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 import sys
   9 import collections
  10
  11 __all__ = ["UserString","MutableString"]
  12
  13 class UserString(collections.Sequence):
  14     def __init__(self, seq):
  15         if isinstance(seq, basestring):
  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, basestring):
  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, basestring):
  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 partition(self, sep):
 106         return self.data.partition(sep)
 107     def replace(self, old, new, maxsplit=-1):
 108         return self.__class__(self.data.replace(old, new, maxsplit))
 109     def rfind(self, sub, start=0, end=sys.maxint):
 110         return self.data.rfind(sub, start, end)
 111     def rindex(self, sub, start=0, end=sys.maxint):
 112         return self.data.rindex(sub, start, end)
 113     def rjust(self, width, *args):
 114         return self.__class__(self.data.rjust(width, *args))
 115     def rpartition(self, sep):
 116         return self.data.rpartition(sep)
 117     def rstrip(self, chars=None): return self.__class__(self.data.rstrip(chars))
 118     def split(self, sep=None, maxsplit=-1):
 119         return self.data.split(sep, maxsplit)
 120     def rsplit(self, sep=None, maxsplit=-1):
 121         return self.data.rsplit(sep, maxsplit)
 122     def splitlines(self, keepends=0): return self.data.splitlines(keepends)
 123     def startswith(self, prefix, start=0, end=sys.maxint):
 124         return self.data.startswith(prefix, start, end)
 125     def strip(self, chars=None): return self.__class__(self.data.strip(chars))
 126     def swapcase(self): return self.__class__(self.data.swapcase())
 127     def title(self): return self.__class__(self.data.title())
 128     def translate(self, *args):
 129         return self.__class__(self.data.translate(*args))
 130     def upper(self): return self.__class__(self.data.upper())
 131     def zfill(self, width): return self.__class__(self.data.zfill(width))
 132
 133 class MutableString(UserString, collections.MutableSequence):
 134     """mutable string objects
 135
 136     Python strings are immutable objects.  This has the advantage, that
 137     strings may be used as dictionary keys.  If this property isn't needed
 138     and you insist on changing string values in place instead, you may cheat
 139     and use MutableString.
 140
 141     But the purpose of this class is an educational one: to prevent
 142     people from inventing their own mutable string class derived
 143     from UserString and than forget thereby to remove (override) the
 144     __hash__ method inherited from UserString.  This would lead to
 145     errors that would be very hard to track down.
 146
 147     A faster and better solution is to rewrite your program using lists."""
 148     def __init__(self, string=""):
 149         self.data = string
 150     def __hash__(self):
 151         raise TypeError, "unhashable type (it is mutable)"
 152     def __setitem__(self, index, sub):
 153         if isinstance(index, slice):
 154             if isinstance(sub, UserString):
 155                 sub = sub.data
 156             elif not isinstance(sub, basestring):
 157                 sub = str(sub)
 158             start, stop, step = index.indices(len(self.data))
 159             if step == -1:
 160                 start, stop = stop+1, start+1
 161                 sub = sub[::-1]
 162             elif step != 1:
 163                 # XXX(twouters): I guess we should be reimplementing
 164                 # the extended slice assignment/deletion algorithm here...
 165                 raise TypeError, "invalid step in slicing assignment"
 166             start = min(start, stop)
 167             self.data = self.data[:start] + sub + self.data[stop:]
 168         else:
 169             if index < 0:
 170                 index += len(self.data)
 171             if index < 0 or index >= len(self.data): raise IndexError
 172             self.data = self.data[:index] + sub + self.data[index+1:]
 173     def __delitem__(self, index):
 174         if isinstance(index, slice):
 175             start, stop, step = index.indices(len(self.data))
 176             if step == -1:
 177                 start, stop = stop+1, start+1
 178             elif step != 1:
 179                 # XXX(twouters): see same block in __setitem__
 180                 raise TypeError, "invalid step in slicing deletion"
 181             start = min(start, stop)
 182             self.data = self.data[:start] + self.data[stop:]
 183         else:
 184             if index < 0:
 185                 index += len(self.data)
 186             if index < 0 or index >= len(self.data): raise IndexError
 187             self.data = self.data[:index] + self.data[index+1:]
 188     def __setslice__(self, start, end, sub):
 189         start = max(start, 0); end = max(end, 0)
 190         if isinstance(sub, UserString):
 191             self.data = self.data[:start]+sub.data+self.data[end:]
 192         elif isinstance(sub, basestring):
 193             self.data = self.data[:start]+sub+self.data[end:]
 194         else:
 195             self.data =  self.data[:start]+str(sub)+self.data[end:]
 196     def __delslice__(self, start, end):
 197         start = max(start, 0); end = max(end, 0)
 198         self.data = self.data[:start] + self.data[end:]
 199     def immutable(self):
 200         return UserString(self.data)
 201     def __iadd__(self, other):
 202         if isinstance(other, UserString):
 203             self.data += other.data
 204         elif isinstance(other, basestring):
 205             self.data += other
 206         else:
 207             self.data += str(other)
 208         return self
 209     def __imul__(self, n):
 210         self.data *= n
 211         return self
 212     def insert(self, index, value):
 213         self[index:index] = value
 214
 215 if __name__ == "__main__":
 216     # execute the regression test to stdout, if called as a script:
 217     import os
 218     called_in_dir, called_as = os.path.split(sys.argv[0])
 219     called_as, py = os.path.splitext(called_as)
 220     if '-q' in sys.argv:
 221         from test import test_support
 222         test_support.verbose = 0
 223     __import__('test.test_' + called_as.lower())