draconisplusplus/include/rfl/Validator.hpp

#ifndef RFL_VALIDATOR_HPP_
#define RFL_VALIDATOR_HPP_

#include <concepts>
#include <functional>
#include <optional>
#include <regex>
#include <string>
#include <type_traits>
#include <utility>

#include "AllOf.hpp"
#include "Result.hpp"
#include "internal/HasValidation.hpp"
#include "internal/StringLiteral.hpp"

namespace rfl {

  template <class T, class V, class... Vs>
    requires internal::HasValidation<AllOf<V, Vs...>, T>
  struct Validator {
   public:
    using ReflectionType = T;
    using ValidationType = std::conditional_t<sizeof...(Vs) == 0, V, AllOf<V, Vs...>>;

    /// Exception-free validation.
    static Result<Validator<T, V, Vs...>> from_value(const T& _value) noexcept {
      try {
        return Validator<T, V, Vs...>(_value);
      } catch (std::exception& e) { return Error(e.what()); }
    }

    Validator() : value_(ValidationType::validate(T()).value()) {}

    Validator(Validator<T, V, Vs...>&& _other) noexcept = default;

    Validator(const Validator<T, V, Vs...>& _other) = default;

    Validator(T&& _value) : value_(ValidationType::validate(_value).value()) {}

    Validator(const T& _value) : value_(ValidationType::validate(_value).value()) {}

    template <class U, typename std::enable_if<std::is_convertible_v<U, T>, bool>::type = true>
    Validator(U&& _value) : value_(ValidationType::validate(T(std::forward<U>(_value))).value()) {}

    template <class U, typename std::enable_if<std::is_convertible_v<U, T>, bool>::type = true>
    Validator(const U& _value) : value_(ValidationType::validate(T(_value)).value()) {}

    ~Validator() = default;

    /// Assigns the underlying object.
    auto& operator=(const T& _value) {
      value_ = ValidationType::validate(_value).value();
      return *this;
    }

    /// Assigns the underlying object.
    auto& operator=(T&& _value) {
      value_ = ValidationType::validate(std::forward<T>(_value)).value();
      return *this;
    }

    /// Assigns the underlying object.
    Validator<T, V, Vs...>& operator=(const Validator<T, V, Vs...>& _other) = default;

    /// Assigns the underlying object.
    Validator<T, V, Vs...>& operator=(Validator<T, V, Vs...>&& _other) noexcept = default;

    /// Assigns the underlying object.
    template <class U, typename std::enable_if<std::is_convertible_v<U, T>, bool>::type = true>
    auto& operator=(U&& _value) noexcept {
      value_ = ValidationType::validate(T(std::forward<U>(_value))).value();
      return *this;
    }

    /// Assigns the underlying object.
    template <class U, typename std::enable_if<std::is_convertible_v<U, T>, bool>::type = true>
    auto& operator=(const U& _value) {
      value_ = ValidationType::validate(T(_value)).value();
      return *this;
    }

    /// Equality operator other Validators.
    bool operator==(const Validator<T, V, Vs...>& _other) const {
      return value() == _other.value();
    }

    /// Exposes the underlying value.
    T& value() { return value_; }

    /// Exposes the underlying value.
    const T& value() const { return value_; }

    /// Necessary for the serialization to work.
    const T& reflection() const { return value_; }

   private:
    /// The underlying value.
    T value_;
  };

  template <class T, class V, class... Vs>
  inline auto operator<=>(const Validator<T, V, Vs...>& _v1, const Validator<T, V, Vs...>& _v2) {
    return _v1.value() <=> _v2.value();
  }

  template <class T, class V, class... Vs>
  inline auto operator<=>(const Validator<T, V, Vs...>& _v, const T& _t) {
    return _v.value() <=> _t;
  }

} // namespace rfl

namespace std {

  template <class T, class V, class... Vs>
  struct hash<rfl::Validator<T, V, Vs...>> {
    size_t operator()(const rfl::Validator<T, V, Vs...>& _v) const { return hash<T>()(_v.value()); }
  };

} // namespace std

#endif