Re: numeric captures (string.find)

[Adrián Pérez <copylight@...>]

El 14/09/2004, a las 23:34, Asko Kauppi escribió:

> Would it be hard to make 'string.find()' return true numbers [...]

I think it's not a true good idea, I agree with some of the opinions in 
the other replies. Even so, it's a matter of adding some lines in 
"lstrlib.c", at the "push_onecapture" function:

static void push_onecapture (MatchState *ms, int i) {
  int l = ms->capture[i].len;
  if (l == CAP_UNFINISHED) luaL_error(ms->L, "unfinished capture");
  if (l == CAP_POSITION)
    lua_pushnumber(ms->L, (lua_Number)(ms->capture[i].init - 
ms->src_init + 1));
  else {
    /* Code added here */
    double converted_number;
    if (convert_strtodouble_ok(ms->capture[i].init, l, 
&converted_number)
       lua_pushnumber(ms->L, converted_number);
    else
       lua_pushlstring(ms->L, ms->capture[i].init, l);
  }
}


static int convert_strtodouble_ok(const char *string, size_t length, 
double *num)
{
   /*
     * Fill with code here: try to convert with the strtod() C 
function, ad if it's OK
     * assign the converted number to *num, and return 1, else return 0.
     */
}


I have not tested this, but keep in mind that this is a sub-optimal 
approach: everytime a capture is pushed back to Lua it gets checked, 
and converted to number if possible. This is done for every capture 
(doing it only for "%d+" would need black magic!).


-ap

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