Source Code for Module flumotion.common.fraction

 1  # -*- Mode: Python; test-case-name: flumotion.test.test_config -*- 
 2  # vi:si:et:sw=4:sts=4:ts=4 
 3  # 
 4  # Flumotion - a streaming media server 
 5  # Copyright (C) 2008 Fluendo, S.L. (www.fluendo.com). 
 6  # All rights reserved. 
 7   
 8  # This file may be distributed and/or modified under the terms of 
 9  # the GNU General Public License version 2 as published by 
10  # the Free Software Foundation. 
11  # This file is distributed without any warranty; without even the implied 
12  # warranty of merchantability or fitness for a particular purpose. 
13  # See "LICENSE.GPL" in the source distribution for more information. 
14   
15  # Licensees having purchased or holding a valid Flumotion Advanced 
16  # Streaming Server license may use this file in accordance with the 
17  # Flumotion Advanced Streaming Server Commercial License Agreement. 
18  # See "LICENSE.Flumotion" in the source distribution for more information. 
19   
20  # Headers in this file shall remain intact. 
21   
22  """convert to and from fractions 
23  """ 
24   
25  __version__ = "$Rev: 7036 $" 
26   
27 -def fractionFromValue(value): 
28      """ 
29      Converts a value to a fraction 
30   
31      @param value: the value to convert to a tuple 
32      @type  value: one of 
33        - string, unicode 
34        - number, eg int/float/long 
35        - two sized tuple 
36   
37      @returns: the fraction 
38      @rtype:   a two sized tuple with 2 integers 
39      """ 
40      def _frac(num, denom=1): 
41          return int(num), int(denom) 
42       
43      if isinstance(value, basestring): 
44          noSlashes = value.count('/') 
45          if noSlashes == 0: 
46              parts = [value] 
47          elif noSlashes == 1: 
48              parts = value.split('/') 
49          else: 
50              raise ValueError('Expected at most one /, not %r' % (value,)) 
51          return _frac(*parts) 
52      elif isinstance(value, tuple): 
53          if len(value) != 2: 
54              raise ValueError( 
55                  "Can only convert two sized tuple to fraction") 
56          return value 
57      elif isinstance(value, (float, int, long)): 
58          return _frac(value) 
59      else: 
60          raise ValueError( 
61              "Cannot convert %r of type %s to a fraction" % ( 
62              value, type(value).__name__)) 
63   
64 -def fractionAsFloat(value): 
65      """ 
66      Converts a fraction to a float 
67      @param value: the value to convert to a tuple, can be one of: 
68      @type value: a two sized tuple with 2 integers 
69      @returns: fraction representation in float 
70      @rtype: float 
71      """ 
72      assert type(value) in [list, tuple], value 
73      assert len(value) == 2, value 
74      return float(value[0]) / float(value[1]) 
75   
76 -def fractionAsString(value): 
77      """ 
78      Converts a fraction to a string 
79      @param value: the value to convert to a tuple, can be one of: 
80      @type value: a two sized tuple with 2 integers 
81      @returns: fraction representation as a string 
82      @rtype: string 
83      """ 
84      assert type(value) in [list, tuple], value 
85      assert len(value) == 2, value 
86      return '%s/%s' % value 
87