/*! @file

    @id $Id$
*/
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#include <iostream>
#include <cstring>
#include <cassert>
#include <type_traits>

#define LOG std::cout<<__PRETTY_FUNCTION__<<std::endl

template<typename T, size_t ROWS=0, size_t COLUMNS=0> class Matrix {

    //........................................................const.variables
  protected:
    
    static const size_t SIZE = ROWS*COLUMNS;
    static const size_t MEM_SIZE = ROWS*COLUMNS*sizeof(T);

    //...............................................................typedefs
  public: 

    /// @name Auxiliary Classes
    ///{

    /// Return One Row as Vector, internally used for element access
    /** Only used to access values:

        @code
        Matrix<int,4,4> m;
        m[2][2] = 1;
        @endcode */
    class RowVector {
      public:
        T& operator[](size_t column) {
          return _v[column];
        }
      protected:
        friend class Matrix;
        RowVector() = delete; // forbidden
        RowVector(T c[COLUMNS]): _v(c) {}
        T *_v;
    };

    /// Same as RowVector, but in a constant environment.
    class ConstRowVector {
      public:
        const T& operator[](size_t column) const {
          return _v[column];
        }
      protected:
        friend class Matrix;
        ConstRowVector() = delete; // forbidden
        ConstRowVector(const T c[COLUMNS]): _v(c) {}
        const T *_v;
    };
    
    ///}

    //................................................................methods
  public:

    /// @name construction
    ///{
    
    Matrix() {
      LOG;
      memset(_c, 0, MEM_SIZE);
    }
    
    template<typename ...ARGS>
        Matrix(ARGS...t): _c{std::forward<T>(t)...} {
      LOG;
      static_assert(sizeof...(t)==SIZE, "variadic matrix initialisation requires correct array size");
    }
    
    Matrix(const Matrix& o) {
      LOG;
      memcpy(_c, o._c, MEM_SIZE);
    }

    ///}

    /// @name operators
    ///{
    
    Matrix& operator=(T oc[ROWS][COLUMNS]) {
      LOG;
      memcpy(_c, oc, MEM_SIZE);
      return *this;
    }
    
    Matrix& operator=(const Matrix& o) {
      LOG;
      memcpy(_c, o._c, MEM_SIZE);
      return *this;
    }
    
    Matrix& operator+=(const Matrix& o) {
      LOG;
      T *to((T*)(_c)+MEM_SIZE), *from((T*)(o._c)+MEM_SIZE);
      while (to>(T*)(_c)) *--to += *--from;
      return *this;
    }

    RowVector operator[](size_t row) {
      return RowVector(_c[row]);
    }
    
    const ConstRowVector operator[](size_t row) const {
      return ConstRowVector(_c[row]);
    }
    
    ///}

    //..............................................................variables
  protected:
    
    T _c[ROWS][COLUMNS];
    
};

template<typename T> class Matrix<T, 0, 0> {

    //..............................................................constants
  public:

    const size_t ROWS;
    const size_t COLUMNS;
    const size_t SIZE;
    const size_t MEM_SIZE;

    //...............................................................typedefs
  public: 

    /// @name Auxiliary Classes
    ///{

    /// Return One Row as Vector, internally used for element access
    /** Only used to access values:

        @code
        Matrix<int,4,4> m;
        m[2][2] = 1;
        @endcode */
    class RowVector {
      public:
        T& operator[](size_t column) {
          assert(column<_m.COLUMNS);
          return _v[column];
        }
      protected:
        friend class Matrix;
        RowVector() = delete; // forbidden
        RowVector(const Matrix& m, T c[]): _m(m), _v(c) {}
        const Matrix& _m;
        T *_v;
    };

    /// Same as RowVector, but in a constant environment.
    class ConstRowVector {
      public:
        const T& operator[](size_t column) const {
          assert(column<_m.COLUMNS);
          return _v[column];
        }
      protected:
        friend class Matrix;
        ConstRowVector() = delete; // forbidden
        ConstRowVector(const Matrix& m, const T c[]): _m(m), _v(c) {}
        const Matrix& _m;
        const T *_v;
    };
    
    ///}

    //................................................................methods
  public:

    /// @name construction
    ///{
    
    Matrix(size_t rows, size_t columns):
        ROWS(rows),
        COLUMNS(columns),
        SIZE(rows*columns),
        MEM_SIZE(rows*columns*sizeof(T)),
        _c(new T[rows*columns]) {
      LOG;
      memset(_c, 0, MEM_SIZE);
    }
    
    template<typename ...ARGS>
        Matrix(size_t rows, size_t columns, ARGS...t):
            Matrix(rows, columns) {
      LOG;
      assert(sizeof...(t)==SIZE);
      copy_args(_c, t...);
    }

    Matrix(const Matrix& o): Matrix(o.ROWS, o.COLUMNS) {
      LOG;
      memcpy(_c, o._c, MEM_SIZE);
    }

    ///}

    /// @name destruction
    ///{

    ~Matrix() {
      delete[] _c;
    }
    
    ///}

    /// @name operators
    ///{
    
    Matrix& operator=(T oc[]) {
      LOG;
      assert(sizeof(oc)==MEM_SIZE);
      memcpy(_c, oc, MEM_SIZE);
      return *this;
    }
    
    Matrix& operator=(const Matrix& o) {
      LOG;
      if (o.ROWS!=ROWS&&o.COLUMNS!=COLUMNS) {
        delete[] _c;
        ROWS = o.ROWS;
        COLUMNS = o.COLUMNS;
        SIZE = o.SIZE;
        MEM_SIZE = o.MEM_SIZE;
        _c = new T[SIZE];
      }
      memcpy(_c, o._c, MEM_SIZE);
      return *this;
    }
    
    Matrix& operator+=(const Matrix& o) {
      LOG;
      assert(o.ROWS==ROWS);
      assert(o.COLUMNS==COLUMNS);
      T *to((T*)(_c)+MEM_SIZE), *from((T*)(o._c)+MEM_SIZE);
      while (to>(T*)(_c)) *--to += *--from;
      return *this;
    }

    RowVector operator[](size_t row) {
      assert(row<ROWS);
      return RowVector(*this, _c+row*COLUMNS);
    }
    
    const ConstRowVector operator[](size_t row) const {
      assert(row<ROWS);
      return ConstRowVector(*this, _c+row*COLUMNS);
    }
    
    ///}

    //................................................................methods
  protected:

    void copy_args(T*) {}
    template<typename ...ARGS>
        void copy_args(T* to, T t1, ARGS...t) {
      *to = t1;
      copy_args(++to, t...);
    }

    //..............................................................variables
  protected:
    
    T* _c;
    
};

template<typename T, size_t ROWS, size_t COLUMNS>
    Matrix<T, ROWS, COLUMNS> operator+(const Matrix<T, ROWS, COLUMNS>& m1, const Matrix<T, ROWS, COLUMNS>& m2) {
  LOG;
  Matrix<T, ROWS, COLUMNS> res(m1);
  return res+=m2;
}
                     
template<typename T, size_t ROWS, size_t COLUMNS>
    std::ostream& operator<<(std::ostream& s, const Matrix<T, ROWS, COLUMNS>& m) {
  LOG;
  for (size_t w = 0; w < m.ROWS; ++w) {
    for (size_t h = 0; h < m.COLUMNS;++h) {
      s<<m[w][h]<<' ';
    }
    s<<'\n';
  }
}