JFind_if.hh

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#ifndef __JLANG__JFIND_IF__
#define __JLANG__JFIND_IF__

#include "JLang/JClass.hh"


/**
 * \author mdejong
 */

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

namespace JLANG {

  /**
   * Template definition of auxiliary class to select objects.
   * The first template argument refers to the data member or member method and
   * the second template argument to the predicate of the corresponding values.
   */
  template<class JTypename_t, class JPredicate_t>
  class JFind_if;


  /**
   * Template specialisation of JFind_if for selection of objects via data member.
   */
  template<class T, class JResult_t, class JPredicate_t>
  class JFind_if<JResult_t T::*, JPredicate_t> {
  public:    

    typedef JResult_t                                   data_type;
    typedef typename JClass<data_type>::argument_type   argument_type;
    typedef JResult_t T::*data_member;                    //!< Type definition of data member
    typedef JPredicate_t  predicate_type;                 //!< Type definition of predicate
        
    
    /**
     * Constructor.
     *
     * \param  member       pointer to data member
     * \param  predicate    predicate method
     */
    JFind_if(data_member           member,
             const predicate_type& predicate) :
      member   (member),
      predicate(predicate)
    {}


    /**
     * Select objets.
     *
     * \param  object       object
     * \return              true if selected; else false
     */
    bool operator()(const T& object) const
    {
      return predicate(object.*member);
    }

  protected:
    data_member           member;
    const predicate_type& predicate;
  };


  /**
   * Template specialisation of JFind_if for selection of objects via member method.
   */
  template<class T, class JResult_t, class JPredicate_t>
  class JFind_if<JResult_t (T::*)() const, JPredicate_t> {
  public:    

    typedef JResult_t                                   data_type;
    typedef typename JClass<data_type>::argument_type   argument_type;
    typedef JResult_t (T::*member_method)() const;        //!< Type definition of member method
    typedef JPredicate_t  predicate_type;                 //!< Type definition of predicate
    
    
    /**
     * Constructor.
     *
     * \param  function     pointer to member method
     * \param  predicate    predicate method
     */
    JFind_if(member_method         function,
             const predicate_type& predicate) :
      function (function),
      predicate(predicate)
    {}


    /**
     * Select objets.
     *
     * \param  object       object
     * \return              true if selected; else false
     */
    bool operator()(const T& object) const
    {
      return predicate((object.*function)());
    }

  protected:
    member_method         function;
    const predicate_type& predicate;
  };


  /**
   * Helper method to create find_if for data member.
   *
   * \param  member       pointer to data member
   * \param  predicate    predicate
   * \return              find_if
   */
  template<class T, class JResult_t, class JPredicate_t>
  JFind_if<JResult_t T::*, JPredicate_t> make_find_if(JResult_t T::*member, const JPredicate_t& predicate)
  {
    return JFind_if<JResult_t T::*, JPredicate_t>(member, predicate);
  }


  /**
   * Helper method to create find_if for return values of member method.
   *
   * \param  function     pointer to member method
   * \param  predicate    predicate
   * \return              find_if
   */
  template<class T, class JResult_t, class JPredicate_t>
  JFind_if<JResult_t (T::*)() const, JPredicate_t> make_find_if(JResult_t (T::*function)() const, const JPredicate_t& predicate)
  {
    return JFind_if<JResult_t (T::*)() const, JPredicate_t>(function, predicate);
  }
}

#endif