blob: db15fc60ccf2867a6cff7a82d7876259046abf7a [file] [log] [blame]
/*
** $Id: lstring.c,v 1.18 1999/02/08 16:28:48 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 NUM_HASHSTR 31
#define NUM_HASHUDATA 31
#define NUM_HASHS (NUM_HASHSTR+NUM_HASHUDATA)
#define gcsizestring(l) (1+(l/64)) /* "weight" for a string with length 'l' */
static TaggedString EMPTY = {{NULL, 2}, 0L, 0,
{{{LUA_T_NIL, {NULL}}, 0L}}, {0}};
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 = 0;
L->string_root[i].nuse = 0;
L->string_root[i].hash = NULL;
}
}
static unsigned long hash_s (char *s, long l) {
unsigned long h = 0; /* seed */
while (l--)
h = h ^ ((h<<5)+(h>>2)+(unsigned char)*(s++));
return h;
}
static int newsize (stringtable *tb) {
int size = tb->size;
int realuse = 0;
int i;
/* count how many entries are really in use */
for (i=0; i<size; i++)
if (tb->hash[i] != NULL && tb->hash[i] != &EMPTY)
realuse++;
return luaO_redimension((realuse+1)*2); /* +1 is the new element */
}
static void grow (stringtable *tb) {
int ns = newsize(tb);
TaggedString **newhash = luaM_newvector(ns, TaggedString *);
int i;
for (i=0; i<ns; i++)
newhash[i] = NULL;
/* rehash */
tb->nuse = 0;
for (i=0; i<tb->size; i++) {
if (tb->hash[i] != NULL && tb->hash[i] != &EMPTY) {
unsigned long h = tb->hash[i]->hash;
int h1 = h%ns;
while (newhash[h1]) {
h1 += (h&(ns-2)) + 1; /* double hashing */
if (h1 >= ns) h1 -= ns;
}
newhash[h1] = tb->hash[i];
tb->nuse++;
}
}
luaM_free(tb->hash);
tb->size = ns;
tb->hash = newhash;
}
static TaggedString *newone_s (char *str, long l, unsigned long h) {
TaggedString *ts = (TaggedString *)luaM_malloc(sizeof(TaggedString)+l);
memcpy(ts->str, str, l);
ts->str[l] = 0; /* ending 0 */
ts->u.s.globalval.ttype = LUA_T_NIL; /* initialize global value */
ts->u.s.len = l;
ts->constindex = 0;
L->nblocks += gcsizestring(l);
ts->head.marked = 0;
ts->head.next = (GCnode *)ts; /* signal it is in no list */
ts->hash = h;
return ts;
}
static TaggedString *newone_u (char *buff, int tag, unsigned long h) {
TaggedString *ts = luaM_new(TaggedString);
ts->u.d.v = buff;
ts->u.d.tag = (tag == LUA_ANYTAG) ? 0 : tag;
ts->constindex = -1; /* tag -> this is a userdata */
L->nblocks++;
ts->head.marked = 0;
ts->head.next = (GCnode *)ts; /* signal it is in no list */
ts->hash = h;
return ts;
}
static TaggedString *insert_s (char *str, long l, stringtable *tb) {
TaggedString *ts;
unsigned long h = hash_s(str, l);
int size = tb->size;
int j = -1;
int h1;
if ((long)tb->nuse*3 >= (long)size*2) {
grow(tb);
size = tb->size;
}
h1 = h%size;
while ((ts = tb->hash[h1]) != NULL) {
if (ts == &EMPTY)
j = h1;
else if (ts->u.s.len == l && (memcmp(str, ts->str, l) == 0))
return ts;
h1 += (h&(size-2)) + 1; /* double hashing */
if (h1 >= size) h1 -= size;
}
/* not found */
if (j != -1) /* is there an EMPTY space? */
h1 = j;
else
tb->nuse++;
ts = tb->hash[h1] = newone_s(str, l, h);
return ts;
}
static TaggedString *insert_u (void *buff, int tag, stringtable *tb) {
TaggedString *ts;
unsigned long h = (unsigned long)buff;
int size = tb->size;
int j = -1;
int h1;
if ((long)tb->nuse*3 >= (long)size*2) {
grow(tb);
size = tb->size;
}
h1 = h%size;
while ((ts = tb->hash[h1]) != NULL) {
if (ts == &EMPTY)
j = h1;
else if ((tag == ts->u.d.tag || tag == LUA_ANYTAG) && buff == ts->u.d.v)
return ts;
h1 += (h&(size-2)) + 1; /* double hashing */
if (h1 >= size) h1 -= size;
}
/* not found */
if (j != -1) /* is there an EMPTY space? */
h1 = j;
else
tb->nuse++;
ts = tb->hash[h1] = newone_u(buff, tag, h);
return ts;
}
TaggedString *luaS_createudata (void *udata, int tag) {
int t = ((unsigned)udata%NUM_HASHUDATA)+NUM_HASHSTR;
return insert_u(udata, tag, &L->string_root[t]);
}
TaggedString *luaS_newlstr (char *str, long l) {
int t = (l==0) ? 0 : ((int)((unsigned char)str[0]*l))%NUM_HASHSTR;
return insert_s(str, l, &L->string_root[t]);
}
TaggedString *luaS_new (char *str) {
return luaS_newlstr(str, strlen(str));
}
TaggedString *luaS_newfixedstring (char *str) {
TaggedString *ts = luaS_new(str);
if (ts->head.marked == 0)
ts->head.marked = 2; /* avoid GC */
return ts;
}
void luaS_free (TaggedString *l) {
while (l) {
TaggedString *next = (TaggedString *)l->head.next;
L->nblocks -= (l->constindex == -1) ? 1 : gcsizestring(l->u.s.len);
luaM_free(l);
l = next;
}
}
/*
** Garbage collection functions.
*/
static void remove_from_list (GCnode *l) {
while (l) {
GCnode *next = l->next;
while (next && !next->marked)
next = l->next = next->next;
l = next;
}
}
TaggedString *luaS_collector (void) {
TaggedString *frees = NULL;
int i;
remove_from_list(&(L->rootglobal));
for (i=0; i<NUM_HASHS; i++) {
stringtable *tb = &L->string_root[i];
int j;
for (j=0; j<tb->size; j++) {
TaggedString *t = tb->hash[j];
if (t == NULL) continue;
if (t->head.marked == 1)
t->head.marked = 0;
else if (!t->head.marked) {
t->head.next = (GCnode *)frees;
frees = t;
tb->hash[j] = &EMPTY;
}
}
}
return frees;
}
TaggedString *luaS_collectudata (void) {
TaggedString *frees = NULL;
int i;
L->rootglobal.next = NULL; /* empty list of globals */
for (i=NUM_HASHSTR; i<NUM_HASHS; i++) {
stringtable *tb = &L->string_root[i];
int j;
for (j=0; j<tb->size; j++) {
TaggedString *t = tb->hash[j];
if (t == NULL || t == &EMPTY)
continue;
LUA_ASSERT(t->constindex == -1, "must be userdata");
t->head.next = (GCnode *)frees;
frees = t;
tb->hash[j] = &EMPTY;
}
}
return frees;
}
void luaS_freeall (void) {
int i;
for (i=0; i<NUM_HASHS; i++) {
stringtable *tb = &L->string_root[i];
int j;
for (j=0; j<tb->size; j++) {
TaggedString *t = tb->hash[j];
if (t == &EMPTY) continue;
luaM_free(t);
}
luaM_free(tb->hash);
}
luaM_free(L->string_root);
}
void luaS_rawsetglobal (TaggedString *ts, TObject *newval) {
ts->u.s.globalval = *newval;
if (ts->head.next == (GCnode *)ts) { /* is not in list? */
ts->head.next = L->rootglobal.next;
L->rootglobal.next = (GCnode *)ts;
}
}
char *luaS_travsymbol (int (*fn)(TObject *)) {
TaggedString *g;
for (g=(TaggedString *)L->rootglobal.next; g; g=(TaggedString *)g->head.next)
if (fn(&g->u.s.globalval))
return g->str;
return NULL;
}
int luaS_globaldefined (char *name) {
TaggedString *ts = luaS_new(name);
return ts->u.s.globalval.ttype != LUA_T_NIL;
}