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// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2017 Gael Guennebaud <gael.guennebaud@inria.fr>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
#ifndef EIGEN_INDEXED_VIEW_HELPER_H
#define EIGEN_INDEXED_VIEW_HELPER_H
namespace Eigen {
/** \namespace Eigen::placeholders
* \ingroup Core_Module
*
* Namespace containing symbolic placeholder and identifiers
*/
namespace placeholders {
namespace internal {
struct symbolic_last_tag {};
}
/** \var last
* \ingroup Core_Module
*
* Can be used as a parameter to Eigen::seq and Eigen::seqN functions to symbolically reference the last element/row/columns
* of the underlying vector or matrix once passed to DenseBase::operator()(const RowIndices&, const ColIndices&).
*
* This symbolic placeholder support standard arithmetic operation.
*
* A typical usage example would be:
* \code
* using namespace Eigen;
* using Eigen::placeholders::last;
* VectorXd v(n);
* v(seq(2,last-2)).setOnes();
* \endcode
*
* \sa end
*/
static const Symbolic::SymbolExpr<internal::symbolic_last_tag> last;
/** \var end
* \ingroup Core_Module
*
* Can be used as a parameter to Eigen::seq and Eigen::seqN functions to symbolically reference the last+1 element/row/columns
* of the underlying vector or matrix once passed to DenseBase::operator()(const RowIndices&, const ColIndices&).
*
* This symbolic placeholder support standard arithmetic operation.
* It is essentially an alias to last+1
*
* \sa last
*/
#ifdef EIGEN_PARSED_BY_DOXYGEN
static const auto end = last+1;
#else
// Using a FixedExpr<1> expression is important here to make sure the compiler
// can fully optimize the computation starting indices with zero overhead.
static const Symbolic::AddExpr<Symbolic::SymbolExpr<internal::symbolic_last_tag>,Symbolic::ValueExpr<Eigen::internal::FixedInt<1> > > end(last+fix<1>());
#endif
} // end namespace placeholders
namespace internal {
// Replace symbolic last/end "keywords" by their true runtime value
inline Index eval_expr_given_size(Index x, Index /* size */) { return x; }
template<int N>
FixedInt<N> eval_expr_given_size(FixedInt<N> x, Index /*size*/) { return x; }
template<typename Derived>
Index eval_expr_given_size(const Symbolic::BaseExpr<Derived> &x, Index size)
{
return x.derived().eval(placeholders::last=size-1);
}
// Extract increment/step at compile time
template<typename T, typename EnableIf = void> struct get_compile_time_incr {
enum { value = UndefinedIncr };
};
// Analogue of std::get<0>(x), but tailored for our needs.
template<typename T>
Index first(const T& x) { return x.first(); }
// IndexedViewCompatibleType/makeIndexedViewCompatible turn an arbitrary object of type T into something usable by MatrixSlice
// The generic implementation is a no-op
template<typename T,int XprSize,typename EnableIf=void>
struct IndexedViewCompatibleType {
typedef T type;
};
template<typename T,typename Q>
const T& makeIndexedViewCompatible(const T& x, Index /*size*/, Q) { return x; }
//--------------------------------------------------------------------------------
// Handling of a single Index
//--------------------------------------------------------------------------------
struct SingleRange {
enum {
SizeAtCompileTime = 1
};
SingleRange(Index val) : m_value(val) {}
Index operator[](Index) const { return m_value; }
Index size() const { return 1; }
Index first() const { return m_value; }
Index m_value;
};
template<> struct get_compile_time_incr<SingleRange> {
enum { value = 1 }; // 1 or 0 ??
};
// Turn a single index into something that looks like an array (i.e., that exposes a .size(), and operatro[](int) methods)
template<typename T, int XprSize>
struct IndexedViewCompatibleType<T,XprSize,typename internal::enable_if<internal::is_integral<T>::value>::type> {
// Here we could simply use Array, but maybe it's less work for the compiler to use
// a simpler wrapper as SingleRange
//typedef Eigen::Array<Index,1,1> type;
typedef SingleRange type;
};
template<typename T, int XprSize>
struct IndexedViewCompatibleType<T, XprSize, typename enable_if<Symbolic::is_symbolic<T>::value>::type> {
typedef SingleRange type;
};
template<typename T>
typename enable_if<Symbolic::is_symbolic<T>::value,SingleRange>::type
makeIndexedViewCompatible(const T& id, Index size, SpecializedType) {
return eval_expr_given_size(id,size);
}
//--------------------------------------------------------------------------------
// Handling of all
//--------------------------------------------------------------------------------
struct all_t { all_t() {} };
// Convert a symbolic 'all' into a usable range type
template<int XprSize>
struct AllRange {
enum { SizeAtCompileTime = XprSize };
AllRange(Index size = XprSize) : m_size(size) {}
Index operator[](Index i) const { return i; }
Index size() const { return m_size.value(); }
Index first() const { return 0; }
variable_if_dynamic<Index,XprSize> m_size;
};
template<int XprSize>
struct IndexedViewCompatibleType<all_t,XprSize> {
typedef AllRange<XprSize> type;
};
template<typename XprSizeType>
inline AllRange<get_fixed_value<XprSizeType>::value> makeIndexedViewCompatible(all_t , XprSizeType size, SpecializedType) {
return AllRange<get_fixed_value<XprSizeType>::value>(size);
}
template<int Size> struct get_compile_time_incr<AllRange<Size> > {
enum { value = 1 };
};
} // end namespace internal
namespace placeholders {
/** \var all
* \ingroup Core_Module
* Can be used as a parameter to DenseBase::operator()(const RowIndices&, const ColIndices&) to index all rows or columns
*/
static const Eigen::internal::all_t all;
}
} // end namespace Eigen
#endif // EIGEN_INDEXED_VIEW_HELPER_H
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