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-rw-r--r--src/ltable.c233
1 files changed, 126 insertions, 107 deletions
diff --git a/src/ltable.c b/src/ltable.c
index 38be00513dc8..d080189f28d0 100644
--- a/src/ltable.c
+++ b/src/ltable.c
@@ -1,5 +1,5 @@
/*
-** $Id: ltable.c,v 2.100 2015/01/05 13:52:37 roberto Exp $
+** $Id: ltable.c,v 2.118 2016/11/07 12:38:35 roberto Exp $
** Lua tables (hash)
** See Copyright Notice in lua.h
*/
@@ -14,8 +14,8 @@
** 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 at
-** least half the slots between 0 and n are in use.
+** 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
@@ -23,9 +23,7 @@
** Hence even when the load factor reaches 100%, performance remains good.
*/
-#include <float.h>
#include <math.h>
-#include <string.h>
#include <limits.h>
#include "lua.h"
@@ -71,13 +69,11 @@
#define hashmod(t,n) (gnode(t, ((n) % ((sizenode(t)-1)|1))))
-#define hashpointer(t,p) hashmod(t, point2int(p))
+#define hashpointer(t,p) hashmod(t, point2uint(p))
#define dummynode (&dummynode_)
-#define isdummy(n) ((n) == dummynode)
-
static const Node dummynode_ = {
{NILCONSTANT}, /* value */
{{NILCONSTANT, 0}} /* key */
@@ -85,31 +81,33 @@ static const Node dummynode_ = {
/*
-** Checks whether a float has a value representable as a lua_Integer
-** (and does the conversion if so)
-*/
-static int numisinteger (lua_Number x, lua_Integer *p) {
- if ((x) == l_floor(x)) /* integral value? */
- return lua_numbertointeger(x, p); /* try as an integer */
- else return 0;
-}
-
-
-/*
-** hash for floating-point numbers
+** 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.
*/
-static Node *hashfloat (const Table *t, lua_Number n) {
+#if !defined(l_hashfloat)
+static int l_hashfloat (lua_Number n) {
int i;
- n = l_mathop(frexp)(n, &i) * cast_num(INT_MAX - DBL_MAX_EXP);
- i += cast_int(n);
- if (i < 0) {
- if (cast(unsigned int, i) == 0u - i) /* use unsigned to avoid overflows */
- i = 0; /* handle INT_MIN */
- i = -i; /* must be a positive value */
+ lua_Integer ni;
+ n = l_mathop(frexp)(n, &i) * -cast_num(INT_MIN);
+ if (!lua_numbertointeger(n, &ni)) { /* is 'n' inf/-inf/NaN? */
+ lua_assert(luai_numisnan(n) || l_mathop(fabs)(n) == cast_num(HUGE_VAL));
+ return 0;
+ }
+ else { /* normal case */
+ unsigned int u = cast(unsigned int, i) + cast(unsigned int, ni);
+ return cast_int(u <= cast(unsigned int, INT_MAX) ? u : ~u);
}
- return hashmod(t, i);
}
-
+#endif
/*
@@ -121,17 +119,11 @@ static Node *mainposition (const Table *t, const TValue *key) {
case LUA_TNUMINT:
return hashint(t, ivalue(key));
case LUA_TNUMFLT:
- return hashfloat(t, fltvalue(key));
+ return hashmod(t, l_hashfloat(fltvalue(key)));
case LUA_TSHRSTR:
return hashstr(t, tsvalue(key));
- case LUA_TLNGSTR: {
- TString *s = tsvalue(key);
- if (s->extra == 0) { /* no hash? */
- s->hash = luaS_hash(getstr(s), s->len, s->hash);
- s->extra = 1; /* now it has its hash */
- }
- return hashstr(t, tsvalue(key));
- }
+ case LUA_TLNGSTR:
+ return hashpow2(t, luaS_hashlongstr(tsvalue(key)));
case LUA_TBOOLEAN:
return hashboolean(t, bvalue(key));
case LUA_TLIGHTUSERDATA:
@@ -139,6 +131,7 @@ static Node *mainposition (const Table *t, const TValue *key) {
case LUA_TLCF:
return hashpointer(t, fvalue(key));
default:
+ lua_assert(!ttisdeadkey(key));
return hashpointer(t, gcvalue(key));
}
}
@@ -219,28 +212,29 @@ int luaH_next (lua_State *L, Table *t, StkId key) {
/*
** 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. Put in '*narray' the optimal size, and
-** return the number of elements that will go to that part.
+** between 2^(i - 1) + 1 and 2^i. 'pna' enters with the total number of
+** integer keys in the table and leaves with the number of keys that
+** will go to the array part; return the optimal size.
*/
-static unsigned int computesizes (unsigned int nums[], unsigned int *narray) {
+static unsigned int computesizes (unsigned int nums[], unsigned int *pna) {
int i;
- unsigned int twotoi; /* 2^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 n = 0; /* optimal size for array part */
- for (i = 0, twotoi = 1; twotoi/2 < *narray; i++, twotoi *= 2) {
+ unsigned int optimal = 0; /* optimal size for array part */
+ /* loop while keys can fill more than half of total size */
+ for (i = 0, twotoi = 1; *pna > twotoi / 2; i++, twotoi *= 2) {
if (nums[i] > 0) {
a += nums[i];
if (a > twotoi/2) { /* more than half elements present? */
- n = twotoi; /* optimal size (till now) */
- na = a; /* all elements up to 'n' will go to array part */
+ optimal = twotoi; /* optimal size (till now) */
+ na = a; /* all elements up to 'optimal' will go to array part */
}
}
- if (a == *narray) break; /* all elements already counted */
}
- *narray = n;
- lua_assert(*narray/2 <= na && na <= *narray);
- return na;
+ lua_assert((optimal == 0 || optimal / 2 < na) && na <= optimal);
+ *pna = na;
+ return optimal;
}
@@ -255,6 +249,11 @@ static int countint (const TValue *key, unsigned int *nums) {
}
+/*
+** 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 */
@@ -281,8 +280,7 @@ static unsigned int numusearray (const Table *t, unsigned int *nums) {
}
-static int numusehash (const Table *t, unsigned int *nums,
- unsigned int *pnasize) {
+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);
@@ -293,7 +291,7 @@ static int numusehash (const Table *t, unsigned int *nums,
totaluse++;
}
}
- *pnasize += ause;
+ *pna += ause;
return totaluse;
}
@@ -308,14 +306,14 @@ static void setarrayvector (lua_State *L, Table *t, unsigned int size) {
static void setnodevector (lua_State *L, Table *t, unsigned int size) {
- int lsize;
if (size == 0) { /* no elements to hash part? */
t->node = cast(Node *, dummynode); /* use common 'dummynode' */
- lsize = 0;
+ t->lsizenode = 0;
+ t->lastfree = NULL; /* signal that it is using dummy node */
}
else {
int i;
- lsize = luaO_ceillog2(size);
+ int lsize = luaO_ceillog2(size);
if (lsize > MAXHBITS)
luaG_runerror(L, "table overflow");
size = twoto(lsize);
@@ -326,9 +324,9 @@ static void setnodevector (lua_State *L, Table *t, unsigned int size) {
setnilvalue(wgkey(n));
setnilvalue(gval(n));
}
+ t->lsizenode = cast_byte(lsize);
+ t->lastfree = gnode(t, size); /* all positions are free */
}
- t->lsizenode = cast_byte(lsize);
- t->lastfree = gnode(t, size); /* all positions are free */
}
@@ -337,7 +335,7 @@ void luaH_resize (lua_State *L, Table *t, unsigned int nasize,
unsigned int i;
int j;
unsigned int oldasize = t->sizearray;
- int oldhsize = t->lsizenode;
+ int oldhsize = allocsizenode(t);
Node *nold = t->node; /* save old hash ... */
if (nasize > oldasize) /* array part must grow? */
setarrayvector(L, t, nasize);
@@ -354,7 +352,7 @@ void luaH_resize (lua_State *L, Table *t, unsigned int nasize,
luaM_reallocvector(L, t->array, oldasize, nasize, TValue);
}
/* re-insert elements from hash part */
- for (j = twoto(oldhsize) - 1; j >= 0; j--) {
+ for (j = oldhsize - 1; j >= 0; j--) {
Node *old = nold + j;
if (!ttisnil(gval(old))) {
/* doesn't need barrier/invalidate cache, as entry was
@@ -362,13 +360,13 @@ void luaH_resize (lua_State *L, Table *t, unsigned int nasize,
setobjt2t(L, luaH_set(L, t, gkey(old)), gval(old));
}
}
- if (!isdummy(nold))
- luaM_freearray(L, nold, cast(size_t, twoto(oldhsize))); /* free old array */
+ if (oldhsize > 0) /* not the dummy node? */
+ luaM_freearray(L, nold, cast(size_t, oldhsize)); /* free old hash */
}
void luaH_resizearray (lua_State *L, Table *t, unsigned int nasize) {
- int nsize = isdummy(t->node) ? 0 : sizenode(t);
+ int nsize = allocsizenode(t);
luaH_resize(L, t, nasize, nsize);
}
@@ -376,21 +374,22 @@ void luaH_resizearray (lua_State *L, Table *t, unsigned int nasize) {
** 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 nasize, na;
+ 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 */
- nasize = numusearray(t, nums); /* count keys in array part */
- totaluse = nasize; /* all those keys are integer keys */
- totaluse += numusehash(t, nums, &nasize); /* count keys in hash part */
+ 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 */
- nasize += countint(ek, nums);
+ na += countint(ek, nums);
totaluse++;
/* compute new size for array part */
- na = computesizes(nums, &nasize);
+ asize = computesizes(nums, &na);
/* resize the table to new computed sizes */
- luaH_resize(L, t, nasize, totaluse - na);
+ luaH_resize(L, t, asize, totaluse - na);
}
@@ -413,7 +412,7 @@ Table *luaH_new (lua_State *L) {
void luaH_free (lua_State *L, Table *t) {
- if (!isdummy(t->node))
+ if (!isdummy(t))
luaM_freearray(L, t->node, cast(size_t, sizenode(t)));
luaM_freearray(L, t->array, t->sizearray);
luaM_free(L, t);
@@ -421,10 +420,12 @@ void luaH_free (lua_State *L, Table *t) {
static Node *getfreepos (Table *t) {
- while (t->lastfree > t->node) {
- t->lastfree--;
- if (ttisnil(gkey(t->lastfree)))
- return t->lastfree;
+ if (!isdummy(t)) {
+ while (t->lastfree > t->node) {
+ t->lastfree--;
+ if (ttisnil(gkey(t->lastfree)))
+ return t->lastfree;
+ }
}
return NULL; /* could not find a free place */
}
@@ -443,25 +444,24 @@ TValue *luaH_newkey (lua_State *L, Table *t, const TValue *key) {
TValue aux;
if (ttisnil(key)) luaG_runerror(L, "table index is nil");
else if (ttisfloat(key)) {
- lua_Number n = fltvalue(key);
lua_Integer k;
- if (luai_numisnan(n))
- luaG_runerror(L, "table index is NaN");
- if (numisinteger(n, &k)) { /* index is int? */
+ if (luaV_tointeger(key, &k, 0)) { /* does index fit in an integer? */
setivalue(&aux, k);
key = &aux; /* insert it as an integer */
}
+ else if (luai_numisnan(fltvalue(key)))
+ luaG_runerror(L, "table index is NaN");
}
mp = mainposition(t, key);
- if (!ttisnil(gval(mp)) || isdummy(mp)) { /* main position is taken? */
+ if (!ttisnil(gval(mp)) || isdummy(t)) { /* main position is taken? */
Node *othern;
Node *f = getfreepos(t); /* get a free place */
if (f == NULL) { /* cannot find a free place? */
rehash(L, t, key); /* grow table */
- /* whatever called 'newkey' takes care of TM cache and GC barrier */
+ /* whatever called 'newkey' takes care of TM cache */
return luaH_set(L, t, key); /* insert key into grown table */
}
- lua_assert(!isdummy(f));
+ lua_assert(!isdummy(t));
othern = mainposition(t, gkey(mp));
if (othern != mp) { /* is colliding node out of its main position? */
/* yes; move colliding node into free position */
@@ -496,7 +496,7 @@ TValue *luaH_newkey (lua_State *L, Table *t, const TValue *key) {
*/
const TValue *luaH_getint (Table *t, lua_Integer key) {
/* (1 <= key && key <= t->sizearray) */
- if (l_castS2U(key - 1) < t->sizearray)
+ if (l_castS2U(key) - 1 < t->sizearray)
return &t->array[key - 1];
else {
Node *n = hashint(t, key);
@@ -508,7 +508,7 @@ const TValue *luaH_getint (Table *t, lua_Integer key) {
if (nx == 0) break;
n += nx;
}
- };
+ }
return luaO_nilobject;
}
}
@@ -517,7 +517,7 @@ const TValue *luaH_getint (Table *t, lua_Integer key) {
/*
** search function for short strings
*/
-const TValue *luaH_getstr (Table *t, TString *key) {
+const TValue *luaH_getshortstr (Table *t, TString *key) {
Node *n = hashstr(t, key);
lua_assert(key->tt == LUA_TSHRSTR);
for (;;) { /* check whether 'key' is somewhere in the chain */
@@ -526,11 +526,41 @@ const TValue *luaH_getstr (Table *t, TString *key) {
return gval(n); /* that's it */
else {
int nx = gnext(n);
- if (nx == 0) break;
+ if (nx == 0)
+ return luaO_nilobject; /* not found */
n += nx;
}
- };
- return luaO_nilobject;
+ }
+}
+
+
+/*
+** "Generic" get version. (Not that generic: not valid for integers,
+** which may be in array part, nor for floats with integral values.)
+*/
+static const TValue *getgeneric (Table *t, const TValue *key) {
+ Node *n = mainposition(t, key);
+ for (;;) { /* check whether 'key' is somewhere in the chain */
+ if (luaV_rawequalobj(gkey(n), key))
+ return gval(n); /* that's it */
+ else {
+ int nx = gnext(n);
+ if (nx == 0)
+ return luaO_nilobject; /* not found */
+ n += nx;
+ }
+ }
+}
+
+
+const TValue *luaH_getstr (Table *t, TString *key) {
+ if (key->tt == LUA_TSHRSTR)
+ return luaH_getshortstr(t, key);
+ else { /* for long strings, use generic case */
+ TValue ko;
+ setsvalue(cast(lua_State *, NULL), &ko, key);
+ return getgeneric(t, &ko);
+ }
}
@@ -539,28 +569,17 @@ const TValue *luaH_getstr (Table *t, TString *key) {
*/
const TValue *luaH_get (Table *t, const TValue *key) {
switch (ttype(key)) {
- case LUA_TSHRSTR: return luaH_getstr(t, tsvalue(key));
+ case LUA_TSHRSTR: return luaH_getshortstr(t, tsvalue(key));
case LUA_TNUMINT: return luaH_getint(t, ivalue(key));
case LUA_TNIL: return luaO_nilobject;
case LUA_TNUMFLT: {
lua_Integer k;
- if (numisinteger(fltvalue(key), &k)) /* index is int? */
+ if (luaV_tointeger(key, &k, 0)) /* index is int? */
return luaH_getint(t, k); /* use specialized version */
- /* else go through */
- }
- default: {
- Node *n = mainposition(t, key);
- for (;;) { /* check whether 'key' is somewhere in the chain */
- if (luaV_rawequalobj(gkey(n), key))
- return gval(n); /* that's it */
- else {
- int nx = gnext(n);
- if (nx == 0) break;
- n += nx;
- }
- };
- return luaO_nilobject;
- }
+ /* else... */
+ } /* FALLTHROUGH */
+ default:
+ return getgeneric(t, key);
}
}
@@ -632,7 +651,7 @@ int luaH_getn (Table *t) {
return i;
}
/* else must find a boundary in hash part */
- else if (isdummy(t->node)) /* hash part is empty? */
+ else if (isdummy(t)) /* hash part is empty? */
return j; /* that is easy... */
else return unbound_search(t, j);
}
@@ -645,6 +664,6 @@ Node *luaH_mainposition (const Table *t, const TValue *key) {
return mainposition(t, key);
}
-int luaH_isdummy (Node *n) { return isdummy(n); }
+int luaH_isdummy (const Table *t) { return isdummy(t); }
#endif
generated by cgit v1.2.3 (git 2.25.1) at 2024-04-26 18:36:06 +0000