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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_INTEGRAL_CONSTANT_H
#define EIGEN_INTEGRAL_CONSTANT_H
#include "../InternalHeaderCheck.h"
namespace Eigen {
namespace internal {
template<int N> class FixedInt;
template<int N> class VariableAndFixedInt;
/** \internal
* \class FixedInt
*
* This class embeds a compile-time integer \c N.
*
* It is similar to c++11 std::integral_constant<int,N> but with some additional features
* such as:
* - implicit conversion to int
* - arithmetic and some bitwise operators: -, +, *, /, %, &, |
* - c++98/14 compatibility with fix<N> and fix<N>() syntax to define integral constants.
*
* It is strongly discouraged to directly deal with this class FixedInt. Instances are expected to
* be created by the user using Eigen::fix<N> or Eigen::fix<N>().
* \code
* internal::cleanup_index_type<T>::type
* internal::cleanup_index_type<T,DynamicKey>::type
* \endcode
* where T can a FixedInt<N>, a pointer to function FixedInt<N> (*)(), or numerous other integer-like representations.
* \c DynamicKey is either Dynamic (default) or DynamicIndex and used to identify true compile-time values.
*
* For convenience, you can extract the compile-time value \c N in a generic way using the following helper:
* \code
* internal::get_fixed_value<T,DefaultVal>::value
* \endcode
* that will give you \c N if T equals FixedInt<N> or FixedInt<N> (*)(), and \c DefaultVal if T does not embed any compile-time value (e.g., T==int).
*
* \sa fix<N>, class VariableAndFixedInt
*/
template<int N> class FixedInt
{
public:
static const int value = N;
EIGEN_CONSTEXPR operator int() const { return value; }
EIGEN_CONSTEXPR
FixedInt() = default;
EIGEN_CONSTEXPR
FixedInt(std::integral_constant<int,N>) {}
EIGEN_CONSTEXPR
FixedInt( VariableAndFixedInt<N> other) {
#ifndef EIGEN_INTERNAL_DEBUGGING
EIGEN_UNUSED_VARIABLE(other);
#endif
eigen_internal_assert(int(other)==N);
}
EIGEN_CONSTEXPR
FixedInt<-N> operator-() const { return FixedInt<-N>(); }
template<int M>
EIGEN_CONSTEXPR
FixedInt<N+M> operator+( FixedInt<M>) const { return FixedInt<N+M>(); }
template<int M>
EIGEN_CONSTEXPR
FixedInt<N-M> operator-( FixedInt<M>) const { return FixedInt<N-M>(); }
template<int M>
EIGEN_CONSTEXPR
FixedInt<N*M> operator*( FixedInt<M>) const { return FixedInt<N*M>(); }
template<int M>
EIGEN_CONSTEXPR
FixedInt<N/M> operator/( FixedInt<M>) const { return FixedInt<N/M>(); }
template<int M>
EIGEN_CONSTEXPR
FixedInt<N%M> operator%( FixedInt<M>) const { return FixedInt<N%M>(); }
template<int M>
EIGEN_CONSTEXPR
FixedInt<N|M> operator|( FixedInt<M>) const { return FixedInt<N|M>(); }
template<int M>
EIGEN_CONSTEXPR
FixedInt<N&M> operator&( FixedInt<M>) const { return FixedInt<N&M>(); }
// Needed in C++14 to allow fix<N>():
EIGEN_CONSTEXPR FixedInt operator() () const { return *this; }
VariableAndFixedInt<N> operator() (int val) const { return VariableAndFixedInt<N>(val); }
};
/** \internal
* \class VariableAndFixedInt
*
* This class embeds both a compile-time integer \c N and a runtime integer.
* Both values are supposed to be equal unless the compile-time value \c N has a special
* value meaning that the runtime-value should be used. Depending on the context, this special
* value can be either Eigen::Dynamic (for positive quantities) or Eigen::DynamicIndex (for
* quantities that can be negative).
*
* It is the return-type of the function Eigen::fix<N>(int), and most of the time this is the only
* way it is used. It is strongly discouraged to directly deal with instances of VariableAndFixedInt.
* Indeed, in order to write generic code, it is the responsibility of the callee to properly convert
* it to either a true compile-time quantity (i.e. a FixedInt<N>), or to a runtime quantity (e.g., an Index)
* using the following generic helper:
* \code
* internal::cleanup_index_type<T>::type
* internal::cleanup_index_type<T,DynamicKey>::type
* \endcode
* where T can be a template instantiation of VariableAndFixedInt or numerous other integer-like representations.
* \c DynamicKey is either Dynamic (default) or DynamicIndex and used to identify true compile-time values.
*
* For convenience, you can also extract the compile-time value \c N using the following helper:
* \code
* internal::get_fixed_value<T,DefaultVal>::value
* \endcode
* that will give you \c N if T equals VariableAndFixedInt<N>, and \c DefaultVal if T does not embed any compile-time value (e.g., T==int).
*
* \sa fix<N>(int), class FixedInt
*/
template<int N> class VariableAndFixedInt
{
public:
static const int value = N;
operator int() const { return m_value; }
VariableAndFixedInt(int val) { m_value = val; }
protected:
int m_value;
};
template<typename T, int Default=Dynamic> struct get_fixed_value {
static const int value = Default;
};
template<int N,int Default> struct get_fixed_value<FixedInt<N>,Default> {
static const int value = N;
};
template<int N,int Default> struct get_fixed_value<VariableAndFixedInt<N>,Default> {
static const int value = N ;
};
template<typename T, int N, int Default>
struct get_fixed_value<variable_if_dynamic<T,N>,Default> {
static const int value = N;
};
template<typename T> EIGEN_DEVICE_FUNC Index get_runtime_value(const T &x) { return x; }
// Cleanup integer/FixedInt/VariableAndFixedInt/etc types:
// By default, no cleanup:
template<typename T, int DynamicKey=Dynamic, typename EnableIf=void> struct cleanup_index_type { typedef T type; };
// Convert any integral type (e.g., short, int, unsigned int, etc.) to Eigen::Index
template<typename T, int DynamicKey> struct cleanup_index_type<T,DynamicKey,std::enable_if_t<internal::is_integral<T>::value>> { typedef Index type; };
// If VariableAndFixedInt does not match DynamicKey, then we turn it to a pure compile-time value:
template<int N, int DynamicKey> struct cleanup_index_type<VariableAndFixedInt<N>, DynamicKey> { typedef FixedInt<N> type; };
// If VariableAndFixedInt matches DynamicKey, then we turn it to a pure runtime-value (aka Index):
template<int DynamicKey> struct cleanup_index_type<VariableAndFixedInt<DynamicKey>, DynamicKey> { typedef Index type; };
template<int N, int DynamicKey> struct cleanup_index_type<std::integral_constant<int,N>, DynamicKey> { typedef FixedInt<N> type; };
} // end namespace internal
#ifndef EIGEN_PARSED_BY_DOXYGEN
template<int N>
constexpr internal::FixedInt<N> fix{};
#else // EIGEN_PARSED_BY_DOXYGEN
/** \var fix<N>()
* \ingroup Core_Module
*
* This \em identifier permits to construct an object embedding a compile-time integer \c N.
*
* \tparam N the compile-time integer value
*
* It is typically used in conjunction with the Eigen::seq and Eigen::seqN functions to pass compile-time values to them:
* \code
* seqN(10,fix<4>,fix<-3>) // <=> [10 7 4 1]
* \endcode
*
* See also the function fix(int) to pass both a compile-time and runtime value.
*
* In c++14, it is implemented as:
* \code
* template<int N> static const internal::FixedInt<N> fix{};
* \endcode
* where internal::FixedInt<N> is an internal template class similar to
* <a href="http://en.cppreference.com/w/cpp/types/integral_constant">\c std::integral_constant </a><tt> <int,N> </tt>
* Here, \c fix<N> is thus an object of type \c internal::FixedInt<N>.
*
* \sa fix<N>(int), seq, seqN
*/
template<int N>
static const auto fix();
/** \fn fix<N>(int)
* \ingroup Core_Module
*
* This function returns an object embedding both a compile-time integer \c N, and a fallback runtime value \a val.
*
* \tparam N the compile-time integer value
* \param val the fallback runtime integer value
*
* This function is a more general version of the \ref fix identifier/function that can be used in template code
* where the compile-time value could turn out to actually mean "undefined at compile-time". For positive integers
* such as a size or a dimension, this case is identified by Eigen::Dynamic, whereas runtime signed integers
* (e.g., an increment/stride) are identified as Eigen::DynamicIndex. In such a case, the runtime value \a val
* will be used as a fallback.
*
* A typical use case would be:
* \code
* template<typename Derived> void foo(const MatrixBase<Derived> &mat) {
* const int N = Derived::RowsAtCompileTime==Dynamic ? Dynamic : Derived::RowsAtCompileTime/2;
* const int n = mat.rows()/2;
* ... mat( seqN(0,fix<N>(n) ) ...;
* }
* \endcode
* In this example, the function Eigen::seqN knows that the second argument is expected to be a size.
* If the passed compile-time value N equals Eigen::Dynamic, then the proxy object returned by fix will be dissmissed, and converted to an Eigen::Index of value \c n.
* Otherwise, the runtime-value \c n will be dissmissed, and the returned ArithmeticSequence will be of the exact same type as <tt> seqN(0,fix<N>) </tt>.
*
* \sa fix, seqN, class ArithmeticSequence
*/
template<int N>
static const auto fix(int val);
#endif // EIGEN_PARSED_BY_DOXYGEN
} // end namespace Eigen
#endif // EIGEN_INTEGRAL_CONSTANT_H