dlist

// vi:set ft=cpp: -*- Mode: C++ -*-
/*
 * (c) 2011 Alexander Warg <warg@os.inf.tu-dresden.de>
 *     economic rights: Technische Universität Dresden (Germany)
 *
 * License: see LICENSE.spdx (in this directory or the directories above)
 */
 
#pragma once
 
namespace cxx {
 
class D_list_item
{
public:
  constexpr D_list_item() : _dli_next(nullptr), _dli_prev(nullptr) {}
 
  D_list_item(D_list_item const &) = delete;
  void operator = (D_list_item const &) = delete;
 
private:
  friend struct D_list_item_policy;
 
  D_list_item *_dli_next, *_dli_prev;
};
 
struct D_list_item_policy
{
  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; }
  static D_list_item *prev(D_list_item const *e) { return e->_dli_prev; }
  static D_list_item *next(D_list_item const *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); }
 
  protected:
    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) = nullptr;
  }
 
  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;
    C::next(e) = C::next(pos._c);
    C::prev(C::next(pos._c)) = e;
    C::next(pos._c) = e;
    return pos;
  }
 
  static Iterator insert_before(T *e, Iterator const &pos)
  {
    C::next(e) = pos._c;
    C::prev(e) = C::prev(pos._c);
    C::next(C::prev(pos._c)) = e;
    C::prev(pos._c) = e;
    return pos;
  }
 
protected:
  static void self_insert(typename C::Item *e)
  { C::next(e) = C::prev(e) = e; }
 
  static void remove_last(T *e)
  { C::next(e) = nullptr; }
 
  static void splice_heads(Const_iterator pos, typename C::Item *other_list)
  {
    typename C::Item *ins_next = pos._c;
    typename C::Item *ins_prev = C::prev(pos._c);
    typename C::Item *other_head = C::next(other_list);
    typename C::Item *other_tail = C::prev(other_list);
 
    C::next(ins_prev) = other_head;
    C::prev(other_head) = ins_prev;
    C::prev(ins_next) = other_tail;
    C::next(other_tail) = ins_next;
  }
 
  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:
  class Iterator : public Base::Iterator
  {
  public:
    Iterator &operator ++ ()
    {
      if (this->_c)
        Base::Iterator::operator ++ ();
 
      if (this->_c == _h)
        this->_c = nullptr;
 
      return *this;
    }
 
    Iterator &operator -- () = delete;
 
  private:
    friend class Sd_list;
 
    explicit Iterator(T *h) : Base::Iterator(h), _h(h) {}
    typename C::Item *_h;
  };
 
  class R_iterator : public Base::Iterator
  {
  public:
    R_iterator &operator ++ ()
    {
      if (this->_c)
        Base::Iterator::operator -- ();
 
      if (this->_c == _h)
        this->_c = nullptr;
 
      return *this;
    }
 
    R_iterator &operator -- () = delete;
 
  private:
    friend class Sd_list;
 
    explicit R_iterator(T *h) : Base::Iterator(h), _h(h) {}
    typename C::Item *_h;
  };
 
  //typedef typename Base::Iterator Iterator;
  enum Pos
  { Back, Front };
 
  Sd_list()
  {
    if (!BSS)
      H::set_head(_f, nullptr);
  }
 
  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, nullptr);
        return;
      }
 
    if (e == H::head(_f))
      H::set_head(_f, static_cast<T*>(C::next(h)));
 
    Base::remove(e);
  }
 
  Iterator erase(Iterator const &e)
  {
    Iterator next = e;
    ++next;
 
    remove(*e);
    return next;
  }
 
  void push(T *e, Pos pos)
  {
    T *h = H::head(_f);
    if (!h)
      {
        Base::self_insert(e);
        H::set_head(_f, 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; }
 
  Iterator begin() { return Iterator(H::head(_f)); }
  Iterator end() { return Iterator(nullptr); }
 
  R_iterator rbegin()
  {
    if (head())
      return R_iterator(static_cast<T*>(C::prev(H::head(_f))));
    return R_iterator(nullptr);
  }
  R_iterator rend() { return R_iterator(nullptr); }
 
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(&_h); }
  ~D_list() { clear(); }
 
  D_list(D_list &&o)
  {
    if (o.empty())
      {
        this->self_insert(&_h);
      }
    else
      {
        Internal_type *p = C::prev(&o._h);
        Internal_type *n = C::next(&o._h);
        C::prev(&_h) = p;
        C::next(&_h) = n;
        C::next(p) = &_h;
        C::prev(n) = &_h;
        o.self_insert(&o._h);
      }
  }
 
  D_list &operator=(D_list &&o)
  {
    if (&o == this)
      return *this;
 
    clear();
 
    if (!o.empty())
      {
        Internal_type *p = C::prev(&o._h);
        Internal_type *n = C::next(&o._h);
        C::prev(&_h) = p;
        C::next(&_h) = n;
        C::next(p) = &_h;
        C::prev(n) = &_h;
        o.self_insert(&o._h);
      }
  }
 
  D_list(D_list const &) = delete;
  void operator = (D_list const &) = delete;
 
  void splice(Const_iterator pos, D_list &&other)
  {
    if (other.empty())
      return;
 
    Base::splice_heads(pos, &other._h);
    other.self_insert(&other._h);
  }
 
  bool empty() const { return C::next(&_h) == &_h; }
 
  static void remove(T *e) { Base::remove(e); }
  Iterator erase(Iterator const &e) { return Base::erase(e); }
 
  void clear()
  {
    // Just clear the _dli_next pointers of all elements. It is the indicator
    // that an element is not on a list.
    Internal_type *i = C::next(&_h);
    while (i != &_h)
      {
        Internal_type *d = i;
        i = C::next(i);
        C::next(d) = nullptr;
      }
 
    this->self_insert(&_h);
  }
 
  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); }
 
  T *pop_back()
  {
    T *ret = *(end()--);
    remove(ret);
    return ret;
  }
 
  T *pop_front()
  {
    T *ret = *begin();
    remove(ret);
    return ret;
  }
 
  Iterator begin() const { return this->__iter(C::next(const_cast<Internal_type *>(&_h))); }
  Iterator end() const { return this->__iter(const_cast<Internal_type *>(&_h)); }
 
  bool has_sibling(T const *e)
  {
    return C::next(const_cast<T*>(e)) != &_h
      || C::prev(const_cast<T*>(e)) != &_h;
  }
 
private:
  Internal_type _h;
};
 
}