mirror of
https://github.com/lua/lua.git
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b4b616bdf2
When reinserting elements into a table during a rehash, the code does not need to invoke all the complexity of a full 'luaH_set': - The table has space for all keys. - The key cannot exist in the new hash. - The keys are valid (not NaN nor nil). - The keys are normalized (1.0 -> 1). - The values cannot be nil. - No barrier needed (the table already pointed to the key and value).
1288 lines
39 KiB
C
1288 lines
39 KiB
C
/*
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** $Id: ltable.c $
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** Lua tables (hash)
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** See Copyright Notice in lua.h
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*/
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#define ltable_c
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#define LUA_CORE
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#include "lprefix.h"
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/*
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** Implementation of tables (aka arrays, objects, or hash tables).
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** Tables keep its elements in two parts: an array part and a hash part.
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** Non-negative integer keys are all candidates to be kept in the array
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** part. The actual size of the array is the largest 'n' such that
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** more than half the slots between 1 and n are in use.
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** Hash uses a mix of chained scatter table with Brent's variation.
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** A main invariant of these tables is that, if an element is not
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** in its main position (i.e. the 'original' position that its hash gives
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** to it), then the colliding element is in its own main position.
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** Hence even when the load factor reaches 100%, performance remains good.
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*/
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#include <math.h>
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#include <limits.h>
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#include <string.h>
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#include "lua.h"
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#include "ldebug.h"
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#include "ldo.h"
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#include "lgc.h"
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#include "lmem.h"
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#include "lobject.h"
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#include "lstate.h"
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#include "lstring.h"
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#include "ltable.h"
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#include "lvm.h"
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/*
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** Only hash parts with at least 2^LIMFORLAST have a 'lastfree' field
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** that optimizes finding a free slot. That field is stored just before
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** the array of nodes, in the same block. Smaller tables do a complete
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** search when looking for a free slot.
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*/
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#define LIMFORLAST 3 /* log2 of real limit (8) */
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/*
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** The union 'Limbox' stores 'lastfree' and ensures that what follows it
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** is properly aligned to store a Node.
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*/
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typedef struct { Node *dummy; Node follows_pNode; } Limbox_aux;
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typedef union {
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Node *lastfree;
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char padding[offsetof(Limbox_aux, follows_pNode)];
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} Limbox;
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#define haslastfree(t) ((t)->lsizenode >= LIMFORLAST)
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#define getlastfree(t) ((cast(Limbox *, (t)->node) - 1)->lastfree)
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/*
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** MAXABITS is the largest integer such that 2^MAXABITS fits in an
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** unsigned int.
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*/
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#define MAXABITS cast_int(sizeof(int) * CHAR_BIT - 1)
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/*
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** MAXASIZEB is the maximum number of elements in the array part such
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** that the size of the array fits in 'size_t'.
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*/
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#define MAXASIZEB (MAX_SIZET/(sizeof(Value) + 1))
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/*
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** MAXASIZE is the maximum size of the array part. It is the minimum
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** between 2^MAXABITS and MAXASIZEB.
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*/
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#define MAXASIZE \
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(((1u << MAXABITS) < MAXASIZEB) ? (1u << MAXABITS) : cast_uint(MAXASIZEB))
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/*
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** MAXHBITS is the largest integer such that 2^MAXHBITS fits in a
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** signed int.
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*/
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#define MAXHBITS (MAXABITS - 1)
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/*
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** MAXHSIZE is the maximum size of the hash part. It is the minimum
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** between 2^MAXHBITS and the maximum size such that, measured in bytes,
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** it fits in a 'size_t'.
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*/
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#define MAXHSIZE luaM_limitN(1u << MAXHBITS, Node)
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/*
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** When the original hash value is good, hashing by a power of 2
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** avoids the cost of '%'.
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*/
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#define hashpow2(t,n) (gnode(t, lmod((n), sizenode(t))))
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/*
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** for other types, it is better to avoid modulo by power of 2, as
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** they can have many 2 factors.
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*/
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#define hashmod(t,n) (gnode(t, ((n) % ((sizenode(t)-1u)|1u))))
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#define hashstr(t,str) hashpow2(t, (str)->hash)
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#define hashboolean(t,p) hashpow2(t, p)
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#define hashpointer(t,p) hashmod(t, point2uint(p))
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#define dummynode (&dummynode_)
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/*
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** Common hash part for tables with empty hash parts. That allows all
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** tables to have a hash part, avoding an extra check ("is there a hash
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** part?") when indexing. Its sole node has an empty value and a key
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** (DEADKEY, NULL) that is different from any valid TValue.
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*/
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static const Node dummynode_ = {
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{{NULL}, LUA_VEMPTY, /* value's value and type */
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LUA_TDEADKEY, 0, {NULL}} /* key type, next, and key value */
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};
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static const TValue absentkey = {ABSTKEYCONSTANT};
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/*
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** Hash for integers. To allow a good hash, use the remainder operator
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** ('%'). If integer fits as a non-negative int, compute an int
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** remainder, which is faster. Otherwise, use an unsigned-integer
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** remainder, which uses all bits and ensures a non-negative result.
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*/
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static Node *hashint (const Table *t, lua_Integer i) {
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lua_Unsigned ui = l_castS2U(i);
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if (ui <= cast_uint(INT_MAX))
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return gnode(t, cast_int(ui) % cast_int((sizenode(t)-1) | 1));
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else
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return hashmod(t, ui);
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}
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/*
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** Hash for floating-point numbers.
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** The main computation should be just
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** n = frexp(n, &i); return (n * INT_MAX) + i
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** but there are some numerical subtleties.
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** In a two-complement representation, INT_MAX does not has an exact
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** representation as a float, but INT_MIN does; because the absolute
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** value of 'frexp' is smaller than 1 (unless 'n' is inf/NaN), the
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** absolute value of the product 'frexp * -INT_MIN' is smaller or equal
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** to INT_MAX. Next, the use of 'unsigned int' avoids overflows when
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** adding 'i'; the use of '~u' (instead of '-u') avoids problems with
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** INT_MIN.
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*/
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#if !defined(l_hashfloat)
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static unsigned l_hashfloat (lua_Number n) {
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int i;
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lua_Integer ni;
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n = l_mathop(frexp)(n, &i) * -cast_num(INT_MIN);
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if (!lua_numbertointeger(n, &ni)) { /* is 'n' inf/-inf/NaN? */
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lua_assert(luai_numisnan(n) || l_mathop(fabs)(n) == cast_num(HUGE_VAL));
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return 0;
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}
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else { /* normal case */
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unsigned int u = cast_uint(i) + cast_uint(ni);
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return (u <= cast_uint(INT_MAX) ? u : ~u);
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}
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}
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#endif
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/*
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** returns the 'main' position of an element in a table (that is,
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** the index of its hash value).
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*/
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static Node *mainpositionTV (const Table *t, const TValue *key) {
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switch (ttypetag(key)) {
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case LUA_VNUMINT: {
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lua_Integer i = ivalue(key);
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return hashint(t, i);
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}
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case LUA_VNUMFLT: {
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lua_Number n = fltvalue(key);
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return hashmod(t, l_hashfloat(n));
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}
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case LUA_VSHRSTR: {
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TString *ts = tsvalue(key);
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return hashstr(t, ts);
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}
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case LUA_VLNGSTR: {
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TString *ts = tsvalue(key);
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return hashpow2(t, luaS_hashlongstr(ts));
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}
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case LUA_VFALSE:
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return hashboolean(t, 0);
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case LUA_VTRUE:
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return hashboolean(t, 1);
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case LUA_VLIGHTUSERDATA: {
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void *p = pvalue(key);
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return hashpointer(t, p);
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}
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case LUA_VLCF: {
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lua_CFunction f = fvalue(key);
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return hashpointer(t, f);
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}
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default: {
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GCObject *o = gcvalue(key);
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return hashpointer(t, o);
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}
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}
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}
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l_sinline Node *mainpositionfromnode (const Table *t, Node *nd) {
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TValue key;
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getnodekey(cast(lua_State *, NULL), &key, nd);
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return mainpositionTV(t, &key);
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}
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/*
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** Check whether key 'k1' is equal to the key in node 'n2'. This
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** equality is raw, so there are no metamethods. Floats with integer
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** values have been normalized, so integers cannot be equal to
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** floats. It is assumed that 'eqshrstr' is simply pointer equality, so
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** that short strings are handled in the default case.
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** A true 'deadok' means to accept dead keys as equal to their original
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** values. All dead keys are compared in the default case, by pointer
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** identity. (Only collectable objects can produce dead keys.) Note that
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** dead long strings are also compared by identity.
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** Once a key is dead, its corresponding value may be collected, and
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** then another value can be created with the same address. If this
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** other value is given to 'next', 'equalkey' will signal a false
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** positive. In a regular traversal, this situation should never happen,
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** as all keys given to 'next' came from the table itself, and therefore
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** could not have been collected. Outside a regular traversal, we
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** have garbage in, garbage out. What is relevant is that this false
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** positive does not break anything. (In particular, 'next' will return
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** some other valid item on the table or nil.)
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*/
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static int equalkey (const TValue *k1, const Node *n2, int deadok) {
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if ((rawtt(k1) != keytt(n2)) && /* not the same variants? */
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!(deadok && keyisdead(n2) && iscollectable(k1)))
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return 0; /* cannot be same key */
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switch (keytt(n2)) {
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case LUA_VNIL: case LUA_VFALSE: case LUA_VTRUE:
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return 1;
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case LUA_VNUMINT:
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return (ivalue(k1) == keyival(n2));
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case LUA_VNUMFLT:
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return luai_numeq(fltvalue(k1), fltvalueraw(keyval(n2)));
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case LUA_VLIGHTUSERDATA:
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return pvalue(k1) == pvalueraw(keyval(n2));
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case LUA_VLCF:
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return fvalue(k1) == fvalueraw(keyval(n2));
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case ctb(LUA_VLNGSTR):
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return luaS_eqlngstr(tsvalue(k1), keystrval(n2));
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default:
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return gcvalue(k1) == gcvalueraw(keyval(n2));
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}
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}
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/*
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** "Generic" get version. (Not that generic: not valid for integers,
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** which may be in array part, nor for floats with integral values.)
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** See explanation about 'deadok' in function 'equalkey'.
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*/
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static const TValue *getgeneric (Table *t, const TValue *key, int deadok) {
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Node *n = mainpositionTV(t, key);
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for (;;) { /* check whether 'key' is somewhere in the chain */
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if (equalkey(key, n, deadok))
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return gval(n); /* that's it */
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else {
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int nx = gnext(n);
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if (nx == 0)
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return &absentkey; /* not found */
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n += nx;
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}
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}
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}
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/*
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** Return the index 'k' (converted to an unsigned) if it is inside
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** the range [1, limit].
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*/
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static unsigned checkrange (lua_Integer k, unsigned limit) {
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return (l_castS2U(k) - 1u < limit) ? cast_uint(k) : 0;
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}
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/*
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** Return the index 'k' if 'k' is an appropriate key to live in the
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** array part of a table, 0 otherwise.
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*/
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#define arrayindex(k) checkrange(k, MAXASIZE)
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/*
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** Check whether an integer key is in the array part of a table and
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** return its index there, or zero.
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*/
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#define ikeyinarray(t,k) checkrange(k, t->asize)
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/*
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** Check whether a key is in the array part of a table and return its
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** index there, or zero.
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*/
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static unsigned keyinarray (Table *t, const TValue *key) {
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return (ttisinteger(key)) ? ikeyinarray(t, ivalue(key)) : 0;
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}
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/*
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** returns the index of a 'key' for table traversals. First goes all
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** elements in the array part, then elements in the hash part. The
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** beginning of a traversal is signaled by 0.
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*/
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static unsigned findindex (lua_State *L, Table *t, TValue *key,
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unsigned asize) {
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unsigned int i;
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if (ttisnil(key)) return 0; /* first iteration */
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i = keyinarray(t, key);
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if (i != 0) /* is 'key' inside array part? */
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return i; /* yes; that's the index */
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else {
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const TValue *n = getgeneric(t, key, 1);
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if (l_unlikely(isabstkey(n)))
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luaG_runerror(L, "invalid key to 'next'"); /* key not found */
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i = cast_uint(nodefromval(n) - gnode(t, 0)); /* key index in hash table */
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/* hash elements are numbered after array ones */
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return (i + 1) + asize;
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}
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}
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int luaH_next (lua_State *L, Table *t, StkId key) {
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unsigned int asize = t->asize;
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unsigned int i = findindex(L, t, s2v(key), asize); /* find original key */
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for (; i < asize; i++) { /* try first array part */
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lu_byte tag = *getArrTag(t, i);
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if (!tagisempty(tag)) { /* a non-empty entry? */
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setivalue(s2v(key), cast_int(i) + 1);
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farr2val(t, i, tag, s2v(key + 1));
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return 1;
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}
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}
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for (i -= asize; i < sizenode(t); i++) { /* hash part */
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if (!isempty(gval(gnode(t, i)))) { /* a non-empty entry? */
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Node *n = gnode(t, i);
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getnodekey(L, s2v(key), n);
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setobj2s(L, key + 1, gval(n));
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return 1;
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}
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}
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return 0; /* no more elements */
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}
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/* Extra space in Node array if it has a lastfree entry */
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#define extraLastfree(t) (haslastfree(t) ? sizeof(Limbox) : 0)
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/* 'node' size in bytes */
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static size_t sizehash (Table *t) {
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return cast_sizet(sizenode(t)) * sizeof(Node) + extraLastfree(t);
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}
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static void freehash (lua_State *L, Table *t) {
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if (!isdummy(t)) {
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/* get pointer to the beginning of Node array */
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char *arr = cast_charp(t->node) - extraLastfree(t);
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luaM_freearray(L, arr, sizehash(t));
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}
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}
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/*
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** {=============================================================
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** Rehash
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** ==============================================================
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*/
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static int insertkey (Table *t, const TValue *key, TValue *value);
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static void newcheckedkey (Table *t, const TValue *key, TValue *value);
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/*
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** Structure to count the keys in a table.
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** 'total' is the total number of keys in the table.
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** 'na' is the number of *array indices* in the table (see 'arrayindex').
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** 'deleted' is true if there are deleted nodes in the hash part.
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** 'nums' is a "count array" where 'nums[i]' is the number of integer
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** keys between 2^(i - 1) + 1 and 2^i. Note that 'na' is the summation
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** of 'nums'.
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*/
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typedef struct {
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unsigned total;
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unsigned na;
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int deleted;
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unsigned nums[MAXABITS + 1];
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} Counters;
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/*
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** Check whether it is worth to use 'na' array entries instead of 'nh'
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** hash nodes. (A hash node uses ~3 times more memory than an array
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** entry: Two values plus 'next' versus one value.) Evaluate with size_t
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** to avoid overflows.
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*/
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#define arrayXhash(na,nh) (cast_sizet(na) <= cast_sizet(nh) * 3)
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/*
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** Compute the optimal size for the array part of table 't'.
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** This size maximizes the number of elements going to the array part
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** while satisfying the condition 'arrayXhash' with the use of memory if
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** all those elements went to the hash part.
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** 'ct->na' enters with the total number of array indices in the table
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** and leaves with the number of keys that will go to the array part;
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** return the optimal size for the array part.
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*/
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static unsigned computesizes (Counters *ct) {
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int i;
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unsigned int twotoi; /* 2^i (candidate for optimal size) */
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unsigned int a = 0; /* number of elements smaller than 2^i */
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unsigned int na = 0; /* number of elements to go to array part */
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unsigned int optimal = 0; /* optimal size for array part */
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/* traverse slices while 'twotoi' does not overflow and total of array
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indices still can satisfy 'arrayXhash' against the array size */
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for (i = 0, twotoi = 1;
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twotoi > 0 && arrayXhash(twotoi, ct->na);
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i++, twotoi *= 2) {
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unsigned nums = ct->nums[i];
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a += nums;
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if (nums > 0 && /* grows array only if it gets more elements... */
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arrayXhash(twotoi, a)) { /* ...while using "less memory" */
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optimal = twotoi; /* optimal size (till now) */
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na = a; /* all elements up to 'optimal' will go to array part */
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}
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}
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ct->na = na;
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return optimal;
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}
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static void countint (lua_Integer key, Counters *ct) {
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unsigned int k = arrayindex(key);
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if (k != 0) { /* is 'key' an array index? */
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ct->nums[luaO_ceillog2(k)]++; /* count as such */
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ct->na++;
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}
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}
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l_sinline int arraykeyisempty (const Table *t, unsigned key) {
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int tag = *getArrTag(t, key - 1);
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return tagisempty(tag);
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}
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/*
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** Count keys in array part of table 't'.
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*/
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static void numusearray (const Table *t, Counters *ct) {
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int lg;
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unsigned int ttlg; /* 2^lg */
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unsigned int ause = 0; /* summation of 'nums' */
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unsigned int i = 1; /* index to traverse all array keys */
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unsigned int asize = t->asize;
|
|
/* 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 (!arraykeyisempty(t, i))
|
|
lc++;
|
|
}
|
|
ct->nums[lg] += lc;
|
|
ause += lc;
|
|
}
|
|
ct->total += ause;
|
|
ct->na += ause;
|
|
}
|
|
|
|
|
|
/*
|
|
** Count keys in hash part of table 't'. As this only happens during
|
|
** a rehash, all nodes have been used. A node can have a nil value only
|
|
** if it was deleted after being created.
|
|
*/
|
|
static void numusehash (const Table *t, Counters *ct) {
|
|
unsigned i = sizenode(t);
|
|
unsigned total = 0;
|
|
while (i--) {
|
|
Node *n = &t->node[i];
|
|
if (isempty(gval(n))) {
|
|
lua_assert(!keyisnil(n)); /* entry was deleted; key cannot be nil */
|
|
ct->deleted = 1;
|
|
}
|
|
else {
|
|
total++;
|
|
if (keyisinteger(n))
|
|
countint(keyival(n), ct);
|
|
}
|
|
}
|
|
ct->total += total;
|
|
}
|
|
|
|
|
|
/*
|
|
** Convert an "abstract size" (number of slots in an array) to
|
|
** "concrete size" (number of bytes in the array).
|
|
*/
|
|
static size_t concretesize (unsigned int size) {
|
|
if (size == 0)
|
|
return 0;
|
|
else /* space for the two arrays plus an unsigned in between */
|
|
return size * (sizeof(Value) + 1) + sizeof(unsigned);
|
|
}
|
|
|
|
|
|
/*
|
|
** Resize the array part of a table. If new size is equal to the old,
|
|
** do nothing. Else, if new size is zero, free the old array. (It must
|
|
** be present, as the sizes are different.) Otherwise, allocate a new
|
|
** array, move the common elements to new proper position, and then
|
|
** frees the old array.
|
|
** We could reallocate the array, but we still would need to move the
|
|
** elements to their new position, so the copy implicit in realloc is a
|
|
** waste. Moreover, most allocators will move the array anyway when the
|
|
** new size is double the old one (the most common case).
|
|
*/
|
|
static Value *resizearray (lua_State *L , Table *t,
|
|
unsigned oldasize,
|
|
unsigned newasize) {
|
|
if (oldasize == newasize)
|
|
return t->array; /* nothing to be done */
|
|
else if (newasize == 0) { /* erasing array? */
|
|
Value *op = t->array - oldasize; /* original array's real address */
|
|
luaM_freemem(L, op, concretesize(oldasize)); /* free it */
|
|
return NULL;
|
|
}
|
|
else {
|
|
size_t newasizeb = concretesize(newasize);
|
|
Value *np = cast(Value *,
|
|
luaM_reallocvector(L, NULL, 0, newasizeb, lu_byte));
|
|
if (np == NULL) /* allocation error? */
|
|
return NULL;
|
|
np += newasize; /* shift pointer to the end of value segment */
|
|
if (oldasize > 0) {
|
|
/* move common elements to new position */
|
|
size_t oldasizeb = concretesize(oldasize);
|
|
Value *op = t->array; /* original array */
|
|
unsigned tomove = (oldasize < newasize) ? oldasize : newasize;
|
|
size_t tomoveb = (oldasize < newasize) ? oldasizeb : newasizeb;
|
|
lua_assert(tomoveb > 0);
|
|
memcpy(np - tomove, op - tomove, tomoveb);
|
|
luaM_freemem(L, op - oldasize, oldasizeb); /* free old block */
|
|
}
|
|
return np;
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
** 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 size) {
|
|
if (size == 0) { /* no elements to hash part? */
|
|
t->node = cast(Node *, dummynode); /* use common 'dummynode' */
|
|
t->lsizenode = 0;
|
|
setdummy(t); /* 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);
|
|
if (lsize < LIMFORLAST) /* no 'lastfree' field? */
|
|
t->node = luaM_newvector(L, size, Node);
|
|
else {
|
|
size_t bsize = size * sizeof(Node) + sizeof(Limbox);
|
|
char *node = luaM_newblock(L, bsize);
|
|
t->node = cast(Node *, node + sizeof(Limbox));
|
|
getlastfree(t) = gnode(t, size); /* all positions are free */
|
|
}
|
|
t->lsizenode = cast_byte(lsize);
|
|
setnodummy(t);
|
|
for (i = 0; i < cast_int(size); i++) {
|
|
Node *n = gnode(t, i);
|
|
gnext(n) = 0;
|
|
setnilkey(n);
|
|
setempty(gval(n));
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
** (Re)insert all elements from the hash part of 'ot' into table 't'.
|
|
*/
|
|
static void reinserthash (lua_State *L, Table *ot, Table *t) {
|
|
unsigned j;
|
|
unsigned 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);
|
|
newcheckedkey(t, &k, gval(old));
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
** Exchange the hash part of 't1' and 't2'. (In 'flags', only the
|
|
** dummy bit must be exchanged: The 'isrealasize' is not related
|
|
** to the hash part, and the metamethod bits do not change during
|
|
** a resize, so the "real" table can keep their values.)
|
|
*/
|
|
static void exchangehashpart (Table *t1, Table *t2) {
|
|
lu_byte lsizenode = t1->lsizenode;
|
|
Node *node = t1->node;
|
|
int bitdummy1 = t1->flags & BITDUMMY;
|
|
t1->lsizenode = t2->lsizenode;
|
|
t1->node = t2->node;
|
|
t1->flags = cast_byte((t1->flags & NOTBITDUMMY) | (t2->flags & BITDUMMY));
|
|
t2->lsizenode = lsizenode;
|
|
t2->node = node;
|
|
t2->flags = cast_byte((t2->flags & NOTBITDUMMY) | bitdummy1);
|
|
}
|
|
|
|
|
|
/*
|
|
** Re-insert into the new hash part of a table the elements from the
|
|
** vanishing slice of the array part.
|
|
*/
|
|
static void reinsertOldSlice (Table *t, unsigned oldasize,
|
|
unsigned newasize) {
|
|
unsigned i;
|
|
for (i = newasize; i < oldasize; i++) { /* traverse vanishing slice */
|
|
lu_byte tag = *getArrTag(t, i);
|
|
if (!tagisempty(tag)) { /* a non-empty entry? */
|
|
TValue key, aux;
|
|
setivalue(&key, l_castU2S(i) + 1); /* make the key */
|
|
farr2val(t, i, tag, &aux); /* copy value into 'aux' */
|
|
insertkey(t, &key, &aux); /* insert entry into the hash part */
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
** Clear new slice of the array.
|
|
*/
|
|
static void clearNewSlice (Table *t, unsigned oldasize, unsigned newasize) {
|
|
for (; oldasize < newasize; oldasize++)
|
|
*getArrTag(t, oldasize) = LUA_VEMPTY;
|
|
}
|
|
|
|
|
|
/*
|
|
** 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.
|
|
** Note that if the new size for the arry part ('newasize') is equal to
|
|
** the old one ('oldasize'), this function will do nothing with that
|
|
** part.
|
|
*/
|
|
void luaH_resize (lua_State *L, Table *t, unsigned newasize,
|
|
unsigned nhsize) {
|
|
Table newt; /* to keep the new hash part */
|
|
unsigned oldasize = t->asize;
|
|
Value *newarray;
|
|
if (newasize > MAXASIZE)
|
|
luaG_runerror(L, "table overflow");
|
|
/* create new hash part with appropriate size into 'newt' */
|
|
newt.flags = 0;
|
|
setnodevector(L, &newt, nhsize);
|
|
if (newasize < oldasize) { /* will array shrink? */
|
|
/* re-insert into the new hash the elements from vanishing slice */
|
|
exchangehashpart(t, &newt); /* pretend table has new hash */
|
|
reinsertOldSlice(t, oldasize, newasize);
|
|
exchangehashpart(t, &newt); /* restore old hash (in case of errors) */
|
|
}
|
|
/* allocate new array */
|
|
newarray = resizearray(L, t, oldasize, newasize);
|
|
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->asize = newasize;
|
|
if (newarray != NULL)
|
|
*lenhint(t) = newasize / 2u; /* set an initial hint */
|
|
clearNewSlice(t, oldasize, newasize);
|
|
/* re-insert elements from old hash part into new parts */
|
|
reinserthash(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) {
|
|
unsigned nsize = allocsizenode(t);
|
|
luaH_resize(L, t, nasize, nsize);
|
|
}
|
|
|
|
|
|
/*
|
|
** Rehash a table. First, count its keys. If there are array indices
|
|
** outside the array part, compute the new best size for that part.
|
|
** Then, resize the table.
|
|
*/
|
|
static void rehash (lua_State *L, Table *t, const TValue *ek) {
|
|
unsigned asize; /* optimal size for array part */
|
|
Counters ct;
|
|
unsigned i;
|
|
unsigned nsize; /* size for the hash part */
|
|
/* reset counts */
|
|
for (i = 0; i <= MAXABITS; i++) ct.nums[i] = 0;
|
|
ct.na = 0;
|
|
ct.deleted = 0;
|
|
ct.total = 1; /* count extra key */
|
|
if (ttisinteger(ek))
|
|
countint(ivalue(ek), &ct); /* extra key may go to array */
|
|
numusehash(t, &ct); /* count keys in hash part */
|
|
if (ct.na == 0) {
|
|
/* no new keys to enter array part; keep it with the same size */
|
|
asize = t->asize;
|
|
}
|
|
else { /* compute best size for array part */
|
|
numusearray(t, &ct); /* count keys in array part */
|
|
asize = computesizes(&ct); /* compute new size for array part */
|
|
}
|
|
/* all keys not in the array part go to the hash part */
|
|
nsize = ct.total - ct.na;
|
|
if (ct.deleted) { /* table has deleted entries? */
|
|
/* insertion-deletion-insertion: give hash some extra size to
|
|
avoid constant resizings */
|
|
nsize += nsize >> 2;
|
|
}
|
|
/* resize the table to new computed sizes */
|
|
luaH_resize(L, t, asize, nsize);
|
|
}
|
|
|
|
/*
|
|
** }=============================================================
|
|
*/
|
|
|
|
|
|
Table *luaH_new (lua_State *L) {
|
|
GCObject *o = luaC_newobj(L, LUA_VTABLE, sizeof(Table));
|
|
Table *t = gco2t(o);
|
|
t->metatable = NULL;
|
|
t->flags = maskflags; /* table has no metamethod fields */
|
|
t->array = NULL;
|
|
t->asize = 0;
|
|
setnodevector(L, t, 0);
|
|
return t;
|
|
}
|
|
|
|
|
|
lu_mem luaH_size (Table *t) {
|
|
lu_mem sz = cast(lu_mem, sizeof(Table)) + concretesize(t->asize);
|
|
if (!isdummy(t))
|
|
sz += sizehash(t);
|
|
return sz;
|
|
}
|
|
|
|
|
|
/*
|
|
** Frees a table.
|
|
*/
|
|
void luaH_free (lua_State *L, Table *t) {
|
|
freehash(L, t);
|
|
resizearray(L, t, t->asize, 0);
|
|
luaM_free(L, t);
|
|
}
|
|
|
|
|
|
static Node *getfreepos (Table *t) {
|
|
if (haslastfree(t)) { /* does it have 'lastfree' information? */
|
|
/* look for a spot before 'lastfree', updating 'lastfree' */
|
|
while (getlastfree(t) > t->node) {
|
|
Node *free = --getlastfree(t);
|
|
if (keyisnil(free))
|
|
return free;
|
|
}
|
|
}
|
|
else { /* no 'lastfree' information */
|
|
unsigned i = sizenode(t);
|
|
while (i--) { /* do a linear search */
|
|
Node *free = gnode(t, i);
|
|
if (keyisnil(free))
|
|
return free;
|
|
}
|
|
}
|
|
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. Return 0 if
|
|
** could not insert key (could not find a free space).
|
|
*/
|
|
static int insertkey (Table *t, const TValue *key, TValue *value) {
|
|
Node *mp = mainpositionTV(t, key);
|
|
/* table cannot already contain the key */
|
|
lua_assert(isabstkey(getgeneric(t, key, 0)));
|
|
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? */
|
|
return 0;
|
|
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(mp, key);
|
|
lua_assert(isempty(gval(mp)));
|
|
setobj2t(cast(lua_State *, 0), gval(mp), value);
|
|
return 1;
|
|
}
|
|
|
|
|
|
/*
|
|
** Insert a key in a table where there is space for that key, the
|
|
** key is valid, and the value is not nil.
|
|
*/
|
|
static void newcheckedkey (Table *t, const TValue *key, TValue *value) {
|
|
unsigned i = keyinarray(t, key);
|
|
if (i > 0) /* is key in the array part? */
|
|
obj2arr(t, i - 1, value); /* set value in the array */
|
|
else {
|
|
int done = insertkey(t, key, value); /* insert key in the hash part */
|
|
lua_assert(done); /* it cannot fail */
|
|
cast(void, done); /* to avoid warnings */
|
|
}
|
|
}
|
|
|
|
|
|
static void luaH_newkey (lua_State *L, Table *t, const TValue *key,
|
|
TValue *value) {
|
|
if (!ttisnil(value)) { /* do not insert nil values */
|
|
int done = insertkey(t, key, value);
|
|
if (!done) { /* could not find a free place? */
|
|
rehash(L, t, key); /* grow table */
|
|
newcheckedkey(t, key, value); /* insert key in grown table */
|
|
}
|
|
luaC_barrierback(L, obj2gco(t), key);
|
|
}
|
|
}
|
|
|
|
|
|
static const TValue *getintfromhash (Table *t, lua_Integer key) {
|
|
Node *n = hashint(t, key);
|
|
lua_assert(!ikeyinarray(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;
|
|
}
|
|
|
|
|
|
static int hashkeyisempty (Table *t, lua_Unsigned key) {
|
|
const TValue *val = getintfromhash(t, l_castU2S(key));
|
|
return isempty(val);
|
|
}
|
|
|
|
|
|
static lu_byte finishnodeget (const TValue *val, TValue *res) {
|
|
if (!ttisnil(val)) {
|
|
setobj(((lua_State*)NULL), res, val);
|
|
}
|
|
return ttypetag(val);
|
|
}
|
|
|
|
|
|
lu_byte luaH_getint (Table *t, lua_Integer key, TValue *res) {
|
|
unsigned k = ikeyinarray(t, key);
|
|
if (k > 0) {
|
|
lu_byte tag = *getArrTag(t, k - 1);
|
|
if (!tagisempty(tag))
|
|
farr2val(t, k - 1, tag, res);
|
|
return tag;
|
|
}
|
|
else
|
|
return finishnodeget(getintfromhash(t, key), res);
|
|
}
|
|
|
|
|
|
/*
|
|
** search function for short strings
|
|
*/
|
|
const TValue *luaH_Hgetshortstr (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;
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
lu_byte luaH_getshortstr (Table *t, TString *key, TValue *res) {
|
|
return finishnodeget(luaH_Hgetshortstr(t, key), res);
|
|
}
|
|
|
|
|
|
static const TValue *Hgetstr (Table *t, TString *key) {
|
|
if (key->tt == LUA_VSHRSTR)
|
|
return luaH_Hgetshortstr(t, key);
|
|
else { /* for long strings, use generic case */
|
|
TValue ko;
|
|
setsvalue(cast(lua_State *, NULL), &ko, key);
|
|
return getgeneric(t, &ko, 0);
|
|
}
|
|
}
|
|
|
|
|
|
lu_byte luaH_getstr (Table *t, TString *key, TValue *res) {
|
|
return finishnodeget(Hgetstr(t, key), res);
|
|
}
|
|
|
|
|
|
TString *luaH_getstrkey (Table *t, TString *key) {
|
|
const TValue *o = Hgetstr(t, key);
|
|
if (!isabstkey(o)) /* string already present? */
|
|
return keystrval(nodefromval(o)); /* get saved copy */
|
|
else
|
|
return NULL;
|
|
}
|
|
|
|
|
|
/*
|
|
** main search function
|
|
*/
|
|
lu_byte luaH_get (Table *t, const TValue *key, TValue *res) {
|
|
const TValue *slot;
|
|
switch (ttypetag(key)) {
|
|
case LUA_VSHRSTR:
|
|
slot = luaH_Hgetshortstr(t, tsvalue(key));
|
|
break;
|
|
case LUA_VNUMINT:
|
|
return luaH_getint(t, ivalue(key), res);
|
|
case LUA_VNIL:
|
|
slot = &absentkey;
|
|
break;
|
|
case LUA_VNUMFLT: {
|
|
lua_Integer k;
|
|
if (luaV_flttointeger(fltvalue(key), &k, F2Ieq)) /* integral index? */
|
|
return luaH_getint(t, k, res); /* use specialized version */
|
|
/* else... */
|
|
} /* FALLTHROUGH */
|
|
default:
|
|
slot = getgeneric(t, key, 0);
|
|
break;
|
|
}
|
|
return finishnodeget(slot, res);
|
|
}
|
|
|
|
|
|
static int finishnodeset (Table *t, const TValue *slot, TValue *val) {
|
|
if (!ttisnil(slot)) {
|
|
setobj(((lua_State*)NULL), cast(TValue*, slot), val);
|
|
return HOK; /* success */
|
|
}
|
|
else if (isabstkey(slot))
|
|
return HNOTFOUND; /* no slot with that key */
|
|
else /* return node encoded */
|
|
return cast_int((cast(Node*, slot) - t->node)) + HFIRSTNODE;
|
|
}
|
|
|
|
|
|
static int rawfinishnodeset (const TValue *slot, TValue *val) {
|
|
if (isabstkey(slot))
|
|
return 0; /* no slot with that key */
|
|
else {
|
|
setobj(((lua_State*)NULL), cast(TValue*, slot), val);
|
|
return 1; /* success */
|
|
}
|
|
}
|
|
|
|
|
|
int luaH_psetint (Table *t, lua_Integer key, TValue *val) {
|
|
lua_assert(!ikeyinarray(t, key));
|
|
return finishnodeset(t, getintfromhash(t, key), val);
|
|
}
|
|
|
|
|
|
static int psetint (Table *t, lua_Integer key, TValue *val) {
|
|
int hres;
|
|
luaH_fastseti(t, key, val, hres);
|
|
return hres;
|
|
}
|
|
|
|
|
|
int luaH_psetshortstr (Table *t, TString *key, TValue *val) {
|
|
return finishnodeset(t, luaH_Hgetshortstr(t, key), val);
|
|
}
|
|
|
|
|
|
int luaH_psetstr (Table *t, TString *key, TValue *val) {
|
|
return finishnodeset(t, Hgetstr(t, key), val);
|
|
}
|
|
|
|
|
|
int luaH_pset (Table *t, const TValue *key, TValue *val) {
|
|
switch (ttypetag(key)) {
|
|
case LUA_VSHRSTR: return luaH_psetshortstr(t, tsvalue(key), val);
|
|
case LUA_VNUMINT: return psetint(t, ivalue(key), val);
|
|
case LUA_VNIL: return HNOTFOUND;
|
|
case LUA_VNUMFLT: {
|
|
lua_Integer k;
|
|
if (luaV_flttointeger(fltvalue(key), &k, F2Ieq)) /* integral index? */
|
|
return psetint(t, k, val); /* use specialized version */
|
|
/* else... */
|
|
} /* FALLTHROUGH */
|
|
default:
|
|
return finishnodeset(t, getgeneric(t, key, 0), val);
|
|
}
|
|
}
|
|
|
|
/*
|
|
** 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,
|
|
TValue *value, int hres) {
|
|
lua_assert(hres != HOK);
|
|
if (hres == HNOTFOUND) {
|
|
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)) {
|
|
setivalue(&aux, k); /* key is equal to an integer */
|
|
key = &aux; /* insert it as an integer */
|
|
}
|
|
else if (l_unlikely(luai_numisnan(f)))
|
|
luaG_runerror(L, "table index is NaN");
|
|
}
|
|
luaH_newkey(L, t, key, value);
|
|
}
|
|
else if (hres > 0) { /* regular Node? */
|
|
setobj2t(L, gval(gnode(t, hres - HFIRSTNODE)), value);
|
|
}
|
|
else { /* array entry */
|
|
hres = ~hres; /* real index */
|
|
obj2arr(t, cast_uint(hres), 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) {
|
|
int hres = luaH_pset(t, key, value);
|
|
if (hres != HOK)
|
|
luaH_finishset(L, t, key, value, hres);
|
|
}
|
|
|
|
|
|
/*
|
|
** Ditto for a GC barrier. (No need to invalidate the TM cache, as
|
|
** integers cannot be keys to metamethods.)
|
|
*/
|
|
void luaH_setint (lua_State *L, Table *t, lua_Integer key, TValue *value) {
|
|
unsigned ik = ikeyinarray(t, key);
|
|
if (ik > 0)
|
|
obj2arr(t, ik - 1, value);
|
|
else {
|
|
int ok = rawfinishnodeset(getintfromhash(t, key), value);
|
|
if (!ok) {
|
|
TValue k;
|
|
setivalue(&k, key);
|
|
luaH_newkey(L, t, &k, 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 (hashkeyisempty(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 (!hashkeyisempty(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 (hashkeyisempty(t, m)) j = m;
|
|
else i = m;
|
|
}
|
|
return i;
|
|
}
|
|
|
|
|
|
static unsigned int binsearch (Table *array, unsigned int i, unsigned int j) {
|
|
lua_assert(i <= j);
|
|
while (j - i > 1u) { /* binary search */
|
|
unsigned int m = (i + j) / 2;
|
|
if (arraykeyisempty(array, m)) j = m;
|
|
else i = m;
|
|
}
|
|
return i;
|
|
}
|
|
|
|
|
|
/* return a border, saving it as a hint for next call */
|
|
static lua_Unsigned newhint (Table *t, unsigned hint) {
|
|
lua_assert(hint <= t->asize);
|
|
*lenhint(t) = hint;
|
|
return hint;
|
|
}
|
|
|
|
|
|
/*
|
|
** Try to find a border in table 't'. (A 'border' is an integer index
|
|
** such that t[i] is present and t[i+1] is absent, or 0 if t[1] is absent,
|
|
** or 'maxinteger' if t[maxinteger] is present.)
|
|
** If there is an array part, try to find a border there. First try
|
|
** to find it in the vicinity of the previous result (hint), to handle
|
|
** cases like 't[#t + 1] = val' or 't[#t] = nil', that move the border
|
|
** by one entry. Otherwise, do a binary search to find the border.
|
|
** If there is no array part, or its last element is non empty, the
|
|
** border may be in the hash part.
|
|
*/
|
|
lua_Unsigned luaH_getn (Table *t) {
|
|
unsigned asize = t->asize;
|
|
if (asize > 0) { /* is there an array part? */
|
|
const unsigned maxvicinity = 4;
|
|
unsigned limit = *lenhint(t); /* start with the hint */
|
|
if (limit == 0)
|
|
limit = 1; /* make limit a valid index in the array */
|
|
if (arraykeyisempty(t, limit)) { /* t[limit] empty? */
|
|
/* there must be a border before 'limit' */
|
|
unsigned i;
|
|
/* look for a border in the vicinity of the hint */
|
|
for (i = 0; i < maxvicinity && limit > 1; i++) {
|
|
limit--;
|
|
if (!arraykeyisempty(t, limit))
|
|
return newhint(t, limit); /* 'limit' is a border */
|
|
}
|
|
/* t[limit] still empty; search for a border in [0, limit) */
|
|
return newhint(t, binsearch(t, 0, limit));
|
|
}
|
|
else { /* 'limit' is present in table; look for a border after it */
|
|
unsigned i;
|
|
/* look for a border in the vicinity of the hint */
|
|
for (i = 0; i < maxvicinity && limit < asize; i++) {
|
|
limit++;
|
|
if (arraykeyisempty(t, limit))
|
|
return newhint(t, limit - 1); /* 'limit - 1' is a border */
|
|
}
|
|
if (arraykeyisempty(t, asize)) { /* last element empty? */
|
|
/* t[limit] not empty; search for a border in [limit, asize) */
|
|
return newhint(t, binsearch(t, limit, asize));
|
|
}
|
|
}
|
|
/* last element non empty; set a hint to speed up findind that again */
|
|
/* (keys in the hash part cannot be hints) */
|
|
*lenhint(t) = asize;
|
|
}
|
|
/* no array part or t[asize] is not empty; check the hash part */
|
|
lua_assert(asize == 0 || !arraykeyisempty(t, asize));
|
|
if (isdummy(t) || hashkeyisempty(t, asize + 1))
|
|
return asize; /* 'asize + 1' is empty */
|
|
else /* 'asize + 1' is also non empty */
|
|
return hash_search(t, asize);
|
|
}
|
|
|
|
|
|
|
|
#if defined(LUA_DEBUG)
|
|
|
|
/* export this function for the test library */
|
|
|
|
Node *luaH_mainposition (const Table *t, const TValue *key) {
|
|
return mainpositionTV(t, key);
|
|
}
|
|
|
|
#endif
|