diff options
author | Gael Guennebaud <g.gael@free.fr> | 2009-08-15 18:35:51 +0200 |
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committer | Gael Guennebaud <g.gael@free.fr> | 2009-08-15 18:35:51 +0200 |
commit | 50c703f0c750ebbf1aaec785dcddeb0fb763877f (patch) | |
tree | 87e59ba3032205c54d972b66120050c526b2c2b6 /Eigen/src/Core/NoAlias.h | |
parent | 13a8956188d1c8441c01a6218dc24c745ff0b210 (diff) |
As proposed on the list:
- rename EvalBeforeAssignBit to MayAliasBit
- make .lazy() remove the MayAliasBit only, and mark it as deprecated
- add a NoAlias pseudo expression, and MatrixBase::noalias() function
Todo:
- we have to decide whether += and -= assume no aliasing by default ?
- once we agree on the API: update the Sparse module and the unit tests respectively.
Diffstat (limited to 'Eigen/src/Core/NoAlias.h')
-rw-r--r-- | Eigen/src/Core/NoAlias.h | 94 |
1 files changed, 94 insertions, 0 deletions
diff --git a/Eigen/src/Core/NoAlias.h b/Eigen/src/Core/NoAlias.h new file mode 100644 index 000000000..5c2b6e3ca --- /dev/null +++ b/Eigen/src/Core/NoAlias.h @@ -0,0 +1,94 @@ +// This file is part of Eigen, a lightweight C++ template library +// for linear algebra. +// +// Copyright (C) 2009 Gael Guennebaud <g.gael@free.fr> +// +// Eigen is free software; you can redistribute it and/or +// modify it under the terms of the GNU Lesser General Public +// License as published by the Free Software Foundation; either +// version 3 of the License, or (at your option) any later version. +// +// Alternatively, you can redistribute it and/or +// modify it under the terms of the GNU General Public License as +// published by the Free Software Foundation; either version 2 of +// the License, or (at your option) any later version. +// +// Eigen is distributed in the hope that it will be useful, but WITHOUT ANY +// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS +// FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License or the +// GNU General Public License for more details. +// +// You should have received a copy of the GNU Lesser General Public +// License and a copy of the GNU General Public License along with +// Eigen. If not, see <http://www.gnu.org/licenses/>. + +#ifndef EIGEN_NOALIAS_H +#define EIGEN_NOALIAS_H + +/** \class NoAlias + * + * \brief Pseudo expression providing an operator = assuming no aliasing + * + * \param ExpressionType the type of the object on which to do the lazy assignment + * + * This class represents an expression with a special assignment operator (operator=) + * assuming no aliasing between the target expression and the source expression. + * It is the return type of MatrixBase::noalias() + * and most of the time this is the only way it is used. + * + * \sa MatrixBase::noalias() + */ +template<typename ExpressionType> +class NoAlias +{ + public: + NoAlias(ExpressionType& expression) : m_expression(expression) {} + + /** Behaves like MatrixBase::lazyAssign() */ + template<typename OtherDerived> + ExpressionType& operator=(const MatrixBase<OtherDerived>& other) + { + return m_expression.lazyAssign(other.derived()); + } + + // TODO could be removed if we decide that += is noalias by default + template<typename OtherDerived> + ExpressionType& operator+=(const MatrixBase<OtherDerived>& other) + { + return m_expression.lazyAssign(m_expression + other.derived()); + } + + // TODO could be removed if we decide that += is noalias by default + template<typename OtherDerived> + ExpressionType& operator-=(const MatrixBase<OtherDerived>& other) + { + return m_expression.lazyAssign(m_expression - other.derived()); + } + + // TODO could be removed if we decide that += is noalias by default + template<typename ProductDerived, typename Lhs, typename Rhs> + ExpressionType& operator+=(const ProductBase<ProductDerived, Lhs,Rhs>& other) + { other.derived().addTo(m_expression); return m_expression; } + + // TODO could be removed if we decide that += is noalias by default + template<typename ProductDerived, typename Lhs, typename Rhs> + ExpressionType& operator-=(const ProductBase<ProductDerived, Lhs,Rhs>& other) + { other.derived().subTo(m_expression); return m_expression; } + + protected: + ExpressionType& m_expression; +}; + + +/** \returns a pseudo expression of \c *this with an operator= assuming + * no aliasing between \c *this and the source expression + * + * \sa class NoAlias + */ +template<typename Derived> +NoAlias<Derived> MatrixBase<Derived>::noalias() +{ + return derived(); +} + +#endif // EIGEN_NOALIAS_H |