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