Re: Replace specific comma's in a string.

[Egor Skriptunoff <egor.skriptunoff@...>]

On Sat, Feb 10, 2018 at 4:18 AM, Paul K wrote:

One case it doesn't handle is the mix of ' and " in the string (as the
string should only be closed with the same quote is was opened with,
assuming both " and ' are allowed).

This code should handle this case (also added examples):

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, "hel,lo", DEV 23',342,534,202,NAME]],
  [[123,"ABC, 'hel,lo, DEV 23",342,534,202,NAME]],
}
local escaped, instring, pos, start = 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
      and (not instring or s == start) then instring, start = not
instring, s end
      if s == ',' and not instring then s = '~' end
      return s
    end)
  print(s)
end

Exactly the same could be done using Lua patterns:

for _,s in ipairs(list) do
  s = s:gsub("\\?.", {['"']='\0\0"', ["'"]="\0\0'", [","]="\0,"})
       :gsub("((%z%z.).-)%2", function(a,b) return a:gsub("%z,", ",")..b end)
       :gsub("%z,", "~")
       :gsub("%z", "")

  print(s)

end