Serializing the unserializables...

Dettagli

Categoria: TSL

Pubblicato Lunedì, 01 Ottobre 2012 01:41

Scritto da Giampa

Visite: 2158

In case it is not possible to modify the source code it is nevertheless possible to serialize it through a specialization of the bitwise operator & for the [i,o]archive classes.

Assuming as example the need of serializing the boost::regex instances we need to specialize the tsl::operator & in the following way:

namespace tsl {

namespace valid {

// the following line will make boost:regex as a valid basic type for tsl during static asserts
template <> struct Basic< boost::regex> : public std::true_type {};

}

// this is the operator specialization in case of named serialization (i.e. with a name provided as label)
template <>
inline OArchive & operator &  (OArchive &out,const Named<const boost::regex&> &t) {
  return out.save(std::get<1>(t).str(),std::get<0>(t));
}

// this is the operator specialization for simple seriaization (i.e. with default name / label)
template <>
inline OArchive & operator & (OArchive &out,const boost::regex &value) {
  return out.save(value.str());
}

// operator specilization for deserialization 
template <>
inline IArchive & operator & (IArchive &in,boost::regex &value) {
  std::string s;
  in.restore(s);
  value=s;
  return in;
}

}

It is now possible to invoke the (de)serializtion operator & as any other serializable class:

// serialization
const boost::regex original(".*[a-z]+");
tsl::OJsonArchive oa(stream);
oa & original;

// deserialization
boost::regex restored;
tsl::IJsonArchive ia(stream);
ia & restored;

The resulting json archive will look like:

 
{
  "TSL_String": ".*[a-z]+"
}

The full example source is below:

#include <boost/regex.hpp>
#include <sstream>

#include <tsl/json_archive.h>

namespace tsl {

namespace valid {

// the following line will make boost:regex as a valid type for tsl during static asserts
template <> struct Basic< boost::regex> : public std::true_type {};

}

// this is the operator specialization in case of named serialization (i.e. with a name provided as label)
template <>
inline OArchive & operator &  (OArchive &out,const Named<const boost::regex&> &t) {
  return out.save(std::get<1>(t).str(),std::get<0>(t));
}

// this is the operator specialization for simple seriaization (i.e. with default name / label)
template <>
inline OArchive & operator & (OArchive &out,const boost::regex &value) {
  return out.save(value.str());
}

// operator specilization for deserialization 
template <>
inline IArchive & operator & (IArchive &in,boost::regex &value) {
  std::string s;
  in.restore(s);
  value=s;
  return in;
}

}

using namespace std;

int main(int argc,const char *argv[]) {
  try {
    stringstream stream;
    stream.unsetf(ios::skipws);
    const boost::regex original(".*[a-z]+");
    { // serialization
      tsl::OJsonArchive oa(stream);
      oa & original;
    }
    cout << stream.str() << endl;
    boost::regex restored;
    { // deserialization
      tsl::IJsonArchive ia(stream);
      ia & restored;
    }
    assert(original==restored);
  } catch (const runtime_error &error) {
    cerr << "Exception: " << error.what() << endl;
  }
}

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