remove1()

void MonomialIdeal::remove1 ( Nmi_node * p )

private

Definition at line 397 of file monideal.cpp.

{
  assert(p != nullptr);
  assert(p->tag == Nmi_node::leaf);
  p->baggage() = nullptr;
  count -= 2;
 
  for (; p != nullptr;)
    {
      p->left->right = p->right;
      p->right->left = p->left;
      Nmi_node *q = p->header;
      p->left = p->right = nullptr;
      delete_mi_node(p);
 
      if (q->right == q->header)  // only the header is left, so delete it
        {
          p = q->down();
          q->down() = nullptr;
          if (p != nullptr) p->down() = nullptr;
          delete_mi_node(q);
          continue;
        }
 
      if (q->left != q->right) return;
 
      if (q->left->exp > 0) return;
 
      Nmi_node *dad = q->down();
      if (q->left->tag == Nmi_node::leaf)
        {
          // set parent of q to be a leaf with baggage of q->left
          // since this is a leaf, dad should be non null
          assert(dad != nullptr);
          dad->tag = Nmi_node::leaf;
          dad->baggage() = q->left->baggage();
        }
      else
        {
          // set parent of q to be node pointing to q->left->down
          q->left->down()->down() = dad;
          if (dad != nullptr)
            dad->down() = q->left->down();
          else
            mi = q->left->down();
          q->left->down() = nullptr;
        }
      q->down() = nullptr;
      delete_mi_node(q);  // Deletes both nodes q, q->left.
      return;
    }
  if (p == nullptr) mi = nullptr;
}

References Nmi_node::baggage(), count, delete_mi_node(), Nmi_node::down, Nmi_node::exp, Nmi_node::header, Nmi_node::leaf, Nmi_node::left, mi, p, Nmi_node::right, and Nmi_node::tag.

Referenced by remove().