--- /dev/null
+/*
+** $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)
+
+
+/*
+** 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
projects / ceph.git / blobdiff