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

// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2008 Gael Guennebaud <[email protected]>
// Copyright (C) 2006-2010 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_BLOCK_H
#define EIGEN_BLOCK_H

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

namespace Eigen {

namespace internal {
traits<Block<XprType_, BlockRows, BlockCols, InnerPanel_>>;

template <typename XprType, int BlockRows = Dynamic, int BlockCols = Dynamic, bool InnerPanel = false,
          bool HasDirectAccess = internal::has_direct_access<XprType>::ret>
class BlockImpl_dense;

}  // end namespace internal

template <typename XprType, int BlockRows, int BlockCols, bool InnerPanel, typename StorageKind>
class BlockImpl;

/** \class Block
 * \ingroup Core_Module
 *
 * \brief Expression of a fixed-size or dynamic-size block
 *
 * \tparam XprType the type of the expression in which we are taking a block
 * \tparam BlockRows the number of rows of the block we are taking at compile time (optional)
 * \tparam BlockCols the number of columns of the block we are taking at compile time (optional)
 * \tparam InnerPanel is true, if the block maps to a set of rows of a row major matrix or
 *         to set of columns of a column major matrix (optional). The parameter allows to determine
 *         at compile time whether aligned access is possible on the block expression.
 *
 * This class represents an expression of either a fixed-size or dynamic-size block. It is the return
 * type of DenseBase::block(Index,Index,Index,Index) and DenseBase::block<int,int>(Index,Index) and
 * most of the time this is the only way it is used.
 *
 * However, if you want to directly manipulate block expressions,
 * for instance if you want to write a function returning such an expression, you
 * will need to use this class.
 *
 * Here is an example illustrating the dynamic case:
 * \include class_Block.cpp
 * Output: \verbinclude class_Block.out
 *
 * \note Even though this expression has dynamic size, in the case where \a XprType
 * has fixed size, this expression inherits a fixed maximal size which means that evaluating
 * it does not cause a dynamic memory allocation.
 *
 * Here is an example illustrating the fixed-size case:
 * \include class_FixedBlock.cpp
 * Output: \verbinclude class_FixedBlock.out
 *
 * \sa DenseBase::block(Index,Index,Index,Index), DenseBase::block(Index,Index), class VectorBlock
 */
template <typename XprType, int BlockRows, int BlockCols, bool InnerPanel>
class Block
    : public BlockImpl<XprType, BlockRows, BlockCols, InnerPanel, typename internal::traits<XprType>::StorageKind> { … };

// The generic default implementation for dense block simply forward to the internal::BlockImpl_dense
// that must be specialized for direct and non-direct access...
BlockImpl<XprType, BlockRows, BlockCols, InnerPanel, Dense>;

namespace internal {

/** \internal Internal implementation of dense Blocks in the general case. */
template <typename XprType, int BlockRows, int BlockCols, bool InnerPanel, bool HasDirectAccess>
class BlockImpl_dense : public internal::dense_xpr_base<Block<XprType, BlockRows, BlockCols, InnerPanel>>::type { … };

/** \internal Internal implementation of dense Blocks in the direct access case.*/
BlockImpl_dense<XprType, BlockRows, BlockCols, InnerPanel, true>;

}  // end namespace internal

}  // end namespace Eigen

#endif  // EIGEN_BLOCK_H