text: /****************************************************************************
  **
  ** Copyright (C) 2009-2014 TEGESO/TEGESOFT and/or its subsidiary(-ies) and mother company.
  ** Contact: Tegesoft Information (contact@tegesoft.com)
  **
  ** This file is part of the CAMP library.
  **
  ** The MIT License (MIT)
  **
  ** Copyright (C) 2009-2014 TEGESO/TEGESOFT and/or its subsidiary(-ies) and mother company.
  **
  ** Permission is hereby granted, free of charge, to any person obtaining a copy
  ** of this software and associated documentation files (the "Software"), to deal
  ** in the Software without restriction, including without limitation the rights
  ** to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  ** copies of the Software, and to permit persons to whom the Software is
  ** furnished to do so, subject to the following conditions:
  ** 
  ** The above copyright notice and this permission notice shall be included in
  ** all copies or substantial portions of the Software.
  ** 
  ** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  ** IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  ** FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  ** AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  ** LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  ** OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  ** THE SOFTWARE.
  **
  ****************************************************************************/
  
  
  #pragma once
  
  
  #include <camp/args.hpp>
  #include <camp/class.hpp>
  #include <camp/classget.hpp>
  #include <camp/valuemapper.hpp>
  
  
  namespace camp
  {
  namespace detail
  {
  /*
   * Implementation of ValueProvider
   * Generic version, use default constructor
   */
  template <typename T, int Type>
  struct ValueProviderImpl
  {
      T operator()() {return T();}
  };
  
  /*
   * Specialization for user types: use metaclass to instanciate
   * so that we get an exception rather than a compile error
   * if the type has no default constructor
   */
  template <typename T>
  struct ValueProviderImpl<T, userType>
  {
      ValueProviderImpl() : m_value(classByType<T>().construct(Args::empty).template get<T*>()) {}
      ~ValueProviderImpl() {classByType<T>().destroy(m_value);}
      T& operator()() {return *m_value;}
      T* m_value;
  };
  
  /*
   * Specialization for pointer to primitive types: use new to allocate objects
   * Here we assume that the caller will take ownership of the returned value
   */
  template <typename T, int Type>
  struct ValueProviderImpl<T*, Type>
  {
      T* operator()() {return new T;}
  };
  
  /*
   * Specialization for pointer to user types: use metaclass to allocate objects
   * Here we assume that the caller will take ownership of the returned value
   */
  template <typename T>
  struct ValueProviderImpl<T*, userType>
  {
      T* operator()() {return classByType<T>().construct(Args::empty).template get<T*>();}
  };
  
  /*
   * Helper structure to instanciate new values based on their type
   */
  template <typename T>
  struct ValueProvider : ValueProviderImpl<T, camp_ext::ValueMapper<T>::type>
  {
  };
  
  } // namespace detail
  
  } // namespace camp
  