Re: unquote?

[Petite Abeille <petite.abeille@...>]

On Oct 4, 2011, at 11:32 PM, Geoff Leyland wrote:

>> Does anyone have a handy function to unquote a string.format %q transformation? I.e. reverse all the quoting performed by %q to revert to the original string, before quoting?
> 
> 
> print(loadstring("return "..("%q"):format("here's a string"))())  ?

Yes, that's a possibility. Unfortunately, as the string content is of unknown nature, simply executing it would be a bit reckless :)

I would rather have a simple string pattern or something.

lstrlib.c addquoted [1] performs quite a few substitutions, so if someone already went through the trouble of reversing it, that would be much appreciated :))

Also, looks like 5.2 implements quoting slightly differently:

static void addquoted (lua_State *L, luaL_Buffer *b, int arg) {
  size_t l;
  const char *s = luaL_checklstring(L, arg, &l);
  luaL_addchar(b, '"');
  while (l--) {
    if (*s == '"' || *s == '\\' || *s == '\n') {
      luaL_addchar(b, '\\');
      luaL_addchar(b, *s);
    }
    else if (*s == '\0' || iscntrl(uchar(*s))) {
      char buff[10];
      if (!isdigit(uchar(*(s+1))))
        sprintf(buff, "\\%d", (int)uchar(*s));
      else
        sprintf(buff, "\\%03d", (int)uchar(*s));
      luaL_addstring(b, buff);
    }
    else
      luaL_addchar(b, *s);
    s++;
  }
  luaL_addchar(b, '"');
}


[1] http://www.lua.org/source/5.1/lstrlib.c.html#addquoted