1 // This file is part of Eigen, a lightweight C++ template library 2 // for linear algebra. 3 // 4 // Copyright (C) 2012 Gael Guennebaud <gael.guennebaud@inria.fr> 5 // 6 // This Source Code Form is subject to the terms of the Mozilla 7 // Public License v. 2.0. If a copy of the MPL was not distributed 8 // with this file, You can obtain one at http://mozilla.org/MPL/2.0/. 9 10 #ifndef EIGEN_REF_H 11 #define EIGEN_REF_H 12 13 namespace Eigen { 14 15 namespace internal { 16 17 template<typename _PlainObjectType, int _Options, typename _StrideType> 18 struct traits<Ref<_PlainObjectType, _Options, _StrideType> > 19 : public traits<Map<_PlainObjectType, _Options, _StrideType> > 20 { 21 typedef _PlainObjectType PlainObjectType; 22 typedef _StrideType StrideType; 23 enum { 24 Options = _Options, 25 Flags = traits<Map<_PlainObjectType, _Options, _StrideType> >::Flags | NestByRefBit, 26 Alignment = traits<Map<_PlainObjectType, _Options, _StrideType> >::Alignment 27 }; 28 29 template<typename Derived> struct match { 30 enum { 31 HasDirectAccess = internal::has_direct_access<Derived>::ret, 32 StorageOrderMatch = PlainObjectType::IsVectorAtCompileTime || Derived::IsVectorAtCompileTime || ((PlainObjectType::Flags&RowMajorBit)==(Derived::Flags&RowMajorBit)), 33 InnerStrideMatch = int(StrideType::InnerStrideAtCompileTime)==int(Dynamic) 34 || int(StrideType::InnerStrideAtCompileTime)==int(Derived::InnerStrideAtCompileTime) 35 || (int(StrideType::InnerStrideAtCompileTime)==0 && int(Derived::InnerStrideAtCompileTime)==1), 36 OuterStrideMatch = Derived::IsVectorAtCompileTime 37 || int(StrideType::OuterStrideAtCompileTime)==int(Dynamic) || int(StrideType::OuterStrideAtCompileTime)==int(Derived::OuterStrideAtCompileTime), 38 // NOTE, this indirection of evaluator<Derived>::Alignment is needed 39 // to workaround a very strange bug in MSVC related to the instantiation 40 // of has_*ary_operator in evaluator<CwiseNullaryOp>. 41 // This line is surprisingly very sensitive. For instance, simply adding parenthesis 42 // as "DerivedAlignment = (int(evaluator<Derived>::Alignment))," will make MSVC fail... 43 DerivedAlignment = int(evaluator<Derived>::Alignment), 44 AlignmentMatch = (int(traits<PlainObjectType>::Alignment)==int(Unaligned)) || (DerivedAlignment >= int(Alignment)), // FIXME the first condition is not very clear, it should be replaced by the required alignment 45 ScalarTypeMatch = internal::is_same<typename PlainObjectType::Scalar, typename Derived::Scalar>::value, 46 MatchAtCompileTime = HasDirectAccess && StorageOrderMatch && InnerStrideMatch && OuterStrideMatch && AlignmentMatch && ScalarTypeMatch 47 }; 48 typedef typename internal::conditional<MatchAtCompileTime,internal::true_type,internal::false_type>::type type; 49 }; 50 51 }; 52 53 template<typename Derived> 54 struct traits<RefBase<Derived> > : public traits<Derived> {}; 55 56 } 57 58 template<typename Derived> class RefBase 59 : public MapBase<Derived> 60 { 61 typedef typename internal::traits<Derived>::PlainObjectType PlainObjectType; 62 typedef typename internal::traits<Derived>::StrideType StrideType; 63 64 public: 65 66 typedef MapBase<Derived> Base; 67 EIGEN_DENSE_PUBLIC_INTERFACE(RefBase) 68 69 EIGEN_DEVICE_FUNC inline Index innerStride() const 70 { 71 return StrideType::InnerStrideAtCompileTime != 0 ? m_stride.inner() : 1; 72 } 73 74 EIGEN_DEVICE_FUNC inline Index outerStride() const 75 { 76 return StrideType::OuterStrideAtCompileTime != 0 ? m_stride.outer() 77 : IsVectorAtCompileTime ? this->size() 78 : int(Flags)&RowMajorBit ? this->cols() 79 : this->rows(); 80 } 81 82 EIGEN_DEVICE_FUNC RefBase() 83 : Base(0,RowsAtCompileTime==Dynamic?0:RowsAtCompileTime,ColsAtCompileTime==Dynamic?0:ColsAtCompileTime), 84 // Stride<> does not allow default ctor for Dynamic strides, so let' initialize it with dummy values: 85 m_stride(StrideType::OuterStrideAtCompileTime==Dynamic?0:StrideType::OuterStrideAtCompileTime, 86 StrideType::InnerStrideAtCompileTime==Dynamic?0:StrideType::InnerStrideAtCompileTime) 87 {} 88 89 EIGEN_INHERIT_ASSIGNMENT_OPERATORS(RefBase) 90 91 protected: 92 93 typedef Stride<StrideType::OuterStrideAtCompileTime,StrideType::InnerStrideAtCompileTime> StrideBase; 94 95 template<typename Expression> 96 EIGEN_DEVICE_FUNC void construct(Expression& expr) 97 { 98 if(PlainObjectType::RowsAtCompileTime==1) 99 { 100 eigen_assert(expr.rows()==1 || expr.cols()==1); 101 ::new (static_cast<Base*>(this)) Base(expr.data(), 1, expr.size()); 102 } 103 else if(PlainObjectType::ColsAtCompileTime==1) 104 { 105 eigen_assert(expr.rows()==1 || expr.cols()==1); 106 ::new (static_cast<Base*>(this)) Base(expr.data(), expr.size(), 1); 107 } 108 else 109 ::new (static_cast<Base*>(this)) Base(expr.data(), expr.rows(), expr.cols()); 110 111 if(Expression::IsVectorAtCompileTime && (!PlainObjectType::IsVectorAtCompileTime) && ((Expression::Flags&RowMajorBit)!=(PlainObjectType::Flags&RowMajorBit))) 112 ::new (&m_stride) StrideBase(expr.innerStride(), StrideType::InnerStrideAtCompileTime==0?0:1); 113 else 114 ::new (&m_stride) StrideBase(StrideType::OuterStrideAtCompileTime==0?0:expr.outerStride(), 115 StrideType::InnerStrideAtCompileTime==0?0:expr.innerStride()); 116 } 117 118 StrideBase m_stride; 119 }; 120 121 /** \class Ref 122 * \ingroup Core_Module 123 * 124 * \brief A matrix or vector expression mapping an existing expression 125 * 126 * \tparam PlainObjectType the equivalent matrix type of the mapped data 127 * \tparam Options specifies the pointer alignment in bytes. It can be: \c #Aligned128, , \c #Aligned64, \c #Aligned32, \c #Aligned16, \c #Aligned8 or \c #Unaligned. 128 * The default is \c #Unaligned. 129 * \tparam StrideType optionally specifies strides. By default, Ref implies a contiguous storage along the inner dimension (inner stride==1), 130 * but accepts a variable outer stride (leading dimension). 131 * This can be overridden by specifying strides. 132 * The type passed here must be a specialization of the Stride template, see examples below. 133 * 134 * This class provides a way to write non-template functions taking Eigen objects as parameters while limiting the number of copies. 135 * A Ref<> object can represent either a const expression or a l-value: 136 * \code 137 * // in-out argument: 138 * void foo1(Ref<VectorXf> x); 139 * 140 * // read-only const argument: 141 * void foo2(const Ref<const VectorXf>& x); 142 * \endcode 143 * 144 * In the in-out case, the input argument must satisfy the constraints of the actual Ref<> type, otherwise a compilation issue will be triggered. 145 * By default, a Ref<VectorXf> can reference any dense vector expression of float having a contiguous memory layout. 146 * Likewise, a Ref<MatrixXf> can reference any column-major dense matrix expression of float whose column's elements are contiguously stored with 147 * the possibility to have a constant space in-between each column, i.e. the inner stride must be equal to 1, but the outer stride (or leading dimension) 148 * can be greater than the number of rows. 149 * 150 * In the const case, if the input expression does not match the above requirement, then it is evaluated into a temporary before being passed to the function. 151 * Here are some examples: 152 * \code 153 * MatrixXf A; 154 * VectorXf a; 155 * foo1(a.head()); // OK 156 * foo1(A.col()); // OK 157 * foo1(A.row()); // Compilation error because here innerstride!=1 158 * foo2(A.row()); // Compilation error because A.row() is a 1xN object while foo2 is expecting a Nx1 object 159 * foo2(A.row().transpose()); // The row is copied into a contiguous temporary 160 * foo2(2*a); // The expression is evaluated into a temporary 161 * foo2(A.col().segment(2,4)); // No temporary 162 * \endcode 163 * 164 * The range of inputs that can be referenced without temporary can be enlarged using the last two template parameters. 165 * Here is an example accepting an innerstride!=1: 166 * \code 167 * // in-out argument: 168 * void foo3(Ref<VectorXf,0,InnerStride<> > x); 169 * foo3(A.row()); // OK 170 * \endcode 171 * The downside here is that the function foo3 might be significantly slower than foo1 because it won't be able to exploit vectorization, and will involve more 172 * expensive address computations even if the input is contiguously stored in memory. To overcome this issue, one might propose to overload internally calling a 173 * template function, e.g.: 174 * \code 175 * // in the .h: 176 * void foo(const Ref<MatrixXf>& A); 177 * void foo(const Ref<MatrixXf,0,Stride<> >& A); 178 * 179 * // in the .cpp: 180 * template<typename TypeOfA> void foo_impl(const TypeOfA& A) { 181 * ... // crazy code goes here 182 * } 183 * void foo(const Ref<MatrixXf>& A) { foo_impl(A); } 184 * void foo(const Ref<MatrixXf,0,Stride<> >& A) { foo_impl(A); } 185 * \endcode 186 * 187 * 188 * \sa PlainObjectBase::Map(), \ref TopicStorageOrders 189 */ 190 template<typename PlainObjectType, int Options, typename StrideType> class Ref 191 : public RefBase<Ref<PlainObjectType, Options, StrideType> > 192 { 193 private: 194 typedef internal::traits<Ref> Traits; 195 template<typename Derived> 196 EIGEN_DEVICE_FUNC inline Ref(const PlainObjectBase<Derived>& expr, 197 typename internal::enable_if<bool(Traits::template match<Derived>::MatchAtCompileTime),Derived>::type* = 0); 198 public: 199 200 typedef RefBase<Ref> Base; 201 EIGEN_DENSE_PUBLIC_INTERFACE(Ref) 202 203 204 #ifndef EIGEN_PARSED_BY_DOXYGEN 205 template<typename Derived> 206 EIGEN_DEVICE_FUNC inline Ref(PlainObjectBase<Derived>& expr, 207 typename internal::enable_if<bool(Traits::template match<Derived>::MatchAtCompileTime),Derived>::type* = 0) 208 { 209 EIGEN_STATIC_ASSERT(bool(Traits::template match<Derived>::MatchAtCompileTime), STORAGE_LAYOUT_DOES_NOT_MATCH); 210 Base::construct(expr.derived()); 211 } 212 template<typename Derived> 213 EIGEN_DEVICE_FUNC inline Ref(const DenseBase<Derived>& expr, 214 typename internal::enable_if<bool(Traits::template match<Derived>::MatchAtCompileTime),Derived>::type* = 0) 215 #else 216 /** Implicit constructor from any dense expression */ 217 template<typename Derived> 218 inline Ref(DenseBase<Derived>& expr) 219 #endif 220 { 221 EIGEN_STATIC_ASSERT(bool(internal::is_lvalue<Derived>::value), THIS_EXPRESSION_IS_NOT_A_LVALUE__IT_IS_READ_ONLY); 222 EIGEN_STATIC_ASSERT(bool(Traits::template match<Derived>::MatchAtCompileTime), STORAGE_LAYOUT_DOES_NOT_MATCH); 223 EIGEN_STATIC_ASSERT(!Derived::IsPlainObjectBase,THIS_EXPRESSION_IS_NOT_A_LVALUE__IT_IS_READ_ONLY); 224 Base::construct(expr.const_cast_derived()); 225 } 226 227 EIGEN_INHERIT_ASSIGNMENT_OPERATORS(Ref) 228 229 }; 230 231 // this is the const ref version 232 template<typename TPlainObjectType, int Options, typename StrideType> class Ref<const TPlainObjectType, Options, StrideType> 233 : public RefBase<Ref<const TPlainObjectType, Options, StrideType> > 234 { 235 typedef internal::traits<Ref> Traits; 236 public: 237 238 typedef RefBase<Ref> Base; 239 EIGEN_DENSE_PUBLIC_INTERFACE(Ref) 240 241 template<typename Derived> 242 EIGEN_DEVICE_FUNC inline Ref(const DenseBase<Derived>& expr, 243 typename internal::enable_if<bool(Traits::template match<Derived>::ScalarTypeMatch),Derived>::type* = 0) 244 { 245 // std::cout << match_helper<Derived>::HasDirectAccess << "," << match_helper<Derived>::OuterStrideMatch << "," << match_helper<Derived>::InnerStrideMatch << "\n"; 246 // std::cout << int(StrideType::OuterStrideAtCompileTime) << " - " << int(Derived::OuterStrideAtCompileTime) << "\n"; 247 // std::cout << int(StrideType::InnerStrideAtCompileTime) << " - " << int(Derived::InnerStrideAtCompileTime) << "\n"; 248 construct(expr.derived(), typename Traits::template match<Derived>::type()); 249 } 250 251 EIGEN_DEVICE_FUNC inline Ref(const Ref& other) : Base(other) { 252 // copy constructor shall not copy the m_object, to avoid unnecessary malloc and copy 253 } 254 255 template<typename OtherRef> 256 EIGEN_DEVICE_FUNC inline Ref(const RefBase<OtherRef>& other) { 257 construct(other.derived(), typename Traits::template match<OtherRef>::type()); 258 } 259 260 protected: 261 262 template<typename Expression> 263 EIGEN_DEVICE_FUNC void construct(const Expression& expr,internal::true_type) 264 { 265 Base::construct(expr); 266 } 267 268 template<typename Expression> 269 EIGEN_DEVICE_FUNC void construct(const Expression& expr, internal::false_type) 270 { 271 internal::call_assignment_no_alias(m_object,expr,internal::assign_op<Scalar,Scalar>()); 272 Base::construct(m_object); 273 } 274 275 protected: 276 TPlainObjectType m_object; 277 }; 278 279 } // end namespace Eigen 280 281 #endif // EIGEN_REF_H 282