Source Code for Module dns.grange

 1  # Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license 
 2   
 3  # Copyright (C) 2012-2017 Nominum, Inc. 
 4  # 
 5  # Permission to use, copy, modify, and distribute this software and its 
 6  # documentation for any purpose with or without fee is hereby granted, 
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17   
18  """DNS GENERATE range conversion.""" 
19   
20  import dns 
21   
22 -def from_text(text): 
23      """Convert the text form of a range in a ``$GENERATE`` statement to an 
24      integer. 
25   
26      *text*, a ``str``, the textual range in ``$GENERATE`` form. 
27   
28      Returns a tuple of three ``int`` values ``(start, stop, step)``. 
29      """ 
30   
31      # TODO, figure out the bounds on start, stop and step. 
32      step = 1 
33      cur = '' 
34      state = 0 
35      # state   0 1 2 3 4 
36      #         x - y / z 
37   
38      if text and text[0] == '-': 
39          raise dns.exception.SyntaxError("Start cannot be a negative number") 
40   
41      for c in text: 
42          if c == '-' and state == 0: 
43              start = int(cur) 
44              cur = '' 
45              state = 2 
46          elif c == '/': 
47              stop = int(cur) 
48              cur = '' 
49              state = 4 
50          elif c.isdigit(): 
51              cur += c 
52          else: 
53              raise dns.exception.SyntaxError("Could not parse %s" % (c)) 
54   
55      if state in (1, 3): 
56          raise dns.exception.SyntaxError() 
57   
58      if state == 2: 
59          stop = int(cur) 
60   
61      if state == 4: 
62          step = int(cur) 
63   
64      assert step >= 1 
65      assert start >= 0 
66      assert start <= stop 
67      # TODO, can start == stop? 
68   
69      return (start, stop, step) 
70