Ref.h (17821B)
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 IsVectorAtCompileTime = PlainObjectType::IsVectorAtCompileTime || Derived::IsVectorAtCompileTime, 32 HasDirectAccess = internal::has_direct_access<Derived>::ret, 33 StorageOrderMatch = IsVectorAtCompileTime || ((PlainObjectType::Flags&RowMajorBit)==(Derived::Flags&RowMajorBit)), 34 InnerStrideMatch = int(StrideType::InnerStrideAtCompileTime)==int(Dynamic) 35 || int(StrideType::InnerStrideAtCompileTime)==int(Derived::InnerStrideAtCompileTime) 36 || (int(StrideType::InnerStrideAtCompileTime)==0 && int(Derived::InnerStrideAtCompileTime)==1), 37 OuterStrideMatch = IsVectorAtCompileTime 38 || int(StrideType::OuterStrideAtCompileTime)==int(Dynamic) || int(StrideType::OuterStrideAtCompileTime)==int(Derived::OuterStrideAtCompileTime), 39 // NOTE, this indirection of evaluator<Derived>::Alignment is needed 40 // to workaround a very strange bug in MSVC related to the instantiation 41 // of has_*ary_operator in evaluator<CwiseNullaryOp>. 42 // This line is surprisingly very sensitive. For instance, simply adding parenthesis 43 // as "DerivedAlignment = (int(evaluator<Derived>::Alignment))," will make MSVC fail... 44 DerivedAlignment = int(evaluator<Derived>::Alignment), 45 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 46 ScalarTypeMatch = internal::is_same<typename PlainObjectType::Scalar, typename Derived::Scalar>::value, 47 MatchAtCompileTime = HasDirectAccess && StorageOrderMatch && InnerStrideMatch && OuterStrideMatch && AlignmentMatch && ScalarTypeMatch 48 }; 49 typedef typename internal::conditional<MatchAtCompileTime,internal::true_type,internal::false_type>::type type; 50 }; 51 52 }; 53 54 template<typename Derived> 55 struct traits<RefBase<Derived> > : public traits<Derived> {}; 56 57 } 58 59 template<typename Derived> class RefBase 60 : public MapBase<Derived> 61 { 62 typedef typename internal::traits<Derived>::PlainObjectType PlainObjectType; 63 typedef typename internal::traits<Derived>::StrideType StrideType; 64 65 public: 66 67 typedef MapBase<Derived> Base; 68 EIGEN_DENSE_PUBLIC_INTERFACE(RefBase) 69 70 EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR inline Index innerStride() const 71 { 72 return StrideType::InnerStrideAtCompileTime != 0 ? m_stride.inner() : 1; 73 } 74 75 EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR inline Index outerStride() const 76 { 77 return StrideType::OuterStrideAtCompileTime != 0 ? m_stride.outer() 78 : IsVectorAtCompileTime ? this->size() 79 : int(Flags)&RowMajorBit ? this->cols() 80 : this->rows(); 81 } 82 83 EIGEN_DEVICE_FUNC RefBase() 84 : Base(0,RowsAtCompileTime==Dynamic?0:RowsAtCompileTime,ColsAtCompileTime==Dynamic?0:ColsAtCompileTime), 85 // Stride<> does not allow default ctor for Dynamic strides, so let' initialize it with dummy values: 86 m_stride(StrideType::OuterStrideAtCompileTime==Dynamic?0:StrideType::OuterStrideAtCompileTime, 87 StrideType::InnerStrideAtCompileTime==Dynamic?0:StrideType::InnerStrideAtCompileTime) 88 {} 89 90 EIGEN_INHERIT_ASSIGNMENT_OPERATORS(RefBase) 91 92 protected: 93 94 typedef Stride<StrideType::OuterStrideAtCompileTime,StrideType::InnerStrideAtCompileTime> StrideBase; 95 96 // Resolves inner stride if default 0. 97 static EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR Index resolveInnerStride(Index inner) { 98 return inner == 0 ? 1 : inner; 99 } 100 101 // Resolves outer stride if default 0. 102 static EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR Index resolveOuterStride(Index inner, Index outer, Index rows, Index cols, bool isVectorAtCompileTime, bool isRowMajor) { 103 return outer == 0 ? isVectorAtCompileTime ? inner * rows * cols : isRowMajor ? inner * cols : inner * rows : outer; 104 } 105 106 // Returns true if construction is valid, false if there is a stride mismatch, 107 // and fails if there is a size mismatch. 108 template<typename Expression> 109 EIGEN_DEVICE_FUNC bool construct(Expression& expr) 110 { 111 // Check matrix sizes. If this is a compile-time vector, we do allow 112 // implicitly transposing. 113 EIGEN_STATIC_ASSERT( 114 EIGEN_PREDICATE_SAME_MATRIX_SIZE(PlainObjectType, Expression) 115 // If it is a vector, the transpose sizes might match. 116 || ( PlainObjectType::IsVectorAtCompileTime 117 && ((int(PlainObjectType::RowsAtCompileTime)==Eigen::Dynamic 118 || int(Expression::ColsAtCompileTime)==Eigen::Dynamic 119 || int(PlainObjectType::RowsAtCompileTime)==int(Expression::ColsAtCompileTime)) 120 && (int(PlainObjectType::ColsAtCompileTime)==Eigen::Dynamic 121 || int(Expression::RowsAtCompileTime)==Eigen::Dynamic 122 || int(PlainObjectType::ColsAtCompileTime)==int(Expression::RowsAtCompileTime)))), 123 YOU_MIXED_MATRICES_OF_DIFFERENT_SIZES 124 ) 125 126 // Determine runtime rows and columns. 127 Index rows = expr.rows(); 128 Index cols = expr.cols(); 129 if(PlainObjectType::RowsAtCompileTime==1) 130 { 131 eigen_assert(expr.rows()==1 || expr.cols()==1); 132 rows = 1; 133 cols = expr.size(); 134 } 135 else if(PlainObjectType::ColsAtCompileTime==1) 136 { 137 eigen_assert(expr.rows()==1 || expr.cols()==1); 138 rows = expr.size(); 139 cols = 1; 140 } 141 // Verify that the sizes are valid. 142 eigen_assert( 143 (PlainObjectType::RowsAtCompileTime == Dynamic) || (PlainObjectType::RowsAtCompileTime == rows)); 144 eigen_assert( 145 (PlainObjectType::ColsAtCompileTime == Dynamic) || (PlainObjectType::ColsAtCompileTime == cols)); 146 147 148 // If this is a vector, we might be transposing, which means that stride should swap. 149 const bool transpose = PlainObjectType::IsVectorAtCompileTime && (rows != expr.rows()); 150 // If the storage format differs, we also need to swap the stride. 151 const bool row_major = ((PlainObjectType::Flags)&RowMajorBit) != 0; 152 const bool expr_row_major = (Expression::Flags&RowMajorBit) != 0; 153 const bool storage_differs = (row_major != expr_row_major); 154 155 const bool swap_stride = (transpose != storage_differs); 156 157 // Determine expr's actual strides, resolving any defaults if zero. 158 const Index expr_inner_actual = resolveInnerStride(expr.innerStride()); 159 const Index expr_outer_actual = resolveOuterStride(expr_inner_actual, 160 expr.outerStride(), 161 expr.rows(), 162 expr.cols(), 163 Expression::IsVectorAtCompileTime != 0, 164 expr_row_major); 165 166 // If this is a column-major row vector or row-major column vector, the inner-stride 167 // is arbitrary, so set it to either the compile-time inner stride or 1. 168 const bool row_vector = (rows == 1); 169 const bool col_vector = (cols == 1); 170 const Index inner_stride = 171 ( (!row_major && row_vector) || (row_major && col_vector) ) ? 172 ( StrideType::InnerStrideAtCompileTime > 0 ? Index(StrideType::InnerStrideAtCompileTime) : 1) 173 : swap_stride ? expr_outer_actual : expr_inner_actual; 174 175 // If this is a column-major column vector or row-major row vector, the outer-stride 176 // is arbitrary, so set it to either the compile-time outer stride or vector size. 177 const Index outer_stride = 178 ( (!row_major && col_vector) || (row_major && row_vector) ) ? 179 ( StrideType::OuterStrideAtCompileTime > 0 ? Index(StrideType::OuterStrideAtCompileTime) : rows * cols * inner_stride) 180 : swap_stride ? expr_inner_actual : expr_outer_actual; 181 182 // Check if given inner/outer strides are compatible with compile-time strides. 183 const bool inner_valid = (StrideType::InnerStrideAtCompileTime == Dynamic) 184 || (resolveInnerStride(Index(StrideType::InnerStrideAtCompileTime)) == inner_stride); 185 if (!inner_valid) { 186 return false; 187 } 188 189 const bool outer_valid = (StrideType::OuterStrideAtCompileTime == Dynamic) 190 || (resolveOuterStride( 191 inner_stride, 192 Index(StrideType::OuterStrideAtCompileTime), 193 rows, cols, PlainObjectType::IsVectorAtCompileTime != 0, 194 row_major) 195 == outer_stride); 196 if (!outer_valid) { 197 return false; 198 } 199 200 ::new (static_cast<Base*>(this)) Base(expr.data(), rows, cols); 201 ::new (&m_stride) StrideBase( 202 (StrideType::OuterStrideAtCompileTime == 0) ? 0 : outer_stride, 203 (StrideType::InnerStrideAtCompileTime == 0) ? 0 : inner_stride ); 204 return true; 205 } 206 207 StrideBase m_stride; 208 }; 209 210 /** \class Ref 211 * \ingroup Core_Module 212 * 213 * \brief A matrix or vector expression mapping an existing expression 214 * 215 * \tparam PlainObjectType the equivalent matrix type of the mapped data 216 * \tparam Options specifies the pointer alignment in bytes. It can be: \c #Aligned128, , \c #Aligned64, \c #Aligned32, \c #Aligned16, \c #Aligned8 or \c #Unaligned. 217 * The default is \c #Unaligned. 218 * \tparam StrideType optionally specifies strides. By default, Ref implies a contiguous storage along the inner dimension (inner stride==1), 219 * but accepts a variable outer stride (leading dimension). 220 * This can be overridden by specifying strides. 221 * The type passed here must be a specialization of the Stride template, see examples below. 222 * 223 * This class provides a way to write non-template functions taking Eigen objects as parameters while limiting the number of copies. 224 * A Ref<> object can represent either a const expression or a l-value: 225 * \code 226 * // in-out argument: 227 * void foo1(Ref<VectorXf> x); 228 * 229 * // read-only const argument: 230 * void foo2(const Ref<const VectorXf>& x); 231 * \endcode 232 * 233 * In the in-out case, the input argument must satisfy the constraints of the actual Ref<> type, otherwise a compilation issue will be triggered. 234 * By default, a Ref<VectorXf> can reference any dense vector expression of float having a contiguous memory layout. 235 * Likewise, a Ref<MatrixXf> can reference any column-major dense matrix expression of float whose column's elements are contiguously stored with 236 * 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) 237 * can be greater than the number of rows. 238 * 239 * 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. 240 * Here are some examples: 241 * \code 242 * MatrixXf A; 243 * VectorXf a; 244 * foo1(a.head()); // OK 245 * foo1(A.col()); // OK 246 * foo1(A.row()); // Compilation error because here innerstride!=1 247 * foo2(A.row()); // Compilation error because A.row() is a 1xN object while foo2 is expecting a Nx1 object 248 * foo2(A.row().transpose()); // The row is copied into a contiguous temporary 249 * foo2(2*a); // The expression is evaluated into a temporary 250 * foo2(A.col().segment(2,4)); // No temporary 251 * \endcode 252 * 253 * The range of inputs that can be referenced without temporary can be enlarged using the last two template parameters. 254 * Here is an example accepting an innerstride!=1: 255 * \code 256 * // in-out argument: 257 * void foo3(Ref<VectorXf,0,InnerStride<> > x); 258 * foo3(A.row()); // OK 259 * \endcode 260 * 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 261 * expensive address computations even if the input is contiguously stored in memory. To overcome this issue, one might propose to overload internally calling a 262 * template function, e.g.: 263 * \code 264 * // in the .h: 265 * void foo(const Ref<MatrixXf>& A); 266 * void foo(const Ref<MatrixXf,0,Stride<> >& A); 267 * 268 * // in the .cpp: 269 * template<typename TypeOfA> void foo_impl(const TypeOfA& A) { 270 * ... // crazy code goes here 271 * } 272 * void foo(const Ref<MatrixXf>& A) { foo_impl(A); } 273 * void foo(const Ref<MatrixXf,0,Stride<> >& A) { foo_impl(A); } 274 * \endcode 275 * 276 * See also the following stackoverflow questions for further references: 277 * - <a href="http://stackoverflow.com/questions/21132538/correct-usage-of-the-eigenref-class">Correct usage of the Eigen::Ref<> class</a> 278 * 279 * \sa PlainObjectBase::Map(), \ref TopicStorageOrders 280 */ 281 template<typename PlainObjectType, int Options, typename StrideType> class Ref 282 : public RefBase<Ref<PlainObjectType, Options, StrideType> > 283 { 284 private: 285 typedef internal::traits<Ref> Traits; 286 template<typename Derived> 287 EIGEN_DEVICE_FUNC inline Ref(const PlainObjectBase<Derived>& expr, 288 typename internal::enable_if<bool(Traits::template match<Derived>::MatchAtCompileTime),Derived>::type* = 0); 289 public: 290 291 typedef RefBase<Ref> Base; 292 EIGEN_DENSE_PUBLIC_INTERFACE(Ref) 293 294 295 #ifndef EIGEN_PARSED_BY_DOXYGEN 296 template<typename Derived> 297 EIGEN_DEVICE_FUNC inline Ref(PlainObjectBase<Derived>& expr, 298 typename internal::enable_if<bool(Traits::template match<Derived>::MatchAtCompileTime),Derived>::type* = 0) 299 { 300 EIGEN_STATIC_ASSERT(bool(Traits::template match<Derived>::MatchAtCompileTime), STORAGE_LAYOUT_DOES_NOT_MATCH); 301 // Construction must pass since we will not create temprary storage in the non-const case. 302 const bool success = Base::construct(expr.derived()); 303 EIGEN_UNUSED_VARIABLE(success) 304 eigen_assert(success); 305 } 306 template<typename Derived> 307 EIGEN_DEVICE_FUNC inline Ref(const DenseBase<Derived>& expr, 308 typename internal::enable_if<bool(Traits::template match<Derived>::MatchAtCompileTime),Derived>::type* = 0) 309 #else 310 /** Implicit constructor from any dense expression */ 311 template<typename Derived> 312 inline Ref(DenseBase<Derived>& expr) 313 #endif 314 { 315 EIGEN_STATIC_ASSERT(bool(internal::is_lvalue<Derived>::value), THIS_EXPRESSION_IS_NOT_A_LVALUE__IT_IS_READ_ONLY); 316 EIGEN_STATIC_ASSERT(bool(Traits::template match<Derived>::MatchAtCompileTime), STORAGE_LAYOUT_DOES_NOT_MATCH); 317 EIGEN_STATIC_ASSERT(!Derived::IsPlainObjectBase,THIS_EXPRESSION_IS_NOT_A_LVALUE__IT_IS_READ_ONLY); 318 // Construction must pass since we will not create temporary storage in the non-const case. 319 const bool success = Base::construct(expr.const_cast_derived()); 320 EIGEN_UNUSED_VARIABLE(success) 321 eigen_assert(success); 322 } 323 324 EIGEN_INHERIT_ASSIGNMENT_OPERATORS(Ref) 325 326 }; 327 328 // this is the const ref version 329 template<typename TPlainObjectType, int Options, typename StrideType> class Ref<const TPlainObjectType, Options, StrideType> 330 : public RefBase<Ref<const TPlainObjectType, Options, StrideType> > 331 { 332 typedef internal::traits<Ref> Traits; 333 public: 334 335 typedef RefBase<Ref> Base; 336 EIGEN_DENSE_PUBLIC_INTERFACE(Ref) 337 338 template<typename Derived> 339 EIGEN_DEVICE_FUNC inline Ref(const DenseBase<Derived>& expr, 340 typename internal::enable_if<bool(Traits::template match<Derived>::ScalarTypeMatch),Derived>::type* = 0) 341 { 342 // std::cout << match_helper<Derived>::HasDirectAccess << "," << match_helper<Derived>::OuterStrideMatch << "," << match_helper<Derived>::InnerStrideMatch << "\n"; 343 // std::cout << int(StrideType::OuterStrideAtCompileTime) << " - " << int(Derived::OuterStrideAtCompileTime) << "\n"; 344 // std::cout << int(StrideType::InnerStrideAtCompileTime) << " - " << int(Derived::InnerStrideAtCompileTime) << "\n"; 345 construct(expr.derived(), typename Traits::template match<Derived>::type()); 346 } 347 348 EIGEN_DEVICE_FUNC inline Ref(const Ref& other) : Base(other) { 349 // copy constructor shall not copy the m_object, to avoid unnecessary malloc and copy 350 } 351 352 template<typename OtherRef> 353 EIGEN_DEVICE_FUNC inline Ref(const RefBase<OtherRef>& other) { 354 construct(other.derived(), typename Traits::template match<OtherRef>::type()); 355 } 356 357 protected: 358 359 template<typename Expression> 360 EIGEN_DEVICE_FUNC void construct(const Expression& expr,internal::true_type) 361 { 362 // Check if we can use the underlying expr's storage directly, otherwise call the copy version. 363 if (!Base::construct(expr)) { 364 construct(expr, internal::false_type()); 365 } 366 } 367 368 template<typename Expression> 369 EIGEN_DEVICE_FUNC void construct(const Expression& expr, internal::false_type) 370 { 371 internal::call_assignment_no_alias(m_object,expr,internal::assign_op<Scalar,Scalar>()); 372 Base::construct(m_object); 373 } 374 375 protected: 376 TPlainObjectType m_object; 377 }; 378 379 } // end namespace Eigen 380 381 #endif // EIGEN_REF_H