Re: Replace specific comma's in a string.

[Coda Highland <chighland@...>]

On Fri, Feb 9, 2018 at 5:40 PM, Paul K <paul@zerobrane.com> wrote:
> Hi Russ,
>
>> The crux of the question is to leave the commas within a quoted items
>> and replace all the outer "separator" commas with tilde (~). So parse this:
>> 123,"ABC, DEV 23",345,534.202,NAME
>> and return this:
>> 123~"ABC, DEV 23"~345~534.202~NAME.
>
> Something like the following may work:
>
> local list = {
>   '123,"ABC, DEV 23",345,,202,NAME',
>   ',"ABC, DEV 23",345,534,202,NAME',
>   '123,"ABC, DEV 23",345,534.202,',
>   '123 , "ABC, DEV 23" , 345 , 534 , 202 , NAME',
>   [[123,"ABC, \"he,llo\", DEV 23",,,,NAME]],
>   [[123,"ABC, \\",llo\", DEV 23,,,,NAME]],
>   [[123,'ABC, "hello", DEV 23',342,534,202,NAME]],
> }
> local escaped, instring, pos = false, false, -1
> for _,s in ipairs(list) do
>   s = s:gsub([[()(["',\\])]], function(p, s)
>       if p > pos+1 then escaped = false end
>       if s == '\\' then escaped, pos = not escaped, p end
>       if (s == '"' or s == "'") and not escaped then instring = not instring end
>       if s == ',' and not instring then s = '~' end
>       return s
>     end)
>   print(s)
> end
>
> This prints:
>
> 123~"ABC, DEV 23"~345~~202~NAME
> ~"ABC, DEV 23"~345~534~202~NAME
> 123~"ABC, DEV 23"~345~534.202~
> 123 ~ "ABC, DEV 23" ~ 345 ~ 534 ~ 202 ~ NAME
> 123~"ABC, \"he,llo\", DEV 23"~~~~NAME
> 123~"ABC, \\"~llo\"~ DEV 23~~~~NAME
> 123~'ABC, "hello", DEV 23'~342~534~202~NAME
>
> Paul.

Indeed, the trivial little state machine has ALWAYS been my preferred
way to solve this class of problem.

/s/ Adam