Model.hpp

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#ifndef AI_TOOLBOX_BANDIT_MODEL_HEADER_FILE
#define AI_TOOLBOX_BANDIT_MODEL_HEADER_FILE
 
#include <AIToolbox/Types.hpp>
#include <AIToolbox/Seeder.hpp>
 
namespace AIToolbox::Bandit {
    template <typename Dist>
    class Model {
        public:
            template <typename... TupleArgs>
            Model(TupleArgs... tupleArgs);
 
            template <typename... Args>
            Model(std::vector<std::tuple<Args...>> args);
 
            decltype(auto) sampleR(size_t a) const;
 
            size_t getA() const;
 
            const std::vector<Dist> & getArms() const;
 
        private:
            mutable std::vector<Dist> arms_;
            mutable AIToolbox::RandomEngine rand_;
    };
 
    template <typename Dist>
    template <typename... TupleArgs>
    Model<Dist>::Model(TupleArgs... tupleArgs) :
        arms_({std::make_from_tuple<Dist>(std::move(tupleArgs))...}), rand_(AIToolbox::Seeder::getSeed())
    {}
 
    template <typename Dist>
    template <typename... Args>
    Model<Dist>::Model(std::vector<std::tuple<Args...>> args) :
        rand_(AIToolbox::Seeder::getSeed())
    {
        arms_.reserve(args.size());
 
        // Here we use a lambda to avoid having to static_cast the correct
        // emplace_back method on the vector.
        for (auto && t : args)
            std::apply([this](auto&&... params){arms_.emplace_back(std::move(params)...);}, std::move(t));
    }
 
    template <typename Dist>
    decltype(auto) Model<Dist>::sampleR(const size_t a) const {
        return arms_[a](rand_);
    }
 
    template <typename Dist>
    size_t Model<Dist>::getA() const { return arms_.size(); }
 
    template <typename Dist>
    const std::vector<Dist> & Model<Dist>::getArms() const { return arms_; }
}
 
#endif