JAbstractObjectWriter.hh

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#ifndef __JLANG__JABSTRACTOBJECTWRITER__
#define __JLANG__JABSTRACTOBJECTWRITER__

#include "JLang/JObjectOutput.hh"
#include "JLang/JTypeList.hh"
#include "JLang/JNullType.hh"
#include "JLang/JException.hh"


/**
 * \author mdejong
 */

namespace JLANG {}
namespace JPP { using namespace JLANG; }

namespace JLANG {

  /**
   * Abstract interface for object writing.
   *
   * This class implements the JObjectOutput interface by transferring
   * the interface methods to a helper object via a single interface method getHelper().
   */
  template<class T>
  struct JAbstractObjectWriter :
    public virtual JObjectOutput<T>
  {
    /**
     * Get helper.
     *
     * \return            pointer to helper
     */
    virtual JObjectOutput<T>* getHelper() const = 0;

    
    /**
     * Object output.
     *
     * \param  object     object
     * \return            true if OK; else false
     */
    virtual bool put(const T& object)
    {
      return (this->getHelper() != NULL && this->getHelper()->put(object));
    }
  };


  /**
   * Abstract interface for object writing for multiple data types.
   *
   * This class recursively implements the JLANG::JObjectOutput interface
   * for all data types by deriving from:
   *  - JAbstractObjectWriter<JHead_t>; and 
   *  - JAbstractObjectWriter<JTail_t>.
   */
  template<class JHead_t, class JTail_t>
  struct JAbstractObjectWriter< JTypeList<JHead_t, JTail_t> > :
    public virtual JObjectOutput< JTypeList<JHead_t, JTail_t> >,
    public JAbstractObjectWriter<JHead_t>,
    public JAbstractObjectWriter<JTail_t>
  {
    using JAbstractObjectWriter<JHead_t>::put;
    using JAbstractObjectWriter<JTail_t>::put;
  };


  /**
   * Terminator class of recursive JAbstractObjectWriter class.
   */
  template<class JHead_t>
  struct JAbstractObjectWriter< JTypeList<JHead_t, JNullType> > :
    public JAbstractObjectWriter<JHead_t>
  {};


  /**
   * Abstract interface for object writing with named access.
   *
   * This class implements the JAccessibleObjectOutput interface by transferring
   * the interface methods to a helper object via a single interface method getHelper().
   */
  template<class T>
  struct JAbstractAccessibleObjectWriter :
    public virtual JAccessibleObjectOutput<T>,
    public JAbstractObjectWriter          <T>
  {
    /**
     * Get helper.
     *
     * \return            pointer to helper
     */
    virtual JAccessibleObjectOutput<T>* getHelper() const = 0;


    /**
     * Check is device is open.
     *
     * \return            true if open; else false
     */
    virtual bool is_open() const
    {
      if (this->getHelper() != NULL)
        return this->getHelper()->is_open();
      else
        return false;
    }


    /**
     * Open device.
     *
     * \param  file_name  file name
     */
    virtual void open(const char* file_name)
    {
      if (this->getHelper() != NULL) {
        this->getHelper()->open(file_name);
      }
    }


    /**
     * Close device.
     */
    virtual void close() 
    {
      if (this->getHelper() != NULL) {
        this->getHelper()->close();
      }
    }
  };
}

#endif