Function luaO_pushvfstring

ThirdParty/lua/lua/lobject.c:348–413

this function handles only '%d', '%c', '%f', '%p', and '%s' conventional formats, plus Lua-specific '%I' and '%U' */

/* this function handles only '%d', '%c', '%f', '%p', and '%s' 
   conventional formats, plus Lua-specific '%I' and '%U' */
const char *luaO_pushvfstring (lua_State *L, const char *fmt, va_list argp) {
  int n = 0;
  for (;;) {
    const char *e = strchr(fmt, '%');
    if (e == NULL) break;
    luaD_checkstack(L, 2);  /* fmt + item */
    pushstr(L, fmt, e - fmt);
    switch (*(e+1)) {
      case 's': {
        const char *s = va_arg(argp, char *);
        if (s == NULL) s = "(null)";
        pushstr(L, s, strlen(s));
        break;
      }
      case 'c': {
        char buff = cast(char, va_arg(argp, int));
        if (lisprint(cast_uchar(buff)))
          pushstr(L, &buff, 1);
        else  /* non-printable character; print its code */
          luaO_pushfstring(L, "<\\%d>", cast_uchar(buff));
        break;
      }
      case 'd': {
        setivalue(L->top++, va_arg(argp, int));
        luaO_tostring(L, L->top - 1);
        break;
      }
      case 'I': {
        setivalue(L->top++, cast(lua_Integer, va_arg(argp, l_uacInt)));
        luaO_tostring(L, L->top - 1);
        break;
      }
      case 'f': {
        setfltvalue(L->top++, cast_num(va_arg(argp, l_uacNumber)));
        luaO_tostring(L, L->top - 1);
        break;
      }
      case 'p': {
        char buff[4*sizeof(void *) + 8]; /* should be enough space for a '%p' */
        int l = sprintf(buff, "%p", va_arg(argp, void *));
        pushstr(L, buff, l);
        break;
      }
      case 'U': {
        char buff[UTF8BUFFSZ];
        int l = luaO_utf8esc(buff, cast(long, va_arg(argp, long)));
        pushstr(L, buff + UTF8BUFFSZ - l, l);
        break;
      }
      case '%': {
        pushstr(L, "%", 1);
        break;
      }
      default: {
        luaG_runerror(L, "invalid option '%%%c' to 'lua_pushfstring'",
                         *(e + 1));
      }
    }