static void remove_successor(pcu_aa_tree* t, struct remove_vars* v)
{
assert(*t);
if (*t != &pcu_aa_bottom)
{ /* search down the tree and set pointers last and deleted */
v->last = *t;
if (v->less(v->x,*t))
remove_successor(&((*t)->left),v);
else
{
v->deleted = *t;
remove_successor(&((*t)->right),v);
}
}
/* at the bottom of the tree we remove the element (if it is present) */
if ((*t == v->last)&&(v->deleted != &pcu_aa_bottom)
&&(!v->less(v->x,v->deleted))&&(!v->less(v->deleted,v->x)))
{
v->successor = *t;
*t = (*t)->right;
}
/* on the way back, we rebalance */
else if (((*t)->left->level < (*t)->level-1)
||((*t)->right->level < (*t)->level-1))
{
--((*t)->level);
if ((*t)->right->level > (*t)->level)
(*t)->right->level = (*t)->level;
skew(t);
skew(&((*t)->right));
skew(&((*t)->right->right));
split(t);
split(&((*t)->right));
}
}
pcu_aa_node* pcu_aa_remove(pcu_aa_node* x, pcu_aa_tree* t, pcu_aa_less* less)
{
struct remove_vars v;
v.x = x;
v.less = less;
v.deleted = &pcu_aa_bottom;
v.last = 0;
v.successor = 0;
remove_successor(t,&v);
if (!v.successor)
return 0;
if (v.successor != v.deleted)
swap_successor(t,&v);
return v.deleted;
}
void ProcessingStep::remove_successor(ProcessingStepPtr step) {
remove_successor(&*step);
}
