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/*
** $Id: lstring.c,v 1.3 2001/11/26 23:00:26 darkgod Exp $
** String table (keeps all strings handled by Lua)
** See Copyright Notice in lua.h
*/
#include <string.h>
#include "lua.h"
#include "lmem.h"
#include "lobject.h"
#include "lstate.h"
#include "lstring.h"
/*
** type equivalent to TString, but with maximum alignment requirements
*/
union L_UTString {
TString ts;
union L_Umaxalign dummy; /* ensures maximum alignment for `local' udata */
};
void luaS_init (lua_State *L) {
L->strt.hash = luaM_newvector(L, 1, TString *);
L->udt.hash = luaM_newvector(L, 1, TString *);
L->nblocks += 2*sizeof(TString *);
L->strt.size = L->udt.size = 1;
L->strt.nuse = L->udt.nuse = 0;
L->strt.hash[0] = L->udt.hash[0] = NULL;
}
void luaS_freeall (lua_State *L) {
LUA_ASSERT(L->strt.nuse==0, "non-empty string table");
L->nblocks -= (L->strt.size + L->udt.size)*sizeof(TString *);
luaM_free(L, L->strt.hash);
LUA_ASSERT(L->udt.nuse==0, "non-empty udata table");
luaM_free(L, L->udt.hash);
}
static unsigned long hash_s (const char *s, size_t l) {
unsigned long h = l; /* seed */
size_t step = (l>>5)|1; /* if string is too long, don't hash all its chars */
for (; l>=step; l-=step)
h = h ^ ((h<<5)+(h>>2)+(unsigned char)*(s++));
return h;
}
void luaS_resize (lua_State *L, stringtable *tb, int newsize) {
TString **newhash = luaM_newvector(L, newsize, TString *);
int i;
for (i=0; i<newsize; i++) newhash[i] = NULL;
/* rehash */
for (i=0; i<tb->size; i++) {
TString *p = tb->hash[i];
while (p) { /* for each node in the list */
TString *next = p->nexthash; /* save next */
unsigned long h = (tb == &L->strt) ? p->u.s.hash : IntPoint(p->u.d.value);
int h1 = h&(newsize-1); /* new position */
LUA_ASSERT(h%newsize == (h&(newsize-1)),
"a&(x-1) == a%x, for x power of 2");
p->nexthash = newhash[h1]; /* chain it in new position */
newhash[h1] = p;
p = next;
}
}
luaM_free(L, tb->hash);
L->nblocks += (newsize - tb->size)*sizeof(TString *);
tb->size = newsize;
tb->hash = newhash;
}
static void newentry (lua_State *L, stringtable *tb, TString *ts, int h) {
ts->nexthash = tb->hash[h]; /* chain new entry */
tb->hash[h] = ts;
tb->nuse++;
if (tb->nuse > (lint32)tb->size && tb->size < MAX_INT/2) /* too crowded? */
luaS_resize(L, tb, tb->size*2);
}
TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
unsigned long h = hash_s(str, l);
int h1 = h & (L->strt.size-1);
TString *ts;
for (ts = L->strt.hash[h1]; ts; ts = ts->nexthash) {
if (ts->len == l && (memcmp(str, ts->str, l) == 0))
return ts;
}
/* not found */
ts = (TString *)luaM_malloc(L, sizestring(l));
ts->marked = 0;
ts->nexthash = NULL;
ts->len = l;
ts->u.s.hash = h;
ts->u.s.constindex = 0;
memcpy(ts->str, str, l);
ts->str[l] = 0; /* ending 0 */
L->nblocks += sizestring(l);
newentry(L, &L->strt, ts, h1); /* insert it on table */
return ts;
}
TString *luaS_newudata (lua_State *L, size_t s, void *udata) {
union L_UTString *uts = (union L_UTString *)luaM_malloc(L,
(lint32)sizeof(union L_UTString)+s);
TString *ts = &uts->ts;
ts->marked = 0;
ts->nexthash = NULL;
ts->len = s;
ts->u.d.tag = 0;
ts->u.d.value = (udata == NULL) ? uts+1 : udata;
L->nblocks += sizestring(s);
/* insert it on table */
newentry(L, &L->udt, ts, IntPoint(ts->u.d.value) & (L->udt.size-1));
return ts;
}
TString *luaS_createudata (lua_State *L, void *udata, int tag) {
int h1 = IntPoint(udata) & (L->udt.size-1);
TString *ts;
for (ts = L->udt.hash[h1]; ts; ts = ts->nexthash) {
if (udata == ts->u.d.value && (tag == ts->u.d.tag || tag == LUA_ANYTAG))
return ts;
}
/* not found */
ts = luaS_newudata(L, 0, udata);
if (tag != LUA_ANYTAG)
ts->u.d.tag = tag;
return ts;
}
TString *luaS_new (lua_State *L, const char *str) {
return luaS_newlstr(L, str, strlen(str));
}
TString *luaS_newfixed (lua_State *L, const char *str) {
TString *ts = luaS_new(L, str);
if (ts->marked == 0) ts->marked = FIXMARK; /* avoid GC */
return ts;
}
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