Iterator.h

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/*********************************************************\
 *  File: Iterator.h                                     *
 *
 *  Copyright (C) 2002-2012 The PixelLight Team (http://www.pixellight.org/)
 *
 *  This file is part of PixelLight.
 *
 *  PixelLight is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Lesser General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  PixelLight is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 *  GNU Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with PixelLight. If not, see <http://www.gnu.org/licenses/>.
\*********************************************************/


#ifndef __PLCORE_CONTAINER_ITERATOR_H__
#define __PLCORE_CONTAINER_ITERATOR_H__
#pragma once


//[-------------------------------------------------------]
//[ Namespace                                             ]
//[-------------------------------------------------------]
namespace PLCore {


//[-------------------------------------------------------]
//[ Forward declarations                                  ]
//[-------------------------------------------------------]
template <class ValueType> class IteratorImpl;


//[-------------------------------------------------------]
//[ Classes                                               ]
//[-------------------------------------------------------]
/**
*  @brief
*    Iterator class
*
*  @remarks
*    If an iterator is used, the iterable (for instance 'Map', 'Container' or 'Heap') the iterator
*    is operating on should not be manipulated by adding/removing new elements because this may
*    produce undefined behavior! Is highly recommended to keep the iterator in the smallest possible
*    local scope and to never keep an iterator as for instance pointer over a long time.
*
*  @verbatim
*    Usage example:
*    Array<String> lstNames;    // Iterable container
*    lstNames.Add("Lenny");     // Add "Lenny" to the iterable container
*    lstNames.Add("Barny");     // Add "Barny" to the iterable container
*    lstNames.Add("Homer");     // Add "Homer" to the iterable container
*    Iterator<String> cIterator = lstNames.GetIterator();   // Get an iterator instance
*    while (cIterator.HasNext())    // Is there a next element?
*        String sName = cIterator.Next();   // Return the next element, in this case, returns "Lenny", then "Barny" and then "Homer"
*  @endverbatim
*
*  @note
*    - As the class same indicates, this is an implementation of the iterator design pattern
*    - An iterator is similar to a "for each loop"
*/
template <class ValueType>
class Iterator {


    //[-------------------------------------------------------]
    //[ Public functions                                      ]
    //[-------------------------------------------------------]
    public:
        /**
        *  @brief
        *    Constructor
        *
        *  @param[in] cIteratorImpl
        *    Reference to the iterator specific implementation
        */
        Iterator(IteratorImpl<ValueType> &cIteratorImpl);

        /**
        *  @brief
        *    Copy constructor
        *
        *  @param[in] cIterator
        *    Source to copy from
        */
        Iterator(const Iterator<ValueType> &cIterator);

        /**
        *  @brief
        *    Destructor
        */
        ~Iterator<ValueType>();

        /**
        *  @brief
        *    Copy operator
        *
        *  @param[in] cIterator
        *    Source to copy from
        *
        *  @return
        *    Reference to this instance
        */
        Iterator<ValueType> &operator =(const Iterator<ValueType> &cIterator);

        /**
        *  @brief
        *    Checks whether the iterator can return a next element
        *
        *  @return
        *    'true' if the iterator can return a next element, else 'false'
        */
        bool HasNext() const;

        /**
        *  @brief
        *    Returns the next element
        *
        *  @return
        *    Reference to the next element, reference to the 'Null'-object on error
        */
        ValueType &Next();

        /**
        *  @brief
        *    Returns the next element
        *
        *  @return
        *    Reference to the next element, reference to the 'Null'-object on error
        */
        ValueType &operator ++();

        /**
        *  @brief
        *    Checks whether the iterator can return a previous element
        *
        *  @return
        *    'true' if the iterator can return a previous element, else 'false'
        */
        bool HasPrevious() const;

        /**
        *  @brief
        *    Returns the previous element
        *
        *  @return
        *    Reference to the previous element, reference to the 'Null'-object on error
        */
        ValueType &Previous();

        /**
        *  @brief
        *    Returns the previous element
        *
        *  @return
        *    Reference to the previous element, reference to the 'Null'-object on error
        */
        ValueType &operator --();


    //[-------------------------------------------------------]
    //[ Private functions                                     ]
    //[-------------------------------------------------------]
    private:
        /**
        *  @brief
        *    Checks whether the current internal iterator implementation is 'shared' and splits it if so
        */
        void UniqueImplementation();


    //[-------------------------------------------------------]
    //[ Private data                                          ]
    //[-------------------------------------------------------]
    private:
        IteratorImpl<ValueType> *m_pIteratorImpl;   /**< Pointer to the iterator specific implementation, always valid */


};


//[-------------------------------------------------------]
//[ Namespace                                             ]
//[-------------------------------------------------------]
} // PLCore


//[-------------------------------------------------------]
//[ Implementation                                        ]
//[-------------------------------------------------------]
#include "PLCore/Container/Iterator.inl"


#endif // __PLCORE_CONTAINER_ITERATOR_H__