/*
** $Id: ltable.c,v 2.72.1.1 2013/04/12 18:48:47 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 <string.h>
#include <assert.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 "lstring.h"
#include "ltable.h"
#include "lvm.h"


/*
** max size of array part is 2^MAXBITS
*/
#if LUAI_BITSINT >= 32
#define MAXBITS		30
#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))


#define dummynode		(&dummynode_)

#define isdummy(n)		((n) == dummynode)

static const Node dummynode_ = {
  {{NILCONSTANT}, 0}, /* anode: value, sequence */
  {NILCONSTANT},      /* key */
  NULL                /* next */
};

static int truesizenode(Table *t) {
   return isdummy(t->node) ? 0 : sizenode(t);
}

/* given a valid anode pointer, return its index */      
static int anodeindex(Table *t, ANode *anode) {
  int aoffs = anode - t->array;
  if (aoffs >= 0 && aoffs < t->sizearray && (t->array+aoffs==anode)) {
    return aoffs;
  }
  Node *node = cast(Node *, anode);
  return (node - t->node) + t->sizearray;
}

/* given a valid anode index, return its pointer */
static ANode *nthanode(Table *t, int n) {
    if (n < t->sizearray) {
        return t->array + n;
    } else {
        return &t->node[n - t->sizearray].anode;
    }
}

static void checksequence(Table *t) {
  assert(t->nnkeys >= 0);
  int nodesize = truesizenode(t);
  int totalanodes = t->sizearray + nodesize;
  for (int i = 0; i < t->nnkeys; i++) {
    int anodeindex = t->sequence[i];
    assert((anodeindex >= 0) && (anodeindex < totalanodes));
    ANode *n = nthanode(t, anodeindex);
    assert(n->i_sequence == i);
  }
  for (int i = 0; i < t->sizearray; i++) {
    int seqno = t->array[i].i_sequence;
    if (seqno != -1) {
        assert((seqno >= 0) && (seqno < t->nnkeys));
        assert(t->sequence[seqno] == i);
    }
  }
  for (int i = 0; i < nodesize; i++) {
    Node *n = t->node + i;
    int seqno = gseq(n);
    if (seqno != -1) {
        assert((seqno >= 0) && (seqno < t->nnkeys));
        assert(t->sequence[seqno] == i + t->sizearray);
    }
  }
}


/*
** hash for lua_Numbers
*/
static Node *hashnum (const Table *t, lua_Number n) {
  int i;
  luai_hashnum(i, n);
  if (i < 0) {
    if (cast(unsigned int, i) == 0u - i)  /* use unsigned to avoid overflows */
      i = 0;  /* handle INT_MIN */
    i = -i;  /* must be a positive value */
  }
  return hashmod(t, i);
}



/*
** 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_TLNGSTR: {
      TString *s = rawtsvalue(key);
      if (s->tsv.extra == 0) {  /* no hash? */
        s->tsv.hash = luaS_hash(getstr(s), s->tsv.len, s->tsv.hash);
        s->tsv.extra = 1;  /* now it has its hash */
      }
      return hashstr(t, rawtsvalue(key));
    }
    case LUA_TSHRSTR:
      return hashstr(t, rawtsvalue(key));
    case LUA_TBOOLEAN:
      return hashboolean(t, bvalue(key));
    case LUA_TLIGHTUSERDATA:
      return hashpointer(t, pvalue(key));
    case LUA_TLCF:
      return hashpointer(t, fvalue(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 */
}

int luaH_nkeys (Table *t) {
    return t->nnkeys;
}

int luaH_nthkey (lua_State *L, Table *t, int n, StkId pair) {
    n -= 1; /* convert to C indexing */
    if ((n < 0) || (n >= t->nnkeys)) {
        setnilvalue(pair+0);
        setnilvalue(pair+1);
        return 0;
    }
    int index = t->sequence[n];
    if (index < t->sizearray) {
        setnvalue(pair + 0, index + 1);
        setobj2s(L, pair + 1, &t->array[index].i_val);
        return 1;
    } else {
        index -= t->sizearray;
        Node *n = t->node + index;
        setobj2s(L, pair + 0, gkey(n));
        setobj2s(L, pair + 1, gval(n));
        return 1;
    }
}

int successorindex (lua_State *L, Table *t, StkId key) {
  int i, seqno;
  if (ttisnil(key)) {
    return 0;
  }
  i = arrayindex(key);
  if (0 < i && i <= t->sizearray) {
    seqno = t->array[i-1].i_sequence + 1;
    if (seqno == 0) {
        if (t->array + (i - 1) == t->lastdeleted) {
            return t->lastdelseq;
        }
        luaG_runerror(L, "next: no such key in table");
    }
    return seqno;
  }
  Node *n = mainposition(t, key);
  for (;;) {  /* check whether `key' is somewhere in the chain */
    /* key may be dead already, but it is ok to use it in `next' */
    if (luaV_rawequalobj(gkey(n), key) ||
        (ttisdeadkey(gkey(n)) && iscollectable(key) &&
            deadvalue(gkey(n)) == gcvalue(key))) {
      seqno = gseq(n) + 1;
      if (seqno == 0) {
        if (ganode(n) == t->lastdeleted) {
            return t->lastdelseq;
        }
        luaG_runerror(L, "next: no such key in table");
      }
      return seqno;
    }
    else n = gnext(n);
    if (n == NULL)
    luaG_runerror(L, "invalid key to " LUA_QL("next"));  /* key not found */
  }
}

int luaH_next (lua_State *L, Table *t, StkId key) {
  int seqno = successorindex(L, t, key);
  if (seqno >= t->nnkeys) {
    return 0;
  }
  int i = t->sequence[seqno];
  if (i < t->sizearray) {
    setnvalue(key + 0, i+1);
    setobj2s(L, key + 1, &t->array[i].i_val);
    return 1;
  } else {
    Node *n = t->node + (i - t->sizearray);
    setobj2s(L, key + 0, gkey(n));
    setobj2s(L, key + 1, gval(n));
    return 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[luaO_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].i_val))
        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(gkey(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, ANode);
  for (i=t->sizearray; i<size; i++) {
     setnilvalue(&t->array[i].i_val);
     t->array[i].i_sequence = -1;
  }
  t->sizearray = size;
}


static void setnodevector (lua_State *L, Table *t, int size) {
  int lsize;
  if (size == 0) {  /* no elements to hash part? */
    t->node = cast(Node *, dummynode);  /* use common `dummynode' */
    lsize = 0;
  }
  else {
    int i;
    lsize = luaO_ceillog2(size);
    if (lsize == 0) lsize = 1;
    if (lsize > MAXBITS)
        luaG_runerror(L, "table overflow");
    size = twoto(lsize);
    t->node = luaM_newvector(L, size, Node);
    for (i=0; i<size; i++) {
      Node *n = gnode(t, i);
      gnext(n) = NULL;
      gseq(n) = -1;
      setnilvalue(gkey(n));
      setnilvalue(gval(n));
    }
  }
  t->lsizenode = cast_byte(lsize);
  t->lastfree = gnode(t, size);  /* all positions are free */
}

static TValue *luaH_newkey(lua_State *L, Table *t, const TValue *key);

static void storeintanode (lua_State *L, Table *t, int key, ANode *anode) {
  const TValue *p = luaH_getint(t, key);
  ANode *cell;
  if (p != luaO_nilobject) {
    cell = cast(ANode *, p);
  } else {
    TValue nk;
    setnvalue(&nk, key);
    cell = cast(ANode *, luaH_newkey(L, t, &nk));
  }
  setobj2t(L, &cell->i_val, &anode->i_val);
  cell->i_sequence = anode->i_sequence;
}

static void storeanode (lua_State *L, Table *t, const TValue *key, ANode *anode) {
  const TValue *p = luaH_get(t, key);
  ANode *cell;
  if (p != luaO_nilobject) {
    cell = cast(ANode *, p);
  } else {
    cell = cast(ANode *, luaH_newkey(L, t, key));
  }
  setobj2t(L, &cell->i_val, &anode->i_val);
  cell->i_sequence = anode->i_sequence;
}


void luaH_resize (lua_State *L, Table *t, int nasize, int nhsize) {
  int i;
  int oldasize = t->sizearray;
  int oldhsize = truesizenode(t);
  Node *nold = t->node;  /* save old hash ... */
  if (nasize > oldasize)  /* array part must grow? */
    setarrayvector(L, t, nasize);
  /* create new hash part with appropriate size */
  setnodevector(L, t, nhsize);
  nhsize = truesizenode(t);
  /* resize the sequence array */
  int oldseqlen = oldasize + oldhsize;
  int newseqlen = nasize + nhsize;
  if (newseqlen < t->nnkeys)
    luaG_runerror(L, "table sequence vector not large enough?");
  luaM_reallocvector(L, t->sequence, oldseqlen, newseqlen, int);
  /* possibly shrink the array part */
  if (nasize < oldasize) {
    t->sizearray = nasize;
    /* re-insert elements from vanishing slice */
    for (i=nasize; i<oldasize; i++) {
      if (!ttisnil(&t->array[i].i_val))
        storeintanode(L, t, i + 1, &t->array[i]);
    }
    /* shrink array */
    luaM_reallocvector(L, t->array, oldasize, nasize, ANode);
  }
  /* re-insert elements from hash part */
  for (i = oldhsize - 1; i >= 0; i--) {
    Node *old = nold+i;
    if (!ttisnil(gval(old))) {
      /* doesn't need barrier/invalidate cache, as entry was
         already present in the table */
      storeanode(L, t, gkey(old), ganode(old));
    }
  }
  /* delete the old node vector */
  if (!isdummy(nold))
    luaM_freearray(L, nold, cast(size_t, oldhsize));
  /* recalculate the entire sequence vector */
  int total = 0;
  for (i = nasize - 1; i >= 0; i--) {
    ANode *anode = &t->array[i];
    if (anode->i_sequence >= 0) {
      assert(anode->i_sequence < t->nnkeys);
      t->sequence[anode->i_sequence] = i;
      total += 1;
    }
  }
  for (i = nhsize - 1; i >= 0; i--) {
    ANode *anode = &t->node[i].anode;
    if (anode->i_sequence >= 0) {
      assert(anode->i_sequence < t->nnkeys);
      t->sequence[anode->i_sequence] = i + t->sizearray;
      total += 1;
    }
  }
  t->nnkeys = total;
}


void luaH_resizearray (lua_State *L, Table *t, int nasize) {
  luaH_resize(L, t, nasize, truesizenode(t));
}


static void rehash (lua_State *L, Table *t, const TValue *ek) {
  int nasize, na;
  int nums[MAXBITS+1];  /* nums[i] = number of keys with 2^(i-1) < k <= 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 */
  luaH_resize(L, t, nasize, totaluse - na);
}



/*
** }=============================================================
*/


Table *luaH_new (lua_State *L) {
  Table *t = &luaC_newobj(L, LUA_TTABLE, sizeof(Table), NULL, 0)->h;
  t->metatable = NULL;
  t->flags = cast_byte(~0);
  t->array = NULL;
  t->sizearray = 0;
  t->node = cast(Node *, dummynode);
  t->lsizenode = 0;
  t->lastfree = gnode(t, 0);
  t->sequence = 0;
  t->nnkeys = 0;
  t->lastdeleted = NULL;
  t->lastdelseq = -1;
  return t;
}


void luaH_free (lua_State *L, Table *t) {
  if (!isdummy(t->node))
    luaM_freearray(L, t->node, cast(size_t, sizenode(t)));
  luaM_freearray(L, t->array, t->sizearray);
  int seqlen = t->sizearray + truesizenode(t);
  luaM_freearray(L, t->sequence, seqlen);
  luaM_free(L, t);
}


static Node *getfreepos (Table *t) {
  while (t->lastfree > t->node) {
    t->lastfree--;
    if (ttisnil(gkey(t->lastfree)))
      return t->lastfree;
  }
  return NULL;  /* could not find a free place */
}



/*
** 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 *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 */
      const TValue *p = luaH_get(t, key);
      if (p != luaO_nilobject)
        return cast(TValue *, p);
      return luaH_newkey(L, t, key);      
    }
    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));
      gseq(mp) = -1;
      int seqno = gseq(n);
      t->sequence[seqno] = (n - t->node) + t->sizearray;
    }
    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);
}


/*
** search function for integers
*/
const TValue *luaH_getint (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].i_val;
  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;
  }
}


/*
** search function for short strings
*/
const TValue *luaH_getstr (Table *t, TString *key) {
  Node *n = hashstr(t, key);
  lua_assert(key->tsv.tt == LUA_TSHRSTR);
  do {  /* check whether `key' is somewhere in the chain */
    if (ttisshrstring(gkey(n)) && eqshrstr(rawtsvalue(gkey(n)), key))
      return gval(n);  /* that's it */
    else n = gnext(n);
  } while (n);
  return luaO_nilobject;
}


/*
** main search function
*/
const TValue *luaH_get (Table *t, const TValue *key) {
  switch (ttype(key)) {
    case LUA_TSHRSTR: return luaH_getstr(t, rawtsvalue(key));
    case LUA_TNIL: return luaO_nilobject;
    case LUA_TNUMBER: {
      int k;
      lua_Number n = nvalue(key);
      lua_number2int(k, n);
      if (luai_numeq(cast_num(k), n)) /* index is int? */
        return luaH_getint(t, k);  /* use specialized version */
      /* else go through */
    }
    default: {
      Node *n = mainposition(t, key);
      do {  /* check whether `key' is somewhere in the chain */
        if (luaV_rawequalobj(gkey(n), key))
          return gval(n);  /* that's it */
        else n = gnext(n);
      } while (n);
      return luaO_nilobject;
    }
  }
}

/* Change an entry to non-nil. */
/* This means the entry must be added to the sequence */
void luaH_setnonnil(Table *t, ANode *anode, const TValue *value) {
  assert(ttisnil(&anode->i_val));
  assert(anode->i_sequence == -1);
  int index = anodeindex(t, anode);
  int totalanodes = t->sizearray + truesizenode(t);
  assert((index >= 0) && (index < totalanodes));
  anode->i_sequence = t->nnkeys++;
  assert((anode->i_sequence >= 0) && (anode->i_sequence < totalanodes));
  t->sequence[anode->i_sequence] = index;
  t->lastdeleted = NULL;
  t->lastdelseq = -1;
  setobj2t(L, &anode->i_val, value);
}

/* Change an entry to nil. */
/* This means the entry must be removed from the sequence */
void luaH_setnil(Table *t, ANode *anode) {
  assert(!ttisnil(&anode->i_val));
  assert((anode->i_sequence >= 0) && (anode->i_sequence < t->nnkeys));
  /* remove the last item from the sequence, and get a pointer to its anode */
  int totalanodes = t->sizearray + truesizenode(t);
  assert((t->nnkeys > 0) && (t->nnkeys <= totalanodes));
  int lastanodeindex = t->sequence[t->nnkeys - 1];
  assert((lastanodeindex >= 0) && (lastanodeindex < totalanodes));
  ANode *lastanode = nthanode(t, lastanodeindex);
  /* move the last anode to the freed slot */
  int freeslot = anode->i_sequence;
  t->sequence[freeslot] = lastanodeindex;
  t->nnkeys -= 1;
  lastanode->i_sequence = freeslot;
  /* clear out the anode */
  anode->i_sequence = -1;
  setnilvalue(&anode->i_val);
}

/*
** beware: when using this function you probably need to check a GC
** barrier and invalidate the TM cache.
*/
void luaH_setupdate (lua_State *L, Table *t, const TValue *key, TValue *value, const TValue *getres) {
  if (!ttisnil(getres)) {
    if (ttisnil(value)) {
      /* replacing a non-nil value with nil */
      ANode *anode = cast(ANode *, getres);
      t->lastdeleted = anode;
      t->lastdelseq = anode->i_sequence;
      luaH_setnil(t, anode);
      checksequence(t);
    } else {
      /* replacing a non-nil value with a different non-nil value */
      TValue *cell = cast(TValue *, getres);
      setobj2t(L, cell, value);
      checksequence(t);
    }
  } else if (getres == luaO_nilobject) {
    if (!ttisnil(value)) {
      /* creating a new key with a non-nil value */
      t->lastdeleted = NULL;
      t->lastdelseq = -1;
      ANode *anode = cast(ANode *, luaH_newkey(L, t, key));
      luaH_setnonnil(t, anode, value);
      checksequence(t);
    }
  } else if (!ttisnil(value)) {
    /* replacing a nil value with a non-nil value */
    t->lastdeleted = NULL;
    t->lastdelseq = -1;
    luaH_setnonnil(t, cast(ANode *, getres), value);
    checksequence(t);
  }
}

void luaH_setvalue (lua_State *L, Table *t, const TValue *key, TValue *value) {
  luaH_setupdate(L, t, key, value, luaH_get(t, key));
}

void luaH_setint (lua_State *L, Table *t, int key, TValue *value) {
  TValue kv;
  setnvalue(&kv, key);
  luaH_setupdate(L, t, &kv, value, luaH_getint(t, key));
}

/*
** 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 = 1;
  unsigned int i = 0;
  /* find `i' and `j' such that i is present and j is not */
  while (!ttisnil(luaH_getint(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_getint(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_getint(t, m))) j = m;
    else i = m;
  }
  return i;
}



#if defined(LUA_DEBUG)

Node *luaH_mainposition (const Table *t, const TValue *key) {
  return mainposition(t, key);
}

int luaH_isdummy (Node *n) { return isdummy(n); }

#endif