InvokePolicies.hpp

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//          Copyright Dominic Koepke 2019 - 2023.
// Distributed under the Boost Software License, Version 1.0.
//    (See accompanying file LICENSE_1_0.txt or copy at
//          https://www.boost.org/LICENSE_1_0.txt)
 
#ifndef SIMPLE_UTILITY_FUNCTIONAL_MIXIN_INVOKE_POLICIES_HPP
#define SIMPLE_UTILITY_FUNCTIONAL_MIXIN_INVOKE_POLICIES_HPP
 
#pragma once
 
#include <concepts>
#include <functional>
#include <type_traits>
#include <utility>
 
#include "Simple-Utility/CRTPBase.hpp"
#include "Simple-Utility/concepts/stl_extensions.hpp"
#include "Simple-Utility/functional/BasicClosure.hpp"
#include "Simple-Utility/tuple/General.hpp"
 
namespace sl::functional::detail
{
    template <class T>
    concept invoke_strategy = std::is_empty_v<T>;
 
    template <concepts::unqualified Derived, invoke_strategy InvokeStrategy>
    class BasicInvokePolicy
        : public CRTPBase<Derived>
    {
    private:
        using CRTPBase<Derived>::derived;
 
    public:
        template <class... Args>
            requires std::invocable<InvokeStrategy, const Derived&, Args...>
        constexpr decltype(auto) operator ()(
            Args&&... args
        ) const & noexcept(std::is_nothrow_invocable_v<InvokeStrategy, const Derived&, Args...>)
        {
            return std::invoke(InvokeStrategy{}, derived(), std::forward<Args>(args)...);
        }
 
        template <class... Args>
            requires std::invocable<InvokeStrategy, Derived&, Args...>
        constexpr decltype(auto) operator ()(Args&&... args) & noexcept(std::is_nothrow_invocable_v<InvokeStrategy, Derived&, Args...>)
        {
            return std::invoke(InvokeStrategy{}, derived(), std::forward<Args>(args)...);
        }
 
        template <class... Args>
            requires std::invocable<InvokeStrategy, const Derived&&, Args...>
        constexpr decltype(auto) operator ()(
            Args&&... args
        ) const && noexcept(std::is_nothrow_invocable_v<InvokeStrategy, const Derived&&, Args...>)
        {
            return std::invoke(InvokeStrategy{}, std::move(derived()), std::forward<Args>(args)...);
        }
 
        template <class... Args>
            requires std::invocable<InvokeStrategy, Derived&&, Args...>
        constexpr decltype(auto) operator ()(
            Args&&... args
        ) && noexcept(std::is_nothrow_invocable_v<InvokeStrategy, Derived&&, Args...>)
        {
            return std::invoke(InvokeStrategy{}, std::move(derived()), std::forward<Args>(args)...);
        }
    };
 
    template <concepts::unqualified Derived, invoke_strategy InvokeStrategy>
    class NodiscardInvokePolicy
        : public CRTPBase<Derived>
    {
    private:
        using CRTPBase<Derived>::derived;
 
    public:
        template <class... Args>
            requires std::invocable<InvokeStrategy, const Derived&, Args...>
        [[nodiscard]]
        constexpr decltype(auto) operator ()(
            Args&&... args
        ) const & noexcept(std::is_nothrow_invocable_v<InvokeStrategy, const Derived&, Args...>)
        {
            return std::invoke(InvokeStrategy{}, derived(), std::forward<Args>(args)...);
        }
 
        template <class... Args>
            requires std::invocable<InvokeStrategy, Derived&, Args...>
        [[nodiscard]]
        constexpr decltype(auto) operator ()(Args&&... args) & noexcept(std::is_nothrow_invocable_v<InvokeStrategy, Derived&, Args...>)
        {
            return std::invoke(InvokeStrategy{}, derived(), std::forward<Args>(args)...);
        }
 
        template <class... Args>
            requires std::invocable<InvokeStrategy, const Derived&&, Args...>
        [[nodiscard]]
        constexpr decltype(auto) operator ()(
            Args&&... args
        ) const && noexcept(std::is_nothrow_invocable_v<InvokeStrategy, const Derived&&, Args...>)
        {
            return std::invoke(InvokeStrategy{}, std::move(derived()), std::forward<Args>(args)...);
        }
 
        template <class... Args>
            requires std::invocable<InvokeStrategy, Derived&&, Args...>
        [[nodiscard]]
        constexpr decltype(auto) operator ()(
            Args&&... args
        ) && noexcept(std::is_nothrow_invocable_v<InvokeStrategy, Derived&&, Args...>)
        {
            return std::invoke(InvokeStrategy{}, std::move(derived()), std::forward<Args>(args)...);
        }
    };
 
    struct InvocableStrategy
    {
        template <class Fn, class... Args>
            requires std::invocable<unwrap_functional_t<Fn&&>, Args...>
        [[nodiscard]]
        constexpr std::invoke_result_t<unwrap_functional_t<Fn&&>, Args...> operator ()(
            Fn&& fn,
            Args&&... args
        ) const noexcept(std::is_nothrow_invocable_v<unwrap_functional_t<Fn&&>, Args...>)
        {
            return std::invoke(
                forward_unwrapped<Fn>(fn),
                std::forward<Args>(args)...);
        }
    };
 
    struct PredicateStrategy
    {
        template <class Fn, class... Args>
            requires std::predicate<unwrap_functional_t<Fn&&>, Args...>
        [[nodiscard]]
        constexpr std::invoke_result_t<unwrap_functional_t<Fn&&>, Args...> operator ()(
            Fn&& fn,
            Args&&... args
        ) const noexcept(std::is_nothrow_invocable_v<unwrap_functional_t<Fn&&>, Args...>)
        {
            return std::invoke(
                forward_unwrapped<Fn>(fn),
                std::forward<Args>(args)...);
        }
    };
 
    struct ApplicableStrategy
    {
        template <class Fn, class Tuple>
            requires concepts::applicable<unwrap_functional_t<Fn&&>, Tuple>
        [[nodiscard]]
        constexpr decltype(auto) operator ()(
            Fn&& fn,
            Tuple&& t
        ) const noexcept(concepts::nothrow_applicable<unwrap_functional_t<Fn&&>, Tuple>)
        {
            return std::apply(
                forward_unwrapped<Fn>(fn),
                std::forward<Tuple>(t));
        }
    };
}
 
namespace sl::functional
{
    template <concepts::unqualified Derived>
    using BasicInvokePolicy = detail::BasicInvokePolicy<Derived, detail::InvocableStrategy>;
 
    template <concepts::unqualified Derived>
    using NodiscardInvokePolicy = detail::NodiscardInvokePolicy<Derived, detail::InvocableStrategy>;
 
    template <concepts::unqualified Derived>
    using PredicateInvokePolicy = detail::NodiscardInvokePolicy<Derived, detail::PredicateStrategy>;
 
    template <concepts::unqualified Derived>
    using BasicApplyPolicy = detail::NodiscardInvokePolicy<Derived, detail::ApplicableStrategy>;
 
    template <concepts::unqualified Derived>
    using NodiscardApplyPolicy = detail::NodiscardInvokePolicy<Derived, detail::ApplicableStrategy>;
 
}
 
#endif