chromium/third_party/eigen3/src/Eigen/src/Core/Stride.h

// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2010 Benoit Jacob <[email protected]>
//
// 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_STRIDE_H
#define EIGEN_STRIDE_H

// IWYU pragma: private
#include "./InternalHeaderCheck.h"

namespace Eigen {

/** \class Stride
 * \ingroup Core_Module
 *
 * \brief Holds strides information for Map
 *
 * This class holds the strides information for mapping arrays with strides with class Map.
 *
 * It holds two values: the inner stride and the outer stride.
 *
 * The inner stride is the pointer increment between two consecutive entries within a given row of a
 * row-major matrix or within a given column of a column-major matrix.
 *
 * The outer stride is the pointer increment between two consecutive rows of a row-major matrix or
 * between two consecutive columns of a column-major matrix.
 *
 * These two values can be passed either at compile-time as template parameters, or at runtime as
 * arguments to the constructor.
 *
 * Indeed, this class takes two template parameters:
 *  \tparam OuterStrideAtCompileTime_ the outer stride, or Dynamic if you want to specify it at runtime.
 *  \tparam InnerStrideAtCompileTime_ the inner stride, or Dynamic if you want to specify it at runtime.
 *
 * Here is an example:
 * \include Map_general_stride.cpp
 * Output: \verbinclude Map_general_stride.out
 *
 * Both strides can be negative. However, a negative stride of -1 cannot be specified at compile time
 * because of the ambiguity with Dynamic which is defined to -1 (historically, negative strides were
 * not allowed).
 *
 * Note that for compile-time vectors (ColsAtCompileTime==1 or RowsAtCompile==1),
 * the inner stride is the pointer increment between two consecutive elements,
 * regardless of storage layout.
 *
 * \sa class InnerStride, class OuterStride, \ref TopicStorageOrders
 */
template <int OuterStrideAtCompileTime_, int InnerStrideAtCompileTime_>
class Stride { … };

/** \brief Convenience specialization of Stride to specify only an inner stride
 * See class Map for some examples */
template <int Value>
class InnerStride : public Stride<0, Value> { … };

/** \brief Convenience specialization of Stride to specify only an outer stride
 * See class Map for some examples */
template <int Value>
class OuterStride : public Stride<Value, 0> { … };

}  // end namespace Eigen

#endif  // EIGEN_STRIDE_H