lua 5.2.3 source lstring.c function luaS_resize -

void luas_resize (lua_state *l, int newsize) {   int i;   stringtable *tb = &g(l)->strt;   /* cannot resize while gc traversing strings */   luac_runtilstate(l, ~bitmask(gcssweepstring));   if (newsize > tb->size) {     luam_reallocvector(l, tb->hash, tb->size, newsize, gcobject *);     (i = tb->size; < newsize; i++) tb->hash[i] = null;   }   /* rehash */   (i=0; i<tb->size; i++) {     gcobject *p = tb->hash[i];     tb->hash[i] = null;     while (p) {  /* each node in list */       gcobject *next = gch(p)->next;  /* save next */       unsigned int h = lmod(gco2ts(p)->hash, newsize);  /* new position */       gch(p)->next = tb->hash[h];  /* chain */       tb->hash[h] = p;       resetoldbit(p);  /* see move old rule */       p = next;     }   }   if (newsize < tb->size) {     /* shrinking slice must 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; } 

when table grows, rehashes. when table shrinks, realloc half size without rehash. can't understand it. how can work ?

well. answer question myself. code works because rehash operation not in first if(newsize > tb->size). works both (newsize > tb->size) , (newsize < tb->size). next time, read code more carefully.