Function str_format

ThirdParty/lua/lua/lstrlib.c:872–942

static int str_format (lua_State *L) {
  int top = lua_gettop(L);
  int arg = 1;
  size_t sfl;
  const char *strfrmt = luaL_checklstring(L, arg, &sfl);
  const char *strfrmt_end = strfrmt+sfl;
  luaL_Buffer b;
  luaL_buffinit(L, &b);
  while (strfrmt < strfrmt_end) {
    if (*strfrmt != L_ESC)
      luaL_addchar(&b, *strfrmt++);
    else if (*++strfrmt == L_ESC)
      luaL_addchar(&b, *strfrmt++);  /* %% */
    else { /* format item */
      char form[MAX_FORMAT];  /* to store the format ('%...') */
      char *buff = luaL_prepbuffsize(&b, MAX_ITEM);  /* to put formatted item */
      int nb = 0;  /* number of bytes in added item */
      if (++arg > top)
        luaL_argerror(L, arg, "no value");
      strfrmt = scanformat(L, strfrmt, form);
      switch (*strfrmt++) {
        case 'c': {
          nb = sprintf(buff, form, (int)luaL_checkinteger(L, arg));
          break;
        }
        case 'd': case 'i':
        case 'o': case 'u': case 'x': case 'X': {
          lua_Integer n = luaL_checkinteger(L, arg);
          addlenmod(form, LUA_INTEGER_FRMLEN);
          nb = sprintf(buff, form, n);
          break;
        }
#if defined(LUA_USE_AFORMAT)
        case 'a': case 'A':
#endif
        case 'e': case 'E': case 'f':
        case 'g': case 'G': {
          addlenmod(form, LUA_NUMBER_FRMLEN);
          nb = sprintf(buff, form, luaL_checknumber(L, arg));
          break;
        }
        case 'q': {
          addquoted(L, &b, arg);
          break;
        }
        case 's': {
          size_t l;
          const char *s = luaL_tolstring(L, arg, &l);
          if (!strchr(form, '.') && l >= 100) {
            /* no precision and string is too long to be formatted;
               keep original string */
            luaL_addvalue(&b);
            break;
          }
          else {
            nb = sprintf(buff, form, s);
            lua_pop(L, 1);  /* remove result from 'luaL_tolstring' */
            break;