python/m5/smartdict.py

   1 # The SmartDict class fixes a couple of issues with using the content
   2 # of os.environ or similar dicts of strings as Python variables:
   3 #
   4 # 1) Undefined variables should return False rather than raising KeyError.
   5 #
   6 # 2) String values of 'False', '0', etc., should evaluate to False
   7 #    (not just the empty string).
   8 #
   9 # #1 is solved by overriding __getitem__, and #2 is solved by using a
  10 # proxy class for values and overriding __nonzero__ on the proxy.
  11 # Everything else is just to (a) make proxies behave like normal
  12 # values otherwise, (b) make sure any dict operation returns a proxy
  13 # rather than a normal value, and (c) coerce values written to the
  14 # dict to be strings.
  15
  16
  17 from convert import *
  18
  19 class SmartDict(dict):
  20
  21     class Proxy(str):
  22         def __int__(self):
  23             return int(to_integer(str(self)))
  24         def __long__(self):
  25             return long(to_integer(str(self)))
  26         def __float__(self):
  27             return float(to_integer(str(self)))
  28         def __nonzero__(self):
  29             return to_bool(str(self))
  30         def convert(self, other):
  31             t = type(other)
  32             if t == bool:
  33                 return bool(self)
  34             if t == int:
  35                 return int(self)
  36             if t == long:
  37                 return long(self)
  38             if t == float:
  39                 return float(self)
  40             return str(self)
  41         def __lt__(self, other):
  42             return self.convert(other) < other
  43         def __le__(self, other):
  44             return self.convert(other) <= other
  45         def __eq__(self, other):
  46             return self.convert(other) == other
  47         def __ne__(self, other):
  48             return self.convert(other) != other
  49         def __gt__(self, other):
  50             return self.convert(other) > other
  51         def __ge__(self, other):
  52             return self.convert(other) >= other
  53
  54         def __add__(self, other):
  55             return self.convert(other) + other
  56         def __sub__(self, other):
  57             return self.convert(other) - other
  58         def __mul__(self, other):
  59             return self.convert(other) * other
  60         def __div__(self, other):
  61             return self.convert(other) / other
  62         def __truediv__(self, other):
  63             return self.convert(other) / other
  64
  65         def __radd__(self, other):
  66             return other + self.convert(other)
  67         def __rsub__(self, other):
  68             return other - self.convert(other)
  69         def __rmul__(self, other):
  70             return other * self.convert(other)
  71         def __rdiv__(self, other):
  72             return other / self.convert(other)
  73         def __rtruediv__(self, other):
  74             return other / self.convert(other)
  75
  76
  77     # __getitem__ uses dict.get() to return 'False' if the key is not
  78     # found (rather than raising KeyError).  Note that this does *not*
  79     # set the key's value to 'False' in the dict, so that even after
  80     # we call env['foo'] we still get a meaningful answer from "'foo'
  81     # in env" (which calls dict.__contains__, which we do not
  82     # override).
  83     def __getitem__(self, key):
  84         return self.Proxy(dict.get(self, key, 'False'))
  85
  86     def __setitem__(self, key, item):
  87         dict.__setitem__(self, key, str(item))
  88
  89     def values(self):
  90         return [ self.Proxy(v) for v in dict.values(self) ]
  91
  92     def itervalues(self):
  93         for value in dict.itervalues(self):
  94             yield self.Proxy(value)
  95
  96     def items(self):
  97         return [ (k, self.Proxy(v)) for k,v in dict.items(self) ]
  98
  99     def iteritems(self):
 100         for key,value in dict.iteritems(self):
 101             yield key, self.Proxy(value)
 102
 103     def get(self, key, default='False'):
 104         return self.Proxy(dict.get(self, key, str(default)))
 105
 106     def setdefault(self, key, default='False'):
 107         return self.Proxy(dict.setdefault(self, key, str(default)))
 108