Function luaH_newkey

third-party/lua-5.2.4/src/ltable.c:405–440

** inserts a new key into a hash table; first, check whether key's main ** position is free. If not, check whether colliding node is in its main ** position or not: if it is not, move colliding node to an empty place and ** put new key in its main position; otherwise (colliding node is in its main ** position), new key goes to an empty position. */

** position), new key goes to an empty position.
*/
TValue *luaH_newkey (lua_State *L, Table *t, const TValue *key) {
  Node *mp;
  if (ttisnil(key)) luaG_runerror(L, "table index is nil");
  else if (ttisnumber(key) && luai_numisnan(L, nvalue(key)))
    luaG_runerror(L, "table index is NaN");
  mp = mainposition(t, key);
  if (!ttisnil(gval(mp)) || isdummy(mp)) {  /* main position is taken? */
    Node *othern;
    Node *n = getfreepos(t);  /* get a free place */
    if (n == NULL) {  /* cannot find a free place? */
      rehash(L, t, key);  /* grow table */
      /* whatever called 'newkey' take care of TM cache and GC barrier */
      return luaH_set(L, t, key);  /* insert key into grown table */
    }
    lua_assert(!isdummy(n));
    othern = mainposition(t, gkey(mp));
    if (othern != mp) {  /* is colliding node out of its main position? */
      /* yes; move colliding node into free position */
      while (gnext(othern) != mp) othern = gnext(othern);  /* find previous */
      gnext(othern) = n;  /* redo the chain with `n' in place of `mp' */
      *n = *mp;  /* copy colliding node into free pos. (mp->next also goes) */
      gnext(mp) = NULL;  /* now `mp' is free */
      setnilvalue(gval(mp));
    }
    else {  /* colliding node is in its own main position */
      /* new node will go into free position */
      gnext(n) = gnext(mp);  /* chain new position */
      gnext(mp) = n;
      mp = n;
    }
  }
  setobj2t(L, gkey(mp), key);
  luaC_barrierback(L, obj2gco(t), key);
  lua_assert(ttisnil(gval(mp)));
  return gval(mp);
}


/*