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