// vi:ft=cpp
/*
 * (c) 2011 Alexander Warg <warg@os.inf.tu-dresden.de>
 *     economic rights: Technische Universität Dresden (Germany)
 *
 * This file is part of TUD:OS and distributed under the terms of the
 * GNU General Public License 2.
 * Please see the COPYING-GPL-2 file for details.
 *
 * As a special exception, you may use this file as part of a free software
 * library without restriction.  Specifically, if other files instantiate
 * templates or use macros or inline functions from this file, or you compile
 * this file and link it with other files to produce an executable, this
 * file does not by itself cause the resulting executable to be covered by
 * the GNU General Public License.  This exception does not however
 * invalidate any other reasons why the executable file might be covered by
 * the GNU General Public License.
 */

#pragma once

namespace cxx {

class D_list_item
{
public:
  D_list_item() : _dli_next(0) {}
private:
  friend class D_list_item_policy;

  D_list_item(D_list_item const &);
  void operator = (D_list_item const &);

  D_list_item *_dli_next, *_dli_prev;
};

class D_list_item_policy
{
public:
  typedef D_list_item Item;
  static D_list_item *&prev(D_list_item *e) { return e->_dli_prev; }
  static D_list_item *&next(D_list_item *e) { return e->_dli_next; }
};

template< typename T >
struct Sd_list_head_policy
{
  typedef T *Head_type;
  static T *head(Head_type h) { return h; }
  static void set_head(Head_type &h, T *v) { h = v; }
};

template<
  typename T,
  typename C = D_list_item_policy
>
class D_list_cyclic
{
protected:
  template< typename VALUE, typename ITEM >
  class __Iterator
  {
  public:
    typedef VALUE *Value_type;
    typedef VALUE *value_type;

    __Iterator() {}

    bool operator == (__Iterator const &o) const
    { return _c == o._c; }

    bool operator != (__Iterator const &o) const
    { return _c != o._c; }

    __Iterator &operator ++ ()
    {
      _c = C::next(_c);
      return *this;
    }

    __Iterator &operator -- ()
    {
      _c = C::prev(_c);
      return *this;
    }

    Value_type operator * () const { return static_cast<Value_type>(_c); }
    Value_type operator -> () const { return static_cast<Value_type>(_c); }

  private:
    friend class D_list_cyclic;

    explicit __Iterator(ITEM *s) : _c(s) {}

    ITEM *_c;
  };

public:
  typedef T *Value_type;
  typedef T *value_type;
  typedef __Iterator<T, typename C::Item> Iterator;
  typedef Iterator Const_iterator;

  static void remove(T *e)
  {
    C::next(C::prev(e)) = C::next(e);
    C::prev(C::next(e)) = C::prev(e);
    C::next(e) = 0;
  }

  static Iterator erase(Iterator const &e)
  {
    typename C::Item *n = C::next(*e);
    remove(*e);
    return __iter(n);
  }

  static Iterator iter(T const *e) { return Iterator(const_cast<T*>(e)); }

  static bool in_list(T const *e) { return C::next(const_cast<T*>(e)); }
  static bool has_sibling(T const *e) { return C::next(const_cast<T*>(e)) != e; }

  static Iterator insert_after(T *e, Iterator const &pos)
  {
    C::prev(e) = *pos;
    C::next(e) = C::next(*pos);
    C::prev(C::next(*pos)) = e;
    C::next(*pos) = e;
    return pos;
  }

  static Iterator insert_before(T *e, Iterator const &pos)
  {
    C::next(e) = *pos;
    C::prev(e) = C::prev(*pos);
    C::next(C::prev(*pos)) = e;
    C::prev(*pos) = e;
    return pos;
  }

  static T *self_insert(T *e)
  { C::next(e) = C::prev(e) = e; return e; }

  static void remove_last(T *e)
  { C::next(e) = 0; }

protected:
  static Iterator __iter(typename C::Item *e) { return Iterator(e); }
};

template<
  typename T,
  typename C = D_list_item_policy,
  typename H = Sd_list_head_policy<T>,
  bool BSS = false
>
class Sd_list : public D_list_cyclic<T, C>
{
private:
  typedef D_list_cyclic<T, C> Base;

public:
  typedef typename Base::Iterator Iterator;
  enum Pos
  { Back, Front };

  Sd_list() { if (!BSS) H::set_head(_f, 0); }

  bool empty() const { return !H::head(_f); }
  T *front() const { return H::head(_f); }

  void remove(T *e)
  {
    T *h = H::head(_f);
    if (e == C::next(e)) // must be the last
      {
        Base::remove_last(e);
        H::set_head(_f, 0);
        return;
      }

    if (e == H::head(_f))
      H::set_head(_f, static_cast<T*>(C::next(h)));

    Base::remove(e);
  }

  Iterator erase(Iterator const &e)
  {
    typename C::Item *n = C::next(*e);
    remove(*e);
    return __iter(n);
  }

  void push(T *e, Pos pos)
  {
    T *h = H::head(_f);
    if (!h)
      H::set_head(_f, Base::self_insert(e));
    else
      {
        Base::insert_before(e, this->iter(h));
        if (pos == Front)
          H::set_head(_f, e);
      }
  }

  void push_back(T *e) { push(e, Back); }
  void push_front(T *e) { push(e, Front); }
  void rotate_to(T *h) { H::set_head(_f, h); }

  typename H::Head_type const &head() const { return _f; }
  typename H::Head_type &head() { return _f; }

private:
  Sd_list(Sd_list const &);
  void operator = (Sd_list const &);

  typename H::Head_type _f;
};

template<
  typename T,
  typename C = D_list_item_policy,
  bool BSS = false
>
class D_list : public D_list_cyclic<T, C>
{
private:
  typedef D_list_cyclic<T, C> Base;
  typedef typename C::Item Internal_type;

public:
  enum Pos
  { Back, Front };

  typedef typename Base::Iterator Iterator;
  typedef typename Base::Const_iterator Const_iterator;
  typedef T* value_type;
  typedef T* Value_type;

  D_list() { this->self_insert(static_cast<T*>(&_h)); }

  bool empty() const { return C::next(static_cast<T*>(&_h)) == &_h; }

  void remove(T *e) { Base::remove(e); }
  void erase(Iterator const &e) { return Base::erase(e); }

  void push(T *e, Pos pos)
  {
    if (pos == Front)
      Base::insert_after(e, end());
    else
      Base::insert_before(e, end());
  }

  void push_back(T *e) { push(e, Back); }
  void push_front(T *e) { push(e, Front); }

  Iterator begin() const { return this->__iter(C::next(const_cast<Internal_type *>(&_h))); }
  Iterator end() const { return this->__iter(const_cast<Internal_type *>(&_h)); }

private:
  D_list(D_list const &);
  void operator = (D_list const &);

  Internal_type _h;
};

}