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Diffstat (limited to '')
| -rw-r--r-- | bruiser/lua-5.3.4/src/ltable.c | 669 |
1 files changed, 669 insertions, 0 deletions
diff --git a/bruiser/lua-5.3.4/src/ltable.c b/bruiser/lua-5.3.4/src/ltable.c new file mode 100644 index 0000000..d080189 --- /dev/null +++ b/bruiser/lua-5.3.4/src/ltable.c @@ -0,0 +1,669 @@ +/* +** $Id: ltable.c,v 2.118 2016/11/07 12:38:35 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; *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 */ + } +} + + +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 = 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 */ + 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 = 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 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)) /* 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 |