unit_value.h

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// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the Apache 2.0 License.
#pragma once
 
#include "ccf/kv/get_name.h"
#include "ccf/kv/hooks.h"
#include "ccf/kv/unit_value_handle.h"
#include "ccf/kv/untyped.h"
 
namespace ccf::kv
{
  template <typename Unit = ccf::kv::serialisers::ZeroBlitUnitCreator>
  class UnitValue : public GetName
  {
  public:
    using ReadOnlyHandle = ccf::kv::ReadableUnitValueHandle<Unit>;
    using WriteOnlyHandle = ccf::kv::WriteableUnitValueHandle<Unit>;
    using Handle = ccf::kv::UnitValueHandle<Unit>;
 
    using Write = std::optional<ccf::kv::serialisers::SerialisedEntry>;
    using MapHook = ccf::kv::MapHook<Write>;
    using CommitHook = ccf::kv::CommitHook<Write>;
 
    using GetName::GetName;
 
    static ccf::kv::serialisers::SerialisedEntry create_unit()
    {
      return Unit::get();
    }
 
  private:
    static Write deserialise_write(const ccf::kv::untyped::Write& w)
    {
      const auto it = w.find(Unit::get());
      if (it == w.end() || !it->second.has_value())
      {
        return std::nullopt;
      }
 
      return Unit::get();
    }
 
  public:
    static ccf::kv::untyped::CommitHook wrap_commit_hook(const CommitHook& hook)
    {
      return [hook](Version v, const ccf::kv::untyped::Write& w) {
        hook(v, deserialise_write(w));
      };
    }
 
    static ccf::kv::untyped::MapHook wrap_map_hook(const MapHook& hook)
    {
      return [hook](Version v, const ccf::kv::untyped::Write& w) {
        return hook(v, deserialise_write(w));
      };
    }
  };
}