28 lines
879 B
Python
28 lines
879 B
Python
from lbrynet.dht import constants
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class Distance(object):
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"""Calculate the XOR result between two string variables.
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Frequently we re-use one of the points so as an optimization
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we pre-calculate the long value of that point.
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"""
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def __init__(self, key):
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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
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self.val_key_one = long(key.encode('hex'), 16)
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def __call__(self, key_two):
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val_key_two = long(key_two.encode('hex'), 16)
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return self.val_key_one ^ val_key_two
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def is_closer(self, a, b):
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"""Returns true is `a` is closer to `key` than `b` is"""
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return self(a) < self(b)
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def to_contact(self, contact):
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"""A convenience function for calculating the distance to a contact"""
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return self(contact.id)
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