[Ocaml-lib-devel] Re: ExtString.String.slice bug

[Bardur A. <sp...@sc...>]

Bardur Arantsson wrote:
> Brian Brunswick wrote:
> 
>> Hi, thanks for extlib!
>>
>> ExtString.String.slice doesn't live up to its documentation of never
>> raising an exception. It fails to check if ~last is out of range, and
>> crashes in String.sub.
>>
>> Is it best to report bugs here, or in the tracker?
>>
>> -- 
> 
> 
> I notice there's been no commit to the CVS with a fix for this even 
> though the bug was reported quite a long time ago, so I'm going to 
> commit this cleaned up and corrected version later today/tomorrow if 
> there are no objections:
> 
>     let clip _min _max x =
>       max _min (min _max x)
>     ;;
> 
>     let slice ?(first=0) ?(last=Sys.max_string_length) s =
>       let i =
>         clip 0 (length s)
>           (if (first<0) then
>              (length s) + first
>            else
>              first)
>       and j =
>         clip 0 (length s)
>           (if (last<0) then
>              (length s) + last
>            else
>              last)
>       in
>         if i>=j || i=length s then
>           create 0
>         else
>           sub s i (j-i)
> 
> 
> Btw, John Skaller is correct in that the behavior was intended to be 
> exactly like Python's slice operator.
> 

I've committed the above version; with slightly less "spacy" syntax.

-- 
Bardur Arantsson
<bar...@TH...>
<bar...@TH...>

- Me? The 13th Duke of Wimbourne? In a student nurse's hall of
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                       The 13th Duke of Wimbourne, 'The Fast Show'