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hash table for strings is rehashed in place

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This commit is contained in:
Roberto Ierusalimschy 2009-04-29 14:09:41 -03:00
parent e091a254df
commit ea44570883
1 changed files with 18 additions and 16 deletions
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34
lstring.c
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@ -1,5 +1,5 @@
/*
** $Id: lstring.c,v 2.11 2008/02/19 18:55:09 roberto Exp roberto $
** $Id: lstring.c,v 2.12 2009/04/17 14:40:13 roberto Exp roberto $
** String table (keeps all strings handled by Lua)
** See Copyright Notice in lua.h
*/
@ -20,30 +20,32 @@
void luaS_resize (lua_State *L, int newsize) {
GCObject **newhash;
stringtable *tb;
int i;
stringtable *tb = &G(L)->strt;
if (G(L)->gcstate == GCSsweepstring)
return; /* cannot resize during GC traverse */
newhash = luaM_newvector(L, newsize, GCObject *);
tb = &G(L)->strt;
for (i=0; i<newsize; i++) newhash[i] = NULL;
if (newsize > tb->size) {
luaM_reallocvector(L, tb->hash, tb->size, newsize, GCObject *);
for (i = tb->size; i < newsize; i++) tb->hash[i] = NULL;
}
/* rehash */
for (i=0; i<tb->size; i++) {
GCObject *p = tb->hash[i];
tb->hash[i] = NULL;
while (p) { /* for each node in the list */
GCObject *next = gch(p)->next; /* save next */
unsigned int h = gco2ts(p)->hash;
int h1 = lmod(h, newsize); /* new position */
lua_assert(cast_int(h%newsize) == lmod(h, newsize));
gch(p)->next = newhash[h1]; /* chain it */
newhash[h1] = p;
unsigned int h = lmod(gco2ts(p)->hash, newsize); /* new position */
gch(p)->next = tb->hash[h]; /* chain it */
tb->hash[h] = p;
p = next;
}
}
luaM_freearray(L, tb->hash, tb->size);
if (newsize < tb->size) {
/* shrinking slice must be empty */
lua_assert(tb->hash[newsize] == NULL && tb->hash[tb->size - 1] == NULL);
luaM_reallocvector(L, tb->hash, tb->size, newsize, GCObject *);
}
tb->size = newsize;
tb->hash = newhash;
}
@ -84,12 +86,12 @@ TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
TString *ts = rawgco2ts(o);
if (h == ts->tsv.hash && ts->tsv.len == l &&
(memcmp(str, getstr(ts), l) == 0)) {
/* string may be dead */
if (isdead(G(L), o)) changewhite(o);
if (isdead(G(L), o)) /* string is dead (but was not collected yet)? */
changewhite(o); /* resurrect it */
return ts;
}
}
return newlstr(L, str, l, h); /* not found */
return newlstr(L, str, l, h); /* not found; create a new string */
}