Element.hpp

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#ifndef HORIZON_CORE_STRUCTURES_LINKEDLIST_ELEMENT_HPP
#define HORIZON_CORE_STRUCTURES_LINKEDLIST_ELEMENT_HPP
 
namespace Horizon
{
namespace Structures
{
namespace LinkedList
{
class Element
{
private:
    friend class Head;
 
    Element *_next;
    Element *_prev;
 
public:
    Element() : _next(nullptr), _prev(nullptr) { }
 
    bool has_next() const  { return (_next && _next->_next != nullptr); }
    bool has_prev() const  { return (_prev && _prev->_prev != nullptr); }
    bool is_in_list() const { return (_next != nullptr && _prev != nullptr); }
 
    Element *next()       { return has_next() ? _next : nullptr; }
    Element const *next() const { return has_next() ? _next : nullptr; }
    Element *prev()       { return has_prev() ? _prev : nullptr; }
    Element const *prev() const { return has_prev() ? _prev : nullptr; }
 
    Element *nocheck_next()       { return _next; }
    Element const *nocheck_next() const { return _next; }
    Element *nocheck_prev()       { return _prev; }
    Element const *nocheck_prev() const { return _prev; }
 
    void delink()
    {
        if (!is_in_list())
            return;
 
        _next->_prev = _prev;
        _prev->_next = _next;
        _next = nullptr;
        _prev = nullptr;
    }
 
    void push_before(Element* pElem)
    {
        pElem->_next = this;
        pElem->_prev = _prev;
        _prev->_next = pElem;
        _prev = pElem;
    }
 
    void push_after(Element* pElem)
    {
        pElem->_prev = this;
        pElem->_next = _next;
        _next->_prev = pElem;
        _next = pElem;
    }
 
private:
    // disable copy and assignment because we don't want to copy Elements and we don't want to assign Elements to each other.
    // This is a linked list, not a copyable list because it is used to manage a list of objects that are not copyable.
    // It should be noted that copying the objects could result in unexpected behavior.
    Element(Element const&) = delete;
    Element& operator=(Element const&) = delete;
 
protected:
    ~Element()
    {
        delink();
    }
};
}
}
}
 
#endif /* HORIZON_CORE_STRUCTURES_HPP */