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/*
** $Id: lstring.c,v 1.34 2000/03/10 18:37:44 roberto Exp roberto $
** String table (keeps all strings handled by Lua)
** See Copyright Notice in lua.h
*/
#include <string.h>
#define LUA_REENTRANT
#include "lmem.h"
#include "lobject.h"
#include "lstate.h"
#include "lstring.h"
#include "lua.h"
#define gcsizestring(L, l) numblocks(L, 0, sizeof(TString)+l)
#define gcsizeudata gcsizestring(L, 0)
void luaS_init (lua_State *L) {
int i;
L->string_root = luaM_newvector(L, NUM_HASHS, stringtable);
for (i=0; i<NUM_HASHS; i++) {
L->string_root[i].size = 1;
L->string_root[i].nuse = 0;
L->string_root[i].hash = luaM_newvector(L, 1, TString *);;
L->string_root[i].hash[0] = NULL;
}
}
void luaS_freeall (lua_State *L) {
int i;
for (i=0; i<NUM_HASHS; i++) {
LUA_ASSERT(L, L->string_root[i].nuse==0, "non-empty string table");
luaM_free(L, L->string_root[i].hash);
}
luaM_free(L, L->string_root);
}
static unsigned long hash_s (const char *s, long l) {
unsigned long h = l; /* seed */
long step = (l>>6)+1; /* if string is too long, don't hash all its chars */
for (; l>0; 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 = (p->constindex == -1) ? IntPoint(p->u.d.value) :
p->u.s.hash;
int h1 = h&(newsize-1); /* new position */
LUA_ASSERT(L, 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);
tb->size = newsize;
tb->hash = newhash;
}
static TString *newone (lua_State *L, long l) {
TString *ts = (TString *)luaM_malloc(L, sizeof(TString)+l*sizeof(char));
ts->marked = 0;
ts->nexthash = NULL;
return ts;
}
static TString *newone_s (lua_State *L, const char *str,
long l, unsigned long h) {
TString *ts = newone(L, l);
memcpy(ts->str, str, l);
ts->str[l] = 0; /* ending 0 */
ts->u.s.len = l;
ts->u.s.hash = h;
ts->constindex = 0;
L->nblocks += gcsizestring(L, l);
return ts;
}
static TString *newone_u (lua_State *L, void *buff, int tag) {
TString *ts = newone(L, 0);
ts->u.d.value = buff;
ts->u.d.tag = (tag == LUA_ANYTAG) ? 0 : tag;
ts->constindex = -1; /* tag -> this is a userdata */
L->nblocks += gcsizeudata;
return ts;
}
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 > tb->size) /* too crowded? */
luaS_resize(L, tb, tb->size*2);
}
TString *luaS_newlstr (lua_State *L, const char *str, long l) {
unsigned long h = hash_s(str, l);
stringtable *tb = &L->string_root[(l==0) ? 0 :
((unsigned int)(str[0]+str[l-1]))&(NUM_HASHSTR-1)];
int h1 = h&(tb->size-1);
TString *ts;
for (ts = tb->hash[h1]; ts; ts = ts->nexthash) {
if (ts->u.s.len == l && (memcmp(str, ts->str, l) == 0))
return ts;
}
/* not found */
ts = newone_s(L, str, l, h); /* create new entry */
newentry(L, tb, ts, h1); /* insert it on table */
return ts;
}
/*
** uses '%' for one hashing with userdata because addresses are too regular,
** so two '&' operations would be highly correlated
*/
TString *luaS_createudata (lua_State *L, void *udata, int tag) {
unsigned long h = IntPoint(udata);
stringtable *tb = &L->string_root[(h%NUM_HASHUDATA)+NUM_HASHSTR];
int h1 = h&(tb->size-1);
TString *ts;
for (ts = tb->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 = newone_u(L, udata, tag);
newentry(L, tb, ts, h1);
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;
}
void luaS_free (lua_State *L, TString *t) {
L->nblocks -= (t->constindex == -1) ? gcsizeudata :
gcsizestring(L, t->u.s.len);
luaM_free(L, t);
}
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