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): return self.__class__(self.data.center(width))
  64     def count(self, sub, start=0, end=sys.maxint):
  65         return self.data.count(sub, start, end)
  66     def decode(self, encoding=None, errors=None): # XXX improve this?
  67         if encoding:
  68             if errors:
  69                 return self.__class__(self.data.decode(encoding, errors))
  70             else:
  71                 return self.__class__(self.data.decode(encoding))
  72         else:
  73             return self.__class__(self.data.decode())
  74     def encode(self, encoding=None, errors=None): # XXX improve this?
  75         if encoding:
  76             if errors:
  77                 return self.__class__(self.data.encode(encoding, errors))
  78             else:
  79                 return self.__class__(self.data.encode(encoding))
  80         else:
  81             return self.__class__(self.data.encode())
  82     def endswith(self, suffix, start=0, end=sys.maxint):
  83         return self.data.endswith(suffix, start, end)
  84     def expandtabs(self, tabsize=8):
  85         return self.__class__(self.data.expandtabs(tabsize))
  86     def find(self, sub, start=0, end=sys.maxint):
  87         return self.data.find(sub, start, end)
  88     def index(self, sub, start=0, end=sys.maxint):
  89         return self.data.index(sub, start, end)
  90     def isalpha(self): return self.data.isalpha()
  91     def isalnum(self): return self.data.isalnum()
  92     def isdecimal(self): return self.data.isdecimal()
  93     def isdigit(self): return self.data.isdigit()
  94     def islower(self): return self.data.islower()
  95     def isnumeric(self): return self.data.isnumeric()
  96     def isspace(self): return self.data.isspace()
  97     def istitle(self): return self.data.istitle()
  98     def isupper(self): return self.data.isupper()
  99     def join(self, seq): return self.data.join(seq)
 100     def ljust(self, width): return self.__class__(self.data.ljust(width))
 101     def lower(self): return self.__class__(self.data.lower())
 102     def lstrip(self, chars=None): return self.__class__(self.data.lstrip(chars))
 103     def replace(self, old, new, maxsplit=-1):
 104         return self.__class__(self.data.replace(old, new, maxsplit))
 105     def rfind(self, sub, start=0, end=sys.maxint):
 106         return self.data.rfind(sub, start, end)
 107     def rindex(self, sub, start=0, end=sys.maxint):
 108         return self.data.rindex(sub, start, end)
 109     def rjust(self, width): return self.__class__(self.data.rjust(width))
 110     def rstrip(self, chars=None): return self.__class__(self.data.rstrip(chars))
 111     def split(self, sep=None, maxsplit=-1):
 112         return self.data.split(sep, maxsplit)
 113     def splitlines(self, keepends=0): return self.data.splitlines(keepends)
 114     def startswith(self, prefix, start=0, end=sys.maxint):
 115         return self.data.startswith(prefix, start, end)
 116     def strip(self, chars=None): return self.__class__(self.data.strip(chars))
 117     def swapcase(self): return self.__class__(self.data.swapcase())
 118     def title(self): return self.__class__(self.data.title())
 119     def translate(self, *args):
 120         return self.__class__(self.data.translate(*args))
 121     def upper(self): return self.__class__(self.data.upper())
 122     def zfill(self, width): return self.__class__(self.data.zfill(width))
 123
 124 class MutableString(UserString):
 125     """mutable string objects
 126
 127     Python strings are immutable objects.  This has the advantage, that
 128     strings may be used as dictionary keys.  If this property isn't needed
 129     and you insist on changing string values in place instead, you may cheat
 130     and use MutableString.
 131
 132     But the purpose of this class is an educational one: to prevent
 133     people from inventing their own mutable string class derived
 134     from UserString and than forget thereby to remove (override) the
 135     __hash__ method inherited from ^UserString.  This would lead to
 136     errors that would be very hard to track down.
 137
 138     A faster and better solution is to rewrite your program using lists."""
 139     def __init__(self, string=""):
 140         self.data = string
 141     def __hash__(self):
 142         raise TypeError, "unhashable type (it is mutable)"
 143     def __setitem__(self, index, sub):
 144         if index < 0 or index >= len(self.data): raise IndexError
 145         self.data = self.data[:index] + sub + self.data[index+1:]
 146     def __delitem__(self, index):
 147         if index < 0 or index >= len(self.data): raise IndexError
 148         self.data = self.data[:index] + self.data[index+1:]
 149     def __setslice__(self, start, end, sub):
 150         start = max(start, 0); end = max(end, 0)
 151         if isinstance(sub, UserString):
 152             self.data = self.data[:start]+sub.data+self.data[end:]
 153         elif isinstance(sub, StringTypes):
 154             self.data = self.data[:start]+sub+self.data[end:]
 155         else:
 156             self.data =  self.data[:start]+str(sub)+self.data[end:]
 157     def __delslice__(self, start, end):
 158         start = max(start, 0); end = max(end, 0)
 159         self.data = self.data[:start] + self.data[end:]
 160     def immutable(self):
 161         return UserString(self.data)
 162     def __iadd__(self, other):
 163         if isinstance(other, UserString):
 164             self.data += other.data
 165         elif isinstance(other, StringTypes):
 166             self.data += other
 167         else:
 168             self.data += str(other)
 169         return self
 170     def __imul__(self, n):
 171         self.data *= n
 172         return self
 173
 174 if __name__ == "__main__":
 175     # execute the regression test to stdout, if called as a script:
 176     import os
 177     called_in_dir, called_as = os.path.split(sys.argv[0])
 178     called_as, py = os.path.splitext(called_as)
 179     if '-q' in sys.argv:
 180         from test import test_support
 181         test_support.verbose = 0
 182     __import__('test.test_' + called_as.lower())