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 StringType, UnicodeType
   9 import sys
  10
  11 __all__ = ["UserString","MutableString"]
  12
  13 class UserString:
  14     def __init__(self, seq):
  15         if isinstance(seq, StringType) or isinstance(seq, UnicodeType):
  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, StringType) or isinstance(other, UnicodeType):
  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, StringType) or isinstance(other, UnicodeType):
  52             return self.__class__(other + self.data)
  53         else:
  54             return self.__class__(str(other) + self.data)
  55     def __iadd__(self, other):
  56         if isinstance(other, UserString):
  57             self.data += other.data
  58         elif isinstance(other, StringType) or isinstance(other, UnicodeType):
  59             self.data += other
  60         else:
  61             self.data += str(other)
  62         return self
  63     def __mul__(self, n):
  64         return self.__class__(self.data*n)
  65     __rmul__ = __mul__
  66     def __imul__(self, n):
  67         self.data *= n
  68         return self
  69
  70     # the following methods are defined in alphabetical order:
  71     def capitalize(self): return self.__class__(self.data.capitalize())
  72     def center(self, width): return self.__class__(self.data.center(width))
  73     def count(self, sub, start=0, end=sys.maxint):
  74         return self.data.count(sub, start, end)
  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): return self.__class__(self.data.ljust(width))
 102     def lower(self): return self.__class__(self.data.lower())
 103     def lstrip(self): return self.__class__(self.data.lstrip())
 104     def replace(self, old, new, maxsplit=-1):
 105         return self.__class__(self.data.replace(old, new, maxsplit))
 106     def rfind(self, sub, start=0, end=sys.maxint):
 107         return self.data.rfind(sub, start, end)
 108     def rindex(self, sub, start=0, end=sys.maxint):
 109         return self.data.rindex(sub, start, end)
 110     def rjust(self, width): return self.__class__(self.data.rjust(width))
 111     def rstrip(self): return self.__class__(self.data.rstrip())
 112     def split(self, sep=None, maxsplit=-1):
 113         return self.data.split(sep, maxsplit)
 114     def splitlines(self, keepends=0): return self.data.splitlines(keepends)
 115     def startswith(self, prefix, start=0, end=sys.maxint):
 116         return self.data.startswith(prefix, start, end)
 117     def strip(self): return self.__class__(self.data.strip())
 118     def swapcase(self): return self.__class__(self.data.swapcase())
 119     def title(self): return self.__class__(self.data.title())
 120     def translate(self, *args):
 121         return self.__class__(self.data.translate(*args))
 122     def upper(self): return self.__class__(self.data.upper())
 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, StringType) or isinstance(sub, UnicodeType):
 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
 163 if __name__ == "__main__":
 164     # execute the regression test to stdout, if called as a script:
 165     import os
 166     called_in_dir, called_as = os.path.split(sys.argv[0])
 167     called_in_dir = os.path.abspath(called_in_dir)
 168     called_as, py = os.path.splitext(called_as)
 169     sys.path.append(os.path.join(called_in_dir, 'test'))
 170     if '-q' in sys.argv:
 171         import test_support
 172         test_support.verbose = 0
 173     __import__('test_' + called_as.lower())