component_accessor.h

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#pragma once
 
#include <stdexcept>
 
namespace OpenSim { class Component; }
 
namespace opyn
{
    class ComponentAccessor {
    protected:
        ComponentAccessor() = default;
        ComponentAccessor(const ComponentAccessor&) = default;
        ComponentAccessor(ComponentAccessor&&) noexcept = default;
        ComponentAccessor& operator=(const ComponentAccessor&) = default;
        ComponentAccessor& operator=(ComponentAccessor&&) noexcept = default;
 
        friend bool operator==(const ComponentAccessor&, const ComponentAccessor&) = default;
    public:
        virtual ~ComponentAccessor() noexcept = default;
 
        const OpenSim::Component& getComponent() const { return implGetComponent(); }
        operator const OpenSim::Component& () const { return getComponent(); }
 
        bool isReadonly() const { return not implCanUpdComponent(); }
        bool canUpdComponent() const { return implCanUpdComponent(); }
        OpenSim::Component& updComponent() { return implUpdComponent(); }
 
    private:
        // Implementors should return a const reference to an initialized (finalized properties, etc.) component
        virtual const OpenSim::Component& implGetComponent() const = 0;
 
        // Implementors may return whether the component contained by the concrete `ComponentAccessor` implementation
        // can be modified in-place.
        //
        // If the response can be `true`, implementors must also override `implUpdComponent` accordingly.
        virtual bool implCanUpdComponent() const { return false; }
 
        // Implementors may return a mutable reference to the contained component. It is up to the caller
        // of `updComponent` to ensure that the component is still valid + initialized after modification.
        //
        // If this is implemented, implementors should override `implCanUpdComponent` accordingly.
        virtual OpenSim::Component& implUpdComponent()
        {
            throw std::runtime_error{"component updating not implemented for this ComponentAccessor"};
        }
    };
}