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/*
** $Id: lstring.c,v 1.26 1999/11/04 17:22:26 roberto Exp roberto $
** String table (keeps all strings handled by Lua)
** See Copyright Notice in lua.h
*/
#include <string.h>
#include "lmem.h"
#include "lobject.h"
#include "lstate.h"
#include "lstring.h"
#include "lua.h"
#define gcsizestring(l) numblocks(0, sizeof(TaggedString)+l)
#define gcsizeudata gcsizestring(0)
/*
** to avoid hash tables with size = 0 (cannot hash with size=0), all
** hash tables are initialized with this `array'. Elements are never
** written here, because this table (with size=1) must grow to get an
** element, and before it grows we replace it for a `real' table.
**
*/
static TaggedString *init_hash[1] = {NULL};
void luaS_init (void) {
int i;
L->string_root = luaM_newvector(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 = init_hash;
}
}
void luaS_freeall (void) {
int i;
for (i=0; i<NUM_HASHS; i++) {
LUA_ASSERT(L->string_root[i].nuse==0, "non-empty string table");
if (L->string_root[i].hash != init_hash)
luaM_free(L->string_root[i].hash);
}
luaM_free(L->string_root);
LUA_ASSERT(init_hash[0] == NULL, "init_hash corrupted");
}
static unsigned long hash_s (const char *s, long l) {
unsigned long h = l; /* seed */
while (l--)
h = h ^ ((h<<5)+(h>>2)+(unsigned char)*(s++));
return h;
}
void luaS_grow (stringtable *tb) {
int ns = luaO_redimension(tb->nuse*2); /* new size */
TaggedString **newhash = luaM_newvector(ns, TaggedString *);
int i;
for (i=0; i<ns; i++) newhash[i] = NULL;
/* rehash */
for (i=0; i<tb->size; i++) {
TaggedString *p = tb->hash[i];
while (p) { /* for each node in the list */
TaggedString *next = p->nexthash; /* save next */
int h = p->hash%ns; /* new position */
p->nexthash = newhash[h]; /* chain it in new position */
newhash[h] = p;
p = next;
}
}
luaM_free(tb->hash);
tb->size = ns;
tb->hash = newhash;
}
static TaggedString *newone (long l, unsigned long h) {
TaggedString *ts = (TaggedString *)luaM_malloc(
sizeof(TaggedString)+l*sizeof(char));
ts->marked = 0;
ts->nexthash = NULL;
ts->hash = h;
return ts;
}
static TaggedString *newone_s (const char *str, long l, unsigned long h) {
TaggedString *ts = newone(l, h);
memcpy(ts->str, str, l);
ts->str[l] = 0; /* ending 0 */
ts->u.s.gv = NULL; /* no global value */
ts->u.s.len = l;
ts->constindex = 0;
L->nblocks += gcsizestring(l);
return ts;
}
static TaggedString *newone_u (void *buff, int tag, unsigned long h) {
TaggedString *ts = newone(0, h);
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 (stringtable *tb, TaggedString *ts, int h) {
tb->nuse++;
if (tb->nuse >= tb->size) { /* no more room? */
if (tb->hash == init_hash) { /* cannot change init_hash */
LUA_ASSERT(h==0, "`init_hash' has size 1");
tb->hash = luaM_newvector(1, TaggedString *); /* so, `clone' it */
tb->hash[0] = NULL;
}
luaS_grow(tb);
h = ts->hash%tb->size; /* new hash position */
}
ts->nexthash = tb->hash[h]; /* chain new entry */
tb->hash[h] = ts;
}
TaggedString *luaS_newlstr (const char *str, long l) {
unsigned long h = hash_s(str, l);
stringtable *tb = &L->string_root[h%NUM_HASHSTR];
int h1 = h%tb->size;
TaggedString *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(str, l, h); /* create new entry */
newentry(tb, ts, h1); /* insert it on table */
return ts;
}
TaggedString *luaS_createudata (void *udata, int tag) {
unsigned long h = IntPoint(udata);
stringtable *tb = &L->string_root[(h%NUM_HASHUDATA)+NUM_HASHSTR];
int h1 = h%tb->size;
TaggedString *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(udata, tag, h);
newentry(tb, ts, h1);
return ts;
}
TaggedString *luaS_new (const char *str) {
return luaS_newlstr(str, strlen(str));
}
TaggedString *luaS_newfixedstring (const char *str) {
TaggedString *ts = luaS_new(str);
if (ts->marked == 0) ts->marked = FIXMARK; /* avoid GC */
return ts;
}
void luaS_free (TaggedString *t) {
if (t->constindex == -1) /* is userdata? */
L->nblocks -= gcsizeudata;
else { /* is string */
L->nblocks -= gcsizestring(t->u.s.len);
luaM_free(t->u.s.gv);
}
luaM_free(t);
}
GlobalVar *luaS_assertglobal (TaggedString *ts) {
GlobalVar *gv = ts->u.s.gv;
if (!gv) { /* no global value yet? */
gv = luaM_new(GlobalVar);
gv->value.ttype = LUA_T_NIL; /* initial value */
gv->name = ts;
gv->next = L->rootglobal; /* chain in global list */
L->rootglobal = gv;
ts->u.s.gv = gv;
}
return gv;
}
GlobalVar *luaS_assertglobalbyname (const char *name) {
return luaS_assertglobal(luaS_new(name));
}
int luaS_globaldefined (const char *name) {
TaggedString *ts = luaS_new(name);
return ts->u.s.gv && ts->u.s.gv->value.ttype != LUA_T_NIL;
}
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