JGroup.hh

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#ifndef __JLANG__JGROUP__
#define __JLANG__JGROUP__

#include "JLang/JException.hh"


/**
 * \author mdejong
 */

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

namespace JLANG {

  /**
   * Auxiliary class for a fixed group of objects. 
   *
   * A group should be defined as follows:
   * <pre>
   *   template<>
   *   const XXX JGroup<XXX>::group[]  =  {
   *     XXX(...),
   *     XXX(...),
   *     ...
   *     XXX(...)
   *   };
   * </pre>
   */
  template<class T>
  struct JGroup {
    /**
     * Number of objects.
     */
    static const int size  =  sizeof(JGroup::group) / sizeof(JGroup::group[0]);


    /**
     * Get unique instance.
     */
    static const JGroup& getInstance()
    {
      static const JGroup object;

      return object;
    }


    /**
     * Get object at given index in group.
     *
     * \param  index           index
     * \return                 object
     */
    const T& operator()(const int index) const
    {
      if (index >= 0 && index < size)
        return this->group[index];
      else
        THROW(JIndexOutOfRange, "JGroup::operator() " << index);
    }


    /**
     * Get index of given objec in group.
     *
     * \param  object          object
     * \return                 index (-1 if object not found)
     */
    int operator()(const T& object) const
    {
      for (int i = 0; i != size; ++i) {
        if (this->group[i] == object) {
          return i;
        }
      }

      return -1;
    }

  private:
    /**
     * Default constructor.
     */
    JGroup() 
    {}

    static const T group[];       //!< actual group
  };
}

#endif