text: /*
  ** $Id: ltable.c,v 2.32.1.2 2007/12/28 15:32:23 roberto Exp $
  ** Lua tables (hash)
  ** See Copyright Notice in lua.h
  */
  
  
  /*
  ** Implementation of tables (aka arrays, objects, or hash tables).
  ** Tables keep its elements in two parts: an array part and a hash part.
  ** Non-negative integer keys are all candidates to be kept in the array
  ** part. The actual size of the array is the largest `n' such that at
  ** least half the slots between 0 and n are in use.
  ** Hash uses a mix of chained scatter table with Brent's variation.
  ** A main invariant of these tables is that, if an element is not
  ** in its main position (i.e. the `original' position that its hash gives
  ** to it), then the colliding element is in its own main position.
  ** Hence even when the load factor reaches 100%, performance remains good.
  */
  
  #include <math.h>
  #include <string.h>
  
  #define ltable_c
  #define LUA_CORE
  
  #include "lua.h"
  
  #include "ldebug.h"
  #include "ldo.h"
  #include "lgc.h"
  #include "lmem.h"
  #include "lobject.h"
  #include "lstate.h"
  #include "ltable.h"
  #include "lrotable.h"
  
  /*
  ** max size of array part is 2^MAXBITS
  */
  #if LUAI_BITSINT > 26
  #define MAXBITS		26
  #else
  #define MAXBITS		(LUAI_BITSINT-2)
  #endif
  
  #define MAXASIZE	(1 << MAXBITS)
  
  
  #define hashpow2(t,n)      (gnode(t, lmod((n), sizenode(t))))
    
  #define hashstr(t,str)  hashpow2(t, (str)->tsv.hash)
  #define hashboolean(t,p)        hashpow2(t, p)
  
  
  /*
  ** for some types, it is better to avoid modulus by power of 2, as
  ** they tend to have many 2 factors.
  */
  #define hashmod(t,n)	(gnode(t, ((n) % ((sizenode(t)-1)|1))))
  
  
  #define hashpointer(t,p)	hashmod(t, IntPoint(p))
  
  
  /*
  ** number of ints inside a lua_Number
  */
  #define numints		cast_int(sizeof(lua_Number)/sizeof(int))
  
  
  
  #define dummynode		(&dummynode_)
  
  static const Node dummynode_ = {
    {{NULL}, LUA_TNIL},  /* value */
    {{{NULL}, LUA_TNIL, NULL}}  /* key */
  };
  
  
  /*
  ** hash for lua_Numbers
  */
  static Node *hashnum (const Table *t, lua_Number n) {
    unsigned int a[numints];
    int i;
    if (luai_numeq(n, 0))  /* avoid problems with -0 */
      return gnode(t, 0);
    memcpy(a, &n, sizeof(a));
    for (i = 1; i < numints; i++) a[0] += a[i];
    return hashmod(t, a[0]);
  }
  
  
  
  /*
  ** returns the `main' position of an element in a table (that is, the index
  ** of its hash value)
  */
  static Node *mainposition (const Table *t, const TValue *key) {
    switch (ttype(key)) {
      case LUA_TNUMBER:
        return hashnum(t, nvalue(key));
      case LUA_TSTRING:
        return hashstr(t, rawtsvalue(key));
      case LUA_TBOOLEAN:
        return hashboolean(t, bvalue(key));
      case LUA_TLIGHTUSERDATA:
      case LUA_TROTABLE:
      case LUA_TLIGHTFUNCTION:
        return hashpointer(t, pvalue(key));
      default:
        return hashpointer(t, gcvalue(key));
    }
  }
  
  
  /*
  ** returns the index for `key' if `key' is an appropriate key to live in
  ** the array part of the table, -1 otherwise.
  */
  static int arrayindex (const TValue *key) {
    if (ttisnumber(key)) {
      lua_Number n = nvalue(key);
      int k;
      lua_number2int(k, n);
      if (luai_numeq(cast_num(k), n))
        return k;
    }
    return -1;  /* `key' did not match some condition */
  }
  
  
  /*
  ** returns the index of a `key' for table traversals. First goes all
  ** elements in the array part, then elements in the hash part. The
  ** beginning of a traversal is signalled by -1.
  */
  static int findindex (lua_State *L, Table *t, StkId key) {
    int i;
    if (ttisnil(key)) return -1;  /* first iteration */
    i = arrayindex(key);
    if (0 < i && i <= t->sizearray)  /* is `key' inside array part? */
      return i-1;  /* yes; that's the index (corrected to C) */
    else {
      Node *n = mainposition(t, key);
      do {  /* check whether `key' is somewhere in the chain */
        /* key may be dead already, but it is ok to use it in `next' */
        if (luaO_rawequalObj(key2tval(n), key) ||
              (ttype(gkey(n)) == LUA_TDEADKEY && iscollectable(key) &&
               gcvalue(gkey(n)) == gcvalue(key))) {
          i = cast_int(n - gnode(t, 0));  /* key index in hash table */
          /* hash elements are numbered after array ones */
          return i + t->sizearray;
        }
        else n = gnext(n);
      } while (n);
      luaG_runerror(L, "invalid key to " LUA_QL("next"));  /* key not found */
      return 0;  /* to avoid warnings */
    }
  }
  
  
  int luaH_next (lua_State *L, Table *t, StkId key) {
    int i = findindex(L, t, key);  /* find original element */
    for (i++; i < t->sizearray; i++) {  /* try first array part */
      if (!ttisnil(&t->array[i])) {  /* a non-nil value? */
        setnvalue(key, cast_num(i+1));
        setobj2s(L, key+1, &t->array[i]);
        return 1;
      }
    }
    for (i -= t->sizearray; i < sizenode(t); i++) {  /* then hash part */
      if (!ttisnil(gval(gnode(t, i)))) {  /* a non-nil value? */
        setobj2s(L, key, key2tval(gnode(t, i)));
        setobj2s(L, key+1, gval(gnode(t, i)));
        return 1;
      }
    }
    return 0;  /* no more elements */
  }
  
  
  int luaH_next_ro (lua_State *L, void *t, StkId key) {
    luaR_next(L, t, key, key+1);
    return ttisnil(key) ? 0 : 1;
  }
  
  
  /*
  ** {=============================================================
  ** Rehash
  ** ==============================================================
  */
  
  
  static int computesizes (int nums[], int *narray) {
    int i;
    int twotoi;  /* 2^i */
    int a = 0;  /* number of elements smaller than 2^i */
    int na = 0;  /* number of elements to go to array part */
    int n = 0;  /* optimal size for array part */
    for (i = 0, twotoi = 1; twotoi/2 < *narray; i++, twotoi *= 2) {
      if (nums[i] > 0) {
        a += nums[i];
        if (a > twotoi/2) {  /* more than half elements present? */
          n = twotoi;  /* optimal size (till now) */
          na = a;  /* all elements smaller than n will go to array part */
        }
      }
      if (a == *narray) break;  /* all elements already counted */
    }
    *narray = n;
    lua_assert(*narray/2 <= na && na <= *narray);
    return na;
  }
  
  
  static int countint (const TValue *key, int *nums) {
    int k = arrayindex(key);
    if (0 < k && k <= MAXASIZE) {  /* is `key' an appropriate array index? */
      nums[ceillog2(k)]++;  /* count as such */
      return 1;
    }
    else
      return 0;
  }
  
  
  static int numusearray (const Table *t, int *nums) {
    int lg;
    int ttlg;  /* 2^lg */
    int ause = 0;  /* summation of `nums' */
    int i = 1;  /* count to traverse all array keys */
    for (lg=0, ttlg=1; lg<=MAXBITS; lg++, ttlg*=2) {  /* for each slice */
      int lc = 0;  /* counter */
      int lim = ttlg;
      if (lim > t->sizearray) {
        lim = t->sizearray;  /* adjust upper limit */
        if (i > lim)
          break;  /* no more elements to count */
      }
      /* count elements in range (2^(lg-1), 2^lg] */
      for (; i <= lim; i++) {
        if (!ttisnil(&t->array[i-1]))
          lc++;
      }
      nums[lg] += lc;
      ause += lc;
    }
    return ause;
  }
  
  
  static int numusehash (const Table *t, int *nums, int *pnasize) {
    int totaluse = 0;  /* total number of elements */
    int ause = 0;  /* summation of `nums' */
    int i = sizenode(t);
    while (i--) {
      Node *n = &t->node[i];
      if (!ttisnil(gval(n))) {
        ause += countint(key2tval(n), nums);
        totaluse++;
      }
    }
    *pnasize += ause;
    return totaluse;
  }
  
  
  static void setarrayvector (lua_State *L, Table *t, int size) {
    int i;
    luaM_reallocvector(L, t->array, t->sizearray, size, TValue);
    for (i=t->sizearray; i<size; i++)
       setnilvalue(&t->array[i]);
    t->sizearray = size;
  }
  
  
  static Node *getfreepos (Table *t) {
    while (t->lastfree-- > t->node) {
      if (ttisnil(gkey(t->lastfree)))
        return t->lastfree;
    }
    return NULL;  /* could not find a free place */
  }
  
  
  static void resizenodevector (lua_State *L, Table *t, int oldsize, int newsize) {
    int lsize;
    if (newsize == 0) {  /* no elements to hash part? */
      t->node = cast(Node *, dummynode);  /* use common `dummynode' */
      lsize = 0;
    }
    else {
      Node *node = t->node;
      int i;
      lsize = ceillog2(newsize);
      if (lsize > MAXBITS)
        luaG_runerror(L, "table overflow");
      newsize = twoto(lsize);
      if (node == dummynode) {
        oldsize = 0;
        node = NULL; /* don't try to realloc `dummynode' pointer. */
      }
      luaM_reallocvector(L, node, oldsize, newsize, Node);
      t->node = node;
      for (i=oldsize; i<newsize; i++) {
        Node *n = gnode(t, i);
        gnext(n) = NULL;
        setnilvalue(gkey(n));
        setnilvalue(gval(n));
      }
    }
    t->lsizenode = cast_byte(lsize);
    t->lastfree = gnode(t, newsize);  /* reset lastfree to end of table. */
  }
  
  
  static Node *find_prev_node(Node *mp, Node *next) {
    Node *prev = mp;
    while (prev != NULL && gnext(prev) != next) prev = gnext(prev);
    return prev;
  }
  
  
  /*
  ** move a node from it's old position to it's new position during a rehash;
  ** first, check whether the moving node'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 moving node in its main position; otherwise
  ** (colliding node is in its main position), moving node goes to an empty position. 
  */
  static int move_node (lua_State *L, Table *t, Node *node) {
    Node *mp = mainposition(t, key2tval(node));
    /* if node is in it's main position, don't need to move node. */
    if (mp == node) return 1;
    /* if node is in it's main position's chain, don't need to move node. */
    if (find_prev_node(mp, node) != NULL) return 1;
    /* is main position is free? */
    if (!ttisnil(gval(mp)) || mp == dummynode) {
      /* no; move main position node if it is out of its main position */
      Node *othermp;
      othermp = mainposition(t, key2tval(mp));
      if (othermp != mp) {  /* is colliding node out of its main position? */
        /* yes; swap colliding node with the node that is being moved. */
        Node *prev;
        Node tmp;
        tmp = *node;
        prev = find_prev_node(othermp, mp);  /* find previous */
        if (prev != NULL) gnext(prev) = node;  /* redo the chain with `n' in place of `mp' */
        *node = *mp;  /* copy colliding node into free pos. (mp->next also goes) */
        *mp = tmp;
        return (prev != NULL) ? 1 : 0; /* is colliding node part of its main position chain? */
      }
      else {  /* colliding node is in its own main position */
        /* add node to main position's chain. */
        gnext(node) = gnext(mp);  /* chain new position */
        gnext(mp) = node;
      }
    }
    else { /* main position is free, move node */
      *mp = *node;
      gnext(node) = NULL;
      setnilvalue(gkey(node));
      setnilvalue(gval(node));
    }
    return 1;
  }
  
  
  static int move_number (lua_State *L, Table *t, Node *node) {
    int key;
    lua_Number n = nvalue(key2tval(node));
    lua_number2int(key, n);
    if (luai_numeq(cast_num(key), nvalue(key2tval(node)))) {/* index is int? */
      /* (1 <= key && key <= t->sizearray) */
      if (cast(unsigned int, key-1) < cast(unsigned int, t->sizearray)) {
        setobjt2t(L, &t->array[key-1], gval(node));
        setnilvalue(gkey(node));
        setnilvalue(gval(node));
        return 1;
      }
    }
    return 0;
  }
  
  
  static void resize_hashpart (lua_State *L, Table *t, int nhsize) {
    int i;
    int lsize=0;
    int oldhsize = (t->node != dummynode) ? twoto(t->lsizenode) : 0;
    if (nhsize > 0) { /* round new hashpart size up to next power of two. */
      lsize=ceillog2(nhsize);
      if (lsize > MAXBITS)
        luaG_runerror(L, "table overflow");
    }
    nhsize = twoto(lsize);
    /* grow hash part to new size. */
    if (oldhsize < nhsize)
      resizenodevector(L, t, oldhsize, nhsize);
    else { /* hash part might be shrinking */
      if (nhsize > 0) {
        t->lsizenode = cast_byte(lsize);
        t->lastfree = gnode(t, nhsize);  /* reset lastfree back to end of table. */
      }
      else { /* new hashpart size is zero. */
        resizenodevector(L, t, oldhsize, nhsize);
        return;
      }
    }
    /* break old chains, try moving int keys to array part and compact keys into new hashpart */
    for (i = 0; i < oldhsize; i++) {
      Node *old = gnode(t, i);
      gnext(old) = NULL;
      if (ttisnil(gval(old))) { /* clear nodes with nil values. */
        setnilvalue(gkey(old));
        continue;
      }
      if (ttisnumber(key2tval(old))) { /* try moving the int keys into array part. */
        if(move_number(L, t, old))
          continue;
      }
      if (i >= nhsize) { /* move all valid keys to indices < nhsize. */
        Node *n = getfreepos(t);  /* get a free place */
        lua_assert(n != dummynode && n != NULL);
        *n = *old;
      }
    }
    /* shrink hash part */
    if (oldhsize > nhsize)
      resizenodevector(L, t, oldhsize, nhsize);
    /* move nodes to their new mainposition and re-create node chains */
    for (i = 0; i < nhsize; i++) {
      Node *curr = gnode(t, i);
      if (!ttisnil(gval(curr)))
        while (move_node(L, t, curr) == 0);
    }
  }
  
  
  static void resize (lua_State *L, Table *t, int nasize, int nhsize) {
    int i;
    int oldasize = t->sizearray;
    if (nasize > oldasize)  /* array part must grow? */
      setarrayvector(L, t, nasize);
    resize_hashpart(L, t, nhsize);
    if (nasize < oldasize) {  /* array part must shrink? */
      t->sizearray = nasize;
      /* re-insert elements from vanishing slice */
      for (i=nasize; i<oldasize; i++) {
        if (!ttisnil(&t->array[i]))
          setobjt2t(L, luaH_setnum(L, t, i+1), &t->array[i]);
      }
      /* shrink array */
      luaM_reallocvector(L, t->array, oldasize, nasize, TValue);
    }
  }
  
  
  void luaH_resizearray (lua_State *L, Table *t, int nasize) {
    int nsize = (t->node == dummynode) ? 0 : sizenode(t);
    resize(L, t, nasize, nsize);
  }
  
  
  static void rehash (lua_State *L, Table *t, const TValue *ek) {
    int nasize, na;
    int nums[MAXBITS+1];  /* nums[i] = number of keys between 2^(i-1) and 2^i */
    int i;
    int totaluse;
    for (i=0; i<=MAXBITS; i++) nums[i] = 0;  /* reset counts */
    nasize = numusearray(t, nums);  /* count keys in array part */
    totaluse = nasize;  /* all those keys are integer keys */
    totaluse += numusehash(t, nums, &nasize);  /* count keys in hash part */
    /* count extra key */
    nasize += countint(ek, nums);
    totaluse++;
    /* compute new size for array part */
    na = computesizes(nums, &nasize);
    /* resize the table to new computed sizes */
    resize(L, t, nasize, totaluse - na);
  }
  
  
  
  /*
  ** }=============================================================
  */
  
  
  Table *luaH_new (lua_State *L, int narray, int nhash) {
    Table *t = luaM_new(L, Table);
    luaC_link(L, obj2gco(t), LUA_TTABLE);
    sethvalue2s(L, L->top, t); /* put table on stack */
    incr_top(L);
    t->metatable = NULL;
    t->flags = cast_byte(~0);
    /* temporary values (kept only if some malloc fails) */
    t->array = NULL;
    t->sizearray = 0;
    t->lsizenode = 0;
    t->node = cast(Node *, dummynode);
    setarrayvector(L, t, narray);
    resizenodevector(L, t, 0, nhash);
    L->top--; /* remove table from stack */
    return t;
  }
  
  
  void luaH_free (lua_State *L, Table *t) {
    if (t->node != dummynode)
      luaM_freearray(L, t->node, sizenode(t), Node);
    luaM_freearray(L, t->array, t->sizearray, TValue);
    luaM_free(L, t);
  }
  
  
  
  /*
  ** 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. 
  */
  static TValue *newkey (lua_State *L, Table *t, const TValue *key) {
    Node *mp = mainposition(t, key);
    if (!ttisnil(gval(mp)) || mp == dummynode) {
      Node *othern;
      Node *n = getfreepos(t);  /* get a free place */
      if (n == NULL) {  /* cannot find a free place? */
        rehash(L, t, key);  /* grow table */
        return luaH_set(L, t, key);  /* re-insert key into grown table */
      }
      lua_assert(n != dummynode);
      othern = mainposition(t, key2tval(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;
      }
    }
    gkey(mp)->value = key->value; gkey(mp)->tt = key->tt;
    luaC_barriert(L, t, key);
    lua_assert(ttisnil(gval(mp)));
    return gval(mp);
  }
  
  
  /*
  ** search function for integers
  */
  const TValue *luaH_getnum (Table *t, int key) {
    /* (1 <= key && key <= t->sizearray) */
    if (cast(unsigned int, key-1) < cast(unsigned int, t->sizearray))
      return &t->array[key-1];
    else {
      lua_Number nk = cast_num(key);
      Node *n = hashnum(t, nk);
      do {  /* check whether `key' is somewhere in the chain */
        if (ttisnumber(gkey(n)) && luai_numeq(nvalue(gkey(n)), nk))
          return gval(n);  /* that's it */
        else n = gnext(n);
      } while (n);
      return luaO_nilobject;
    }
  }
  
  /* same thing for rotables */
  const TValue *luaH_getnum_ro (void *t, int key) {
    const TValue *res = luaR_findentry(t, NULL, key, NULL);
    return res ? res : luaO_nilobject;
  }
  
  
  /*
  ** search function for strings
  */
  const TValue *luaH_getstr (Table *t, TString *key) {
    Node *n = hashstr(t, key);
    do {  /* check whether `key' is somewhere in the chain */
      if (ttisstring(gkey(n)) && rawtsvalue(gkey(n)) == key)
        return gval(n);  /* that's it */
      else n = gnext(n);
    } while (n);
    return luaO_nilobject;
  }
  
  /* same thing for rotables */
  const TValue *luaH_getstr_ro (void *t, TString *key) {
    char keyname[LUA_MAX_ROTABLE_NAME + 1];
    const TValue *res;  
    if (!t)
      return luaO_nilobject;
    luaR_getcstr(keyname, key, LUA_MAX_ROTABLE_NAME);   
    res = luaR_findentry(t, keyname, 0, NULL);
    return res ? res : luaO_nilobject;
  }
  
  
  /*
  ** main search function
  */
  const TValue *luaH_get (Table *t, const TValue *key) {
    switch (ttype(key)) {
      case LUA_TNIL: return luaO_nilobject;
      case LUA_TSTRING: return luaH_getstr(t, rawtsvalue(key));
      case LUA_TNUMBER: {
        int k;
        lua_Number n = nvalue(key);
        lua_number2int(k, n);
        if (luai_numeq(cast_num(k), nvalue(key))) /* index is int? */
          return luaH_getnum(t, k);  /* use specialized version */
        /* else go through */
      }
      default: {
        Node *n = mainposition(t, key);
        do {  /* check whether `key' is somewhere in the chain */
          if (luaO_rawequalObj(key2tval(n), key))
            return gval(n);  /* that's it */
          else n = gnext(n);
        } while (n);
        return luaO_nilobject;
      }
    }
  }
  
  /* same thing for rotables */
  const TValue *luaH_get_ro (void *t, const TValue *key) {
    switch (ttype(key)) {
      case LUA_TNIL: return luaO_nilobject;
      case LUA_TSTRING: return luaH_getstr_ro(t, rawtsvalue(key));
      case LUA_TNUMBER: {
        int k;
        lua_Number n = nvalue(key);
        lua_number2int(k, n);
        if (luai_numeq(cast_num(k), nvalue(key))) /* index is int? */
          return luaH_getnum_ro(t, k);  /* use specialized version */
        /* else go through */
      }
      default: {
        return luaO_nilobject;
      }
    }
  }
  
  
  TValue *luaH_set (lua_State *L, Table *t, const TValue *key) {
    const TValue *p = luaH_get(t, key);
    t->flags = 0;
    if (p != luaO_nilobject)
      return cast(TValue *, p);
    else {
      if (ttisnil(key)) luaG_runerror(L, "table index is nil");
      else if (ttisnumber(key) && luai_numisnan(nvalue(key)))
        luaG_runerror(L, "table index is NaN");
      return newkey(L, t, key);
    }
  }
  
  
  TValue *luaH_setnum (lua_State *L, Table *t, int key) {
    const TValue *p = luaH_getnum(t, key);
    if (p != luaO_nilobject)
      return cast(TValue *, p);
    else {
      TValue k;
      setnvalue(&k, cast_num(key));
      return newkey(L, t, &k);
    }
  }
  
  
  TValue *luaH_setstr (lua_State *L, Table *t, TString *key) {
    const TValue *p = luaH_getstr(t, key);
    if (p != luaO_nilobject)
      return cast(TValue *, p);
    else {
      TValue k;
      setsvalue(L, &k, key);
      return newkey(L, t, &k);
    }
  }
  
  
  static int unbound_search (Table *t, unsigned int j) {
    unsigned int i = j;  /* i is zero or a present index */
    j++;
    /* find `i' and `j' such that i is present and j is not */
    while (!ttisnil(luaH_getnum(t, j))) {
      i = j;
      j *= 2;
      if (j > cast(unsigned int, MAX_INT)) {  /* overflow? */
        /* table was built with bad purposes: resort to linear search */
        i = 1;
        while (!ttisnil(luaH_getnum(t, i))) i++;
        return i - 1;
      }
    }
    /* now do a binary search between them */
    while (j - i > 1) {
      unsigned int m = (i+j)/2;
      if (ttisnil(luaH_getnum(t, m))) j = m;
      else i = m;
    }
    return i;
  }
  
  
  /*
  ** Try to find a boundary in table `t'. A `boundary' is an integer index
  ** such that t[i] is non-nil and t[i+1] is nil (and 0 if t[1] is nil).
  */
  int luaH_getn (Table *t) {
    unsigned int j = t->sizearray;
    if (j > 0 && ttisnil(&t->array[j - 1])) {
      /* there is a boundary in the array part: (binary) search for it */
      unsigned int i = 0;
      while (j - i > 1) {
        unsigned int m = (i+j)/2;
        if (ttisnil(&t->array[m - 1])) j = m;
        else i = m;
      }
      return i;
    }
    /* else must find a boundary in hash part */
    else if (t->node == dummynode)  /* hash part is empty? */
      return j;  /* that is easy... */
    else return unbound_search(t, j);
  }
  
  /* same thing for rotables */
  int luaH_getn_ro (void *t) {
    int i = 1, len=0;
    
    while(luaR_findentry(t, NULL, i ++, NULL))
      len ++;
    return len;
  }
  
  #if defined(LUA_DEBUG)
  
  Node *luaH_mainposition (const Table *t, const TValue *key) {
    return mainposition(t, key);
  }
  
  int luaH_isdummy (Node *n) { return n == dummynode; }
  
  #endif
  