Re: gsub bug? 2 results from anchored gsub

[Tim Hill <drtimhill@...>]

> On Jul 27, 2015, at 12:28 AM, Sean Conner <sean@conman.org> wrote:
> 
>> 
>>> ("d//"):gsub("/*$", "/")
>>    d// 2
>> 
>> This result suggests that there is an empty string being matched
>> between the last "/" and the end of the string.
>> It's matching the // and replacing that with "/"; but then it gets
>> confused and matches the empty string at the end, and ends up
>> inserting an extra /
>> Using 'print' as the match confirms:
>> 
>>> ("d//"):gsub("/*$", print)
>>    //
>> 
>>    d// 2
>> 
>> Is this a bug in string.gsub?
> 
>  No.  You're telling Lua that you want to match zero or more '/' followed
> by the end of string.  Going through "d//", it first finds "//", which is
> zero or more '/', and replaces it with a slash.  It then finds "END OF LINE"
> [1], which is zero or more '/', and replaces it with a slash.  It's working
> as intended.
> 
>  -spc (You may have to switch to LPEG ... )
> 
> [1]	Thus sayeth the Master Control Program.
> 

Hmm .. my vote goes with the OP. Matches are greedy so the first match should be on “//“ AND the end of the string. I found this interesting:

(“d//“):gsub(“/+$”, “/“)
	d/ 1

—Tim