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 (at) inria.fr> 5 // Copyright (C) 2009-2010 Benoit Jacob <jacob.benoit.1 (at) 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 /** \class ReturnByValue 17 * \ingroup Core_Module 18 * 19 */ 20 21 namespace internal { 22 23 template<typename Derived> 24 struct traits<ReturnByValue<Derived> > 25 : public traits<typename traits<Derived>::ReturnType> 26 { 27 enum { 28 // We're disabling the DirectAccess because e.g. the constructor of 29 // the Block-with-DirectAccess expression requires to have a coeffRef method. 30 // Also, we don't want to have to implement the stride stuff. 31 Flags = (traits<typename traits<Derived>::ReturnType>::Flags 32 | EvalBeforeNestingBit) & ~DirectAccessBit 33 }; 34 }; 35 36 /* The ReturnByValue object doesn't even have a coeff() method. 37 * So the only way that nesting it in an expression can work, is by evaluating it into a plain matrix. 38 * So internal::nested always gives the plain return matrix type. 39 * 40 * FIXME: I don't understand why we need this specialization: isn't this taken care of by the EvalBeforeNestingBit ?? 41 */ 42 template<typename Derived,int n,typename PlainObject> 43 struct nested<ReturnByValue<Derived>, n, PlainObject> 44 { 45 typedef typename traits<Derived>::ReturnType type; 46 }; 47 48 } // end namespace internal 49 50 template<typename Derived> class ReturnByValue 51 : internal::no_assignment_operator, public internal::dense_xpr_base< ReturnByValue<Derived> >::type 52 { 53 public: 54 typedef typename internal::traits<Derived>::ReturnType ReturnType; 55 56 typedef typename internal::dense_xpr_base<ReturnByValue>::type Base; 57 EIGEN_DENSE_PUBLIC_INTERFACE(ReturnByValue) 58 59 template<typename Dest> 60 inline void evalTo(Dest& dst) const 61 { static_cast<const Derived*>(this)->evalTo(dst); } 62 inline Index rows() const { return static_cast<const Derived*>(this)->rows(); } 63 inline Index cols() const { return static_cast<const Derived*>(this)->cols(); } 64 65 #ifndef EIGEN_PARSED_BY_DOXYGEN 66 #define Unusable YOU_ARE_TRYING_TO_ACCESS_A_SINGLE_COEFFICIENT_IN_A_SPECIAL_EXPRESSION_WHERE_THAT_IS_NOT_ALLOWED_BECAUSE_THAT_WOULD_BE_INEFFICIENT 67 class Unusable{ 68 Unusable(const Unusable&) {} 69 Unusable& operator=(const Unusable&) {return *this;} 70 }; 71 const Unusable& coeff(Index) const { return *reinterpret_cast<const Unusable*>(this); } 72 const Unusable& coeff(Index,Index) const { return *reinterpret_cast<const Unusable*>(this); } 73 Unusable& coeffRef(Index) { return *reinterpret_cast<Unusable*>(this); } 74 Unusable& coeffRef(Index,Index) { return *reinterpret_cast<Unusable*>(this); } 75 template<int LoadMode> Unusable& packet(Index) const; 76 template<int LoadMode> Unusable& packet(Index, Index) const; 77 #endif 78 }; 79 80 template<typename Derived> 81 template<typename OtherDerived> 82 Derived& DenseBase<Derived>::operator=(const ReturnByValue<OtherDerived>& other) 83 { 84 other.evalTo(derived()); 85 return derived(); 86 } 87 88 template<typename Derived> 89 template<typename OtherDerived> 90 Derived& DenseBase<Derived>::lazyAssign(const ReturnByValue<OtherDerived>& other) 91 { 92 other.evalTo(derived()); 93 return derived(); 94 } 95 96 97 } // end namespace Eigen 98 99 #endif // EIGEN_RETURNBYVALUE_H 100
