Lib/UserString.py

   1 #!/usr/bin/env python
   2 ## vim:ts=4:et:nowrap
   3 """A user-defined wrapper around string objects
   4
   5 Note: string objects have grown methods in Python 1.6
   6 This module requires Python 1.6 or later.
   7 """
   8 from types import StringTypes
   9 import sys
  10
  11 __all__ = ["UserString","MutableString"]
  12
  13 class UserString:
  14     def __init__(self, seq):
  15         if isinstance(seq, StringTypes):
  16             self.data = seq
  17         elif isinstance(seq, UserString):
  18             self.data = seq.data[:]
  19         else:
  20             self.data = str(seq)
  21     def __str__(self): return str(self.data)
  22     def __repr__(self): return repr(self.data)
  23     def __int__(self): return int(self.data)
  24     def __long__(self): return long(self.data)
  25     def __float__(self): return float(self.data)
  26     def __complex__(self): return complex(self.data)
  27     def __hash__(self): return hash(self.data)
  28
  29     def __cmp__(self, string):
  30         if isinstance(string, UserString):
  31             return cmp(self.data, string.data)
  32         else:
  33             return cmp(self.data, string)
  34     def __contains__(self, char):
  35         return char in self.data
  36
  37     def __len__(self): return len(self.data)
  38     def __getitem__(self, index): return self.__class__(self.data[index])
  39     def __getslice__(self, start, end):
  40         start = max(start, 0); end = max(end, 0)
  41         return self.__class__(self.data[start:end])
  42
  43     def __add__(self, other):
  44         if isinstance(other, UserString):
  45             return self.__class__(self.data + other.data)
  46         elif isinstance(other, StringTypes):
  47             return self.__class__(self.data + other)
  48         else:
  49             return self.__class__(self.data + str(other))
  50     def __radd__(self, other):
  51         if isinstance(other, StringTypes):
  52             return self.__class__(other + self.data)
  53         else:
  54             return self.__class__(str(other) + self.data)
  55     def __mul__(self, n):
  56         return self.__class__(self.data*n)
  57     __rmul__ = __mul__
  58     def __mod__(self, args):
  59         return self.__class__(self.data % args)
  60
  61     # the following methods are defined in alphabetical order:
  62     def capitalize(self): return self.__class__(self.data.capitalize())
  63     def center(self, width, *args):
  64         return self.__class__(self.data.center(width, *args))
  65     def count(self, sub, start=0, end=sys.maxint):
  66         return self.data.count(sub, start, end)
  67     def decode(self, encoding=None, errors=None): # XXX improve this?
  68         if encoding:
  69             if errors:
  70                 return self.__class__(self.data.decode(encoding, errors))
  71             else:
  72                 return self.__class__(self.data.decode(encoding))
  73         else:
  74             return self.__class__(self.data.decode())
  75     def encode(self, encoding=None, errors=None): # XXX improve this?
  76         if encoding:
  77             if errors:
  78                 return self.__class__(self.data.encode(encoding, errors))
  79             else:
  80                 return self.__class__(self.data.encode(encoding))
  81         else:
  82             return self.__class__(self.data.encode())
  83     def endswith(self, suffix, start=0, end=sys.maxint):
  84         return self.data.endswith(suffix, start, end)
  85     def expandtabs(self, tabsize=8):
  86         return self.__class__(self.data.expandtabs(tabsize))
  87     def find(self, sub, start=0, end=sys.maxint):
  88         return self.data.find(sub, start, end)
  89     def index(self, sub, start=0, end=sys.maxint):
  90         return self.data.index(sub, start, end)
  91     def isalpha(self): return self.data.isalpha()
  92     def isalnum(self): return self.data.isalnum()
  93     def isdecimal(self): return self.data.isdecimal()
  94     def isdigit(self): return self.data.isdigit()
  95     def islower(self): return self.data.islower()
  96     def isnumeric(self): return self.data.isnumeric()
  97     def isspace(self): return self.data.isspace()
  98     def istitle(self): return self.data.istitle()
  99     def isupper(self): return self.data.isupper()
 100     def join(self, seq): return self.data.join(seq)
 101     def ljust(self, width, *args):
 102         return self.__class__(self.data.ljust(width, *args))
 103     def lower(self): return self.__class__(self.data.lower())
 104     def lstrip(self, chars=None): return self.__class__(self.data.lstrip(chars))
 105     def replace(self, old, new, maxsplit=-1):
 106         return self.__class__(self.data.replace(old, new, maxsplit))
 107     def rfind(self, sub, start=0, end=sys.maxint):
 108         return self.data.rfind(sub, start, end)
 109     def rindex(self, sub, start=0, end=sys.maxint):
 110         return self.data.rindex(sub, start, end)
 111     def rjust(self, width, *args):
 112         return self.__class__(self.data.rjust(width, *args))
 113     def rstrip(self, chars=None): return self.__class__(self.data.rstrip(chars))
 114     def split(self, sep=None, maxsplit=-1):
 115         return self.data.split(sep, maxsplit)
 116     def rsplit(self, sep=None, maxsplit=-1):
 117         return self.data.rsplit(sep, maxsplit)
 118     def splitlines(self, keepends=0): return self.data.splitlines(keepends)
 119     def startswith(self, prefix, start=0, end=sys.maxint):
 120         return self.data.startswith(prefix, start, end)
 121     def strip(self, chars=None): return self.__class__(self.data.strip(chars))
 122     def swapcase(self): return self.__class__(self.data.swapcase())
 123     def title(self): return self.__class__(self.data.title())
 124     def translate(self, *args):
 125         return self.__class__(self.data.translate(*args))
 126     def upper(self): return self.__class__(self.data.upper())
 127     def zfill(self, width): return self.__class__(self.data.zfill(width))
 128
 129 class MutableString(UserString):
 130     """mutable string objects
 131
 132     Python strings are immutable objects.  This has the advantage, that
 133     strings may be used as dictionary keys.  If this property isn't needed
 134     and you insist on changing string values in place instead, you may cheat
 135     and use MutableString.
 136
 137     But the purpose of this class is an educational one: to prevent
 138     people from inventing their own mutable string class derived
 139     from UserString and than forget thereby to remove (override) the
 140     __hash__ method inherited from UserString.  This would lead to
 141     errors that would be very hard to track down.
 142
 143     A faster and better solution is to rewrite your program using lists."""
 144     def __init__(self, string=""):
 145         self.data = string
 146     def __hash__(self):
 147         raise TypeError, "unhashable type (it is mutable)"
 148     def __setitem__(self, index, sub):
 149         if index < 0:
 150             index += len(self.data)
 151         if index < 0 or index >= len(self.data): raise IndexError
 152         self.data = self.data[:index] + sub + self.data[index+1:]
 153     def __delitem__(self, index):
 154         if index < 0:
 155             index += len(self.data)
 156         if index < 0 or index >= len(self.data): raise IndexError
 157         self.data = self.data[:index] + self.data[index+1:]
 158     def __setslice__(self, start, end, sub):
 159         start = max(start, 0); end = max(end, 0)
 160         if isinstance(sub, UserString):
 161             self.data = self.data[:start]+sub.data+self.data[end:]
 162         elif isinstance(sub, StringTypes):
 163             self.data = self.data[:start]+sub+self.data[end:]
 164         else:
 165             self.data =  self.data[:start]+str(sub)+self.data[end:]
 166     def __delslice__(self, start, end):
 167         start = max(start, 0); end = max(end, 0)
 168         self.data = self.data[:start] + self.data[end:]
 169     def immutable(self):
 170         return UserString(self.data)
 171     def __iadd__(self, other):
 172         if isinstance(other, UserString):
 173             self.data += other.data
 174         elif isinstance(other, StringTypes):
 175             self.data += other
 176         else:
 177             self.data += str(other)
 178         return self
 179     def __imul__(self, n):
 180         self.data *= n
 181         return self
 182
 183 if __name__ == "__main__":
 184     # execute the regression test to stdout, if called as a script:
 185     import os
 186     called_in_dir, called_as = os.path.split(sys.argv[0])
 187     called_as, py = os.path.splitext(called_as)
 188     if '-q' in sys.argv:
 189         from test import test_support
 190         test_support.verbose = 0
 191     __import__('test.test_' + called_as.lower())