mirror of https://github.com/rusefi/lua.git
double hashing for string tables.
This commit is contained in:
Roberto Ierusalimschy
parent
63a752f961
commit
d7294c6de8
97
lstring.c
97
lstring.c
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@ -1,5 +1,5 @@
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/*
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** $Id: lstring.c,v 1.14 1998/07/27 17:06:17 roberto Exp roberto $
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** $Id: lstring.c,v 1.15 1998/08/10 21:36:32 roberto Exp roberto $
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** String table (keeps all strings handled by Lua)
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** See Copyright Notice in lua.h
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*/
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@ -25,8 +25,7 @@ static TaggedString EMPTY = {{NULL, 2}, 0L, 0,
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{{{LUA_T_NIL, {NULL}}, 0L}}, {0}};
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void luaS_init (void)
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{
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void luaS_init (void) {
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int i;
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L->string_root = luaM_newvector(NUM_HASHS, stringtable);
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for (i=0; i<NUM_HASHS; i++) {
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@ -37,8 +36,7 @@ void luaS_init (void)
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}
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static unsigned long hash_s (char *s, long l)
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{
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static unsigned long hash_s (char *s, long l) {
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unsigned long h = 0; /* seed */
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while (l--)
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h = h ^ ((h<<5)+(h>>2)+(unsigned char)*(s++));
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@ -53,13 +51,12 @@ static int newsize (stringtable *tb) {
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for (i=0; i<size; i++)
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if (tb->hash[i] != NULL && tb->hash[i] != &EMPTY)
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realuse++;
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return luaO_redimension((realuse+1)*2); /* +1 is the new element */
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return luaO_redimension((realuse+1)*2+6); /* +1 is the new element, +6 to
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ensure minimum size of 8 (for double hashing) */
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}
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static void grow (stringtable *tb)
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{
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static void grow (stringtable *tb) {
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int ns = newsize(tb);
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TaggedString **newhash = luaM_newvector(ns, TaggedString *);
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int i;
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@ -69,10 +66,12 @@ static void grow (stringtable *tb)
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tb->nuse = 0;
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for (i=0; i<tb->size; i++) {
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if (tb->hash[i] != NULL && tb->hash[i] != &EMPTY) {
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int h = tb->hash[i]->hash%ns;
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while (newhash[h])
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h = (h+1)%ns;
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newhash[h] = tb->hash[i];
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unsigned long h = tb->hash[i]->hash;
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int h1 = h%ns;
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int h2 = 8-(h&7);
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while (newhash[h1])
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h1 = (h1+h2)%ns;
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newhash[h1] = tb->hash[i];
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tb->nuse++;
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}
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}
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@ -82,8 +81,7 @@ static void grow (stringtable *tb)
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}
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static TaggedString *newone_s (char *str, long l, unsigned long h)
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{
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static TaggedString *newone_s (char *str, long l, unsigned long h) {
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TaggedString *ts = (TaggedString *)luaM_malloc(sizeof(TaggedString)+l);
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memcpy(ts->str, str, l);
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ts->str[l] = 0; /* ending 0 */
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@ -97,8 +95,7 @@ static TaggedString *newone_s (char *str, long l, unsigned long h)
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return ts;
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}
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static TaggedString *newone_u (char *buff, int tag, unsigned long h)
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{
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static TaggedString *newone_u (char *buff, int tag, unsigned long h) {
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TaggedString *ts = luaM_new(TaggedString);
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ts->u.d.v = buff;
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ts->u.d.tag = (tag == LUA_ANYTAG) ? 0 : tag;
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@ -110,82 +107,76 @@ static TaggedString *newone_u (char *buff, int tag, unsigned long h)
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return ts;
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}
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static TaggedString *insert_s (char *str, long l, stringtable *tb)
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{
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static TaggedString *insert_s (char *str, long l, stringtable *tb) {
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TaggedString *ts;
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unsigned long h = hash_s(str, l);
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int size = tb->size;
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int i;
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int j = -1;
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int h1;
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int h2 = 8-(h&7); /* for double hashing */
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if ((long)tb->nuse*3 >= (long)size*2) {
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grow(tb);
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size = tb->size;
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}
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for (i = h%size; (ts = tb->hash[i]) != NULL; ) {
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for (h1 = h%size; (ts = tb->hash[h1]) != NULL; h1 = (h1+h2)%size) {
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if (ts == &EMPTY)
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j = i;
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j = h1;
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else if (ts->constindex >= 0 &&
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ts->u.s.len == l &&
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(memcmp(str, ts->str, l) == 0))
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return ts;
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if (++i == size) i=0;
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}
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/* not found */
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if (j != -1) /* is there an EMPTY space? */
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i = j;
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h1 = j;
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else
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tb->nuse++;
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ts = tb->hash[i] = newone_s(str, l, h);
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ts = tb->hash[h1] = newone_s(str, l, h);
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return ts;
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}
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static TaggedString *insert_u (void *buff, int tag, stringtable *tb)
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{
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static TaggedString *insert_u (void *buff, int tag, stringtable *tb) {
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TaggedString *ts;
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unsigned long h = (unsigned long)buff;
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int size = tb->size;
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int i;
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int j = -1;
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int h1;
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int h2 = 8-(h&7); /* for double hashing */
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if ((long)tb->nuse*3 >= (long)size*2) {
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grow(tb);
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size = tb->size;
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}
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for (i = h%size; (ts = tb->hash[i]) != NULL; ) {
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for (h1 = h%size; (ts = tb->hash[h1]) != NULL; h1 = (h1+h2)%size) {
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if (ts == &EMPTY)
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j = i;
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j = h1;
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else if (ts->constindex < 0 && /* is a udata? */
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(tag == ts->u.d.tag || tag == LUA_ANYTAG) &&
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buff == ts->u.d.v)
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return ts;
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if (++i == size) i=0;
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}
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/* not found */
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if (j != -1) /* is there an EMPTY space? */
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i = j;
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h1 = j;
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else
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tb->nuse++;
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ts = tb->hash[i] = newone_u(buff, tag, h);
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ts = tb->hash[h1] = newone_u(buff, tag, h);
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return ts;
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}
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TaggedString *luaS_createudata (void *udata, int tag)
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{
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TaggedString *luaS_createudata (void *udata, int tag) {
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return insert_u(udata, tag, &L->string_root[(unsigned)udata%NUM_HASHS]);
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}
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TaggedString *luaS_newlstr (char *str, long l)
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{
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TaggedString *luaS_newlstr (char *str, long l) {
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int i = (l==0)?0:(unsigned char)str[0];
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return insert_s(str, l, &L->string_root[i%NUM_HASHS]);
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}
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TaggedString *luaS_new (char *str)
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{
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TaggedString *luaS_new (char *str) {
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return luaS_newlstr(str, strlen(str));
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}
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TaggedString *luaS_newfixedstring (char *str)
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{
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TaggedString *luaS_newfixedstring (char *str) {
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TaggedString *ts = luaS_new(str);
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if (ts->head.marked == 0)
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ts->head.marked = 2; /* avoid GC */
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@ -193,8 +184,7 @@ TaggedString *luaS_newfixedstring (char *str)
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}
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void luaS_free (TaggedString *l)
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{
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void luaS_free (TaggedString *l) {
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while (l) {
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TaggedString *next = (TaggedString *)l->head.next;
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L->nblocks -= (l->constindex == -1) ? 1 : gcsizestring(l->u.s.len);
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@ -208,8 +198,7 @@ void luaS_free (TaggedString *l)
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** Garbage collection functions.
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*/
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static void remove_from_list (GCnode *l)
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{
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static void remove_from_list (GCnode *l) {
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while (l) {
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GCnode *next = l->next;
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while (next && !next->marked)
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@ -219,8 +208,7 @@ static void remove_from_list (GCnode *l)
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}
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TaggedString *luaS_collector (void)
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{
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TaggedString *luaS_collector (void) {
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TaggedString *frees = NULL;
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int i;
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remove_from_list(&(L->rootglobal));
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@ -243,8 +231,7 @@ TaggedString *luaS_collector (void)
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}
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TaggedString *luaS_collectudata (void)
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{
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TaggedString *luaS_collectudata (void) {
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TaggedString *frees = NULL;
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int i;
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L->rootglobal.next = NULL; /* empty list of globals */
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@ -264,8 +251,7 @@ TaggedString *luaS_collectudata (void)
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}
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void luaS_freeall (void)
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{
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void luaS_freeall (void) {
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int i;
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for (i=0; i<NUM_HASHS; i++) {
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stringtable *tb = &L->string_root[i];
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@ -281,8 +267,7 @@ void luaS_freeall (void)
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}
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void luaS_rawsetglobal (TaggedString *ts, TObject *newval)
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{
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void luaS_rawsetglobal (TaggedString *ts, TObject *newval) {
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ts->u.s.globalval = *newval;
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if (ts->head.next == (GCnode *)ts) { /* is not in list? */
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ts->head.next = L->rootglobal.next;
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@ -291,8 +276,7 @@ void luaS_rawsetglobal (TaggedString *ts, TObject *newval)
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}
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char *luaS_travsymbol (int (*fn)(TObject *))
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{
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char *luaS_travsymbol (int (*fn)(TObject *)) {
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TaggedString *g;
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for (g=(TaggedString *)L->rootglobal.next; g; g=(TaggedString *)g->head.next)
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if (fn(&g->u.s.globalval))
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@ -301,8 +285,7 @@ char *luaS_travsymbol (int (*fn)(TObject *))
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}
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int luaS_globaldefined (char *name)
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{
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int luaS_globaldefined (char *name) {
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TaggedString *ts = luaS_new(name);
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return ts->u.s.globalval.ttype != LUA_T_NIL;
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}
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