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