JValve.hh

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#ifndef __JLANG__JVALVE__
#define __JLANG__JVALVE__

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

/**
 * \author mdejong
 */

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

namespace JLANG {

  /**
   * Auxiliary class for selection of data type.
   */
  template<class T>
  struct JValve :
    public JDefault< JValve<T> >
  {
    /**
     * Default constructor.
     *
     * By default, the valve is open.
     */
    JValve() :
      status(true)
    {}

    
    /**
     * Constructor.
     *
     * \param  controller controller of valve
     */
    template<class JController_t>
    JValve(const JController_t& controller)
    {
      (*this)(controller);
    }

    
    /**
     * Check if valve is open.
     *
     * \return            true if open; else false
     */
    bool is_open() const
    {
      return status;
    }

    
    /**
     * Open valve.
     */
    void open()
    {
      status = true;
    }

    
    /**
     * Close valve.
     */
    void close()
    {
      status = false;
    }


    /**
     * Set valve.
     *
     * The template argument <tt>JController_t</tt> refers to a data structure 
     * which should provide for the function object operator:
     * <pre>
     *   bool operator()(JType<T>& type) const;    // get status of valve
     * </pre>
     *
     * \param  controller controller of valve
     */
    template<class JController_t>
    JValve& operator()(const JController_t& controller)
    {
      if (controller(JType<T>()))
        this->open();
      else
        this->close();

      return *this;
    }
    
  protected:
    bool status;
  };
  

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

    /**
     * Default constructor.
     */
    JValve()
    {}

    
    /**
     * Constructor.
     *
     * \param  controller controller of valve
     */
    template<class JController_t>
    JValve(const JController_t& controller)
    {
      (*this)(controller);
    }


    /**
     * Set valve.
     *
     * The template argument <tt>JController_t</tt> refers to a data structure 
     * which should provide for the function object operator:
     * <pre>
     *   bool operator()(JType<T>& type) const;    // get status of valve
     * </pre>
     *
     * \param  controller controller of valve
     */
    template<class JController_t>
    JValve& operator()(const JController_t& controller)
    {
      static_cast<JValve<JHead_t>&>(*this)(controller);
      static_cast<JValve<JTail_t>&>(*this)(controller);

      return *this;
    }
  };

  
  /**
   * Terminator class of recursive JValve class.
   */
  template<class JHead_t>
  struct JValve< JTypeList<JHead_t, JNullType> > :
    public JValve<JHead_t>
  {
    /**
     * Default constructor.
     */
    JValve()
    {}

    
    /**
     * Constructor.
     *
     * \param  controller controller of valve
     */
    template<class JController_t>
    JValve(const JController_t& controller)
    {
      (*this)(controller);
    }
  };
}

#endif