concepts.hpp

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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
#ifndef NDN_UTIL_CONCEPTS_HPP
#define NDN_UTIL_CONCEPTS_HPP

#include <boost/concept/usage.hpp>
#include "../encoding/block.hpp"
#include "../encoding/encoding-buffer.hpp"

namespace ndn {

template<class X>
class WireEncodable
{
public:
  BOOST_CONCEPT_USAGE(WireEncodable)
  {
    Block block = j.wireEncode();
    block.size(); // avoid 'unused variable block'
  }

private:
  X j;
};

template<class X>
class WireEncodableWithEncodingBuffer
{
public:
  BOOST_CONCEPT_USAGE(WireEncodableWithEncodingBuffer)
  {
    EncodingEstimator estimator;
    size_t estimatedSize = j.wireEncode(estimator);

    EncodingBuffer encoder(estimatedSize, 0);
    j.wireEncode(encoder);
  }

private:
  X j;
};

template<class X>
class WireDecodable
{
public:
  BOOST_CONCEPT_USAGE(WireDecodable)
  {
    Block block;
    X j(block);
    j.wireDecode(block);
  }
};

template<class X>
class Hashable
{
public:
  BOOST_CONCEPT_USAGE(Hashable)
  {
    X hash;
    uint8_t* buf = 0;
    size_t size = hash.DigestSize();

    hash.Update(buf, size);
    hash.Final(buf);
    hash.Restart();
  }
};

// NDN_CXX_ASSERT_DEFAULT_CONSTRUCTIBLE and NDN_CXX_ASSERT_FORWARD_ITERATOR
// originally written as part of NFD codebase

namespace detail {

// As of Boost 1.54.0, the internal implementation of BOOST_CONCEPT_ASSERT does not allow
// multiple assertions on the same line, so we have to combine multiple concepts together.

template<typename T>
class StlForwardIteratorConcept : public boost::ForwardIterator<T>
                                , public boost::DefaultConstructible<T>
{
};

} // namespace detail

#define NDN_CXX_ASSERT_DEFAULT_CONSTRUCTIBLE(T) \
  static_assert(std::is_default_constructible<T>::value, \
                #T " must be default-constructible"); \
  BOOST_CONCEPT_ASSERT((boost::DefaultConstructible<T>))

#define NDN_CXX_ASSERT_FORWARD_ITERATOR(T) \
  BOOST_CONCEPT_ASSERT((::ndn::detail::StlForwardIteratorConcept<T>)); \
  static_assert(std::is_default_constructible<T>::value, \
                #T " must be default-constructible")


} // namespace ndn

#endif // NDN_UTIL_CONCEPTS_HPP