XrdClArg.hh

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//------------------------------------------------------------------------------
// Copyright (c) 2011-2017 by European Organization for Nuclear Research (CERN)
// Author: Krzysztof Jamrog <krzysztof.piotr.jamrog@cern.ch>,
//         Michal Simon <michal.simon@cern.ch>
//------------------------------------------------------------------------------
// This file is part of the XRootD software suite.
//
// XRootD 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 3 of the License, or
// (at your option) any later version.
//
// XRootD 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 General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with XRootD.  If not, see <http://www.gnu.org/licenses/>.
//
// In applying this licence, CERN does not waive the privileges and immunities
// granted to it by virtue of its status as an Intergovernmental Organization
// or submit itself to any jurisdiction.
//------------------------------------------------------------------------------

#ifndef __XRD_CL_OPERATION_PARAMS_HH__
#define __XRD_CL_OPERATION_PARAMS_HH__

#include "XrdCl/XrdClFwd.hh"
#include "XrdCl/XrdClOptional.hh"

#include <future>
#include <string>
#include <sstream>
#include <unordered_map>

namespace XrdCl
{

  //----------------------------------------------------------------------------
  //----------------------------------------------------------------------------
  template<typename T>
  class ArgBase
  {
    public:

      //------------------------------------------------------------------------
      //------------------------------------------------------------------------
      ArgBase()
      {
      }

      //------------------------------------------------------------------------
      //------------------------------------------------------------------------
      virtual ~ArgBase()
      {
      }

      //------------------------------------------------------------------------
      //------------------------------------------------------------------------
      ArgBase( T value ) : holder( new PlainValue( std::move( value ) ) )
      {
      }

      //------------------------------------------------------------------------
      //------------------------------------------------------------------------
      ArgBase( std::future<T> &&ftr ) : holder( new FutureValue( std::move( ftr ) ) )
      {
      }

      //------------------------------------------------------------------------
      //------------------------------------------------------------------------
      ArgBase( const Fwd<T> &fwd ) : holder( new FwdValue( fwd ) )
      {
      }

      //------------------------------------------------------------------------
      //------------------------------------------------------------------------
      ArgBase( ArgBase &&arg ) : holder( std::move( arg.holder ) )
      {
      }

      //------------------------------------------------------------------------
      //------------------------------------------------------------------------
      inline T& Get() const
      {
        if( !holder ) throw std::logic_error( "XrdCl::ArgBase::Get(): value not set." );
        return holder->Get();
      }

      operator T() const
      {
        return Get();
      }

    protected:

      //------------------------------------------------------------------------
      //------------------------------------------------------------------------
      struct ValueHolder
      {
        //----------------------------------------------------------------------
        //----------------------------------------------------------------------
        virtual ~ValueHolder()
        {
        }

        //----------------------------------------------------------------------
        //----------------------------------------------------------------------
        virtual T& Get() = 0;
      };

      //------------------------------------------------------------------------
      //------------------------------------------------------------------------
      struct PlainValue : public ValueHolder
      {
          //--------------------------------------------------------------------
          //--------------------------------------------------------------------
          PlainValue( T &&value ) : value( std::move( value ) )
          {
          }

          //--------------------------------------------------------------------
          //--------------------------------------------------------------------
          T& Get()
          {
            return value;
          }

        private:
          //--------------------------------------------------------------------
          //--------------------------------------------------------------------
          T value;
      };

      //------------------------------------------------------------------------
      //------------------------------------------------------------------------
      struct FutureValue : public ValueHolder
      {
          //--------------------------------------------------------------------
          //--------------------------------------------------------------------
          FutureValue( std::future<T> &&ftr ) : ftr( std::move( ftr ) )
          {
          }

          //--------------------------------------------------------------------
          //--------------------------------------------------------------------
          T& Get()
          {
            if( val ) return *val;
            val = ftr.get();
            return *val;
          }

        private:
          //--------------------------------------------------------------------
          //--------------------------------------------------------------------
          std::future<T> ftr;
          Optional<T>    val;
      };

      //------------------------------------------------------------------------
      //------------------------------------------------------------------------
      struct FwdValue : public ValueHolder
      {
          //--------------------------------------------------------------------
          //--------------------------------------------------------------------
          FwdValue( const Fwd<T> &fwd ) : fwd( fwd )
          {
          }

          //--------------------------------------------------------------------
          //--------------------------------------------------------------------
          T& Get()
          {
            return *fwd;
          }

        private:
          //--------------------------------------------------------------------
          //--------------------------------------------------------------------
          Fwd<T> fwd;
      };

      //------------------------------------------------------------------------
      //------------------------------------------------------------------------
      std::unique_ptr<ValueHolder> holder;
  };

  //----------------------------------------------------------------------------
  //----------------------------------------------------------------------------
  template<typename T>
  class Arg : public ArgBase<T>
  {
    public:

      //------------------------------------------------------------------------
      //------------------------------------------------------------------------
      Arg()
      {
      }

      //------------------------------------------------------------------------
      //------------------------------------------------------------------------
      Arg( T value ) : ArgBase<T>( std::move( value ) )
      {
      }

      //------------------------------------------------------------------------
      //------------------------------------------------------------------------
      Arg( std::future<T> &&ftr ) : ArgBase<T>( std::move( ftr ) )
      {
      }

      //------------------------------------------------------------------------
      //------------------------------------------------------------------------
      Arg( const Fwd<T> &fwd ) : ArgBase<T>( fwd )
      {
      }

      //------------------------------------------------------------------------
      //------------------------------------------------------------------------
      Arg( Arg &&arg ) : ArgBase<T>( std::move( arg ) )
      {
      }

      //------------------------------------------------------------------------
      //------------------------------------------------------------------------
      Arg& operator=( Arg &&arg )
      {
        if( &arg == this ) return *this;
        this->holder = std::move( arg.holder );
        return *this;
      }
  };

  //----------------------------------------------------------------------------
  //----------------------------------------------------------------------------
  template<>
  class Arg<std::string> : public ArgBase<std::string>
  {
    public:

      //------------------------------------------------------------------------
      //------------------------------------------------------------------------
      Arg()
      {
      }

      //------------------------------------------------------------------------
      //------------------------------------------------------------------------
      Arg( std::string str ) : ArgBase<std::string>( str )
      {
      }

      //------------------------------------------------------------------------
      //------------------------------------------------------------------------
      Arg( const char *cstr ) : ArgBase<std::string>( cstr )
      {
      }

      //------------------------------------------------------------------------
      //------------------------------------------------------------------------
      Arg( std::future<std::string> &&ftr ) : ArgBase<std::string>( std::move( ftr ) )
      {
      }

      //------------------------------------------------------------------------
      //------------------------------------------------------------------------
      Arg( const Fwd<std::string> &fwd ) : ArgBase<std::string>( fwd )
      {
      }


      //------------------------------------------------------------------------
      //-----------------------------------------------------------------------
      Arg( Arg &&arg ) : ArgBase<std::string>( std::move( arg ) )
      {
      }

      //------------------------------------------------------------------------
      //------------------------------------------------------------------------
      Arg& operator=( Arg &&arg )
      {
        if( &arg == this ) return *this;
        this->holder = std::move( arg.holder );
        return *this;
      }
  };
}

#endif // __XRD_CL_OPERATION_PARAMS_HH__