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Diffstat (limited to 'source/luametatex/source/luacore/lua54/src/ltable.c')
| -rw-r--r-- | source/luametatex/source/luacore/lua54/src/ltable.c | 980 |
1 files changed, 980 insertions, 0 deletions
diff --git a/source/luametatex/source/luacore/lua54/src/ltable.c b/source/luametatex/source/luacore/lua54/src/ltable.c new file mode 100644 index 000000000..1b1cd2415 --- /dev/null +++ b/source/luametatex/source/luacore/lua54/src/ltable.c @@ -0,0 +1,980 @@ +/* +** $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 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 integers. To allow a good hash, use the remainder operator +** ('%'). If integer fits as a non-negative int, compute an int +** remainder, which is faster. Otherwise, use an unsigned-integer +** remainder, which uses all bits and ensures a non-negative result. +*/ +static Node *hashint (const Table *t, lua_Integer i) { + lua_Unsigned ui = l_castS2U(i); + if (ui <= (unsigned int)INT_MAX) + return hashmod(t, cast_int(ui)); + else + return hashmod(t, ui); +} + + +/* +** 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). +*/ +static Node *mainpositionTV (const Table *t, const TValue *key) { + switch (ttypetag(key)) { + case LUA_VNUMINT: { + lua_Integer i = ivalue(key); + return hashint(t, i); + } + case LUA_VNUMFLT: { + lua_Number n = fltvalue(key); + return hashmod(t, l_hashfloat(n)); + } + case LUA_VSHRSTR: { + TString *ts = tsvalue(key); + return hashstr(t, ts); + } + case LUA_VLNGSTR: { + TString *ts = tsvalue(key); + 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 = pvalue(key); + return hashpointer(t, p); + } + case LUA_VLCF: { + lua_CFunction f = fvalue(key); + return hashpointer(t, f); + } + default: { + GCObject *o = gcvalue(key); + return hashpointer(t, o); + } + } +} + + +l_sinline Node *mainpositionfromnode (const Table *t, Node *nd) { + TValue key; + getnodekey(cast(lua_State *, NULL), &key, nd); + return mainpositionTV(t, &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 = mainpositionfromnode(t, 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 |