1 // This file is part of Eigen, a lightweight C++ template library 2 // for linear algebra. 3 // 4 // Copyright (C) 2008-2010 Gael Guennebaud <gael.guennebaud (at) inria.fr> 5 // Copyright (C) 2006-2008 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_VECTORBLOCK_H 12 #define EIGEN_VECTORBLOCK_H 13 14 namespace Eigen { 15 16 /** \class VectorBlock 17 * \ingroup Core_Module 18 * 19 * \brief Expression of a fixed-size or dynamic-size sub-vector 20 * 21 * \param VectorType the type of the object in which we are taking a sub-vector 22 * \param Size size of the sub-vector we are taking at compile time (optional) 23 * 24 * This class represents an expression of either a fixed-size or dynamic-size sub-vector. 25 * It is the return type of DenseBase::segment(Index,Index) and DenseBase::segment<int>(Index) and 26 * most of the time this is the only way it is used. 27 * 28 * However, if you want to directly maniputate sub-vector expressions, 29 * for instance if you want to write a function returning such an expression, you 30 * will need to use this class. 31 * 32 * Here is an example illustrating the dynamic case: 33 * \include class_VectorBlock.cpp 34 * Output: \verbinclude class_VectorBlock.out 35 * 36 * \note Even though this expression has dynamic size, in the case where \a VectorType 37 * has fixed size, this expression inherits a fixed maximal size which means that evaluating 38 * it does not cause a dynamic memory allocation. 39 * 40 * Here is an example illustrating the fixed-size case: 41 * \include class_FixedVectorBlock.cpp 42 * Output: \verbinclude class_FixedVectorBlock.out 43 * 44 * \sa class Block, DenseBase::segment(Index,Index,Index,Index), DenseBase::segment(Index,Index) 45 */ 46 47 namespace internal { 48 template<typename VectorType, int Size> 49 struct traits<VectorBlock<VectorType, Size> > 50 : public traits<Block<VectorType, 51 traits<VectorType>::Flags & RowMajorBit ? 1 : Size, 52 traits<VectorType>::Flags & RowMajorBit ? Size : 1> > 53 { 54 }; 55 } 56 57 template<typename VectorType, int Size> class VectorBlock 58 : public Block<VectorType, 59 internal::traits<VectorType>::Flags & RowMajorBit ? 1 : Size, 60 internal::traits<VectorType>::Flags & RowMajorBit ? Size : 1> 61 { 62 typedef Block<VectorType, 63 internal::traits<VectorType>::Flags & RowMajorBit ? 1 : Size, 64 internal::traits<VectorType>::Flags & RowMajorBit ? Size : 1> Base; 65 enum { 66 IsColVector = !(internal::traits<VectorType>::Flags & RowMajorBit) 67 }; 68 public: 69 EIGEN_DENSE_PUBLIC_INTERFACE(VectorBlock) 70 71 using Base::operator=; 72 73 /** Dynamic-size constructor 74 */ 75 inline VectorBlock(VectorType& vector, Index start, Index size) 76 : Base(vector, 77 IsColVector ? start : 0, IsColVector ? 0 : start, 78 IsColVector ? size : 1, IsColVector ? 1 : size) 79 { 80 EIGEN_STATIC_ASSERT_VECTOR_ONLY(VectorBlock); 81 } 82 83 /** Fixed-size constructor 84 */ 85 inline VectorBlock(VectorType& vector, Index start) 86 : Base(vector, IsColVector ? start : 0, IsColVector ? 0 : start) 87 { 88 EIGEN_STATIC_ASSERT_VECTOR_ONLY(VectorBlock); 89 } 90 }; 91 92 93 } // end namespace Eigen 94 95 #endif // EIGEN_VECTORBLOCK_H 96
