ReturnByValue.h
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1 // This file is part of Eigen, a lightweight C++ template library
2 // for linear algebra.
3 //
4 // Copyright (C) 2009-2010 Gael Guennebaud <gael.guennebaud@inria.fr>
5 // Copyright (C) 2009-2010 Benoit Jacob <jacob.benoit.1@gmail.com>
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_RETURNBYVALUE_H
12 #define EIGEN_RETURNBYVALUE_H
13 
14 namespace Eigen {
15 
16 namespace internal {
17 
18 template<typename Derived>
19 struct traits<ReturnByValue<Derived> >
20  : public traits<typename traits<Derived>::ReturnType>
21 {
22  enum {
23  // We're disabling the DirectAccess because e.g. the constructor of
24  // the Block-with-DirectAccess expression requires to have a coeffRef method.
25  // Also, we don't want to have to implement the stride stuff.
28  };
29 };
30 
31 /* The ReturnByValue object doesn't even have a coeff() method.
32  * So the only way that nesting it in an expression can work, is by evaluating it into a plain matrix.
33  * So internal::nested always gives the plain return matrix type.
34  *
35  * FIXME: I don't understand why we need this specialization: isn't this taken care of by the EvalBeforeNestingBit ??
36  * Answer: EvalBeforeNestingBit should be deprecated since we have the evaluators
37  */
38 template<typename Derived,int n,typename PlainObject>
39 struct nested_eval<ReturnByValue<Derived>, n, PlainObject>
40 {
42 };
43 
44 } // end namespace internal
45 
50 template<typename Derived> class ReturnByValue
51  : public internal::dense_xpr_base< ReturnByValue<Derived> >::type, internal::no_assignment_operator
52 {
53  public:
55 
58 
59  template<typename Dest>
61  inline void evalTo(Dest& dst) const
62  { static_cast<const Derived*>(this)->evalTo(dst); }
64  inline Index rows() const EIGEN_NOEXCEPT { return static_cast<const Derived*>(this)->rows(); }
66  inline Index cols() const EIGEN_NOEXCEPT { return static_cast<const Derived*>(this)->cols(); }
67 
68 #ifndef EIGEN_PARSED_BY_DOXYGEN
69 #define Unusable YOU_ARE_TRYING_TO_ACCESS_A_SINGLE_COEFFICIENT_IN_A_SPECIAL_EXPRESSION_WHERE_THAT_IS_NOT_ALLOWED_BECAUSE_THAT_WOULD_BE_INEFFICIENT
70  class Unusable{
71  Unusable(const Unusable&) {}
72  Unusable& operator=(const Unusable&) {return *this;}
73  };
74  const Unusable& coeff(Index) const { return *reinterpret_cast<const Unusable*>(this); }
75  const Unusable& coeff(Index,Index) const { return *reinterpret_cast<const Unusable*>(this); }
76  Unusable& coeffRef(Index) { return *reinterpret_cast<Unusable*>(this); }
77  Unusable& coeffRef(Index,Index) { return *reinterpret_cast<Unusable*>(this); }
78 #undef Unusable
79 #endif
80 };
81 
82 template<typename Derived>
83 template<typename OtherDerived>
85 {
86  other.evalTo(derived());
87  return derived();
88 }
89 
90 namespace internal {
91 
92 // Expression is evaluated in a temporary; default implementation of Assignment is bypassed so that
93 // when a ReturnByValue expression is assigned, the evaluator is not constructed.
94 // TODO: Finalize port to new regime; ReturnByValue should not exist in the expression world
95 
96 template<typename Derived>
97 struct evaluator<ReturnByValue<Derived> >
98  : public evaluator<typename internal::traits<Derived>::ReturnType>
99 {
103 
104  EIGEN_DEVICE_FUNC explicit evaluator(const XprType& xpr)
105  : m_result(xpr.rows(), xpr.cols())
106  {
107  ::new (static_cast<Base*>(this)) Base(m_result);
108  xpr.evalTo(m_result);
109  }
110 
111 protected:
112  PlainObject m_result;
113 };
114 
115 } // end namespace internal
116 
117 } // end namespace Eigen
118 
119 #endif // EIGEN_RETURNBYVALUE_H
EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR Index rows() const EIGEN_NOEXCEPT
Definition: ReturnByValue.h:64
const unsigned int DirectAccessBit
Definition: Constants.h:155
int n
Namespace containing all symbols from the Eigen library.
Definition: jet.h:637
internal::traits< Derived >::ReturnType PlainObject
#define Unusable
Definition: ReturnByValue.h:69
Unusable & operator=(const Unusable &)
Definition: ReturnByValue.h:72
EIGEN_DEVICE_FUNC evaluator(const XprType &xpr)
#define EIGEN_NOEXCEPT
Definition: Macros.h:1418
EIGEN_DEFAULT_DENSE_INDEX_TYPE Index
The Index type as used for the API.
Definition: Meta.h:74
Unusable & coeffRef(Index)
Definition: ReturnByValue.h:76
EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE Derived & operator=(const DenseBase< OtherDerived > &other)
Definition: Assign.h:39
#define EIGEN_CONSTEXPR
Definition: Macros.h:787
EIGEN_DEVICE_FUNC void evalTo(Dest &dst) const
Definition: ReturnByValue.h:61
#define EIGEN_DEVICE_FUNC
Definition: Macros.h:976
EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR Index cols() const EIGEN_NOEXCEPT
Definition: ReturnByValue.h:66
Unusable & coeffRef(Index, Index)
Definition: ReturnByValue.h:77
const Unusable & coeff(Index) const
Definition: ReturnByValue.h:74
internal::dense_xpr_base< ReturnByValue >::type Base
Definition: ReturnByValue.h:56
#define EIGEN_DENSE_PUBLIC_INTERFACE(Derived)
Definition: Macros.h:1283
const unsigned int EvalBeforeNestingBit
Definition: Constants.h:70
internal::traits< Derived >::ReturnType ReturnType
Definition: ReturnByValue.h:54
const Unusable & coeff(Index, Index) const
Definition: ReturnByValue.h:75
Definition: pytypes.h:1370


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autogenerated on Tue Jul 4 2023 02:35:34