AnyStopToken.hpp

//------------------------------------------------------------------------------
/*
    This file is part of clio: https://github.com/XRPLF/clio
    Copyright (c) 2024, the clio developers.
 
    Permission to use, copy, modify, and distribute this software for any
    purpose with or without fee is hereby granted, provided that the above
    copyright notice and this permission notice appear in all copies.
 
    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================
 
#pragma once
 
#include "util/Assert.hpp"
#include "util/async/Concepts.hpp"
 
#include <boost/asio/spawn.hpp>
 
#include <chrono>
#include <memory>
#include <type_traits>
#include <utility>
 
namespace util::async {
 
class AnyStopToken {
public:
    template <SomeStopToken TokenType>
        requires NotSameAs<TokenType, AnyStopToken>
    /* implicit */ AnyStopToken(TokenType&& token)
        : pimpl_{std::make_unique<Model<TokenType>>(std::forward<TokenType>(token))}
    {
    }
 
    ~AnyStopToken() = default;
 
    AnyStopToken(AnyStopToken const& other) : pimpl_{other.pimpl_->clone()}
    {
    }
 
    AnyStopToken&
    operator=(AnyStopToken const& rhs)
    {
        AnyStopToken copy{rhs};
        pimpl_.swap(copy.pimpl_);
        return *this;
    }
 
    AnyStopToken(AnyStopToken&&) = default;
 
    AnyStopToken&
    operator=(AnyStopToken&&) = default;
    [[nodiscard]] bool
    isStopRequested() const noexcept
    {
        return pimpl_->isStopRequested();
    }
 
    [[nodiscard]]
    operator bool() const noexcept
    {
        return isStopRequested();
    }
 
    [[nodiscard]]
    operator boost::asio::yield_context() const
    {
        return pimpl_->yieldContext();
    }
 
private:
    struct Concept {
        virtual ~Concept() = default;
 
        [[nodiscard]] virtual bool
        isStopRequested() const noexcept = 0;
 
        [[nodiscard]] virtual std::unique_ptr<Concept>
        clone() const = 0;
 
        [[nodiscard]] virtual boost::asio::yield_context
        yieldContext() const = 0;
    };
 
    template <SomeStopToken TokenType>
    struct Model : Concept {
        TokenType token;
 
        Model(TokenType&& token) : token{std::move(token)}
        {
        }
 
        [[nodiscard]] bool
        isStopRequested() const noexcept override
        {
            return token.isStopRequested();
        }
 
        [[nodiscard]] std::unique_ptr<Concept>
        clone() const override
        {
            return std::make_unique<Model>(*this);
        }
 
        [[nodiscard]] boost::asio::yield_context
        yieldContext() const override
        {
            if constexpr (std::is_convertible_v<TokenType, boost::asio::yield_context>) {
                return token;
            }
 
            ASSERT(false, "Token type does not support conversion to boost::asio::yield_context");
            std::unreachable();
        }
    };
 
private:
    std::unique_ptr<Concept> pimpl_;
};
 
}  // namespace util::async