--- /dev/null
+/*
+** $Id: ltable.c,v 2.118.1.4 2018/06/08 16:22:51 roberto Exp $
+** 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"
+
+
+/*
+** Maximum size of array part (MAXASIZE) is 2^MAXABITS. MAXABITS is
+** the largest integer such that MAXASIZE fits in an unsigned int.
+*/
+#define MAXABITS cast_int(sizeof(int) * CHAR_BIT - 1)
+#define MAXASIZE (1u << MAXABITS)
+
+/*
+** Maximum size of hash part is 2^MAXHBITS. MAXHBITS is the largest
+** integer such that 2^MAXHBITS fits in a signed int. (Note that the
+** maximum number of elements in a table, 2^MAXABITS + 2^MAXHBITS, still
+** fits comfortably in an unsigned int.)
+*/
+#define MAXHBITS (MAXABITS - 1)
+
+
+#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_ = {
+ {NILCONSTANT}, /* value */
+ {{NILCONSTANT, 0}} /* key */
+};
+
+
+/*
+** 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(unsigned int, i) + cast(unsigned int, ni);
+ return cast_int(u <= cast(unsigned int, INT_MAX) ? u : ~u);
+ }
+}
+#endif
+
+
+/*
+** 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_TNUMINT:
+ return hashint(t, ivalue(key));
+ case LUA_TNUMFLT:
+ return hashmod(t, l_hashfloat(fltvalue(key)));
+ case LUA_TSHRSTR:
+ return hashstr(t, tsvalue(key));
+ case LUA_TLNGSTR:
+ return hashpow2(t, luaS_hashlongstr(tsvalue(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:
+ lua_assert(!ttisdeadkey(key));
+ 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, 0 otherwise.
+*/
+static unsigned int arrayindex (const TValue *key) {
+ if (ttisinteger(key)) {
+ lua_Integer k = ivalue(key);
+ if (0 < k && (lua_Unsigned)k <= MAXASIZE)
+ return cast(unsigned int, k); /* 'key' is an appropriate array index */
+ }
+ return 0; /* '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 0.
+*/
+static unsigned int findindex (lua_State *L, Table *t, StkId key) {
+ unsigned int i;
+ if (ttisnil(key)) return 0; /* first iteration */
+ i = arrayindex(key);
+ if (i != 0 && i <= t->sizearray) /* is 'key' inside array part? */
+ return i; /* yes; that's the index */
+ else {
+ int nx;
+ 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 + 1) + t->sizearray;
+ }
+ nx = gnext(n);
+ if (nx == 0)
+ luaG_runerror(L, "invalid key to 'next'"); /* key not found */
+ else n += nx;
+ }
+ }
+}
+
+
+int luaH_next (lua_State *L, Table *t, StkId key) {
+ unsigned int i = findindex(L, t, key); /* find original element */
+ for (; i < t->sizearray; i++) { /* try first array part */
+ if (!ttisnil(&t->array[i])) { /* a non-nil value? */
+ setivalue(key, i + 1);
+ setobj2s(L, key+1, &t->array[i]);
+ return 1;
+ }
+ }
+ for (i -= t->sizearray; cast_int(i) < sizenode(t); i++) { /* 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
+** ==============================================================
+*/
+
+/*
+** 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.
+*/
+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) {
+ if (nums[i] > 0) {
+ 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 (const TValue *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 */
+ /* traverse each slice */
+ for (lg = 0, ttlg = 1; lg <= MAXABITS; lg++, ttlg *= 2) {
+ unsigned int lc = 0; /* counter */
+ unsigned 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, 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 (!ttisnil(gval(n))) {
+ ause += countint(gkey(n), nums);
+ totaluse++;
+ }
+ }
+ *pna += ause;
+ return totaluse;
+}
+
+
+static void setarrayvector (lua_State *L, Table *t, unsigned int size) {
+ unsigned 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, 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)
+ 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;
+ setnilvalue(wgkey(n));
+ setnilvalue(gval(n));
+ }
+ t->lsizenode = cast_byte(lsize);
+ t->lastfree = gnode(t, size); /* all positions are free */
+ }
+}
+
+
+typedef struct {
+ Table *t;
+ unsigned int nhsize;
+} AuxsetnodeT;
+
+
+static void auxsetnode (lua_State *L, void *ud) {
+ AuxsetnodeT *asn = cast(AuxsetnodeT *, ud);
+ setnodevector(L, asn->t, asn->nhsize);
+}
+
+
+void luaH_resize (lua_State *L, Table *t, unsigned int nasize,
+ unsigned int nhsize) {
+ unsigned int i;
+ int j;
+ AuxsetnodeT asn;
+ unsigned int oldasize = t->sizearray;
+ int oldhsize = allocsizenode(t);
+ Node *nold = t->node; /* save old hash ... */
+ if (nasize > oldasize) /* array part must grow? */
+ setarrayvector(L, t, nasize);
+ /* create new hash part with appropriate size */
+ asn.t = t; asn.nhsize = nhsize;
+ if (luaD_rawrunprotected(L, auxsetnode, &asn) != LUA_OK) { /* mem. error? */
+ setarrayvector(L, t, oldasize); /* array back to its original size */
+ luaD_throw(L, LUA_ERRMEM); /* rethrow memory error */
+ }
+ 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 (j = oldhsize - 1; j >= 0; j--) {
+ Node *old = nold + j;
+ 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 (oldhsize > 0) /* not the dummy node? */
+ luaM_freearray(L, nold, cast(size_t, oldhsize)); /* free old hash */
+}
+
+
+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 */
+ 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 */
+ na += countint(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_TTABLE, sizeof(Table));
+ Table *t = gco2t(o);
+ 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))
+ 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) {
+ if (!isdummy(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;
+ TValue aux;
+ if (ttisnil(key)) luaG_runerror(L, "table index is nil");
+ else if (ttisfloat(key)) {
+ lua_Integer k;
+ if (luaV_tointeger(key, &k, 0)) { /* does index fit in an integer? */
+ setivalue(&aux, k);
+ key = &aux; /* insert it as an integer */
+ }
+ else if (luai_numisnan(fltvalue(key)))
+ luaG_runerror(L, "table index is NaN");
+ }
+ mp = mainposition(t, key);
+ if (!ttisnil(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, gkey(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 */
+ }
+ setnilvalue(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->i_key, key);
+ luaC_barrierback(L, t, key);
+ lua_assert(ttisnil(gval(mp)));
+ return gval(mp);
+}
+
+
+/*
+** search function for integers
+*/
+const TValue *luaH_getint (Table *t, lua_Integer key) {
+ /* (1 <= key && key <= t->sizearray) */
+ if (l_castS2U(key) - 1 < t->sizearray)
+ return &t->array[key - 1];
+ else {
+ Node *n = hashint(t, key);
+ for (;;) { /* check whether 'key' is somewhere in the chain */
+ if (ttisinteger(gkey(n)) && ivalue(gkey(n)) == key)
+ return gval(n); /* that's it */
+ else {
+ int nx = gnext(n);
+ if (nx == 0) break;
+ n += nx;
+ }
+ }
+ return luaO_nilobject;
+ }
+}
+
+
+/*
+** search function for short strings
+*/
+const TValue *luaH_getshortstr (Table *t, TString *key) {
+ Node *n = hashstr(t, key);
+ lua_assert(key->tt == LUA_TSHRSTR);
+ for (;;) { /* check whether 'key' is somewhere in the chain */
+ const TValue *k = gkey(n);
+ if (ttisshrstring(k) && eqshrstr(tsvalue(k), key))
+ return gval(n); /* that's it */
+ else {
+ int nx = gnext(n);
+ if (nx == 0)
+ return luaO_nilobject; /* not found */
+ n += nx;
+ }
+ }
+}
+
+
+/*
+** "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 = mainposition(t, key);
+ for (;;) { /* check whether 'key' is somewhere in the chain */
+ if (luaV_rawequalobj(gkey(n), key))
+ return gval(n); /* that's it */
+ else {
+ int nx = gnext(n);
+ if (nx == 0)
+ return luaO_nilobject; /* not found */
+ n += nx;
+ }
+ }
+}
+
+
+const TValue *luaH_getstr (Table *t, TString *key) {
+ if (key->tt == LUA_TSHRSTR)
+ 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 (ttype(key)) {
+ case LUA_TSHRSTR: return luaH_getshortstr(t, tsvalue(key));
+ case LUA_TNUMINT: return luaH_getint(t, ivalue(key));
+ case LUA_TNIL: return luaO_nilobject;
+ case LUA_TNUMFLT: {
+ lua_Integer k;
+ if (luaV_tointeger(key, &k, 0)) /* index is int? */
+ 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 (p != luaO_nilobject)
+ 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 (p != luaO_nilobject)
+ cell = cast(TValue *, p);
+ else {
+ TValue k;
+ setivalue(&k, key);
+ cell = luaH_newkey(L, t, &k);
+ }
+ setobj2t(L, cell, value);
+}
+
+
+static lua_Unsigned unbound_search (Table *t, lua_Unsigned j) {
+ lua_Unsigned 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;
+ if (j > l_castS2U(LUA_MAXINTEGER) / 2) { /* overflow? */
+ /* table was built with bad purposes: resort to linear search */
+ i = 1;
+ while (!ttisnil(luaH_getint(t, i))) i++;
+ return i - 1;
+ }
+ j *= 2;
+ }
+ /* now do a binary search between them */
+ while (j - i > 1) {
+ lua_Unsigned 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).
+*/
+lua_Unsigned 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)) /* 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 (const Table *t) { return isdummy(t); }
+
+#endif
projects / ceph.git / blobdiff