1 import itertools
   2 
   3 fields = []
   4 accumulator = []
   5 fieldType = None
   6 
   7 
   8 def endField():
   9     global accumulator
  10     global fields
  11     global fieldType
  12     stringMap = { "alpha" : -30, "beta" : -20, "rc" : -10, "final" : None }
  13     if accumulator:
  14         s = "".join(accumulator)
  15         if s in stringMap:
  16             value = stringMap[s]
  17             if value is not None:
  18                 fields.append(value)
  19         elif fieldType == 'ascii':
  20             fields.extend([ord(c.upper()) for c in accumulator])
  21         else:
  22             assert fieldType == 'digits'
  23             while len(accumulator) > 1 and accumulator[0] == '0':
  24                 accumulator.pop(0)
  25             fields.append(int(s))
  26     accumulator = []
  27     fieldType = None
  28 
  29 
  30 
  31 def split_version(s):
  32     """Splits a version string into a tuple of integers."""
  33 
  34     global accumulator
  35     global fields
  36     global fieldType
  37 
  38     fields = []
  39 
  40     for c in s:
  41         if c.isdigit():
  42             if fieldType == 'ascii':
  43                 endField()
  44             fieldType = 'digits'
  45             accumulator.append(c)
  46             continue
  47         if c.isalpha():
  48             if fieldType == 'digits':
  49                 endField()
  50             fieldType = 'ascii'
  51             accumulator.append(c)
  52             continue
  53         endField()
  54     endField()
  55     while fields and (fields[-1] == 0):
  56         fields.pop()
  57     return tuple(fields)
  58 
  59 def _split_nonfinal(v):
  60     for i, field in enumerate(v):
  61         if field < 0:
  62             return v[:i], v[i:]
  63     return v, ()
  64 
  65 def compare_version_tuples(a, b):
  66     """Compares two version tuples.
  67 
  68     Returns 0 if they are equivalent,
  69     a negative number if the first version is less than the second version,
  70     and a positive number if the first version is greater than the second version.
  71     """
  72     a, aBeta = _split_nonfinal(a)
  73     b, bBeta = _split_nonfinal(b)
  74     for fa, fb in itertools.chain(itertools.izip_longest(a, b, fillvalue=0), itertools.izip_longest(aBeta, bBeta, fillvalue=0)):
  75         if fa == fb:
  76             continue
  77         return 1 if (fa > fb) else -1
  78     return 0
  79 
  80 def is_final(a):
  81     """Returns true if this is a 'final' version.
  82     Returns false if it is not a 'final' version (an alpha, beta, rc)."""
  83     for field in a:
  84         if field < 0:
  85             return False
  86     return True
  87 
  88 if __name__ == "__main__":
  89     for s, version in (
  90     ("1.2", (1, 2)),
  91     ("1.2.0", (1, 2)),
  92     ("1.0alpha1", (1, 0, -30, 1)),
  93     ("1.0 alpha 1", (1, 0, -30, 1)),
  94     ("1-0pa3", (1, 0, ord('p'.upper()), ord('a'.upper()), 3)),
  95     ("1.003", (1, 3)),
  96     ("1.3", (1, 3)),
  97     ):
  98         assert split_version(s) == version
  99     
 100     for s in """
 101     1.0 1.0            0
 102     1.0 1              0
 103     1.0 1.0.0.0        0
 104     1.0 1.2           -1
 105     1.2.0 1            1
 106     1.0alpha1 1.0     -1
 107     1.0alpha 1.0beta  -1
 108     1-0p3 1-0p4       -1
 109     1.003 1.4         -1
 110     1.0.0.0 1alpha3    1
 111     """.strip().split("\n"):
 112         v1, v2, expected = s.split()[:3]
 113         expected = int(expected)
 114         result = compare_version_tuples(split_version(v1), split_version(v2))
 115         assert result == expected