1// This file is part of Eigen, a lightweight C++ template library
2// for linear algebra.
3//
4// Copyright (C) 2007-2010 Benoit Jacob <jacob.benoit.1@gmail.com>
5// Copyright (C) 2008 Gael Guennebaud <gael.guennebaud@inria.fr>
6//
7// This Source Code Form is subject to the terms of the Mozilla
8// Public License v. 2.0. If a copy of the MPL was not distributed
9// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
10
11#ifndef EIGEN_MAP_H
12#define EIGEN_MAP_H
13
14namespace Eigen {
15
16namespace internal {
17template<typename PlainObjectType, int MapOptions, typename StrideType>
18struct traits<Map<PlainObjectType, MapOptions, StrideType> >
19  : public traits<PlainObjectType>
20{
21  typedef traits<PlainObjectType> TraitsBase;
22  enum {
23    InnerStrideAtCompileTime = StrideType::InnerStrideAtCompileTime == 0
24                             ? int(PlainObjectType::InnerStrideAtCompileTime)
25                             : int(StrideType::InnerStrideAtCompileTime),
26    OuterStrideAtCompileTime = StrideType::OuterStrideAtCompileTime == 0
27                             ? int(PlainObjectType::OuterStrideAtCompileTime)
28                             : int(StrideType::OuterStrideAtCompileTime),
29    Alignment = int(MapOptions)&int(AlignedMask),
30    Flags0 = TraitsBase::Flags & (~NestByRefBit),
31    Flags = is_lvalue<PlainObjectType>::value ? int(Flags0) : (int(Flags0) & ~LvalueBit)
32  };
33private:
34  enum { Options }; // Expressions don't have Options
35};
36}
37
38/** \class Map
39  * \ingroup Core_Module
40  *
41  * \brief A matrix or vector expression mapping an existing array of data.
42  *
43  * \tparam PlainObjectType the equivalent matrix type of the mapped data
44  * \tparam MapOptions specifies the pointer alignment in bytes. It can be: \c #Aligned128, , \c #Aligned64, \c #Aligned32, \c #Aligned16, \c #Aligned8 or \c #Unaligned.
45  *                The default is \c #Unaligned.
46  * \tparam StrideType optionally specifies strides. By default, Map assumes the memory layout
47  *                   of an ordinary, contiguous array. This can be overridden by specifying strides.
48  *                   The type passed here must be a specialization of the Stride template, see examples below.
49  *
50  * This class represents a matrix or vector expression mapping an existing array of data.
51  * It can be used to let Eigen interface without any overhead with non-Eigen data structures,
52  * such as plain C arrays or structures from other libraries. By default, it assumes that the
53  * data is laid out contiguously in memory. You can however override this by explicitly specifying
54  * inner and outer strides.
55  *
56  * Here's an example of simply mapping a contiguous array as a \ref TopicStorageOrders "column-major" matrix:
57  * \include Map_simple.cpp
58  * Output: \verbinclude Map_simple.out
59  *
60  * If you need to map non-contiguous arrays, you can do so by specifying strides:
61  *
62  * Here's an example of mapping an array as a vector, specifying an inner stride, that is, the pointer
63  * increment between two consecutive coefficients. Here, we're specifying the inner stride as a compile-time
64  * fixed value.
65  * \include Map_inner_stride.cpp
66  * Output: \verbinclude Map_inner_stride.out
67  *
68  * Here's an example of mapping an array while specifying an outer stride. Here, since we're mapping
69  * as a column-major matrix, 'outer stride' means the pointer increment between two consecutive columns.
70  * Here, we're specifying the outer stride as a runtime parameter. Note that here \c OuterStride<> is
71  * a short version of \c OuterStride<Dynamic> because the default template parameter of OuterStride
72  * is  \c Dynamic
73  * \include Map_outer_stride.cpp
74  * Output: \verbinclude Map_outer_stride.out
75  *
76  * For more details and for an example of specifying both an inner and an outer stride, see class Stride.
77  *
78  * \b Tip: to change the array of data mapped by a Map object, you can use the C++
79  * placement new syntax:
80  *
81  * Example: \include Map_placement_new.cpp
82  * Output: \verbinclude Map_placement_new.out
83  *
84  * This class is the return type of PlainObjectBase::Map() but can also be used directly.
85  *
86  * \sa PlainObjectBase::Map(), \ref TopicStorageOrders
87  */
88template<typename PlainObjectType, int MapOptions, typename StrideType> class Map
89  : public MapBase<Map<PlainObjectType, MapOptions, StrideType> >
90{
91  public:
92
93    typedef MapBase<Map> Base;
94    EIGEN_DENSE_PUBLIC_INTERFACE(Map)
95
96    typedef typename Base::PointerType PointerType;
97    typedef PointerType PointerArgType;
98    EIGEN_DEVICE_FUNC
99    inline PointerType cast_to_pointer_type(PointerArgType ptr) { return ptr; }
100
101    EIGEN_DEVICE_FUNC
102    inline Index innerStride() const
103    {
104      return StrideType::InnerStrideAtCompileTime != 0 ? m_stride.inner() : 1;
105    }
106
107    EIGEN_DEVICE_FUNC
108    inline Index outerStride() const
109    {
110      return StrideType::OuterStrideAtCompileTime != 0 ? m_stride.outer()
111           : IsVectorAtCompileTime ? this->size()
112           : int(Flags)&RowMajorBit ? this->cols()
113           : this->rows();
114    }
115
116    /** Constructor in the fixed-size case.
117      *
118      * \param dataPtr pointer to the array to map
119      * \param stride optional Stride object, passing the strides.
120      */
121    EIGEN_DEVICE_FUNC
122    explicit inline Map(PointerArgType dataPtr, const StrideType& stride = StrideType())
123      : Base(cast_to_pointer_type(dataPtr)), m_stride(stride)
124    {
125      PlainObjectType::Base::_check_template_params();
126    }
127
128    /** Constructor in the dynamic-size vector case.
129      *
130      * \param dataPtr pointer to the array to map
131      * \param size the size of the vector expression
132      * \param stride optional Stride object, passing the strides.
133      */
134    EIGEN_DEVICE_FUNC
135    inline Map(PointerArgType dataPtr, Index size, const StrideType& stride = StrideType())
136      : Base(cast_to_pointer_type(dataPtr), size), m_stride(stride)
137    {
138      PlainObjectType::Base::_check_template_params();
139    }
140
141    /** Constructor in the dynamic-size matrix case.
142      *
143      * \param dataPtr pointer to the array to map
144      * \param rows the number of rows of the matrix expression
145      * \param cols the number of columns of the matrix expression
146      * \param stride optional Stride object, passing the strides.
147      */
148    EIGEN_DEVICE_FUNC
149    inline Map(PointerArgType dataPtr, Index rows, Index cols, const StrideType& stride = StrideType())
150      : Base(cast_to_pointer_type(dataPtr), rows, cols), m_stride(stride)
151    {
152      PlainObjectType::Base::_check_template_params();
153    }
154
155    EIGEN_INHERIT_ASSIGNMENT_OPERATORS(Map)
156
157  protected:
158    StrideType m_stride;
159};
160
161
162} // end namespace Eigen
163
164#endif // EIGEN_MAP_H
165