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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