Function iter_aux

third-party/lua-5.3.5/src/lutf8lib.c:201–222

static int iter_aux (lua_State *L) {
  size_t len;
  const char *s = luaL_checklstring(L, 1, &len);
  lua_Integer n = lua_tointeger(L, 2) - 1;
  if (n < 0)  /* first iteration? */
    n = 0;  /* start from here */
  else if (n < (lua_Integer)len) {
    n++;  /* skip current byte */
    while (iscont(s + n)) n++;  /* and its continuations */
  }
  if (n >= (lua_Integer)len)
    return 0;  /* no more codepoints */
  else {
    int code;
    const char *next = utf8_decode(s + n, &code);
    if (next == NULL || iscont(next))
      return luaL_error(L, "invalid UTF-8 code");
    lua_pushinteger(L, n + 1);
    lua_pushinteger(L, code);
    return 2;
  }
}


static int iter_codes (lua_State *L) {