from sha import sha
import whrandom
-## takes a 20 bit hash, big-endian, and returns it expressed a long python integer
def intify(hstr):
- assert(len(hstr) == 20)
- return eval('0x' + hstr.encode('hex') + 'L')
+ """20 bit hash, big-endian -> long python integer"""
+ assert len(hstr) == 20
+ return long(hstr.encode('hex'), 16))
-## takes a long int and returns a 20-character string
def stringify(int):
+ """long int -> 20-character string"""
str = hex(int)[2:]
if str[-1] == 'L':
- str = str[:-1]
+ str = str[:-1]
if len(str) % 2 != 0:
- str = '0' + str
+ str = '0' + str
str = str.decode('hex')
return (20 - len(str)) *'\x00' + str
-## returns the distance between two 160-bit hashes expressed as 20-character strings
def distance(a, b):
+ """distance between two 160-bit hashes expressed as 20-character strings"""
return intify(a) ^ intify(b)
-## returns a new pseudorandom globally unique ID string
def newID():
+ """returns a new pseudorandom globally unique ID string"""
h = sha()
for i in range(20):
- h.update(chr(whrandom.randrange(0,256)))
+ h.update(chr(whrandom.randrange(0,256)))
return h.digest()
def newIDInRange(min, max):
def randRange(min, max):
return min + intify(newID()) % (max - min)
+
+### Test Cases ###
import unittest
class NewID(unittest.TestCase):
def testLength(self):
- self.assertEqual(len(newID()), 20)
+ self.assertEqual(len(newID()), 20)
def testHundreds(self):
- for x in xrange(100):
- self.testLength
+ for x in xrange(100):
+ self.testLength
class Intify(unittest.TestCase):
known = [('\0' * 20, 0),
- ('\xff' * 20, 2L**160 - 1),
- ]
+ ('\xff' * 20, 2L**160 - 1),
+ ]
def testKnown(self):
- for str, value in self.known:
- self.assertEqual(intify(str), value)
+ for str, value in self.known:
+ self.assertEqual(intify(str), value)
def testEndianessOnce(self):
- h = newID()
- while h[-1] == '\xff':
- h = newID()
- k = h[:-1] + chr(ord(h[-1]) + 1)
- self.assertEqual(intify(k) - intify(h), 1)
+ h = newID()
+ while h[-1] == '\xff':
+ h = newID()
+ k = h[:-1] + chr(ord(h[-1]) + 1)
+ self.assertEqual(intify(k) - intify(h), 1)
def testEndianessLots(self):
- for x in xrange(100):
- self.testEndianessOnce()
+ for x in xrange(100):
+ self.testEndianessOnce()
class Disantance(unittest.TestCase):
known = [
- (("\0" * 20, "\xff" * 20), 2**160L -1),
- ((sha("foo").digest(), sha("foo").digest()), 0),
- ((sha("bar").digest(), sha("bar").digest()), 0)
- ]
+ (("\0" * 20, "\xff" * 20), 2**160L -1),
+ ((sha("foo").digest(), sha("foo").digest()), 0),
+ ((sha("bar").digest(), sha("bar").digest()), 0)
+ ]
def testKnown(self):
- for pair, dist in self.known:
- self.assertEqual(distance(pair[0], pair[1]), dist)
+ for pair, dist in self.known:
+ self.assertEqual(distance(pair[0], pair[1]), dist)
def testCommutitive(self):
- for i in xrange(100):
- x, y, z = newID(), newID(), newID()
- self.assertEqual(distance(x,y) ^ distance(y, z), distance(x, z))
-
+ for i in xrange(100):
+ x, y, z = newID(), newID(), newID()
+ self.assertEqual(distance(x,y) ^ distance(y, z), distance(x, z))
+
class RandRange(unittest.TestCase):
def testOnce(self):
- a = intify(newID())
- b = intify(newID())
- if a < b:
- c = randRange(a, b)
- self.assertEqual(a <= c < b, 1, "output out of range %d %d %d" % (b, c, a))
- else:
- c = randRange(b, a)
- assert b <= c < a, "output out of range %d %d %d" % (b, c, a)
+ a = intify(newID())
+ b = intify(newID())
+ if a < b:
+ c = randRange(a, b)
+ self.assertEqual(a <= c < b, 1, "output out of range %d %d %d" % (b, c, a))
+ else:
+ c = randRange(b, a)
+ assert b <= c < a, "output out of range %d %d %d" % (b, c, a)
def testOneHundredTimes(self):
- for i in xrange(100):
- self.testOnce()
+ for i in xrange(100):
+ self.testOnce()
if __name__ == '__main__':
unittest.main()
-
\ No newline at end of file
+