dtrenew.c

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#include        <cdt/dthdr.h>
#include        <stddef.h>
 
/*      Renew the object at the current finger.
**
**      Written by Kiem-Phong Vo (5/25/96)
*/
 
void* dtrenew(Dt_t* dt, void* obj)
{
        void*   key;
        Dtlink_t        *e, *t, **s;
        Dtdisc_t*       disc = dt->disc;
 
        UNFLATTEN(dt);
 
        if(!(e = dt->data->here) || _DTOBJ(e,disc->link) != obj)
                return NULL;
 
        if(dt->data->type&DT_QUEUE)
                return obj;
        else if(dt->data->type&(DT_OSET|DT_OBAG) )
        {       if(!e->right )  /* make left child the new root */
                        dt->data->here = e->left;
                else            /* make right child the new root */
                {       dt->data->here = e->right;
 
                        /* merge left subtree to right subtree */
                        if(e->left)
                        {       for(t = e->right; t->left; t = t->left)
                                        ;
                                t->left = e->left;
                        }
                }
        }
        else /*if(dt->data->type&(DT_SET|DT_BAG))*/
        {       s = dt->data->htab + HINDEX(dt->data->ntab,e->hash);
                if((t = *s) == e)
                        *s = e->right;
                else
                {       for(; t->right != e; t = t->right)
                                ;
                        t->right = e->right;
                }
                key = _DTKEY(obj,disc->key,disc->size);
                e->hash = dtstrhash(key, disc->size);
                dt->data->here = NULL;
        }
 
        dt->data->size -= 1;
        return dt->meth->searchf(dt, e, DT_RENEW) ? obj : NULL;
}