evaluation_detail.hpp

#pragma once
 
#include <cstddef>
#include <optional>
 
#include <launchdarkly/data/evaluation_reason.hpp>
 
namespace launchdarkly {
 
template <typename T>
class EvaluationDetail {
   public:
    EvaluationDetail(T value,
                     std::optional<std::size_t> variation_index,
                     std::optional<EvaluationReason> reason);
 
    EvaluationDetail(enum EvaluationReason::ErrorKind error_kind,
                     T default_value);
 
    EvaluationDetail(EvaluationReason reason);
 
    [[nodiscard]] T const& Value() const;
 
    [[nodiscard]] std::optional<std::size_t> VariationIndex() const;
 
    [[nodiscard]] bool IsError() const;
 
    [[nodiscard]] std::optional<EvaluationReason> const& Reason() const;
 
    T const& operator*() const;
 
   private:
    T value_;
    std::optional<std::size_t> variation_index_;
    std::optional<EvaluationReason> reason_;
};
 
/*
 * Holds details for the C bindings, omitting the generic type parameter
 * that is needed for EvaluationDetail<T>. Instead, the bindings will
 * directly return the evaluation result, and fill in a detail structure
 * using an out parameter.
 */
struct CEvaluationDetail {
    template <typename T>
    CEvaluationDetail(EvaluationDetail<T> const& detail)
        : variation_index(detail.VariationIndex()), reason(detail.Reason()) {}
    std::optional<std::size_t> variation_index;
    std::optional<EvaluationReason> reason;
};
 
}  // namespace launchdarkly