+++ /dev/null
-/*
-** $Id: ltable.c,v 2.117 2015/11/19 19:16:22 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_)
-
-#define isdummy(n) ((n) == 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; *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) {
- 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 > 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 */
-}
-
-
-void luaH_resize (lua_State *L, Table *t, unsigned int nasize,
- unsigned int nhsize) {
- unsigned int i;
- int j;
- unsigned 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 (j = twoto(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 (!isdummy(nold))
- luaM_freearray(L, nold, cast(size_t, twoto(oldhsize))); /* free old hash */
-}
-
-
-void luaH_resizearray (lua_State *L, Table *t, unsigned int nasize) {
- int nsize = isdummy(t->node) ? 0 : sizenode(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->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;
- 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)) { /* index is int? */
- 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(mp)) { /* 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(f));
- 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 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;
- if (j > cast(unsigned int, MAX_INT)/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) {
- 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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