SequenceTerminationFieldSuffix.h

//
// Copyright 2015 - 2025 (C). Alex Robenko. All rights reserved.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
#pragma once
 
#include "comms/Assert.h"
#include "comms/details/tag.h"
#include "comms/ErrorStatus.h"
#include "comms/util/type_traits.h"
 
#include <iterator>
 
namespace comms
{
 
namespace field
{
 
namespace adapter
{
 
template <typename TTermField, typename TBase>
class SequenceTerminationFieldSuffix : public TBase
{
    using BaseImpl = TBase;
    using TermField = TTermField;
 
    static_assert(!TermField::isVersionDependent(),
            "Suffix fields must not be version dependent");
 
public:
    using ValueType = typename BaseImpl::ValueType;
    using ElementType = typename BaseImpl::ElementType;
 
    SequenceTerminationFieldSuffix() = default;
 
    explicit SequenceTerminationFieldSuffix(const ValueType& val)
      : BaseImpl(val)
    {
    }
 
    explicit SequenceTerminationFieldSuffix(ValueType&& val)
      : BaseImpl(std::move(val))
    {
    }
 
    SequenceTerminationFieldSuffix(const SequenceTerminationFieldSuffix&) = default;
    SequenceTerminationFieldSuffix(SequenceTerminationFieldSuffix&&) = default;
    SequenceTerminationFieldSuffix& operator=(const SequenceTerminationFieldSuffix&) = default;
    SequenceTerminationFieldSuffix& operator=(SequenceTerminationFieldSuffix&&) = default;
 
    constexpr std::size_t length() const
    {
        return m_termField.length() + BaseImpl::length();
    }
 
    static constexpr std::size_t minLength()
    {
        return TermField::minLength() + BaseImpl::minLength();
    }
 
    static constexpr std::size_t maxLength()
    {
        return TermField::maxLength() + BaseImpl::maxLength();
    }
 
    template <typename TIter>
    comms::ErrorStatus read(TIter& iter, std::size_t len)
    {
        using IterType = typename std::decay<decltype(iter)>::type;
        using IterTag = typename std::iterator_traits<IterType>::iterator_category;
        static_assert(std::is_base_of<std::random_access_iterator_tag, IterTag>::value,
            "Only random access iterator for reading is supported with comms::option::def::SequenceTerminationFieldSuffix option");
 
        using ReadElemTag =
            typename comms::util::LazyShallowConditional<
                std::is_integral<ElementType>::value && (sizeof(ElementType) == sizeof(std::uint8_t))
            >::template Type<
                RawDataTag,
                FieldTag
            >;
 
        return readInternal(iter, len, ReadElemTag());
    }
 
    static constexpr bool hasReadNoStatus()
    {
        return false;
    }
 
    template <typename TIter>
    void readNoStatus(TIter& iter) = delete;
 
    template <typename TIter>
    comms::ErrorStatus write(TIter& iter, std::size_t len) const
    {
        auto trailLen = m_termField.length();
        auto es = BaseImpl::write(iter, len - trailLen);
        if (es != comms::ErrorStatus::Success) {
            return es;
        }
 
        return m_termField.write(iter, trailLen);
    }
 
    template <typename TIter>
    void writeNoStatus(TIter& iter) const
    {
        BaseImpl::writeNoStatus(iter);
        m_termField.writeNoStatus(iter);
    }
 
    TermField& terminationFieldSuffix()
    {
        return m_termField;
    }
 
    const TermField& terminationFieldSuffix() const
    {
        return m_termField;
    }
 
private:
    template <typename... TParams>
    using RawDataTag = comms::details::tag::Tag1<>;
 
    template <typename... TParams>
    using FieldTag = comms::details::tag::Tag2<>;
 
    template <typename TIter, typename... TParams>
    comms::ErrorStatus readInternal(TIter& iter, std::size_t len, FieldTag<TParams...>)
    {
        BaseImpl::clear();
        while (true) {
            auto iterCpy = iter;
            auto es = m_termField.read(iterCpy, len);
            if (es == comms::ErrorStatus::Success) {
                std::advance(iter, std::distance(iter, iterCpy));
                return es;
            }
 
            auto& elem = BaseImpl::createBack();
            es = BaseImpl::readElement(elem, iter, len);
            if (es != comms::ErrorStatus::Success) {
                BaseImpl::value().pop_back();
                return es;
            }
        }
 
        return comms::ErrorStatus::Success;
    }
 
    template <typename TIter, typename... TParams>
    comms::ErrorStatus readInternal(TIter& iter, std::size_t len, RawDataTag<TParams...>)
    {
        std::size_t consumed = 0U;
        std::size_t termFieldLen = 0U;
        while (consumed < len) {
            auto iterCpy = iter + consumed;
            auto es = m_termField.read(iterCpy, len - consumed);
            if (es == comms::ErrorStatus::Success) {
                termFieldLen = static_cast<std::size_t>(std::distance(iter + consumed, iterCpy));
                break;
            }
 
            ++consumed;
        }
 
        if (len <= consumed) {
            return comms::ErrorStatus::NotEnoughData;
        }
 
        auto iterCpy = iter;
        auto es = BaseImpl::read(iterCpy, consumed);
        if (es != comms::ErrorStatus::Success) {
            return es;
        }
 
        auto fullConsumeLen = consumed + termFieldLen;
        COMMS_ASSERT(fullConsumeLen <= len);
        std::advance(iter, fullConsumeLen);
        return comms::ErrorStatus::Success;
    }
 
    TermField m_termField;
};
 
}  // namespace adapter
 
}  // namespace field
 
}  // namespace comms