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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) ** String table (keeps all strings handled by Lua)
** See Copyright Notice in lua.h ** See Copyright Notice in lua.h
*/ */
@@ -20,30 +20,32 @@
void luaS_resize (lua_State *L, int newsize) { void luaS_resize (lua_State *L, int newsize) {
GCObject **newhash;
stringtable *tb;
int i; int i;
stringtable *tb = &G(L)->strt;
if (G(L)->gcstate == GCSsweepstring) if (G(L)->gcstate == GCSsweepstring)
return; /* cannot resize during GC traverse */ return; /* cannot resize during GC traverse */
newhash = luaM_newvector(L, newsize, GCObject *); if (newsize > tb->size) {
tb = &G(L)->strt; luaM_reallocvector(L, tb->hash, tb->size, newsize, GCObject *);
for (i=0; i<newsize; i++) newhash[i] = NULL; for (i = tb->size; i < newsize; i++) tb->hash[i] = NULL;
}
/* rehash */ /* rehash */
for (i=0; i<tb->size; i++) { for (i=0; i<tb->size; i++) {
GCObject *p = tb->hash[i]; GCObject *p = tb->hash[i];
tb->hash[i] = NULL;
while (p) { /* for each node in the list */ while (p) { /* for each node in the list */
GCObject *next = gch(p)->next; /* save next */ GCObject *next = gch(p)->next; /* save next */
unsigned int h = gco2ts(p)->hash; unsigned int h = lmod(gco2ts(p)->hash, newsize); /* new position */
int h1 = lmod(h, newsize); /* new position */ gch(p)->next = tb->hash[h]; /* chain it */
lua_assert(cast_int(h%newsize) == lmod(h, newsize)); tb->hash[h] = p;
gch(p)->next = newhash[h1]; /* chain it */
newhash[h1] = p;
p = next; 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->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); TString *ts = rawgco2ts(o);
if (h == ts->tsv.hash && ts->tsv.len == l && if (h == ts->tsv.hash && ts->tsv.len == l &&
(memcmp(str, getstr(ts), l) == 0)) { (memcmp(str, getstr(ts), l) == 0)) {
/* string may be dead */ if (isdead(G(L), o)) /* string is dead (but was not collected yet)? */
if (isdead(G(L), o)) changewhite(o); changewhite(o); /* resurrect it */
return ts; return ts;
} }
} }
return newlstr(L, str, l, h); /* not found */ return newlstr(L, str, l, h); /* not found; create a new string */
} }