SampleItem.h

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//  ************************************************************************************************
//
//  BornAgain: simulate and fit reflection and scattering
//
//! @file      GUI/Model/Sample/SampleItem.h
//! @brief     Defines class SampleItem
//!
//! @homepage  http://www.bornagainproject.org
//! @license   GNU General Public License v3 or higher (see COPYING)
//! @copyright Forschungszentrum Jülich GmbH 2021
//! @authors   Scientific Computing Group at MLZ (see CITATION, AUTHORS)
//
//  ************************************************************************************************
 
#ifndef BORNAGAIN_GUI_MODEL_SAMPLE_SAMPLEITEM_H
#define BORNAGAIN_GUI_MODEL_SAMPLE_SAMPLEITEM_H
 
#include <variant>
 
class MultiLayerItem;
class LayerItem;
class ParticleLayoutItem;
class ItemWithParticles;
class SessionItem;
 
using VariantForSampleItems =
    std::variant<MultiLayerItem*, LayerItem*, ParticleLayoutItem*, ItemWithParticles*>;
 
//! This can hold any item which belongs to a sample.
//!
//! Removes the need to derive every xxxItem from a same base class and then try dynamic_cast'ing
//! it.
class SampleItem : public VariantForSampleItems {
public:
    template <typename T>
    SampleItem(T* item)
        : base(item)
    {
    }
 
    //! Short version to get a contained pointer (the std::get_if would return pointer-to-pointer)
    template <typename T>
    T get_if()
    {
        if (T* pp = std::get_if<T>(this))
            return *pp;
        return nullptr;
    }
 
private:
    using base = VariantForSampleItems;
};
 
#endif // BORNAGAIN_GUI_MODEL_SAMPLE_SAMPLEITEM_H