118 lines
4.1 KiB
C++
118 lines
4.1 KiB
C++
// This file is part of Eigen, a lightweight C++ template library
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// for linear algebra.
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//
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// Copyright (C) 2009-2010 Gael Guennebaud <gael.guennebaud@inria.fr>
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// Copyright (C) 2009-2010 Benoit Jacob <jacob.benoit.1@gmail.com>
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//
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// This Source Code Form is subject to the terms of the Mozilla
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// Public License v. 2.0. If a copy of the MPL was not distributed
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// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
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#ifndef EIGEN_RETURNBYVALUE_H
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#define EIGEN_RETURNBYVALUE_H
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namespace Eigen {
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namespace internal {
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template<typename Derived>
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struct traits<ReturnByValue<Derived> >
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: public traits<typename traits<Derived>::ReturnType>
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{
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enum {
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// We're disabling the DirectAccess because e.g. the constructor of
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// the Block-with-DirectAccess expression requires to have a coeffRef method.
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// Also, we don't want to have to implement the stride stuff.
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Flags = (traits<typename traits<Derived>::ReturnType>::Flags
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| EvalBeforeNestingBit) & ~DirectAccessBit
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};
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};
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/* The ReturnByValue object doesn't even have a coeff() method.
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* So the only way that nesting it in an expression can work, is by evaluating it into a plain matrix.
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* So internal::nested always gives the plain return matrix type.
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*
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* FIXME: I don't understand why we need this specialization: isn't this taken care of by the EvalBeforeNestingBit ??
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* Answer: EvalBeforeNestingBit should be deprecated since we have the evaluators
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*/
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template<typename Derived,int n,typename PlainObject>
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struct nested_eval<ReturnByValue<Derived>, n, PlainObject>
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{
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typedef typename traits<Derived>::ReturnType type;
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};
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} // end namespace internal
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/** \class ReturnByValue
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* \ingroup Core_Module
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*
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*/
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template<typename Derived> class ReturnByValue
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: public internal::dense_xpr_base< ReturnByValue<Derived> >::type, internal::no_assignment_operator
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{
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public:
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typedef typename internal::traits<Derived>::ReturnType ReturnType;
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typedef typename internal::dense_xpr_base<ReturnByValue>::type Base;
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EIGEN_DENSE_PUBLIC_INTERFACE(ReturnByValue)
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template<typename Dest>
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EIGEN_DEVICE_FUNC
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inline void evalTo(Dest& dst) const
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{ static_cast<const Derived*>(this)->evalTo(dst); }
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EIGEN_DEVICE_FUNC inline Index rows() const { return static_cast<const Derived*>(this)->rows(); }
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EIGEN_DEVICE_FUNC inline Index cols() const { return static_cast<const Derived*>(this)->cols(); }
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#ifndef EIGEN_PARSED_BY_DOXYGEN
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#define Unusable YOU_ARE_TRYING_TO_ACCESS_A_SINGLE_COEFFICIENT_IN_A_SPECIAL_EXPRESSION_WHERE_THAT_IS_NOT_ALLOWED_BECAUSE_THAT_WOULD_BE_INEFFICIENT
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class Unusable{
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Unusable(const Unusable&) {}
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Unusable& operator=(const Unusable&) {return *this;}
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};
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const Unusable& coeff(Index) const { return *reinterpret_cast<const Unusable*>(this); }
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const Unusable& coeff(Index,Index) const { return *reinterpret_cast<const Unusable*>(this); }
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Unusable& coeffRef(Index) { return *reinterpret_cast<Unusable*>(this); }
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Unusable& coeffRef(Index,Index) { return *reinterpret_cast<Unusable*>(this); }
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#undef Unusable
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#endif
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};
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template<typename Derived>
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template<typename OtherDerived>
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Derived& DenseBase<Derived>::operator=(const ReturnByValue<OtherDerived>& other)
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{
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other.evalTo(derived());
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return derived();
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}
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namespace internal {
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// Expression is evaluated in a temporary; default implementation of Assignment is bypassed so that
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// when a ReturnByValue expression is assigned, the evaluator is not constructed.
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// TODO: Finalize port to new regime; ReturnByValue should not exist in the expression world
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template<typename Derived>
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struct evaluator<ReturnByValue<Derived> >
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: public evaluator<typename internal::traits<Derived>::ReturnType>
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{
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typedef ReturnByValue<Derived> XprType;
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typedef typename internal::traits<Derived>::ReturnType PlainObject;
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typedef evaluator<PlainObject> Base;
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EIGEN_DEVICE_FUNC explicit evaluator(const XprType& xpr)
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: m_result(xpr.rows(), xpr.cols())
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{
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::new (static_cast<Base*>(this)) Base(m_result);
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xpr.evalTo(m_result);
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}
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protected:
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PlainObject m_result;
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};
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} // end namespace internal
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} // end namespace Eigen
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#endif // EIGEN_RETURNBYVALUE_H
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