) -> int:
|
|
if len(key_two) != constants.hash_length:
|
|
raise ValueError(f"invalid length of key to compare: {len(key_two)}")
|
|
val_key_two = int.from_bytes(key_two, 'big')
|
|
return self.val_key_one ^ val_key_two
|
|
|
|
def is_closer(self, a: bytes, b: bytes) -> bool:
|
|
"""Returns true is `a` is closer to `key` than `b` is"""
|
|
return self(a) < self(b)
|