Re: Feature request: plain option for gsub

[Dirk Laurie <dirk.laurie@...>]

2014-08-21 16:54 GMT+02:00 Jonas Thiem <jonasthiem@googlemail.com>:

> I wrote up this lengthy function which is supposed to behave like
> a gsub with plain=True

That "lengthy" is a challenge ... here is my attempt, which has the
same fourth parameter that gsub has. 'gfind' is an independently
useful iterator form of find, except that the default is plain: you need
to specify "false" as second argument to get a pattern.

string.gfind = function (str,plain)
-- for j,i in str:gfind(plain),s do iterates through pairs i,j that would
-- be returned by s:find(str,init,plain) for suitably chosen init
   return function(a,idx)
      local i,j = a:find(str,(idx or 0)+1,plain)
      return j,i
   end
end

string.rawgsub = function(s, pattern, repl, n)
-- like gsub, except matching is plain
   n = n or 0
   local buffer={}
   local oldk=1
   for j,i in pattern:gfind(true),s do
      if i>oldk then buffer[#buffer+1]=s:sub(oldk,i-1) end
      buffer[#buffer+1]=repl
      oldk=j+1
      n=n-1
      if n==0 then break end
   end
   return table.concat(buffer)..s:sub(oldk,#s)
end

> a="abcdefgbcgfhjtubc"
> return a:rawgsub("bc","BC",2) --> aBCdefgBCgfhjtubc