1 files changed, 924 insertions, 0 deletions

diff --git a/src/lua/ltable.c b/src/lua/ltable.c
new file mode 100644
index 0000000..d7eb69a
--- /dev/null
+++ b/src/lua/ltable.c
@@ -0,0 +1,924 @@
+/*
+** $Id: ltable.c $
+** Lua tables (hash)
+** See Copyright Notice in lua.h
+*/
+
+#define ltable_c
+#define LUA_CORE
+
+#include "lprefix.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
+** 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.
+*/
+
+#include <math.h>
+#include <limits.h>
+
+#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"
+
+
+/*
+** 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)
+
+
+#define hashpow2(t,n)           (gnode(t, lmod((n), sizenode(t))))
+
+#define hashstr(t,str)          hashpow2(t, (str)->hash)
+#define hashboolean(t,p)        hashpow2(t, p)
+#define hashint(t,i)            hashpow2(t, i)
+
+
+/*
+** 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, 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:
+      return hashint(t, ivalueraw(*kvl));
+    case LUA_VNUMFLT:
+      return hashmod(t, l_hashfloat(fltvalueraw(*kvl)));
+    case LUA_VSHRSTR:
+      return hashstr(t, tsvalueraw(*kvl));
+    case LUA_VLNGSTR:
+      return hashpow2(t, luaS_hashlongstr(tsvalueraw(*kvl)));
+    case LUA_VFALSE:
+      return hashboolean(t, 0);
+    case LUA_VTRUE:
+      return hashboolean(t, 1);
+    case LUA_VLIGHTUSERDATA:
+      return hashpointer(t, pvalueraw(*kvl));
+    case LUA_VLCF:
+      return hashpointer(t, fvalueraw(*kvl));
+    default:
+      return hashpointer(t, gcvalueraw(*kvl));
+  }
+}
+
+
+/*
+** 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.
+*/
+static int equalkey (const TValue *k1, const Node *n2) {
+  if (rawtt(k1) != keytt(n2))  /* not the same variants? */
+   return 0;  /* cannot be same key */
+  switch (ttypetag(k1)) {
+    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 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.)
+*/
+static const TValue *getgeneric (Table *t, const TValue *key) {
+  Node *n = mainpositionTV(t, key);
+  for (;;) {  /* check whether 'key' is somewhere in the chain */
+    if (equalkey(key, n))
+      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);
+    if (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);
+      setobjt2t(L, 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 (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(~0);
+  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.
+*/
+TValue *luaH_newkey (lua_State *L, Table *t, const TValue *key) {
+  Node *mp;
+  TValue aux;
+  if (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 (unlikely(luai_numisnan(f)))
+      luaG_runerror(L, "table index is NaN");
+  }
+  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 */
+      return luaH_set(L, t, key);  /* insert key into grown table */
+    }
+    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)));
+  return gval(mp);
+}
+
+
+/*
+** 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);
+  }
+}
+
+
+/*
+** 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);
+  }
+}
+
+
+/*
+** beware: when using this function you probably need to check a GC
+** barrier and invalidate the TM cache.
+*/
+TValue *luaH_set (lua_State *L, Table *t, const TValue *key) {
+  const TValue *p = luaH_get(t, key);
+  if (!isabstkey(p))
+    return cast(TValue *, p);
+  else return luaH_newkey(L, t, key);
+}
+
+
+void luaH_setint (lua_State *L, Table *t, lua_Integer key, TValue *value) {
+  const TValue *p = luaH_getint(t, key);
+  TValue *cell;
+  if (!isabstkey(p))
+    cell = cast(TValue *, p);
+  else {
+    TValue k;
+    setivalue(&k, key);
+    cell = luaH_newkey(L, t, &k);
+  }
+  setobj2t(L, cell, 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