uncertain.hpp

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#pragma once
#include <cmath>
#include <iostream>
#include <map>
#include <memory>
#include <type_traits>
#include <utility>

 
namespace sigma {
 
// Foward Declaration
namespace detail_ {
template<typename T>
class Setter; // Class to alter values inside Uncertain
} // namespace detail_

template<typename ValueType>
class Uncertain {
public:
    using my_t = Uncertain<ValueType>;

    using value_t = ValueType;

    using dep_sd_t = value_t;

    using dep_sd_ptr = std::shared_ptr<dep_sd_t>;

    using deps_map_t = std::map<dep_sd_ptr, value_t>;

    Uncertain() noexcept = default;

    Uncertain(value_t mean) : m_mean_(mean), m_sd_(0.0) {}

    Uncertain(value_t mean, value_t sd);

    value_t mean() const { return m_mean_; }

    value_t sd() const { return m_sd_; }

    const deps_map_t& deps() const { return m_deps_; }
 
private:
    value_t m_mean_;

    value_t m_sd_;

    deps_map_t m_deps_ = {};

    template<typename T>
    friend class detail_::Setter;
 
}; // class Uncertain
 
// -- Out-of-line Definitions --------------------------------------------------
 
template<typename ValueType>
Uncertain<ValueType>::Uncertain(value_t mean, value_t sd) :
  m_mean_(mean), m_sd_(std::abs(sd)) {
    m_deps_.emplace(
      std::make_pair(std::make_shared<dep_sd_t>(sd), value_t{1.0}));
}
 
// -- Utility functions --------------------------------------------------------

template<typename ValueType>
std::ostream& operator<<(std::ostream& os, const Uncertain<ValueType>& u) {
    os << u.mean() << "+/-" << u.sd();
    return os;
}

template<typename ValueType1, typename ValueType2>
bool operator==(const Uncertain<ValueType1>& lhs,
                const Uncertain<ValueType2>& rhs) {
    if constexpr(!std::is_same_v<ValueType1, ValueType2>) {
        return false;
    } else {
        if(lhs.mean() != rhs.mean()) return false;
        if(lhs.sd() != rhs.sd()) return false;
        if(lhs.deps() != rhs.deps()) return false;
        return true;
    }
}

template<typename ValueType1, typename ValueType2>
bool operator!=(const Uncertain<ValueType1>& lhs,
                const Uncertain<ValueType2>& rhs) {
    return !(lhs == rhs);
}

template<typename ValueType1, typename ValueType2>
bool operator<(const Uncertain<ValueType1>& lhs,
               const Uncertain<ValueType2>& rhs) {
    return lhs.mean() < rhs.mean();
}

template<typename ValueType1, typename ValueType2>
bool operator>(const Uncertain<ValueType1>& lhs,
               const Uncertain<ValueType2>& rhs) {
    return rhs < lhs;
}

template<typename ValueType1, typename ValueType2>
bool operator<=(const Uncertain<ValueType1>& lhs,
                const Uncertain<ValueType2>& rhs) {
    return (lhs == rhs) || (lhs < rhs);
}

template<typename ValueType1, typename ValueType2>
bool operator>=(const Uncertain<ValueType1>& lhs,
                const Uncertain<ValueType2>& rhs) {
    return (lhs == rhs) || (lhs > rhs);
}

using UFloat = Uncertain<float>;

using UDouble = Uncertain<double>;
 
} // namespace sigma