--- /dev/null
+/*
+** $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>
+
+#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}, /* value */
+ {{NILCONSTANT, NULL}} /* key */
+};
+
+
+/*
+** 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 */
+}
+
+
+/*
+** 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 -1.
+*/
+static int findindex (lua_State *L, Table *t, StkId key) {
+ int i;
+ if (ttisnil(key)) return -1; /* first iteration */
+ i = arrayindex(key);
+ if (0 < i && i <= t->sizearray) /* is `key' inside array part? */
+ return i-1; /* yes; that's the index (corrected to C) */
+ else {
+ Node *n = mainposition(t, key);
+ 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))) {
+ i = cast_int(n - gnode(t, 0)); /* key index in hash table */
+ /* hash elements are numbered after array ones */
+ return i + t->sizearray;
+ }
+ else n = gnext(n);
+ 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 i = findindex(L, t, key); /* find original element */
+ for (i++; i < t->sizearray; i++) { /* try first array part */
+ if (!ttisnil(&t->array[i])) { /* a non-nil value? */
+ setnvalue(key, cast_num(i+1));
+ setobj2s(L, key+1, &t->array[i]);
+ return 1;
+ }
+ }
+ for (i -= t->sizearray; i < sizenode(t); i++) { /* then hash part */
+ if (!ttisnil(gval(gnode(t, i)))) { /* a non-nil value? */
+ setobj2s(L, key, gkey(gnode(t, i)));
+ setobj2s(L, key+1, gval(gnode(t, i)));
+ return 1;
+ }
+ }
+ return 0; /* no more elements */
+}
+
+
+/*
+** {=============================================================
+** 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]))
+ 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, TValue);
+ for (i=t->sizearray; i<size; i++)
+ setnilvalue(&t->array[i]);
+ 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 > 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;
+ setnilvalue(gkey(n));
+ setnilvalue(gval(n));
+ }
+ }
+ t->lsizenode = cast_byte(lsize);
+ t->lastfree = gnode(t, size); /* all positions are free */
+}
+
+
+void luaH_resize (lua_State *L, Table *t, int nasize, int nhsize) {
+ int i;
+ int oldasize = t->sizearray;
+ int oldhsize = t->lsizenode;
+ 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);
+ if (nasize < oldasize) { /* array part must shrink? */
+ t->sizearray = nasize;
+ /* re-insert elements from vanishing slice */
+ for (i=nasize; i<oldasize; i++) {
+ if (!ttisnil(&t->array[i]))
+ luaH_setint(L, t, i + 1, &t->array[i]);
+ }
+ /* shrink array */
+ luaM_reallocvector(L, t->array, oldasize, nasize, TValue);
+ }
+ /* re-insert elements from hash part */
+ for (i = twoto(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 */
+ setobjt2t(L, luaH_set(L, t, gkey(old)), gval(old));
+ }
+ }
+ if (!isdummy(nold))
+ luaM_freearray(L, nold, cast(size_t, twoto(oldhsize))); /* free old array */
+}
+
+
+void luaH_resizearray (lua_State *L, Table *t, int nasize) {
+ int nsize = isdummy(t->node) ? 0 : sizenode(t);
+ luaH_resize(L, t, nasize, nsize);
+}
+
+
+static void rehash (lua_State *L, Table *t, const TValue *ek) {
+ int nasize, na;
+ int nums[MAXBITS+1]; /* nums[i] = number of keys 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;
+ setnodevector(L, t, 0);
+ 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);
+ 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.
+*/
+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 */
+ return luaH_set(L, t, key); /* insert key into grown table */
+ }
+ 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));
+ }
+ 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];
+ 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;
+ }
+ }
+}
+
+
+/*
+** 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 (p != luaO_nilobject)
+ return cast(TValue *, p);
+ else return luaH_newkey(L, t, key);
+}
+
+
+void luaH_setint (lua_State *L, Table *t, int key, TValue *value) {
+ const TValue *p = luaH_getint(t, key);
+ TValue *cell;
+ if (p != luaO_nilobject)
+ cell = cast(TValue *, p);
+ else {
+ TValue k;
+ setnvalue(&k, cast_num(key));
+ cell = luaH_newkey(L, t, &k);
+ }
+ setobj2t(L, cell, value);
+}
+
+
+static int unbound_search (Table *t, unsigned int j) {
+ unsigned int i = j; /* i is zero or a present index */
+ j++;
+ /* find `i' and `j' such that i is present and j is not */
+ while (!ttisnil(luaH_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;
+}
+
+
+/*
+** Try to find a boundary in table `t'. A `boundary' is an integer index
+** such that t[i] is non-nil and t[i+1] is nil (and 0 if t[1] is nil).
+*/
+int luaH_getn (Table *t) {
+ unsigned int j = t->sizearray;
+ if (j > 0 && ttisnil(&t->array[j - 1])) {
+ /* there is a boundary in the array part: (binary) search for it */
+ unsigned int i = 0;
+ while (j - i > 1) {
+ unsigned int m = (i+j)/2;
+ if (ttisnil(&t->array[m - 1])) j = m;
+ else i = m;
+ }
+ return i;
+ }
+ /* else must find a boundary in hash part */
+ else if (isdummy(t->node)) /* hash part is empty? */
+ return j; /* that is easy... */
+ else return unbound_search(t, j);
+}
+
+
+
+#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
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