etl/basic_intrusive_forward_list.h

///\file

/******************************************************************************
The MIT License(MIT)

Embedded Template Library.
https://github.com/ETLCPP/etl
http://www.etlcpp.com

Copyright(c) 2015 jwellbelove

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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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******************************************************************************/

//*****************************************************************************
// This forward list is intended for internal library use.
// It may be used as a very low cost intrusive forward list.
// Elements in the list are accessed as basic_intrusive_forward_list_node.
// Code using this list will be required to cast to the real data type.
// etl::basic_intrusive_forward_list will throw no exceptions or errors.
//*****************************************************************************

#ifndef __ETL_BASIC_INTRUSIVE_FORWARD_LIST__
#define __ETL_BASIC_INTRUSIVE_FORWARD_LIST__

#include <iterator>
#include <stddef.h>

#include "nullptr.h"
#include "type_traits.h"
#include "basic_intrusive_forward_list_node.h"

namespace etl
{
  //***************************************************************************
  /// An intrusive forward list.
  ///\ingroup basic_intrusive_forward_list
  //***************************************************************************
  class basic_intrusive_forward_list
  {
  public:

    // Node typedef.
    typedef basic_intrusive_forward_list_node node_t;

    // STL style typedefs.
    typedef node_t        value_type;
    typedef node_t*       pointer;
    typedef const node_t* const_pointer;
    typedef node_t&       reference;
    typedef const node_t& const_reference;
    typedef size_t        size_type;

  public:

    //*************************************************************************
    /// iterator.
    //*************************************************************************
    class iterator : public std::iterator<std::forward_iterator_tag, value_type>
    {
    public:

      friend class basic_intrusive_forward_list;

      iterator()
        : p_node(nullptr)
      {
      }

      iterator(node_t& node)
        : p_node(&node)
      {
      }

      iterator(const iterator& other)
        : p_node(other.p_node)
      {
      }

      iterator& operator ++()
      {
        p_node = p_node->next;
        return *this;
      }

      iterator operator ++(int)
      {
        iterator temp(*this);
        p_node = p_node->next;
        return temp;
      }

      iterator operator =(const iterator& other)
      {
        p_node = other.p_node;
        return *this;
      }

      reference operator *()
      {
        return *p_node;
      }

      const_reference operator *() const
      {
        return *p_node;
      }

      pointer operator &()
      {
        return p_node;
      }

      const_pointer operator &() const
      {
        return p_node;
      }

      pointer operator ->()
      {
        return p_node;
      }

      const_pointer operator ->() const
      {
        return p_node;
      }

      friend bool operator == (const iterator& lhs, const iterator& rhs)
      {
        return lhs.p_node == rhs.p_node;
      }

      friend bool operator != (const iterator& lhs, const iterator& rhs)
      {
        return !(lhs == rhs);
      }

      template<typename T>
      T& ref_cast()
      {
        return static_cast<T&>(*p_node);
      }

      template<typename T>
      const T& ref_cast() const
      {
        return static_cast<const T&>(*p_node);
      }

    private:

      node_t* p_node;
    };

    //*************************************************************************
    /// const_iterator
    //*************************************************************************
    class const_iterator : public std::iterator<std::forward_iterator_tag, const value_type>
    {
    public:

      friend class basic_intrusive_forward_list;

      const_iterator()
        : p_node(nullptr)
      {
      }

      const_iterator(node_t& node)
        : p_node(&node)
      {
      }

      const_iterator(const node_t& node)
        : p_node(&node)
      {
      }

      const_iterator(const basic_intrusive_forward_list::iterator& other)
        : p_node(other.p_node)
      {
      }

      const_iterator(const const_iterator& other)
        : p_node(other.p_node)
      {
      }

      const_iterator& operator ++()
      {
        p_node = p_node->next;
        return *this;
      }

      const_iterator operator ++(int)
      {
        const_iterator temp(*this);
        p_node = p_node->next;
        return temp;
      }

      const_iterator operator =(const const_iterator& other)
      {
        p_node = other.p_node;
        return *this;
      }

      const_reference operator *() const
      {
        return *p_node;
      }

      const_pointer operator &() const
      {
        return p_node;
      }

      const_pointer operator ->() const
      {
        return p_node;
      }

      friend bool operator == (const const_iterator& lhs, const const_iterator& rhs)
      {
        return lhs.p_node == rhs.p_node;
      }

      friend bool operator != (const const_iterator& lhs, const const_iterator& rhs)
      {
        return !(lhs == rhs);
      }

      template<typename T>
      const T& ref_cast() const
      {
        return static_cast<const T&>(*p_node);
      }

    private:

      const node_t* p_node;
    };

		typedef std::iterator_traits<iterator>::difference_type difference_type;

    //*************************************************************************
    /// Constructor.
    //*************************************************************************
    basic_intrusive_forward_list()
    {
      initialise();
    }

    //*************************************************************************
    /// Constructor from range
    //*************************************************************************
    template <typename TIterator>
    basic_intrusive_forward_list(TIterator first, TIterator last)
    {
      assign(first, last);
    }

    //*************************************************************************
    /// Gets the beginning of the basic_intrusive_forward_list.
    //*************************************************************************
    iterator begin()
    {
      return iterator(get_head());
    }

    //*************************************************************************
    /// Gets the beginning of the basic_intrusive_forward_list.
    //*************************************************************************
    const_iterator begin() const
    {
      return const_iterator(get_head());
    }

    //*************************************************************************
    /// Gets before the beginning of the basic_intrusive_forward_list.
    //*************************************************************************
    iterator before_begin()
    {
      return iterator(start_node);
    }

    //*************************************************************************
    /// Gets before the beginning of the basic_intrusive_forward_list.
    //*************************************************************************
    const_iterator before_begin() const
    {
      return const_iterator(start_node);
    }

    //*************************************************************************
    /// Gets the beginning of the basic_intrusive_forward_list.
    //*************************************************************************
    const_iterator cbegin() const
    {
      return const_iterator(get_head());
    }

    //*************************************************************************
    /// Gets the end of the basic_intrusive_forward_list.
    //*************************************************************************
    iterator end()
    {
      return iterator();
    }

    //*************************************************************************
    /// Gets the end of the basic_intrusive_forward_list.
    //*************************************************************************
    const_iterator end() const
    {
      return const_iterator();
    }

    //*************************************************************************
    /// Gets the end of the basic_intrusive_forward_list.
    //*************************************************************************
    const_iterator cend() const
    {
      return const_iterator();
    }

    //*************************************************************************
    /// Clears the basic_intrusive_forward_list.
    //*************************************************************************
    void clear()
    {
      initialise();
    }

    //*************************************************************************
    /// Gets a reference to the first element.
    //*************************************************************************
    template <typename T>
    T& front()
    {
      return static_cast<T&>(get_head());
    }

    //*************************************************************************
    /// Gets a const reference to the first element.
    //*************************************************************************
    template <typename T>
    const_reference front() const
    {
      return static_cast<const T&>(get_head());
    }

    //*************************************************************************
    /// Assigns a range of values to the basic_intrusive_forward_list.
    //*************************************************************************
    template <typename TIterator>
    void assign(TIterator first, TIterator last)
    {
      initialise();

      node_t* p_last_node = &start_node;

      // Add all of the elements.
      while (first != last)
      {
        node_t& node = *first++;
        join(p_last_node, &node);
        join(&node, nullptr);
        p_last_node = &node;
      }
    }

    //*************************************************************************
    /// Pushes a value to the front of the basic_intrusive_forward_list.
    //*************************************************************************
    void push_front(node_t& value)
    {
      insert_node_after(start_node, value);
    }

    //*************************************************************************
    /// Removes a value from the front of the basic_intrusive_forward_list.
    //*************************************************************************
    void pop_front()
    {
      if (!empty())
      {
        remove_node_after(start_node);
      }
    }

    //*************************************************************************
    /// Reverses the basic_intrusive_forward_list.
    //*************************************************************************
    void reverse()
    {
      if ((start_node.next == nullptr) || (start_node.next->next == nullptr))
      {
        return;
      }
      
      node_t* first  = nullptr;         // To keep first node
      node_t* second = start_node.next; // To keep second node
      node_t* track  = start_node.next; // Track the list

      while (track != NULL)
      {
        track = track->next;  // Track point to next node;
        second->next = first; // Second node point to first
        first  = second;      // Move first node to next
        second = track;       // Move second node to next
      }

      join(&start_node, first);
    }

    //*************************************************************************
    /// Inserts a value to the basic_intrusive_forward_list after the specified position.
    //*************************************************************************
    iterator insert_after(iterator position, node_t& value)
    {
      insert_node_after(*position.p_node, value);

      return iterator(value);
    }

    //*************************************************************************
    /// Inserts a range of values to the basic_intrusive_forward_list after the specified position.
    //*************************************************************************
    template <typename TIterator>
    void insert_after(iterator position, TIterator first, TIterator last)
    {
      while (first != last)
      {
        // Set up the next free node.
        insert_node_after(*position.p_node, *first++);
        ++position;
      }
    }

    //*************************************************************************
    /// Erases the value at the specified position.
    //*************************************************************************
    iterator erase_after(iterator position)
    {
      iterator next(position);
      ++next;
      ++next;

      remove_node_after(*position.p_node);

      return next;
    }

    //*************************************************************************
    /// Erases a range of elements.
    //*************************************************************************
    iterator erase_after(iterator first, iterator last)
    {
      node_t* p_first = first.p_node;
      node_t* p_last  = last.p_node;
      node_t* p_next  = p_first->next;

      // Join the ends.
      join(p_first, p_last);

      p_first = p_next;

      // Erase the ones in between.
      while (p_first != p_last)
      {
        p_next  = p_first->next; // Remember the next node.
        p_first = p_next;        // Move to the next node.
      }

      if (p_next == nullptr)
      {
        return end();
      }
      else
      {
        return iterator(*p_last);
      }
    }
    
    //*************************************************************************
    /// Returns true if the list has no elements.
    //*************************************************************************
    bool empty() const
    {
      return start_node.next == nullptr;
    }

  private:

    node_t start_node; ///< The node that acts as the basic_intrusive_forward_list start.

    //*************************************************************************
    /// Join two nodes.
    //*************************************************************************
    void join(node_t* left, node_t* right)
    {
      left->next = right;
    }

    //*************************************************************************
    /// Insert a node.
    //*************************************************************************
    void insert_node_after(node_t& position, node_t& node)
    {
      // Connect to the basic_intrusive_forward_list.
      join(&node,     position.next);
      join(&position, &node);
    }

    //*************************************************************************
    /// Remove a node.
    //*************************************************************************
    void remove_node_after(node_t& node)
    {
      // The node to erase.
      node_t* p_node = node.next;

      if (p_node != nullptr)
      {
        // Disconnect the node from the basic_intrusive_forward_list.
        join(&node, p_node->next);
      }
    }

    //*************************************************************************
    /// Get the head node.
    //*************************************************************************
    node_t& get_head()
    {
      return *start_node.next;
    }

    //*************************************************************************
    /// Get the head node.
    //*************************************************************************
    const node_t& get_head() const
    {
      return *start_node.next;
    }

    //*************************************************************************
    /// Initialise the basic_intrusive_forward_list.
    //*************************************************************************
    void initialise()
    {
      start_node.next = nullptr;
    }

    // Disabled.
    basic_intrusive_forward_list(const basic_intrusive_forward_list& other);
    basic_intrusive_forward_list& operator = (const basic_intrusive_forward_list& rhs);
  };
}

#endif