BidirectionalIterator.h

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/*
 * Copyright(c) Sophist Solutions, Inc. 1990-2025.  All rights reserved
 */
#ifndef _Stroika_Foundation_Traversal_BidirectionalIterator_h_
#define _Stroika_Foundation_Traversal_BidirectionalIterator_h_ 1
 
#include "Stroika/Foundation/StroikaPreComp.h"
 
#include <iterator>
 
#include "Stroika/Foundation/Common/Common.h"
 
#include "Iterator.h"
 
/**
 *
 *  \file
 *              ****VERY ROUGH UNUSABLE DRAFT
 *
 *  \note Code-Status:  <a href="Code-Status.md#Draft">Draft</a>
 *
 */
 
namespace Stroika::Foundation::Traversal {
 
    /**
     */
    template <typename T, typename BASE_STD_ITERATOR = DefaultIteratorTraits<bidirectional_iterator_tag, T>>
    class BidirectionalIterator : public Iterator<T, BASE_STD_ITERATOR> {
    private:
        using inherited = Iterator<T, BASE_STD_ITERATOR>;
 
    public:
        class IRep;
 
    public:
        using BidirectionalIteratorRepSharedPtr = unique_ptr<IRep>;
 
    public:
        /**
         *  \brief
         *      This overload is usually not called directly. Instead, iterators are
         *      usually created from a container (eg. Bag<T>::begin()).
         *
         *  Iterators are safely copyable, preserving their current position.
         *
         *  \pre RequireNotNull (rep.get ())
         */
        explicit BidirectionalIterator (const BidirectionalIteratorRepSharedPtr& rep);
        BidirectionalIterator (const BidirectionalIterator& from);
        BidirectionalIterator () = delete;
 
    private:
        /**
         *  Mostly internal type to select a constructor for the special END iterator.
         */
        enum ConstructionFlagForceAtEnd_ {
            ForceAtEnd
        };
 
    private:
        BidirectionalIterator (ConstructionFlagForceAtEnd_);
 
    public:
        /**
         *  \brief  Iterators are safely copyable, preserving their current position.
         */
        nonvirtual BidirectionalIterator& operator= (const BidirectionalIterator& rhs) = default;
 
    public:
        // @todo add operator--
 
    public:
        /**
         *  \brief
         *      Used by *somecontainer*::end ()
         *
         *  GetEmptyIterator () returns a special iterator which is always empty - always 'at the end'.
         *  This is handy in implementing STL-style 'if (a != b)' style iterator comparisons.
         */
        static BidirectionalIterator GetEmptyIterator ();
    };
 
    /**
     */
    template <typename T, typename BASE_STD_ITERATOR>
    class BidirectionalIterator<T, BASE_STD_ITERATOR>::IRep : public Iterator<T, BASE_STD_ITERATOR>::IRep {
    protected:
        IRep () = default;
    };
 
}
 
/*
 ********************************************************************************
 ******************************* Implementation Details *************************
 ********************************************************************************
 */
 
#include "BidirectionalIterator.inl"
 
#endif /*_Stroika_Foundation_Traversal_BidirectionalIterator_h_ */