default_value.hpp

// Copyright (C) 2022-2023 by Camden Mannett.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE or copy at https://www.boost.org/LICENSE_1_0.txt)
 
#pragma once
 
#include "arg_router/config.hpp"
#include "arg_router/policy/policy.hpp"
 
namespace arg_router::policy
{
template <typename T>
class default_value
{
public:
    using value_type = T;
 
    constexpr static auto priority = std::size_t{500};
 
    constexpr explicit default_value(value_type value) noexcept : value_{std::move(value)} {}
 
    template <typename ValueType, typename... Parents>
    [[nodiscard]] constexpr ValueType missing_phase(
        [[maybe_unused]] const Parents&... parents) const noexcept
    {
        return value_;
    }
 
private:
    value_type value_;
};
 
template <typename T>
struct is_policy<default_value<T>> : std::true_type {
};
}  // namespace arg_router::policy