JObjectSelector.hh

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#ifndef __JLANG__JOBJECTSELECTOR__
#define __JLANG__JOBJECTSELECTOR__

#include "JLang/JDefault.hh"
#include "JLang/JTypeList.hh"
#include "JLang/JClass.hh"

/**
 * \author mdejong
 */

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

namespace JLANG {

  /**
   * Interface for selection of objects.
   */
  template<class T>
  struct JObjectSelector :
    public JDefault< JObjectSelector<T> >
  {
    /**
     * Type definition of argument of interface method.
     */
    typedef typename JClass<T>::argument_type  argument_type;


    /**
     * Virtual destructor.
     */
    virtual ~JObjectSelector()
    {}

    
    /**
     * Accept object.
     *
     * \param  object     object
     * \return            true if accepted; else false
     */
    virtual bool accept(argument_type object) const 
    {
      return true;
    }
  };


  /**
   * Interface for multiple selection of objects.
   *
   * This class recursively defines the JLANG::JObjectSelector interface
   * for all data types by deriving from:
   *  - JObjectSelector<JHead_t>; and 
   *  - JObjectSelector<JTail_t>.
   */
  template<class JHead_t, class JTail_t>
  struct JObjectSelector< JTypeList<JHead_t, JTail_t> > :
    public JDefault< JObjectSelector< JTypeList<JHead_t, JTail_t> > >,
    public virtual JObjectSelector<JHead_t>,
    public virtual JObjectSelector<JTail_t>
  {
    using JDefault< JObjectSelector< JTypeList<JHead_t, JTail_t> > >::getDefault;
  };

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

#endif