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