text: /*
  ** $Id: ltable.c $
  ** Lua tables (hash)
  ** See Copyright Notice in lua.h
  */
  
  #define ltable_c
  #define LUA_CORE
  
  #include "third_party/lua/ldebug.h"
  #include "third_party/lua/ldo.h"
  #include "third_party/lua/lgc.h"
  #include "third_party/lua/lmem.h"
  #include "third_party/lua/lobject.h"
  #include "third_party/lua/lprefix.h"
  #include "third_party/lua/lstate.h"
  #include "third_party/lua/lstring.h"
  #include "third_party/lua/ltable.h"
  #include "third_party/lua/lua.h"
  #include "third_party/lua/lvm.h"
  
  /* clang-format off */
  
  /*
  ** 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
  ** more than half the slots between 1 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.
  */
  
  
  /*
  ** MAXABITS is the largest integer such that MAXASIZE fits in an
  ** unsigned int.
  */
  #define MAXABITS	cast_int(sizeof(int) * CHAR_BIT - 1)
  
  
  /*
  ** MAXASIZE is the maximum size of the array part. It is the minimum
  ** between 2^MAXABITS and the maximum size that, measured in bytes,
  ** fits in a 'size_t'.
  */
  #define MAXASIZE	luaM_limitN(1u << MAXABITS, TValue)
  
  /*
  ** MAXHBITS is the largest integer such that 2^MAXHBITS fits in a
  ** signed int.
  */
  #define MAXHBITS	(MAXABITS - 1)
  
  
  /*
  ** MAXHSIZE is the maximum size of the hash part. It is the minimum
  ** between 2^MAXHBITS and the maximum size such that, measured in bytes,
  ** it fits in a 'size_t'.
  */
  #define MAXHSIZE	luaM_limitN(1u << MAXHBITS, Node)
  
  
  /*
  ** When the original hash value is good, hashing by a power of 2
  ** avoids the cost of '%'.
  */
  #define hashpow2(t,n)		(gnode(t, lmod((n), sizenode(t))))
  
  /*
  ** for other types, it is better to avoid modulo by power of 2, as
  ** they can have many 2 factors.
  */
  #define hashmod(t,n)	(gnode(t, ((n) % ((sizenode(t)-1)|1))))
  
  
  #define hashstr(t,str)		hashpow2(t, (str)->hash)
  #define hashboolean(t,p)	hashpow2(t, p)
  
  #define hashint(t,i)		hashpow2(t, i)
  
  
  #define hashpointer(t,p)	hashmod(t, point2uint(p))
  
  
  #define dummynode		(&dummynode_)
  
  static const Node dummynode_ = {
    {{NULL}, LUA_VEMPTY,  /* value's value and type */
     LUA_VNIL, 0, {NULL}}  /* key type, next, and key value */
  };
  
  
  static const TValue absentkey = {ABSTKEYCONSTANT};
  
  
  
  /*
  ** Hash for floating-point numbers.
  ** The main computation should be just
  **     n = frexp(n, &i); return (n * INT_MAX) + i
  ** but there are some numerical subtleties.
  ** In a two-complement representation, INT_MAX does not has an exact
  ** representation as a float, but INT_MIN does; because the absolute
  ** value of 'frexp' is smaller than 1 (unless 'n' is inf/NaN), the
  ** absolute value of the product 'frexp * -INT_MIN' is smaller or equal
  ** to INT_MAX. Next, the use of 'unsigned int' avoids overflows when
  ** adding 'i'; the use of '~u' (instead of '-u') avoids problems with
  ** INT_MIN.
  */
  #if !defined(l_hashfloat)
  static int l_hashfloat (lua_Number n) {
    int i;
    lua_Integer ni;
    n = l_mathop(frexp)(n, &i) * -cast_num(INT_MIN);
    if (!lua_numbertointeger(n, &ni)) {  /* is 'n' inf/-inf/NaN? */
      lua_assert(luai_numisnan(n) || l_mathop(fabs)(n) == cast_num(HUGE_VAL));
      return 0;
    }
    else {  /* normal case */
      unsigned int u = cast_uint(i) + cast_uint(ni);
      return cast_int(u <= cast_uint(INT_MAX) ? u : ~u);
    }
  }
  #endif
  
  
  /*
  ** returns the 'main' position of an element in a table (that is,
  ** the index of its hash value). The key comes broken (tag in 'ktt'
  ** and value in 'vkl') so that we can call it on keys inserted into
  ** nodes.
  */
  static Node *mainposition (const Table *t, int ktt, const Value *kvl) {
    switch (withvariant(ktt)) {
      case LUA_VNUMINT: {
        lua_Integer key = ivalueraw(*kvl);
        return hashint(t, key);
      }
      case LUA_VNUMFLT: {
        lua_Number n = fltvalueraw(*kvl);
        return hashmod(t, l_hashfloat(n));
      }
      case LUA_VSHRSTR: {
        TString *ts = tsvalueraw(*kvl);
        return hashstr(t, ts);
      }
      case LUA_VLNGSTR: {
        TString *ts = tsvalueraw(*kvl);
        return hashpow2(t, luaS_hashlongstr(ts));
      }
      case LUA_VFALSE:
        return hashboolean(t, 0);
      case LUA_VTRUE:
        return hashboolean(t, 1);
      case LUA_VLIGHTUSERDATA: {
        void *p = pvalueraw(*kvl);
        return hashpointer(t, p);
      }
      case LUA_VLCF: {
        lua_CFunction f = fvalueraw(*kvl);
        return hashpointer(t, f);
      }
      default: {
        GCObject *o = gcvalueraw(*kvl);
        return hashpointer(t, o);
      }
    }
  }
  
  
  /*
  ** Returns the main position of an element given as a 'TValue'
  */
  static Node *mainpositionTV (const Table *t, const TValue *key) {
    return mainposition(t, rawtt(key), valraw(key));
  }
  
  
  /*
  ** Check whether key 'k1' is equal to the key in node 'n2'. This
  ** equality is raw, so there are no metamethods. Floats with integer
  ** values have been normalized, so integers cannot be equal to
  ** floats. It is assumed that 'eqshrstr' is simply pointer equality, so
  ** that short strings are handled in the default case.
  ** A true 'deadok' means to accept dead keys as equal to their original
  ** values. All dead keys are compared in the default case, by pointer
  ** identity. (Only collectable objects can produce dead keys.) Note that
  ** dead long strings are also compared by identity.
  ** Once a key is dead, its corresponding value may be collected, and
  ** then another value can be created with the same address. If this
  ** other value is given to 'next', 'equalkey' will signal a false
  ** positive. In a regular traversal, this situation should never happen,
  ** as all keys given to 'next' came from the table itself, and therefore
  ** could not have been collected. Outside a regular traversal, we
  ** have garbage in, garbage out. What is relevant is that this false
  ** positive does not break anything.  (In particular, 'next' will return
  ** some other valid item on the table or nil.)
  */
  static int equalkey (const TValue *k1, const Node *n2, int deadok) {
    if ((rawtt(k1) != keytt(n2)) &&  /* not the same variants? */
         !(deadok && keyisdead(n2) && iscollectable(k1)))
     return 0;  /* cannot be same key */
    switch (keytt(n2)) {
      case LUA_VNIL: case LUA_VFALSE: case LUA_VTRUE:
        return 1;
      case LUA_VNUMINT:
        return (ivalue(k1) == keyival(n2));
      case LUA_VNUMFLT:
        return luai_numeq(fltvalue(k1), fltvalueraw(keyval(n2)));
      case LUA_VLIGHTUSERDATA:
        return pvalue(k1) == pvalueraw(keyval(n2));
      case LUA_VLCF:
        return fvalue(k1) == fvalueraw(keyval(n2));
      case ctb(LUA_VLNGSTR):
        return luaS_eqlngstr(tsvalue(k1), keystrval(n2));
      default:
        return gcvalue(k1) == gcvalueraw(keyval(n2));
    }
  }
  
  
  /*
  ** True if value of 'alimit' is equal to the real size of the array
  ** part of table 't'. (Otherwise, the array part must be larger than
  ** 'alimit'.)
  */
  #define limitequalsasize(t)	(isrealasize(t) || ispow2((t)->alimit))
  
  
  /*
  ** Returns the real size of the 'array' array
  */
  LUAI_FUNC unsigned int luaH_realasize (const Table *t) {
    if (limitequalsasize(t))
      return t->alimit;  /* this is the size */
    else {
      unsigned int size = t->alimit;
      /* compute the smallest power of 2 not smaller than 'n' */
      size |= (size >> 1);
      size |= (size >> 2);
      size |= (size >> 4);
      size |= (size >> 8);
      size |= (size >> 16);
  #if (UINT_MAX >> 30) > 3
      size |= (size >> 32);  /* unsigned int has more than 32 bits */
  #endif
      size++;
      lua_assert(ispow2(size) && size/2 < t->alimit && t->alimit < size);
      return size;
    }
  }
  
  
  /*
  ** Check whether real size of the array is a power of 2.
  ** (If it is not, 'alimit' cannot be changed to any other value
  ** without changing the real size.)
  */
  static int ispow2realasize (const Table *t) {
    return (!isrealasize(t) || ispow2(t->alimit));
  }
  
  
  static unsigned int setlimittosize (Table *t) {
    t->alimit = luaH_realasize(t);
    setrealasize(t);
    return t->alimit;
  }
  
  
  #define limitasasize(t)	check_exp(isrealasize(t), t->alimit)
  
  
  
  /*
  ** "Generic" get version. (Not that generic: not valid for integers,
  ** which may be in array part, nor for floats with integral values.)
  ** See explanation about 'deadok' in function 'equalkey'.
  */
  static const TValue *getgeneric (Table *t, const TValue *key, int deadok) {
    Node *n = mainpositionTV(t, key);
    for (;;) {  /* check whether 'key' is somewhere in the chain */
      if (equalkey(key, n, deadok))
        return gval(n);  /* that's it */
      else {
        int nx = gnext(n);
        if (nx == 0)
          return &absentkey;  /* not found */
        n += nx;
      }
    }
  }
  
  
  /*
  ** returns the index for 'k' if 'k' is an appropriate key to live in
  ** the array part of a table, 0 otherwise.
  */
  static unsigned int arrayindex (lua_Integer k) {
    if (l_castS2U(k) - 1u < MAXASIZE)  /* 'k' in [1, MAXASIZE]? */
      return cast_uint(k);  /* 'key' is an appropriate array index */
    else
      return 0;
  }
  
  
  /*
  ** 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 signaled by 0.
  */
  static unsigned int findindex (lua_State *L, Table *t, TValue *key,
                                 unsigned int asize) {
    unsigned int i;
    if (ttisnil(key)) return 0;  /* first iteration */
    i = ttisinteger(key) ? arrayindex(ivalue(key)) : 0;
    if (i - 1u < asize)  /* is 'key' inside array part? */
      return i;  /* yes; that's the index */
    else {
      const TValue *n = getgeneric(t, key, 1);
      if (l_unlikely(isabstkey(n)))
        luaG_runerror(L, "invalid key to 'next'");  /* key not found */
      i = cast_int(nodefromval(n) - gnode(t, 0));  /* key index in hash table */
      /* hash elements are numbered after array ones */
      return (i + 1) + asize;
    }
  }
  
  
  int luaH_next (lua_State *L, Table *t, StkId key) {
    unsigned int asize = luaH_realasize(t);
    unsigned int i = findindex(L, t, s2v(key), asize);  /* find original key */
    for (; i < asize; i++) {  /* try first array part */
      if (!isempty(&t->array[i])) {  /* a non-empty entry? */
        setivalue(s2v(key), i + 1);
        setobj2s(L, key + 1, &t->array[i]);
        return 1;
      }
    }
    for (i -= asize; cast_int(i) < sizenode(t); i++) {  /* hash part */
      if (!isempty(gval(gnode(t, i)))) {  /* a non-empty entry? */
        Node *n = gnode(t, i);
        getnodekey(L, s2v(key), n);
        setobj2s(L, key + 1, gval(n));
        return 1;
      }
    }
    return 0;  /* no more elements */
  }
  
  
  static void freehash (lua_State *L, Table *t) {
    if (!isdummy(t))
      luaM_freearray(L, t->node, cast_sizet(sizenode(t)));
  }
  
  
  /*
  ** {=============================================================
  ** Rehash
  ** ==============================================================
  */
  
  /*
  ** Compute the optimal size for the array part of table 't'. 'nums' is a
  ** "count array" where 'nums[i]' is the number of integers in the table
  ** between 2^(i - 1) + 1 and 2^i. 'pna' enters with the total number of
  ** integer keys in the table and leaves with the number of keys that
  ** will go to the array part; return the optimal size.  (The condition
  ** 'twotoi > 0' in the for loop stops the loop if 'twotoi' overflows.)
  */
  static unsigned int computesizes (unsigned int nums[], unsigned int *pna) {
    int i;
    unsigned int twotoi;  /* 2^i (candidate for optimal size) */
    unsigned int a = 0;  /* number of elements smaller than 2^i */
    unsigned int na = 0;  /* number of elements to go to array part */
    unsigned int optimal = 0;  /* optimal size for array part */
    /* loop while keys can fill more than half of total size */
    for (i = 0, twotoi = 1;
         twotoi > 0 && *pna > twotoi / 2;
         i++, twotoi *= 2) {
      a += nums[i];
      if (a > twotoi/2) {  /* more than half elements present? */
        optimal = twotoi;  /* optimal size (till now) */
        na = a;  /* all elements up to 'optimal' will go to array part */
      }
    }
    lua_assert((optimal == 0 || optimal / 2 < na) && na <= optimal);
    *pna = na;
    return optimal;
  }
  
  
  static int countint (lua_Integer key, unsigned int *nums) {
    unsigned int k = arrayindex(key);
    if (k != 0) {  /* is 'key' an appropriate array index? */
      nums[luaO_ceillog2(k)]++;  /* count as such */
      return 1;
    }
    else
      return 0;
  }
  
  
  /*
  ** Count keys in array part of table 't': Fill 'nums[i]' with
  ** number of keys that will go into corresponding slice and return
  ** total number of non-nil keys.
  */
  static unsigned int numusearray (const Table *t, unsigned int *nums) {
    int lg;
    unsigned int ttlg;  /* 2^lg */
    unsigned int ause = 0;  /* summation of 'nums' */
    unsigned int i = 1;  /* count to traverse all array keys */
    unsigned int asize = limitasasize(t);  /* real array size */
    /* traverse each slice */
    for (lg = 0, ttlg = 1; lg <= MAXABITS; lg++, ttlg *= 2) {
      unsigned int lc = 0;  /* counter */
      unsigned int lim = ttlg;
      if (lim > asize) {
        lim = asize;  /* 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 (!isempty(&t->array[i-1]))
          lc++;
      }
      nums[lg] += lc;
      ause += lc;
    }
    return ause;
  }
  
  
  static int numusehash (const Table *t, unsigned int *nums, unsigned int *pna) {
    int totaluse = 0;  /* total number of elements */
    int ause = 0;  /* elements added to 'nums' (can go to array part) */
    int i = sizenode(t);
    while (i--) {
      Node *n = &t->node[i];
      if (!isempty(gval(n))) {
        if (keyisinteger(n))
          ause += countint(keyival(n), nums);
        totaluse++;
      }
    }
    *pna += ause;
    return totaluse;
  }
  
  
  /*
  ** Creates an array for the hash part of a table with the given
  ** size, or reuses the dummy node if size is zero.
  ** The computation for size overflow is in two steps: the first
  ** comparison ensures that the shift in the second one does not
  ** overflow.
  */
  static void setnodevector (lua_State *L, Table *t, unsigned int size) {
    if (size == 0) {  /* no elements to hash part? */
      t->node = cast(Node *, dummynode);  /* use common 'dummynode' */
      t->lsizenode = 0;
      t->lastfree = NULL;  /* signal that it is using dummy node */
    }
    else {
      int i;
      int lsize = luaO_ceillog2(size);
      if (lsize > MAXHBITS || (1u << lsize) > MAXHSIZE)
        luaG_runerror(L, "table overflow");
      size = twoto(lsize);
      t->node = luaM_newvector(L, size, Node);
      for (i = 0; i < (int)size; i++) {
        Node *n = gnode(t, i);
        gnext(n) = 0;
        setnilkey(n);
        setempty(gval(n));
      }
      t->lsizenode = cast_byte(lsize);
      t->lastfree = gnode(t, size);  /* all positions are free */
    }
  }
  
  
  /*
  ** (Re)insert all elements from the hash part of 'ot' into table 't'.
  */
  static void reinsert (lua_State *L, Table *ot, Table *t) {
    int j;
    int size = sizenode(ot);
    for (j = 0; j < size; j++) {
      Node *old = gnode(ot, j);
      if (!isempty(gval(old))) {
        /* doesn't need barrier/invalidate cache, as entry was
           already present in the table */
        TValue k;
        getnodekey(L, &k, old);
        luaH_set(L, t, &k, gval(old));
      }
    }
  }
  
  
  /*
  ** Exchange the hash part of 't1' and 't2'.
  */
  static void exchangehashpart (Table *t1, Table *t2) {
    lu_byte lsizenode = t1->lsizenode;
    Node *node = t1->node;
    Node *lastfree = t1->lastfree;
    t1->lsizenode = t2->lsizenode;
    t1->node = t2->node;
    t1->lastfree = t2->lastfree;
    t2->lsizenode = lsizenode;
    t2->node = node;
    t2->lastfree = lastfree;
  }
  
  
  /*
  ** Resize table 't' for the new given sizes. Both allocations (for
  ** the hash part and for the array part) can fail, which creates some
  ** subtleties. If the first allocation, for the hash part, fails, an
  ** error is raised and that is it. Otherwise, it copies the elements from
  ** the shrinking part of the array (if it is shrinking) into the new
  ** hash. Then it reallocates the array part.  If that fails, the table
  ** is in its original state; the function frees the new hash part and then
  ** raises the allocation error. Otherwise, it sets the new hash part
  ** into the table, initializes the new part of the array (if any) with
  ** nils and reinserts the elements of the old hash back into the new
  ** parts of the table.
  */
  void luaH_resize (lua_State *L, Table *t, unsigned int newasize,
                                            unsigned int nhsize) {
    unsigned int i;
    Table newt;  /* to keep the new hash part */
    unsigned int oldasize = setlimittosize(t);
    TValue *newarray;
    /* create new hash part with appropriate size into 'newt' */
    setnodevector(L, &newt, nhsize);
    if (newasize < oldasize) {  /* will array shrink? */
      t->alimit = newasize;  /* pretend array has new size... */
      exchangehashpart(t, &newt);  /* and new hash */
      /* re-insert into the new hash the elements from vanishing slice */
      for (i = newasize; i < oldasize; i++) {
        if (!isempty(&t->array[i]))
          luaH_setint(L, t, i + 1, &t->array[i]);
      }
      t->alimit = oldasize;  /* restore current size... */
      exchangehashpart(t, &newt);  /* and hash (in case of errors) */
    }
    /* allocate new array */
    newarray = luaM_reallocvector(L, t->array, oldasize, newasize, TValue);
    if (l_unlikely(newarray == NULL && newasize > 0)) {  /* allocation failed? */
      freehash(L, &newt);  /* release new hash part */
      luaM_error(L);  /* raise error (with array unchanged) */
    }
    /* allocation ok; initialize new part of the array */
    exchangehashpart(t, &newt);  /* 't' has the new hash ('newt' has the old) */
    t->array = newarray;  /* set new array part */
    t->alimit = newasize;
    for (i = oldasize; i < newasize; i++)  /* clear new slice of the array */
       setempty(&t->array[i]);
    /* re-insert elements from old hash part into new parts */
    reinsert(L, &newt, t);  /* 'newt' now has the old hash */
    freehash(L, &newt);  /* free old hash part */
  }
  
  
  void luaH_resizearray (lua_State *L, Table *t, unsigned int nasize) {
    int nsize = allocsizenode(t);
    luaH_resize(L, t, nasize, nsize);
  }
  
  /*
  ** nums[i] = number of keys 'k' where 2^(i - 1) < k <= 2^i
  */
  static void rehash (lua_State *L, Table *t, const TValue *ek) {
    unsigned int asize;  /* optimal size for array part */
    unsigned int na;  /* number of keys in the array part */
    unsigned int nums[MAXABITS + 1];
    int i;
    int totaluse;
    for (i = 0; i <= MAXABITS; i++) nums[i] = 0;  /* reset counts */
    setlimittosize(t);
    na = numusearray(t, nums);  /* count keys in array part */
    totaluse = na;  /* all those keys are integer keys */
    totaluse += numusehash(t, nums, &na);  /* count keys in hash part */
    /* count extra key */
    if (ttisinteger(ek))
      na += countint(ivalue(ek), nums);
    totaluse++;
    /* compute new size for array part */
    asize = computesizes(nums, &na);
    /* resize the table to new computed sizes */
    luaH_resize(L, t, asize, totaluse - na);
  }
  
  
  
  /*
  ** }=============================================================
  */
  
  
  Table *luaH_new (lua_State *L) {
    GCObject *o = luaC_newobj(L, LUA_VTABLE, sizeof(Table));
    Table *t = gco2t(o);
    t->metatable = NULL;
    t->flags = cast_byte(maskflags);  /* table has no metamethod fields */
    t->array = NULL;
    t->alimit = 0;
    setnodevector(L, t, 0);
    return t;
  }
  
  
  void luaH_free (lua_State *L, Table *t) {
    freehash(L, t);
    luaM_freearray(L, t->array, luaH_realasize(t));
    luaM_free(L, t);
  }
  
  
  static Node *getfreepos (Table *t) {
    if (!isdummy(t)) {
      while (t->lastfree > t->node) {
        t->lastfree--;
        if (keyisnil(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.
  */
  void luaH_newkey (lua_State *L, Table *t, const TValue *key, TValue *value) {
    Node *mp;
    TValue aux;
    if (l_unlikely(ttisnil(key)))
      luaG_runerror(L, "table index is nil");
    else if (ttisfloat(key)) {
      lua_Number f = fltvalue(key);
      lua_Integer k;
      if (luaV_flttointeger(f, &k, F2Ieq)) {  /* does key fit in an integer? */
        setivalue(&aux, k);
        key = &aux;  /* insert it as an integer */
      }
      else if (l_unlikely(luai_numisnan(f)))
        luaG_runerror(L, "table index is NaN");
    }
    if (ttisnil(value))
      return;  /* do not insert nil values */
    mp = mainpositionTV(t, key);
    if (!isempty(gval(mp)) || isdummy(t)) {  /* main position is taken? */
      Node *othern;
      Node *f = getfreepos(t);  /* get a free place */
      if (f == NULL) {  /* cannot find a free place? */
        rehash(L, t, key);  /* grow table */
        /* whatever called 'newkey' takes care of TM cache */
        luaH_set(L, t, key, value);  /* insert key into grown table */
        return;
      }
      lua_assert(!isdummy(t));
      othern = mainposition(t, keytt(mp), &keyval(mp));
      if (othern != mp) {  /* is colliding node out of its main position? */
        /* yes; move colliding node into free position */
        while (othern + gnext(othern) != mp)  /* find previous */
          othern += gnext(othern);
        gnext(othern) = cast_int(f - othern);  /* rechain to point to 'f' */
        *f = *mp;  /* copy colliding node into free pos. (mp->next also goes) */
        if (gnext(mp) != 0) {
          gnext(f) += cast_int(mp - f);  /* correct 'next' */
          gnext(mp) = 0;  /* now 'mp' is free */
        }
        setempty(gval(mp));
      }
      else {  /* colliding node is in its own main position */
        /* new node will go into free position */
        if (gnext(mp) != 0)
          gnext(f) = cast_int((mp + gnext(mp)) - f);  /* chain new position */
        else lua_assert(gnext(f) == 0);
        gnext(mp) = cast_int(f - mp);
        mp = f;
      }
    }
    setnodekey(L, mp, key);
    luaC_barrierback(L, obj2gco(t), key);
    lua_assert(isempty(gval(mp)));
    setobj2t(L, gval(mp), value);
  }
  
  
  /*
  ** Search function for integers. If integer is inside 'alimit', get it
  ** directly from the array part. Otherwise, if 'alimit' is not equal to
  ** the real size of the array, key still can be in the array part. In
  ** this case, try to avoid a call to 'luaH_realasize' when key is just
  ** one more than the limit (so that it can be incremented without
  ** changing the real size of the array).
  */
  const TValue *luaH_getint (Table *t, lua_Integer key) {
    if (l_castS2U(key) - 1u < t->alimit)  /* 'key' in [1, t->alimit]? */
      return &t->array[key - 1];
    else if (!limitequalsasize(t) &&  /* key still may be in the array part? */
             (l_castS2U(key) == t->alimit + 1 ||
              l_castS2U(key) - 1u < luaH_realasize(t))) {
      t->alimit = cast_uint(key);  /* probably '#t' is here now */
      return &t->array[key - 1];
    }
    else {
      Node *n = hashint(t, key);
      for (;;) {  /* check whether 'key' is somewhere in the chain */
        if (keyisinteger(n) && keyival(n) == key)
          return gval(n);  /* that's it */
        else {
          int nx = gnext(n);
          if (nx == 0) break;
          n += nx;
        }
      }
      return &absentkey;
    }
  }
  
  
  /*
  ** search function for short strings
  */
  const TValue *luaH_getshortstr (Table *t, TString *key) {
    Node *n = hashstr(t, key);
    lua_assert(key->tt == LUA_VSHRSTR);
    for (;;) {  /* check whether 'key' is somewhere in the chain */
      if (keyisshrstr(n) && eqshrstr(keystrval(n), key))
        return gval(n);  /* that's it */
      else {
        int nx = gnext(n);
        if (nx == 0)
          return &absentkey;  /* not found */
        n += nx;
      }
    }
  }
  
  
  const TValue *luaH_getstr (Table *t, TString *key) {
    if (key->tt == LUA_VSHRSTR)
      return luaH_getshortstr(t, key);
    else {  /* for long strings, use generic case */
      TValue ko;
      setsvalue(cast(lua_State *, NULL), &ko, key);
      return getgeneric(t, &ko, 0);
    }
  }
  
  
  /*
  ** main search function
  */
  const TValue *luaH_get (Table *t, const TValue *key) {
    switch (ttypetag(key)) {
      case LUA_VSHRSTR: return luaH_getshortstr(t, tsvalue(key));
      case LUA_VNUMINT: return luaH_getint(t, ivalue(key));
      case LUA_VNIL: return &absentkey;
      case LUA_VNUMFLT: {
        lua_Integer k;
        if (luaV_flttointeger(fltvalue(key), &k, F2Ieq)) /* integral index? */
          return luaH_getint(t, k);  /* use specialized version */
        /* else... */
      }  /* FALLTHROUGH */
      default:
        return getgeneric(t, key, 0);
    }
  }
  
  
  /*
  ** Finish a raw "set table" operation, where 'slot' is where the value
  ** should have been (the result of a previous "get table").
  ** Beware: when using this function you probably need to check a GC
  ** barrier and invalidate the TM cache.
  */
  void luaH_finishset (lua_State *L, Table *t, const TValue *key,
                                     const TValue *slot, TValue *value) {
    if (isabstkey(slot))
      luaH_newkey(L, t, key, value);
    else
      setobj2t(L, cast(TValue *, slot), value);
  }
  
  
  /*
  ** beware: when using this function you probably need to check a GC
  ** barrier and invalidate the TM cache.
  */
  void luaH_set (lua_State *L, Table *t, const TValue *key, TValue *value) {
    const TValue *slot = luaH_get(t, key);
    luaH_finishset(L, t, key, slot, value);
  }
  
  
  void luaH_setint (lua_State *L, Table *t, lua_Integer key, TValue *value) {
    const TValue *p = luaH_getint(t, key);
    if (isabstkey(p)) {
      TValue k;
      setivalue(&k, key);
      luaH_newkey(L, t, &k, value);
    }
    else
      setobj2t(L, cast(TValue *, p), value);
  }
  
  
  /*
  ** Try to find a boundary in the hash part of table 't'. From the
  ** caller, we know that 'j' is zero or present and that 'j + 1' is
  ** present. We want to find a larger key that is absent from the
  ** table, so that we can do a binary search between the two keys to
  ** find a boundary. We keep doubling 'j' until we get an absent index.
  ** If the doubling would overflow, we try LUA_MAXINTEGER. If it is
  ** absent, we are ready for the binary search. ('j', being max integer,
  ** is larger or equal to 'i', but it cannot be equal because it is
  ** absent while 'i' is present; so 'j > i'.) Otherwise, 'j' is a
  ** boundary. ('j + 1' cannot be a present integer key because it is
  ** not a valid integer in Lua.)
  */
  static lua_Unsigned hash_search (Table *t, lua_Unsigned j) {
    lua_Unsigned i;
    if (j == 0) j++;  /* the caller ensures 'j + 1' is present */
    do {
      i = j;  /* 'i' is a present index */
      if (j <= l_castS2U(LUA_MAXINTEGER) / 2)
        j *= 2;
      else {
        j = LUA_MAXINTEGER;
        if (isempty(luaH_getint(t, j)))  /* t[j] not present? */
          break;  /* 'j' now is an absent index */
        else  /* weird case */
          return j;  /* well, max integer is a boundary... */
      }
    } while (!isempty(luaH_getint(t, j)));  /* repeat until an absent t[j] */
    /* i < j  &&  t[i] present  &&  t[j] absent */
    while (j - i > 1u) {  /* do a binary search between them */
      lua_Unsigned m = (i + j) / 2;
      if (isempty(luaH_getint(t, m))) j = m;
      else i = m;
    }
    return i;
  }
  
  
  static unsigned int binsearch (const TValue *array, unsigned int i,
                                                      unsigned int j) {
    while (j - i > 1u) {  /* binary search */
      unsigned int m = (i + j) / 2;
      if (isempty(&array[m - 1])) 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 present and t[i+1] is absent, or 0 if t[1] is absent
  ** and 'maxinteger' if t[maxinteger] is present.)
  ** (In the next explanation, we use Lua indices, that is, with base 1.
  ** The code itself uses base 0 when indexing the array part of the table.)
  ** The code starts with 'limit = t->alimit', a position in the array
  ** part that may be a boundary.
  **
  ** (1) If 't[limit]' is empty, there must be a boundary before it.
  ** As a common case (e.g., after 't[#t]=nil'), check whether 'limit-1'
  ** is present. If so, it is a boundary. Otherwise, do a binary search
  ** between 0 and limit to find a boundary. In both cases, try to
  ** use this boundary as the new 'alimit', as a hint for the next call.
  **
  ** (2) If 't[limit]' is not empty and the array has more elements
  ** after 'limit', try to find a boundary there. Again, try first
  ** the special case (which should be quite frequent) where 'limit+1'
  ** is empty, so that 'limit' is a boundary. Otherwise, check the
  ** last element of the array part. If it is empty, there must be a
  ** boundary between the old limit (present) and the last element
  ** (absent), which is found with a binary search. (This boundary always
  ** can be a new limit.)
  **
  ** (3) The last case is when there are no elements in the array part
  ** (limit == 0) or its last element (the new limit) is present.
  ** In this case, must check the hash part. If there is no hash part
  ** or 'limit+1' is absent, 'limit' is a boundary.  Otherwise, call
  ** 'hash_search' to find a boundary in the hash part of the table.
  ** (In those cases, the boundary is not inside the array part, and
  ** therefore cannot be used as a new limit.)
  */
  lua_Unsigned luaH_getn (Table *t) {
    unsigned int limit = t->alimit;
    if (limit > 0 && isempty(&t->array[limit - 1])) {  /* (1)? */
      /* there must be a boundary before 'limit' */
      if (limit >= 2 && !isempty(&t->array[limit - 2])) {
        /* 'limit - 1' is a boundary; can it be a new limit? */
        if (ispow2realasize(t) && !ispow2(limit - 1)) {
          t->alimit = limit - 1;
          setnorealasize(t);  /* now 'alimit' is not the real size */
        }
        return limit - 1;
      }
      else {  /* must search for a boundary in [0, limit] */
        unsigned int boundary = binsearch(t->array, 0, limit);
        /* can this boundary represent the real size of the array? */
        if (ispow2realasize(t) && boundary > luaH_realasize(t) / 2) {
          t->alimit = boundary;  /* use it as the new limit */
          setnorealasize(t);
        }
        return boundary;
      }
    }
    /* 'limit' is zero or present in table */
    if (!limitequalsasize(t)) {  /* (2)? */
      /* 'limit' > 0 and array has more elements after 'limit' */
      if (isempty(&t->array[limit]))  /* 'limit + 1' is empty? */
        return limit;  /* this is the boundary */
      /* else, try last element in the array */
      limit = luaH_realasize(t);
      if (isempty(&t->array[limit - 1])) {  /* empty? */
        /* there must be a boundary in the array after old limit,
           and it must be a valid new limit */
        unsigned int boundary = binsearch(t->array, t->alimit, limit);
        t->alimit = boundary;
        return boundary;
      }
      /* else, new limit is present in the table; check the hash part */
    }
    /* (3) 'limit' is the last element and either is zero or present in table */
    lua_assert(limit == luaH_realasize(t) &&
               (limit == 0 || !isempty(&t->array[limit - 1])));
    if (isdummy(t) || isempty(luaH_getint(t, cast(lua_Integer, limit + 1))))
      return limit;  /* 'limit + 1' is absent */
    else  /* 'limit + 1' is also present */
      return hash_search(t, limit);
  }
  
  
  
  #if defined(LUA_DEBUG)
  
  /* export these functions for the test library */
  
  Node *luaH_mainposition (const Table *t, const TValue *key) {
    return mainpositionTV(t, key);
  }
  
  int luaH_isdummy (const Table *t) { return isdummy(t); }
  
  #endif
  