default_field_codec.h

// Copyright 2023:
//   GobySoft, LLC (2013-)
//   Community contributors (see AUTHORS file)
// File authors:
//   Toby Schneider <toby@gobysoft.org>
//
//
// This file is part of the Dynamic Compact Control Language Library
// ("DCCL").
//
// DCCL is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 2.1 of the License, or
// (at your option) any later version.
//
// DCCL is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with DCCL.  If not, see <http://www.gnu.org/licenses/>.
#include "codec.h"
 
#ifndef CODEC_VERSION
#error CODEC_VERSION must be set
#endif
 
#ifndef CODEC_VERSION_NAMESPACE
#error CODEC_VERSION_NAMESPACE must be set
#endif
 
#ifndef DCCL_DEFAULT_FIELD_CODEC_HEADER_H
#define DCCL_DEFAULT_FIELD_CODEC_HEADER_H
 
namespace dccl
{
 
namespace internal
{
 
//
// Helper functions to reduce copy/paste in set_default_codecs()
//
template <int version> struct DefaultFieldCodecLoader
{
    static_assert(sizeof(DefaultFieldCodecLoader) == 0,
                  "Must use specialization of DefaultFieldCodecLoader");
};
 
template <int version> struct TimeCodecLoader
{
    static_assert(sizeof(TimeCodecLoader) == 0, "Must use specialization of TimeCodecLoader");
};
 
template <int version> struct StaticCodecLoader
{
    static_assert(sizeof(StaticCodecLoader) == 0, "Must use specialization of StaticCodecLoader");
};
 
template <int version> struct PresenceCodecLoader
{
    static_assert(sizeof(PresenceCodecLoader) == 0,
                  "Must use specialization of PresenceCodecLoader");
};
 
template <int version> struct VarBytesCodecLoader
{
    static_assert(sizeof(VarBytesCodecLoader) == 0,
                  "Must use specialization of VarBytesCodecLoader");
};
 
template <int version> struct HashCodecLoader
{
    static_assert(sizeof(HashCodecLoader) == 0, "Must use specialization of HashCodecLoader");
};
 
template <int version> struct CRCCodecLoader
{
    static_assert(sizeof(CRCCodecLoader) == 0, "Must use specialization of CRCCodecLoader");
};
 
} // namespace internal
} // namespace dccl
#endif
 
namespace dccl
{
namespace internal
{
// replace recursion with C++ 17 fold expression when we switch to C++ 17 or newer
template <> struct DefaultFieldCodecLoader<CODEC_VERSION>
{
    // entry
    static void add(FieldCodecManagerLocal& manager)
    {
        using namespace CODEC_VERSION_NAMESPACE;
        using google::protobuf::FieldDescriptor;
 
        std::string name = ::dccl::Codec::default_codec_name(CODEC_VERSION);
        manager.add<DefaultBoolCodec>(name);
        manager.add<DefaultStringCodec, FieldDescriptor::TYPE_STRING>(name);
        manager.add<DefaultBytesCodec, FieldDescriptor::TYPE_BYTES>(name);
        manager.add<DefaultEnumCodec>(name);
        manager.add<DefaultMessageCodec, FieldDescriptor::TYPE_MESSAGE>(name);
 
        add<true, double, float, int32, int64, uint32, uint64>(manager);
    }
 
    // recurse
    template <bool enable, typename T, typename... Types>
    static void add(FieldCodecManagerLocal& manager)
    {
        using namespace CODEC_VERSION_NAMESPACE;
        std::string name = ::dccl::Codec::default_codec_name(CODEC_VERSION);
        manager.add<DefaultNumericFieldCodec<T>>(name);
        // recurse
        add<enable, Types...>(manager);
    }
 
    // last
    template <bool enable> static void add(FieldCodecManagerLocal& manager) {}
};
 
template <int version> struct TimeCodecLoader;
template <> struct TimeCodecLoader<CODEC_VERSION>
{
    static void add(FieldCodecManagerLocal& manager,
                    const std::string& name = "dccl.time" + std::to_string(CODEC_VERSION))
    {
        add<true, double, int64, uint64>(manager, name);
    }
 
    template <bool enable, typename T, typename... Types>
    static void add(FieldCodecManagerLocal& manager, const std::string& name)
    {
        using namespace CODEC_VERSION_NAMESPACE;
        manager.add<TimeCodec<T>>(name);
        add<enable, Types...>(manager, name);
    }
    template <bool enable> static void add(FieldCodecManagerLocal& manager, const std::string& name)
    {
    }
};
 
template <> struct StaticCodecLoader<CODEC_VERSION>
{
    static void add(FieldCodecManagerLocal& manager,
                    const std::string& name = "dccl.static" + std::to_string(CODEC_VERSION))
    {
        add<true, std::string, double, float, int32, int64, uint32, uint64>(manager, name);
    }
 
    template <bool enable, typename T, typename... Types>
    static void add(FieldCodecManagerLocal& manager, const std::string& name)
    {
        using namespace CODEC_VERSION_NAMESPACE;
        manager.add<StaticCodec<T>>(name);
        add<enable, Types...>(manager, name);
    }
 
    template <bool enable> static void add(FieldCodecManagerLocal& manager, const std::string& name)
    {
    }
};
 
#if CODEC_VERSION >= 3
template <> struct PresenceCodecLoader<CODEC_VERSION>
{
    static void add(FieldCodecManagerLocal& manager)
    {
        using namespace CODEC_VERSION_NAMESPACE;
        using google::protobuf::FieldDescriptor;
 
        manager.add<PresenceBitCodec<DefaultBoolCodec>>(name_);
        manager.add<PresenceBitCodec<DefaultStringCodec>, FieldDescriptor::TYPE_STRING>(name_);
        manager.add<PresenceBitCodec<DefaultBytesCodec>, FieldDescriptor::TYPE_BYTES>(name_);
        manager.add<PresenceBitCodec<DefaultEnumCodec>>(name_);
 
        // use normal default meessage codec
        manager.add<DefaultMessageCodec, FieldDescriptor::TYPE_MESSAGE>(name_);
        add<true, double, float, int32, int64, uint32, uint64>(manager);
    }
 
    template <bool enable, typename T, typename... Types>
    static void add(FieldCodecManagerLocal& manager)
    {
        using namespace CODEC_VERSION_NAMESPACE;
        std::string name = ::dccl::Codec::default_codec_name(CODEC_VERSION);
        manager.add<PresenceBitCodec<DefaultNumericFieldCodec<T>>>(name_);
        add<enable, Types...>(manager);
    }
 
    template <bool enable> static void add(FieldCodecManagerLocal& manager) {}
 
  private:
    static const std::string name_;
};
 
const std::string PresenceCodecLoader<CODEC_VERSION>::name_{"dccl.presence" +
                                                            std::to_string(CODEC_VERSION)};
 
template <> struct VarBytesCodecLoader<CODEC_VERSION>
{
    static void add(FieldCodecManagerLocal& manager)
    {
        using namespace CODEC_VERSION_NAMESPACE;
        manager.add<VarBytesCodec>("dccl.var_bytes" + std::to_string(CODEC_VERSION));
    }
};
 
#endif
 
#if CODEC_VERSION >= 4
template <> struct HashCodecLoader<CODEC_VERSION>
{
    static void add(FieldCodecManagerLocal& manager, std::set<int> versions = {CODEC_VERSION})
    {
        using namespace CODEC_VERSION_NAMESPACE;
        // backport versions
        for (int v : versions) manager.add<HashCodec>("dccl.hash" + std::to_string(v));
    }
};
 
template <> struct CRCCodecLoader<CODEC_VERSION>
{
    static void add(FieldCodecManagerLocal& manager, std::set<int> versions = {CODEC_VERSION})
    {
        using namespace CODEC_VERSION_NAMESPACE;
        // Register version-suffixed names for backwards compatibility
        for (int v : versions)
        {
            manager.add<CRC16Codec>("dccl.crc16" + std::to_string(v));
            manager.add<CRC32Codec>("dccl.crc32" + std::to_string(v));
        }
        // Register plain names so users can write codec: "dccl.crc16" or "dccl.crc32".
        // The FieldCodecManager auto-appends the codec version only when the name does NOT
        // end in a digit, so "dccl.crc16" and "dccl.crc32" (which end in digits) must be
        // registered explicitly without a version suffix.
        manager.add<CRC16Codec>("dccl.crc16");
        manager.add<CRC32Codec>("dccl.crc32");
    }
};
 
#endif
 
} // namespace internal
} // namespace dccl
 
#undef CODEC_VERSION
#undef CODEC_VERSION_NAMESPACE