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ltable.c
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/*
** $Id: ltable.c,v 1.8 1997/12/09 13:35:19 roberto Exp roberto $
** Lua tables (hash)
** See Copyright Notice in lua.h
*/
#include <stdlib.h>
#include "lauxlib.h"
#include "lmem.h"
#include "lobject.h"
#include "lstate.h"
#include "ltable.h"
#include "lua.h"
#define gcsize(n) (1+(n/16))
#define nuse(t) ((t)->nuse)
#define nodevector(t) ((t)->node)
#define REHASH_LIMIT 0.70 /* avoid more than this % full */
#define TagDefault LUA_T_ARRAY;
static long int hashindex (TObject *ref)
{
long int h;
switch (ttype(ref)) {
case LUA_T_NUMBER:
h = (long int)nvalue(ref);
break;
case LUA_T_STRING: case LUA_T_USERDATA:
h = (IntPoint)tsvalue(ref);
break;
case LUA_T_CLOSURE:
h = (IntPoint)clvalue(ref);
break;
case LUA_T_PROTO:
h = (IntPoint)tfvalue(ref);
break;
case LUA_T_CPROTO:
h = (IntPoint)fvalue(ref);
break;
case LUA_T_ARRAY:
h = (IntPoint)avalue(ref);
break;
default:
lua_error("unexpected type to index table");
h = 0; /* to avoid warnings */
}
return (h >= 0 ? h : -(h+1));
}
static int present (Hash *t, TObject *key)
{
int tsize = nhash(t);
long int h = hashindex(key);
int h1 = h%tsize;
TObject *rf = ref(node(t, h1));
if (ttype(rf) != LUA_T_NIL && !luaO_equalObj(key, rf)) {
int h2 = h%(tsize-2) + 1;
do {
h1 = (h1+h2)%tsize;
rf = ref(node(t, h1));
} while (ttype(rf) != LUA_T_NIL && !luaO_equalObj(key, rf));
}
return h1;
}
/*
** Alloc a vector node
*/
static Node *hashnodecreate (int nhash)
{
Node *v = luaM_newvector(nhash, Node);
int i;
for (i=0; i<nhash; i++)
ttype(ref(&v[i])) = LUA_T_NIL;
return v;
}
/*
** Delete a hash
*/
static void hashdelete (Hash *t)
{
luaM_free(nodevector(t));
luaM_free(t);
}
void luaH_free (Hash *frees)
{
while (frees) {
Hash *next = (Hash *)frees->head.next;
L->nblocks -= gcsize(frees->nhash);
hashdelete(frees);
frees = next;
}
}
Hash *luaH_new (int nhash)
{
Hash *t = luaM_new(Hash);
nhash = luaO_redimension((int)((float)nhash/REHASH_LIMIT));
nodevector(t) = hashnodecreate(nhash);
nhash(t) = nhash;
nuse(t) = 0;
t->htag = TagDefault;
luaO_insertlist(&(L->roottable), (GCnode *)t);
L->nblocks += gcsize(nhash);
return t;
}
/*
** Rehash:
** Check if table has deleted slots. It it has, it does not need to
** grow, since rehash will reuse them.
*/
static int emptyslots (Hash *t)
{
int i;
for (i=nhash(t)-1; i>=0; i--) {
Node *n = node(t, i);
if (ttype(ref(n)) != LUA_T_NIL && ttype(val(n)) == LUA_T_NIL)
return 1;
}
return 0;
}
static void rehash (Hash *t)
{
int nold = nhash(t);
Node *vold = nodevector(t);
int i;
if (!emptyslots(t))
nhash(t) = luaO_redimension(nhash(t));
nodevector(t) = hashnodecreate(nhash(t));
for (i=0; i<nold; i++) {
Node *n = vold+i;
if (ttype(ref(n)) != LUA_T_NIL && ttype(val(n)) != LUA_T_NIL)
*node(t, present(t, ref(n))) = *n; /* copy old node to luaM_new hash */
}
L->nblocks += gcsize(t->nhash)-gcsize(nold);
luaM_free(vold);
}
/*
** If the hash node is present, return its pointer, otherwise return
** null.
*/
TObject *luaH_get (Hash *t, TObject *ref)
{
int h = present(t, ref);
if (ttype(ref(node(t, h))) != LUA_T_NIL) return val(node(t, h));
else return NULL;
}
/*
** If the hash node is present, return its pointer, otherwise create a luaM_new
** node for the given reference and also return its pointer.
*/
TObject *luaH_set (Hash *t, TObject *ref)
{
Node *n = node(t, present(t, ref));
if (ttype(ref(n)) == LUA_T_NIL) {
nuse(t)++;
if ((float)nuse(t) > (float)nhash(t)*REHASH_LIMIT) {
rehash(t);
n = node(t, present(t, ref));
}
*ref(n) = *ref;
ttype(val(n)) = LUA_T_NIL;
}
return (val(n));
}
static Node *hashnext (Hash *t, int i)
{
Node *n;
int tsize = nhash(t);
if (i >= tsize)
return NULL;
n = node(t, i);
while (ttype(ref(n)) == LUA_T_NIL || ttype(val(n)) == LUA_T_NIL) {
if (++i >= tsize)
return NULL;
n = node(t, i);
}
return node(t, i);
}
Node *luaH_next (TObject *o, TObject *r)
{
Hash *t = avalue(o);
if (ttype(r) == LUA_T_NIL)
return hashnext(t, 0);
else {
int i = present(t, r);
Node *n = node(t, i);
luaL_arg_check(ttype(ref(n))!=LUA_T_NIL && ttype(val(n))!=LUA_T_NIL,
2, "key not found");
return hashnext(t, i+1);
}
}