JTypeSelector.hh

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#ifndef __JLANG__JTYPESELECTOR__
#define __JLANG__JTYPESELECTOR__

#include "JLang/JObjectSelector.hh"
#include "JLang/JType.hh"

/**
 * \author mdejong
 */

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

namespace JLANG {

  /**
   * Auxiliary class for selection of data type.
   *
   * This class implements the JLANG::JObjectSelector interface.
   */
  template<class T>
  struct JTypeSelector :
    public virtual JObjectSelector<T>
  {
    /**
     * Type definition of argument of interface method.
     */
    typedef typename JObjectSelector<T>::argument_type  argument_type;

    
    /**
     * Default constructor.
     */
    JTypeSelector() :
      is_enabled(true)
    {}

    
    /**
     * Constructor.
     *
     * \param  selector   selector
     */
    template<class JSelector_t>
    JTypeSelector(const JSelector_t& selector)
    {
      (*this)(selector);
    }

    
    /**
     * Accept data type.
     *
     * \return            true if accepted; else false
     */
    virtual bool accept() const
    {
      return is_enabled;
    }

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


    /**
     * Set acceptance.
     *
     * \param  status     enabled status
     */
    void set(const bool status)
    {
      this->is_enabled = status;
    }


    /**
     * Set selection.
     *
     * The template argument <tt>JSelector_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 data type
     * </pre>
     *
     * \param  selector   selector
     */
    template<class JSelector_t>
    JTypeSelector& operator()(const JSelector_t& selector)
    {
      this->is_enabled = selector(JType<T>());

      return *this;
    }

    static JTypeSelector selector;
    
  protected:
    bool is_enabled;
  };

  /**
   * Selector.
   */
  template<class T>
  JTypeSelector<T> JTypeSelector<T>::selector;
  

  /**
   * Auxiliary class for selection of multiple data types.
   *
   * This class recursively defines the JLANG::JTypeSelector interface
   * for all data types by deriving from:
   *  - JTypeSelector<JHead_t>; and 
   *  - JTypeSelector<JTail_t>.
   */
  template<class JHead_t, class JTail_t>
  struct JTypeSelector< JTypeList<JHead_t, JTail_t> > :
    public JTypeSelector<JHead_t>,
    public JTypeSelector<JTail_t>,
    public virtual JObjectSelector< JTypeList<JHead_t, JTail_t> >
  {
    /**
     * Default constructor.
     */
    JTypeSelector()
    {}

    
    /**
     * Constructor.
     *
     * \param  selector   selector
     */
    template<class JSelector_t>
    JTypeSelector(const JSelector_t& selector)
    {
      (*this)(selector);
    }


    /**
     * Set selection.
     *
     * The template argument <tt>JSelector_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 data type
     * </pre>
     *
     * \param  selector   selector
     */
    template<class JSelector_t>
    JTypeSelector& operator()(const JSelector_t& selector)
    {
      static_cast<JTypeSelector<JHead_t>&>(*this)(selector);
      static_cast<JTypeSelector<JTail_t>&>(*this)(selector);

      return *this;
    }

    static JTypeSelector selector;
  };

  /**
   * Selector.
   */
  template<class JHead_t, class JTail_t>
  JTypeSelector< JTypeList<JHead_t, JTail_t> > JTypeSelector< JTypeList<JHead_t, JTail_t> >::selector;

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

    
    /**
     * Constructor.
     *
     * \param  selector   selector
     */
    template<class JSelector_t>
    JTypeSelector(const JSelector_t& selector)
    {
      (*this)(selector);
    }
  };
}

#endif