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avoids type punning for table keys

This commit is contained in:
Roberto Ierusalimschy 2006-01-10 10:51:53 -02:00
parent fa936f8fa9
commit ffb798e1e2
3 changed files with 42 additions and 35 deletions
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14
lobject.h
View File

@ -1,5 +1,5 @@
/* /*
** $Id: lobject.h,v 2.17 2005/06/13 14:19:00 roberto Exp roberto $ ** $Id: lobject.h,v 2.18 2005/10/24 17:37:33 roberto Exp roberto $
** Type definitions for Lua objects ** Type definitions for Lua objects
** See Copyright Notice in lua.h ** See Copyright Notice in lua.h
*/ */
@ -323,9 +323,12 @@ typedef union Closure {
** Tables ** Tables
*/ */
typedef struct TKey { typedef union TKey {
TValuefields; struct {
struct Node *next; /* for chaining */ TValuefields;
struct Node *next; /* for chaining */
} nk;
TValue tvk;
} TKey; } TKey;
@ -360,8 +363,9 @@ typedef struct Table {
#define sizenode(t) (twoto((t)->lsizenode)) #define sizenode(t) (twoto((t)->lsizenode))
#define luaO_nilobject (&luaO_nilobject_)
LUAI_DATA const TValue luaO_nilobject; LUAI_DATA const TValue luaO_nilobject_;
#define ceillog2(x) (luaO_log2((x)-1) + 1) #define ceillog2(x) (luaO_log2((x)-1) + 1)

49
ltable.c
View File

@ -1,5 +1,5 @@
/* /*
** $Id: ltable.c,v 2.28 2005/11/25 13:29:32 roberto Exp roberto $ ** $Id: ltable.c,v 2.29 2005/12/22 16:19:56 roberto Exp roberto $
** Lua tables (hash) ** Lua tables (hash)
** See Copyright Notice in lua.h ** See Copyright Notice in lua.h
*/ */
@ -70,9 +70,9 @@
const Node luaH_dummynode = { const Node luaH_dummynode_ = {
{{NULL}, LUA_TNIL}, /* value */ {{NULL}, LUA_TNIL}, /* value */
{{NULL}, LUA_TNIL, NULL} /* key */ {{{NULL}, LUA_TNIL, NULL}} /* key */
}; };
@ -270,7 +270,7 @@ static void setarrayvector (lua_State *L, Table *t, int size) {
static void setnodevector (lua_State *L, Table *t, int size) { static void setnodevector (lua_State *L, Table *t, int size) {
int lsize; int lsize;
if (size == 0) { /* no elements to hash part? */ if (size == 0) { /* no elements to hash part? */
t->node = cast(Node *, &luaH_dummynode); /* use common `dummynode' */ t->node = cast(Node *, luaH_dummynode); /* use common `dummynode' */
lsize = 0; lsize = 0;
} }
else { else {
@ -281,9 +281,10 @@ static void setnodevector (lua_State *L, Table *t, int size) {
size = twoto(lsize); size = twoto(lsize);
t->node = luaM_newvector(L, size, Node); t->node = luaM_newvector(L, size, Node);
for (i=0; i<size; i++) { for (i=0; i<size; i++) {
gnext(&t->node[i]) = NULL; Node *n = gnode(t, i);
setnilvalue(gkey(gnode(t, i))); gnext(n) = NULL;
setnilvalue(gval(gnode(t, i))); setnilvalue(gkey(n));
setnilvalue(gval(n));
} }
} }
t->lsizenode = cast_byte(lsize); t->lsizenode = cast_byte(lsize);
@ -316,13 +317,13 @@ static void resize (lua_State *L, Table *t, int nasize, int nhsize) {
if (!ttisnil(gval(old))) if (!ttisnil(gval(old)))
setobjt2t(L, luaH_set(L, t, key2tval(old)), gval(old)); setobjt2t(L, luaH_set(L, t, key2tval(old)), gval(old));
} }
if (nold != &luaH_dummynode) if (nold != luaH_dummynode)
luaM_freearray(L, nold, twoto(oldhsize), Node); /* free old array */ luaM_freearray(L, nold, twoto(oldhsize), Node); /* free old array */
} }
void luaH_resizearray (lua_State *L, Table *t, int nasize) { void luaH_resizearray (lua_State *L, Table *t, int nasize) {
int nsize = (t->node == &luaH_dummynode) ? 0 : sizenode(t); int nsize = (t->node == luaH_dummynode) ? 0 : sizenode(t);
resize(L, t, nasize, nsize); resize(L, t, nasize, nsize);
} }
@ -361,7 +362,7 @@ Table *luaH_new (lua_State *L, int narray, int nhash) {
t->array = NULL; t->array = NULL;
t->sizearray = 0; t->sizearray = 0;
t->lsizenode = 0; t->lsizenode = 0;
t->node = cast(Node *, &luaH_dummynode); t->node = cast(Node *, luaH_dummynode);
setarrayvector(L, t, narray); setarrayvector(L, t, narray);
setnodevector(L, t, nhash); setnodevector(L, t, nhash);
return t; return t;
@ -369,7 +370,7 @@ Table *luaH_new (lua_State *L, int narray, int nhash) {
void luaH_free (lua_State *L, Table *t) { void luaH_free (lua_State *L, Table *t) {
if (t->node != &luaH_dummynode) if (t->node != luaH_dummynode)
luaM_freearray(L, t->node, sizenode(t), Node); luaM_freearray(L, t->node, sizenode(t), Node);
luaM_freearray(L, t->array, t->sizearray, TValue); luaM_freearray(L, t->array, t->sizearray, TValue);
luaM_free(L, t); luaM_free(L, t);
@ -395,14 +396,14 @@ static Node *getfreepos (Table *t) {
*/ */
static TValue *newkey (lua_State *L, Table *t, const TValue *key) { static TValue *newkey (lua_State *L, Table *t, const TValue *key) {
Node *mp = luaH_mainposition(t, key); Node *mp = luaH_mainposition(t, key);
if (!ttisnil(gval(mp)) || mp == &luaH_dummynode) { if (!ttisnil(gval(mp)) || mp == luaH_dummynode) {
Node *othern; Node *othern;
Node *n = getfreepos(t); /* get a free place */ Node *n = getfreepos(t); /* get a free place */
if (n == NULL) { /* cannot find a free place? */ if (n == NULL) { /* cannot find a free place? */
rehash(L, t, key); /* grow table */ rehash(L, t, key); /* grow table */
return luaH_set(L, t, key); /* re-insert key into grown table */ return luaH_set(L, t, key); /* re-insert key into grown table */
} }
lua_assert(n != &luaH_dummynode); lua_assert(n != luaH_dummynode);
othern = luaH_mainposition(t, key2tval(mp)); othern = luaH_mainposition(t, key2tval(mp));
if (othern != mp) { /* is colliding node out of its main position? */ if (othern != mp) { /* is colliding node out of its main position? */
/* yes; move colliding node into free position */ /* yes; move colliding node into free position */
@ -441,7 +442,7 @@ const TValue *luaH_getnum (Table *t, int key) {
return gval(n); /* that's it */ return gval(n); /* that's it */
else n = gnext(n); else n = gnext(n);
} while (n); } while (n);
return &luaO_nilobject; return luaO_nilobject;
} }
} }
@ -456,7 +457,7 @@ const TValue *luaH_getstr (Table *t, TString *key) {
return gval(n); /* that's it */ return gval(n); /* that's it */
else n = gnext(n); else n = gnext(n);
} while (n); } while (n);
return &luaO_nilobject; return luaO_nilobject;
} }
@ -465,7 +466,7 @@ const TValue *luaH_getstr (Table *t, TString *key) {
*/ */
const TValue *luaH_get (Table *t, const TValue *key) { const TValue *luaH_get (Table *t, const TValue *key) {
switch (ttype(key)) { switch (ttype(key)) {
case LUA_TNIL: return &luaO_nilobject; case LUA_TNIL: return luaO_nilobject;
case LUA_TSTRING: return luaH_getstr(t, rawtsvalue(key)); case LUA_TSTRING: return luaH_getstr(t, rawtsvalue(key));
case LUA_TNUMBER: { case LUA_TNUMBER: {
int k; int k;
@ -482,7 +483,7 @@ const TValue *luaH_get (Table *t, const TValue *key) {
return gval(n); /* that's it */ return gval(n); /* that's it */
else n = gnext(n); else n = gnext(n);
} while (n); } while (n);
return &luaO_nilobject; return luaO_nilobject;
} }
} }
} }
@ -491,7 +492,7 @@ const TValue *luaH_get (Table *t, const TValue *key) {
TValue *luaH_set (lua_State *L, Table *t, const TValue *key) { TValue *luaH_set (lua_State *L, Table *t, const TValue *key) {
const TValue *p = luaH_get(t, key); const TValue *p = luaH_get(t, key);
t->flags = 0; t->flags = 0;
if (p != &luaO_nilobject) if (p != luaO_nilobject)
return cast(TValue *, p); return cast(TValue *, p);
else { else {
if (ttisnil(key)) luaG_runerror(L, "table index is nil"); if (ttisnil(key)) luaG_runerror(L, "table index is nil");
@ -504,7 +505,7 @@ TValue *luaH_set (lua_State *L, Table *t, const TValue *key) {
TValue *luaH_setnum (lua_State *L, Table *t, int key) { TValue *luaH_setnum (lua_State *L, Table *t, int key) {
const TValue *p = luaH_getnum(t, key); const TValue *p = luaH_getnum(t, key);
if (p != &luaO_nilobject) if (p != luaO_nilobject)
return cast(TValue *, p); return cast(TValue *, p);
else { else {
TValue k; TValue k;
@ -516,7 +517,7 @@ TValue *luaH_setnum (lua_State *L, Table *t, int key) {
TValue *luaH_setstr (lua_State *L, Table *t, TString *key) { TValue *luaH_setstr (lua_State *L, Table *t, TString *key) {
const TValue *p = luaH_getstr(t, key); const TValue *p = luaH_getstr(t, key);
if (p != &luaO_nilobject) if (p != luaO_nilobject)
return cast(TValue *, p); return cast(TValue *, p);
else { else {
TValue k; TValue k;
@ -528,11 +529,11 @@ TValue *luaH_setstr (lua_State *L, Table *t, TString *key) {
static int unbound_search (Table *t, unsigned int j) { static int unbound_search (Table *t, unsigned int j) {
unsigned int i = j; /* i is zero or a present index */ unsigned int i = j; /* i is zero or a present index */
j = j+1; j++;
/* find `i' and `j' such that i is present and j is not */ /* find `i' and `j' such that i is present and j is not */
while (!ttisnil(luaH_getnum(t, j))) { while (!ttisnil(luaH_getnum(t, j))) {
i = j; i = j;
j = i*2; j *= 2;
if (j > cast(unsigned int, MAX_INT)) { /* overflow? */ if (j > cast(unsigned int, MAX_INT)) { /* overflow? */
/* table was built with bad purposes: resort to linear search */ /* table was built with bad purposes: resort to linear search */
i = 1; i = 1;
@ -541,7 +542,7 @@ static int unbound_search (Table *t, unsigned int j) {
} }
} }
/* now do a binary search between them */ /* now do a binary search between them */
while (i < j-1) { while (j - i > 1) {
unsigned int m = (i+j)/2; unsigned int m = (i+j)/2;
if (ttisnil(luaH_getnum(t, m))) j = m; if (ttisnil(luaH_getnum(t, m))) j = m;
else i = m; else i = m;
@ -567,7 +568,7 @@ int luaH_getn (Table *t) {
return i; return i;
} }
/* else must find a boundary in hash part */ /* else must find a boundary in hash part */
else if (t->node == &luaH_dummynode) /* hash part is empty? */ else if (t->node == luaH_dummynode) /* hash part is empty? */
return j; /* that is easy... */ return j; /* that is easy... */
else return unbound_search(t, j); else return unbound_search(t, j);
} }

14
ltable.h
View File

@ -1,5 +1,5 @@
/* /*
** $Id: ltable.h,v 2.7 2005/04/25 19:24:10 roberto Exp roberto $ ** $Id: ltable.h,v 2.8 2005/06/06 13:30:25 roberto Exp roberto $
** Lua tables (hash) ** Lua tables (hash)
** See Copyright Notice in lua.h ** See Copyright Notice in lua.h
*/ */
@ -11,15 +11,13 @@
#define gnode(t,i) (&(t)->node[i]) #define gnode(t,i) (&(t)->node[i])
#define gkey(n) (&(n)->i_key) #define gkey(n) (&(n)->i_key.nk)
#define gval(n) (&(n)->i_val) #define gval(n) (&(n)->i_val)
#define gnext(n) ((n)->i_key.next) #define gnext(n) ((n)->i_key.nk.next)
#define key2tval(n) (cast(const TValue *, gkey(n))) #define key2tval(n) (&(n)->i_key.tvk)
LUAI_DATA const Node luaH_dummynode;
LUAI_FUNC const TValue *luaH_getnum (Table *t, int key); LUAI_FUNC const TValue *luaH_getnum (Table *t, int key);
LUAI_FUNC TValue *luaH_setnum (lua_State *L, Table *t, int key); LUAI_FUNC TValue *luaH_setnum (lua_State *L, Table *t, int key);
LUAI_FUNC const TValue *luaH_getstr (Table *t, TString *key); LUAI_FUNC const TValue *luaH_getstr (Table *t, TString *key);
@ -35,5 +33,9 @@ LUAI_FUNC int luaH_getn (Table *t);
/* exported only for debugging */ /* exported only for debugging */
LUAI_FUNC Node *luaH_mainposition (const Table *t, const TValue *key); LUAI_FUNC Node *luaH_mainposition (const Table *t, const TValue *key);
#define luaH_dummynode (&luaH_dummynode_)
LUAI_DATA const Node luaH_dummynode_;
#endif #endif