Thomas Lotze wrote:
>Hi,
>
>I think I need an iterator over a string of characters pulling them out
>one by one, like a usual iterator over a str does. At the same time the
>thing should allow seeking and telling like a file-like object:
>
>
Okay, first off, this is never going to be *fast* compared to something
coded in C and wrapped with Python. You are dealing with every single
character as a Python object, so let's forget fast for the moment and do
a straightforward implementation:
class Franken( str ):
frankenIndex = 0
def __iter__( self ):
while self.frankenIndex < len(self):
yield self[ self.frankenIndex ]
self.frankenIndex += 1
self.frankenIndex = 0
def seek( self, index ):
self.frankenIndex = index
def tell( self, index ):
return self.frankenIndex
if __name__ == "__main__":
f = Franken( 'abcdefg' )
for c in f:
print 'char', c
if c == 'c':
break
f.seek( 5 )
l1 = list( f )
l2 = list( f )
assert l1 == [ 'f','g' ]
assert l2 == list(str(f))
print 'first list', l1
print 'second list', l2
If you want to speed it up, you can optimise for various string sizes
(eg using a slice of the string and the built-in iterator when
appropriate), but in the end, it's not going to be anywhere near as fast
as a C-engine tokeniser, so I'd personally spend more time on elegance
than on speed...
Anywho, have fun,
Mike
--
________________________________________________
Mike C. Fletcher
Designer, VR Plumber, Coder
http://www.vrplumber.com
http://blog.vrplumber.com
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