lbry-sdk/lbrynet/dht/distance.py

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from lbrynet.dht import constants
class Distance:
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"""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.
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"""
def __init__(self, key):
if len(key) != constants.key_bits // 8:
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raise ValueError("invalid key length: %i" % len(key))
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self.key = key
self.val_key_one = int.from_bytes(key, 'big')
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def __call__(self, key_two):
val_key_two = int.from_bytes(key_two, 'big')
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return self.val_key_one ^ val_key_two
def is_closer(self, a, b):
"""Returns true is `a` is closer to `key` than `b` is"""
return self(a) < self(b)
def to_contact(self, contact):
"""A convenience function for calculating the distance to a contact"""
return self(contact.id)