Handler.h

 
#ifndef ACTIVE_SERIALISE_DOC_HANDLER
#define ACTIVE_SERIALISE_DOC_HANDLER
 
#include "Active/Serialise/Document/Transportable.h"
 
#include <concepts>
#include <functional>
#include <memory>
 
namespace active::serialise::doc {
    
    template<typename T> requires Reconstructable<T>
    void* reconstructFunc(const Object& incoming) {
        try {
            return new T(incoming);
        } catch(...) {
            return nullptr; //Object constructors should throw an exception if incoming data isn't viable (NB: only use for unrecoverable problems)
        }
    }
    
    class Handler {
    public:
        
        // MARK: Types
        
        using Shared = std::shared_ptr<Handler>;
        
            //Factory function for reconstructing instances from a serialised document object
        using Reconstruction = std::function<void*(const Object& object)>;
        
        // MARK: Constructors
        
        Handler() {}
        
        // MARK: Functions (const)
        
        template<typename T, class Obj> requires Reconstructable<T> && Typed<Obj>
        T* reconstruct(const Obj& incoming) const {
            if (auto maker = reconstruction.find(incoming.docType); (maker != reconstruction.end()) && (maker->second.first == &typeid(T)))
                return reinterpret_cast<T*>(maker->second.second(incoming));
            return nullptr;
        } //reconstruct
        
        // MARK: Functions (mutating)
        
        template<typename T> requires Transportable<T>
        void add(std::initializer_list<active::utility::String> const& tags) {
            for (const auto& tag : tags) {
                add<T>(tag);
            }
        }
        
        template<typename T> requires Transportable<T>
        void add(const active::utility::String& tag) {
            reconstruction[tag] = std::make_pair( &typeid(T), reconstructFunc<T>);
        }
        
    private:
        std::unordered_map<active::utility::String, std::pair<const std::type_info*, Reconstruction>> reconstruction;
    };
 
}
 
#endif  //ACTIVE_SERIALISE_DOC_HANDLER