/********************************************************************
**                Image Component Library (ICL)                    **
**                                                                 **
** Copyright (C) 2006-2013 CITEC, University of Bielefeld          **
**                         Neuroinformatics Group                  **
** Website: www.iclcv.org and                                      **
**          http://opensource.cit-ec.de/projects/icl               **
**                                                                 **
** File   : ICLUtils/src/ICLUtils/FixedArray.h                     **
** Module : ICLUtils                                               **
** Authors: Christof Elbrechter                                    **
**                                                                 **
**                                                                 **
** GNU LESSER GENERAL PUBLIC LICENSE                               **
** This file may be used under the terms of the GNU Lesser General **
** Public License version 3.0 as published by the                  **
**                                                                 **
** Free Software Foundation and appearing in the file LICENSE.LGPL **
** included in the packaging of this file.  Please review the      **
** following information to ensure the license requirements will   **
** be met: http://www.gnu.org/licenses/lgpl-3.0.txt                **
**                                                                 **
** The development of this software was supported by the           **
** Excellence Cluster EXC 277 Cognitive Interaction Technology.    **
** The Excellence Cluster EXC 277 is a grant of the Deutsche       **
** Forschungsgemeinschaft (DFG) in the context of the German       **
** Excellence Initiative.                                          **
**                                                                 **
********************************************************************/

#pragma once

#include <ICLUtils/CompatMacros.h>

namespace icl{
  namespace utils{
    /// Fixed C++-array wrapper class for data handling
    /** This class is specialized for the DIM values 1,2,3 and 4
        FixedArray<T,1> contains a union that shares the 
        1-dim data with a single value x. FixedArray<T,2>
        has extra values x,y,  then x,y,z and finally x,y,z,w
        (w can also be called h)
    */
    template<class T,unsigned int DIM>
    struct FixedArray{
      T m_data[DIM];
      
      /// index access operator
      T &operator[](unsigned int idx) { return m_data[idx]; }

      /// index access operator (const)
      const T &operator[](unsigned int idx) const { return m_data[idx]; }
    };
    
    /// Specialization for 1D-vectors providing a value x
    template<class T>
    struct FixedArray<T, 1u>{
      union{
        T m_data[1];
        T x;
      };

      /// empty constructor (leaving data uninitialized)
      FixedArray(){}
      
      /// constructor with given value x
      FixedArray(const T &x) : x(x){}

      /// index access operator
      T &operator[](unsigned int idx) { return m_data[idx]; }

      /// index access operator (const)
      const T &operator[](unsigned int idx) const { return m_data[idx]; }
      
      /// reinterprect FixedArray<T,1u> as a scalar
      inline operator T() const{
        return x;
      }
    };

    /// Specialization for 2D-matrics providing direct access to values x, y
    template<class T>
    struct FixedArray<T, 2u>{
      union{
        T m_data[2];
        struct { T x; T y; };
      };

      /// empty constructor (leaving data uninitialized)
      FixedArray(){}

      /// constructor with given values, x and y
      FixedArray(const T &x, const T &y) : x(x),y (y){}

      /// index access operator
      T &operator[](unsigned int idx) { return m_data[idx]; }

      /// index access operator (const)
      const T &operator[](unsigned int idx) const { return m_data[idx]; }
    };


    /// Specialization for 3D-matrics providing direct access to values x, y, z
    template<class T>
    struct FixedArray<T, 3u>{

      /// empty constructor (leaving data uninitialized)
      FixedArray(){}

      /// constructor with given values, x, y and z
      FixedArray(const T &x, const T &y, const T &z) : x(x), y(y), z(z){}

      union{
        T m_data[3];
        struct { T x; T y; T z; };
      };
      /// index access operator
      T &operator[](unsigned int idx) { return m_data[idx]; }

      /// index access operator (const)
      const T &operator[](unsigned int idx) const { return m_data[idx]; }
    };

    /// Specialization for 4D-matrics providing direct access to values x, y, z and h
    template<class T>
    struct FixedArray<T, 4u>{

      /// empty constructor (leaving data uninitialized)
      FixedArray(){}

      /// constructor with given values, x, y, z and w
      FixedArray(const T &x, const T &y, const T &z, const T &w) : x(x), y(y), z(z), w(w){}

      union{
        T m_data[4];
        struct { 
          T x; 
          T y; 
          T z; 
          union { 
            T h;
            T w;
          };
        };
      };

      /// index access operator
      T &operator[](unsigned int idx) { return m_data[idx]; }
      
      /// index access operator (const)
      const T &operator[](unsigned int idx) const { return m_data[idx]; }
    };
        
  } // namespace utils
} // namespace icl