program_name.hpp

// Copyright (C) 2022 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/policy/policy.hpp"
 
namespace arg_router::policy
{
template <typename S>
class program_name_t
{
public:
    using string_type = S;
 
    constexpr explicit program_name_t([[maybe_unused]] S str = {}) noexcept {}
 
    [[nodiscard]] constexpr static std::string_view program_name() noexcept { return S::get(); }
 
private:
    static_assert(utility::utf8::count(program_name()) > 1,
                  "Program names must be longer than one character");
    static_assert(!utility::utf8::contains_whitespace(program_name()),
                  "Program names cannot contain whitespace");
};
 
template <typename S>
constexpr auto program_name = program_name_t<S>{};
 
template <typename S>
struct is_policy<program_name_t<S>> : std::true_type {
};
}  // namespace arg_router::policy