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