text: // This file is part of Eigen, a lightweight C++ template library
  // for linear algebra.
  //
  // Copyright (C) 2007-2010 Benoit Jacob <jacob.benoit.1@gmail.com>
  // Copyright (C) 2008 Gael Guennebaud <gael.guennebaud@inria.fr>
  //
  // This Source Code Form is subject to the terms of the Mozilla
  // Public License v. 2.0. If a copy of the MPL was not distributed
  // with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
  
  #ifndef EIGEN_MAP_H
  #define EIGEN_MAP_H
  
  namespace Eigen { 
  
  namespace internal {
  template<typename PlainObjectType, int MapOptions, typename StrideType>
  struct traits<Map<PlainObjectType, MapOptions, StrideType> >
    : public traits<PlainObjectType>
  {
    typedef traits<PlainObjectType> TraitsBase;
    enum {
      PlainObjectTypeInnerSize = ((traits<PlainObjectType>::Flags&RowMajorBit)==RowMajorBit)
                               ? PlainObjectType::ColsAtCompileTime
                               : PlainObjectType::RowsAtCompileTime,
  
      InnerStrideAtCompileTime = StrideType::InnerStrideAtCompileTime == 0
                               ? int(PlainObjectType::InnerStrideAtCompileTime)
                               : int(StrideType::InnerStrideAtCompileTime),
      OuterStrideAtCompileTime = StrideType::OuterStrideAtCompileTime == 0
                               ? (InnerStrideAtCompileTime==Dynamic || PlainObjectTypeInnerSize==Dynamic
                                  ? Dynamic
                                  : int(InnerStrideAtCompileTime) * int(PlainObjectTypeInnerSize))
                               : int(StrideType::OuterStrideAtCompileTime),
      Alignment = int(MapOptions)&int(AlignedMask),
      Flags0 = TraitsBase::Flags & (~NestByRefBit),
      Flags = is_lvalue<PlainObjectType>::value ? int(Flags0) : (int(Flags0) & ~LvalueBit)
    };
  private:
    enum { Options }; // Expressions don't have Options
  };
  }
  
  /** \class Map
    * \ingroup Core_Module
    *
    * \brief A matrix or vector expression mapping an existing array of data.
    *
    * \tparam PlainObjectType the equivalent matrix type of the mapped data
    * \tparam MapOptions specifies the pointer alignment in bytes. It can be: \c #Aligned128, , \c #Aligned64, \c #Aligned32, \c #Aligned16, \c #Aligned8 or \c #Unaligned.
    *                The default is \c #Unaligned.
    * \tparam StrideType optionally specifies strides. By default, Map assumes the memory layout
    *                   of an ordinary, contiguous array. This can be overridden by specifying strides.
    *                   The type passed here must be a specialization of the Stride template, see examples below.
    *
    * This class represents a matrix or vector expression mapping an existing array of data.
    * It can be used to let Eigen interface without any overhead with non-Eigen data structures,
    * such as plain C arrays or structures from other libraries. By default, it assumes that the
    * data is laid out contiguously in memory. You can however override this by explicitly specifying
    * inner and outer strides.
    *
    * Here's an example of simply mapping a contiguous array as a \ref TopicStorageOrders "column-major" matrix:
    * \include Map_simple.cpp
    * Output: \verbinclude Map_simple.out
    *
    * If you need to map non-contiguous arrays, you can do so by specifying strides:
    *
    * Here's an example of mapping an array as a vector, specifying an inner stride, that is, the pointer
    * increment between two consecutive coefficients. Here, we're specifying the inner stride as a compile-time
    * fixed value.
    * \include Map_inner_stride.cpp
    * Output: \verbinclude Map_inner_stride.out
    *
    * Here's an example of mapping an array while specifying an outer stride. Here, since we're mapping
    * as a column-major matrix, 'outer stride' means the pointer increment between two consecutive columns.
    * Here, we're specifying the outer stride as a runtime parameter. Note that here \c OuterStride<> is
    * a short version of \c OuterStride<Dynamic> because the default template parameter of OuterStride
    * is  \c Dynamic
    * \include Map_outer_stride.cpp
    * Output: \verbinclude Map_outer_stride.out
    *
    * For more details and for an example of specifying both an inner and an outer stride, see class Stride.
    *
    * \b Tip: to change the array of data mapped by a Map object, you can use the C++
    * placement new syntax:
    *
    * Example: \include Map_placement_new.cpp
    * Output: \verbinclude Map_placement_new.out
    *
    * This class is the return type of PlainObjectBase::Map() but can also be used directly.
    *
    * \sa PlainObjectBase::Map(), \ref TopicStorageOrders
    */
  template<typename PlainObjectType, int MapOptions, typename StrideType> class Map
    : public MapBase<Map<PlainObjectType, MapOptions, StrideType> >
  {
    public:
  
      typedef MapBase<Map> Base;
      EIGEN_DENSE_PUBLIC_INTERFACE(Map)
  
      typedef typename Base::PointerType PointerType;
      typedef PointerType PointerArgType;
      EIGEN_DEVICE_FUNC
      inline PointerType cast_to_pointer_type(PointerArgType ptr) { return ptr; }
  
      EIGEN_DEVICE_FUNC
      inline Index innerStride() const
      {
        return StrideType::InnerStrideAtCompileTime != 0 ? m_stride.inner() : 1;
      }
  
      EIGEN_DEVICE_FUNC
      inline Index outerStride() const
      {
        return int(StrideType::OuterStrideAtCompileTime) != 0 ? m_stride.outer()
             : int(internal::traits<Map>::OuterStrideAtCompileTime) != Dynamic ? Index(internal::traits<Map>::OuterStrideAtCompileTime)
             : IsVectorAtCompileTime ? (this->size() * innerStride())
             : (int(Flags)&RowMajorBit) ? (this->cols() * innerStride())
             : (this->rows() * innerStride());
      }
  
      /** Constructor in the fixed-size case.
        *
        * \param dataPtr pointer to the array to map
        * \param stride optional Stride object, passing the strides.
        */
      EIGEN_DEVICE_FUNC
      explicit inline Map(PointerArgType dataPtr, const StrideType& stride = StrideType())
        : Base(cast_to_pointer_type(dataPtr)), m_stride(stride)
      {
        PlainObjectType::Base::_check_template_params();
      }
  
      /** Constructor in the dynamic-size vector case.
        *
        * \param dataPtr pointer to the array to map
        * \param size the size of the vector expression
        * \param stride optional Stride object, passing the strides.
        */
      EIGEN_DEVICE_FUNC
      inline Map(PointerArgType dataPtr, Index size, const StrideType& stride = StrideType())
        : Base(cast_to_pointer_type(dataPtr), size), m_stride(stride)
      {
        PlainObjectType::Base::_check_template_params();
      }
  
      /** Constructor in the dynamic-size matrix case.
        *
        * \param dataPtr pointer to the array to map
        * \param rows the number of rows of the matrix expression
        * \param cols the number of columns of the matrix expression
        * \param stride optional Stride object, passing the strides.
        */
      EIGEN_DEVICE_FUNC
      inline Map(PointerArgType dataPtr, Index rows, Index cols, const StrideType& stride = StrideType())
        : Base(cast_to_pointer_type(dataPtr), rows, cols), m_stride(stride)
      {
        PlainObjectType::Base::_check_template_params();
      }
  
      EIGEN_INHERIT_ASSIGNMENT_OPERATORS(Map)
  
    protected:
      StrideType m_stride;
  };
  
  
  } // end namespace Eigen
  
  #endif // EIGEN_MAP_H
  