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      1 // This file is part of Eigen, a lightweight C++ template library
      2 // for linear algebra.
      3 //
      4 // Copyright (C) 2008 Gael Guennebaud <gael.guennebaud (at) inria.fr>
      5 // Copyright (C) 2006-2010 Benoit Jacob <jacob.benoit.1 (at) gmail.com>
      6 //
      7 // This Source Code Form is subject to the terms of the Mozilla
      8 // Public License v. 2.0. If a copy of the MPL was not distributed
      9 // with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
     10 
     11 #ifndef EIGEN_BLOCK_H
     12 #define EIGEN_BLOCK_H
     13 
     14 namespace Eigen {
     15 
     16 /** \class Block
     17   * \ingroup Core_Module
     18   *
     19   * \brief Expression of a fixed-size or dynamic-size block
     20   *
     21   * \param XprType the type of the expression in which we are taking a block
     22   * \param BlockRows the number of rows of the block we are taking at compile time (optional)
     23   * \param BlockCols the number of columns of the block we are taking at compile time (optional)
     24   * \param _DirectAccessStatus \internal used for partial specialization
     25   *
     26   * This class represents an expression of either a fixed-size or dynamic-size block. It is the return
     27   * type of DenseBase::block(Index,Index,Index,Index) and DenseBase::block<int,int>(Index,Index) and
     28   * most of the time this is the only way it is used.
     29   *
     30   * However, if you want to directly maniputate block expressions,
     31   * for instance if you want to write a function returning such an expression, you
     32   * will need to use this class.
     33   *
     34   * Here is an example illustrating the dynamic case:
     35   * \include class_Block.cpp
     36   * Output: \verbinclude class_Block.out
     37   *
     38   * \note Even though this expression has dynamic size, in the case where \a XprType
     39   * has fixed size, this expression inherits a fixed maximal size which means that evaluating
     40   * it does not cause a dynamic memory allocation.
     41   *
     42   * Here is an example illustrating the fixed-size case:
     43   * \include class_FixedBlock.cpp
     44   * Output: \verbinclude class_FixedBlock.out
     45   *
     46   * \sa DenseBase::block(Index,Index,Index,Index), DenseBase::block(Index,Index), class VectorBlock
     47   */
     48 
     49 namespace internal {
     50 template<typename XprType, int BlockRows, int BlockCols, bool InnerPanel, bool HasDirectAccess>
     51 struct traits<Block<XprType, BlockRows, BlockCols, InnerPanel, HasDirectAccess> > : traits<XprType>
     52 {
     53   typedef typename traits<XprType>::Scalar Scalar;
     54   typedef typename traits<XprType>::StorageKind StorageKind;
     55   typedef typename traits<XprType>::XprKind XprKind;
     56   typedef typename nested<XprType>::type XprTypeNested;
     57   typedef typename remove_reference<XprTypeNested>::type _XprTypeNested;
     58   enum{
     59     MatrixRows = traits<XprType>::RowsAtCompileTime,
     60     MatrixCols = traits<XprType>::ColsAtCompileTime,
     61     RowsAtCompileTime = MatrixRows == 0 ? 0 : BlockRows,
     62     ColsAtCompileTime = MatrixCols == 0 ? 0 : BlockCols,
     63     MaxRowsAtCompileTime = BlockRows==0 ? 0
     64                          : RowsAtCompileTime != Dynamic ? int(RowsAtCompileTime)
     65                          : int(traits<XprType>::MaxRowsAtCompileTime),
     66     MaxColsAtCompileTime = BlockCols==0 ? 0
     67                          : ColsAtCompileTime != Dynamic ? int(ColsAtCompileTime)
     68                          : int(traits<XprType>::MaxColsAtCompileTime),
     69     XprTypeIsRowMajor = (int(traits<XprType>::Flags)&RowMajorBit) != 0,
     70     IsRowMajor = (MaxRowsAtCompileTime==1&&MaxColsAtCompileTime!=1) ? 1
     71                : (MaxColsAtCompileTime==1&&MaxRowsAtCompileTime!=1) ? 0
     72                : XprTypeIsRowMajor,
     73     HasSameStorageOrderAsXprType = (IsRowMajor == XprTypeIsRowMajor),
     74     InnerSize = IsRowMajor ? int(ColsAtCompileTime) : int(RowsAtCompileTime),
     75     InnerStrideAtCompileTime = HasSameStorageOrderAsXprType
     76                              ? int(inner_stride_at_compile_time<XprType>::ret)
     77                              : int(outer_stride_at_compile_time<XprType>::ret),
     78     OuterStrideAtCompileTime = HasSameStorageOrderAsXprType
     79                              ? int(outer_stride_at_compile_time<XprType>::ret)
     80                              : int(inner_stride_at_compile_time<XprType>::ret),
     81     MaskPacketAccessBit = (InnerSize == Dynamic || (InnerSize % packet_traits<Scalar>::size) == 0)
     82                        && (InnerStrideAtCompileTime == 1)
     83                         ? PacketAccessBit : 0,
     84     MaskAlignedBit = (InnerPanel && (OuterStrideAtCompileTime!=Dynamic) && (((OuterStrideAtCompileTime * int(sizeof(Scalar))) % 16) == 0)) ? AlignedBit : 0,
     85     FlagsLinearAccessBit = (RowsAtCompileTime == 1 || ColsAtCompileTime == 1) ? LinearAccessBit : 0,
     86     FlagsLvalueBit = is_lvalue<XprType>::value ? LvalueBit : 0,
     87     FlagsRowMajorBit = IsRowMajor ? RowMajorBit : 0,
     88     Flags0 = traits<XprType>::Flags & ( (HereditaryBits & ~RowMajorBit) |
     89                                         DirectAccessBit |
     90                                         MaskPacketAccessBit |
     91                                         MaskAlignedBit),
     92     Flags = Flags0 | FlagsLinearAccessBit | FlagsLvalueBit | FlagsRowMajorBit
     93   };
     94 };
     95 }
     96 
     97 template<typename XprType, int BlockRows, int BlockCols, bool InnerPanel, bool HasDirectAccess> class Block
     98   : public internal::dense_xpr_base<Block<XprType, BlockRows, BlockCols, InnerPanel, HasDirectAccess> >::type
     99 {
    100   public:
    101 
    102     typedef typename internal::dense_xpr_base<Block>::type Base;
    103     EIGEN_DENSE_PUBLIC_INTERFACE(Block)
    104 
    105     class InnerIterator;
    106 
    107     /** Column or Row constructor
    108       */
    109     inline Block(XprType& xpr, Index i)
    110       : m_xpr(xpr),
    111         // It is a row if and only if BlockRows==1 and BlockCols==XprType::ColsAtCompileTime,
    112         // and it is a column if and only if BlockRows==XprType::RowsAtCompileTime and BlockCols==1,
    113         // all other cases are invalid.
    114         // The case a 1x1 matrix seems ambiguous, but the result is the same anyway.
    115         m_startRow( (BlockRows==1) && (BlockCols==XprType::ColsAtCompileTime) ? i : 0),
    116         m_startCol( (BlockRows==XprType::RowsAtCompileTime) && (BlockCols==1) ? i : 0),
    117         m_blockRows(BlockRows==1 ? 1 : xpr.rows()),
    118         m_blockCols(BlockCols==1 ? 1 : xpr.cols())
    119     {
    120       eigen_assert( (i>=0) && (
    121           ((BlockRows==1) && (BlockCols==XprType::ColsAtCompileTime) && i<xpr.rows())
    122         ||((BlockRows==XprType::RowsAtCompileTime) && (BlockCols==1) && i<xpr.cols())));
    123     }
    124 
    125     /** Fixed-size constructor
    126       */
    127     inline Block(XprType& xpr, Index startRow, Index startCol)
    128       : m_xpr(xpr), m_startRow(startRow), m_startCol(startCol),
    129         m_blockRows(BlockRows), m_blockCols(BlockCols)
    130     {
    131       EIGEN_STATIC_ASSERT(RowsAtCompileTime!=Dynamic && ColsAtCompileTime!=Dynamic,THIS_METHOD_IS_ONLY_FOR_FIXED_SIZE)
    132       eigen_assert(startRow >= 0 && BlockRows >= 1 && startRow + BlockRows <= xpr.rows()
    133              && startCol >= 0 && BlockCols >= 1 && startCol + BlockCols <= xpr.cols());
    134     }
    135 
    136     /** Dynamic-size constructor
    137       */
    138     inline Block(XprType& xpr,
    139           Index startRow, Index startCol,
    140           Index blockRows, Index blockCols)
    141       : m_xpr(xpr), m_startRow(startRow), m_startCol(startCol),
    142                           m_blockRows(blockRows), m_blockCols(blockCols)
    143     {
    144       eigen_assert((RowsAtCompileTime==Dynamic || RowsAtCompileTime==blockRows)
    145           && (ColsAtCompileTime==Dynamic || ColsAtCompileTime==blockCols));
    146       eigen_assert(startRow >= 0 && blockRows >= 0 && startRow + blockRows <= xpr.rows()
    147           && startCol >= 0 && blockCols >= 0 && startCol + blockCols <= xpr.cols());
    148     }
    149 
    150     EIGEN_INHERIT_ASSIGNMENT_OPERATORS(Block)
    151 
    152     inline Index rows() const { return m_blockRows.value(); }
    153     inline Index cols() const { return m_blockCols.value(); }
    154 
    155     inline Scalar& coeffRef(Index row, Index col)
    156     {
    157       EIGEN_STATIC_ASSERT_LVALUE(XprType)
    158       return m_xpr.const_cast_derived()
    159                .coeffRef(row + m_startRow.value(), col + m_startCol.value());
    160     }
    161 
    162     inline const Scalar& coeffRef(Index row, Index col) const
    163     {
    164       return m_xpr.derived()
    165                .coeffRef(row + m_startRow.value(), col + m_startCol.value());
    166     }
    167 
    168     EIGEN_STRONG_INLINE const CoeffReturnType coeff(Index row, Index col) const
    169     {
    170       return m_xpr.coeff(row + m_startRow.value(), col + m_startCol.value());
    171     }
    172 
    173     inline Scalar& coeffRef(Index index)
    174     {
    175       EIGEN_STATIC_ASSERT_LVALUE(XprType)
    176       return m_xpr.const_cast_derived()
    177              .coeffRef(m_startRow.value() + (RowsAtCompileTime == 1 ? 0 : index),
    178                        m_startCol.value() + (RowsAtCompileTime == 1 ? index : 0));
    179     }
    180 
    181     inline const Scalar& coeffRef(Index index) const
    182     {
    183       return m_xpr.const_cast_derived()
    184              .coeffRef(m_startRow.value() + (RowsAtCompileTime == 1 ? 0 : index),
    185                        m_startCol.value() + (RowsAtCompileTime == 1 ? index : 0));
    186     }
    187 
    188     inline const CoeffReturnType coeff(Index index) const
    189     {
    190       return m_xpr
    191              .coeff(m_startRow.value() + (RowsAtCompileTime == 1 ? 0 : index),
    192                     m_startCol.value() + (RowsAtCompileTime == 1 ? index : 0));
    193     }
    194 
    195     template<int LoadMode>
    196     inline PacketScalar packet(Index row, Index col) const
    197     {
    198       return m_xpr.template packet<Unaligned>
    199               (row + m_startRow.value(), col + m_startCol.value());
    200     }
    201 
    202     template<int LoadMode>
    203     inline void writePacket(Index row, Index col, const PacketScalar& x)
    204     {
    205       m_xpr.const_cast_derived().template writePacket<Unaligned>
    206               (row + m_startRow.value(), col + m_startCol.value(), x);
    207     }
    208 
    209     template<int LoadMode>
    210     inline PacketScalar packet(Index index) const
    211     {
    212       return m_xpr.template packet<Unaligned>
    213               (m_startRow.value() + (RowsAtCompileTime == 1 ? 0 : index),
    214                m_startCol.value() + (RowsAtCompileTime == 1 ? index : 0));
    215     }
    216 
    217     template<int LoadMode>
    218     inline void writePacket(Index index, const PacketScalar& x)
    219     {
    220       m_xpr.const_cast_derived().template writePacket<Unaligned>
    221          (m_startRow.value() + (RowsAtCompileTime == 1 ? 0 : index),
    222           m_startCol.value() + (RowsAtCompileTime == 1 ? index : 0), x);
    223     }
    224 
    225     #ifdef EIGEN_PARSED_BY_DOXYGEN
    226     /** \sa MapBase::data() */
    227     inline const Scalar* data() const;
    228     inline Index innerStride() const;
    229     inline Index outerStride() const;
    230     #endif
    231 
    232     const typename internal::remove_all<typename XprType::Nested>::type& nestedExpression() const
    233     {
    234       return m_xpr;
    235     }
    236 
    237     Index startRow() const
    238     {
    239       return m_startRow.value();
    240     }
    241 
    242     Index startCol() const
    243     {
    244       return m_startCol.value();
    245     }
    246 
    247   protected:
    248 
    249     const typename XprType::Nested m_xpr;
    250     const internal::variable_if_dynamic<Index, XprType::RowsAtCompileTime == 1 ? 0 : Dynamic> m_startRow;
    251     const internal::variable_if_dynamic<Index, XprType::ColsAtCompileTime == 1 ? 0 : Dynamic> m_startCol;
    252     const internal::variable_if_dynamic<Index, RowsAtCompileTime> m_blockRows;
    253     const internal::variable_if_dynamic<Index, ColsAtCompileTime> m_blockCols;
    254 };
    255 
    256 /** \internal */
    257 template<typename XprType, int BlockRows, int BlockCols, bool InnerPanel>
    258 class Block<XprType,BlockRows,BlockCols, InnerPanel,true>
    259   : public MapBase<Block<XprType, BlockRows, BlockCols, InnerPanel, true> >
    260 {
    261   public:
    262 
    263     typedef MapBase<Block> Base;
    264     EIGEN_DENSE_PUBLIC_INTERFACE(Block)
    265 
    266     EIGEN_INHERIT_ASSIGNMENT_OPERATORS(Block)
    267 
    268     /** Column or Row constructor
    269       */
    270     inline Block(XprType& xpr, Index i)
    271       : Base(internal::const_cast_ptr(&xpr.coeffRef(
    272               (BlockRows==1) && (BlockCols==XprType::ColsAtCompileTime) ? i : 0,
    273               (BlockRows==XprType::RowsAtCompileTime) && (BlockCols==1) ? i : 0)),
    274              BlockRows==1 ? 1 : xpr.rows(),
    275              BlockCols==1 ? 1 : xpr.cols()),
    276         m_xpr(xpr)
    277     {
    278       eigen_assert( (i>=0) && (
    279           ((BlockRows==1) && (BlockCols==XprType::ColsAtCompileTime) && i<xpr.rows())
    280         ||((BlockRows==XprType::RowsAtCompileTime) && (BlockCols==1) && i<xpr.cols())));
    281       init();
    282     }
    283 
    284     /** Fixed-size constructor
    285       */
    286     inline Block(XprType& xpr, Index startRow, Index startCol)
    287       : Base(internal::const_cast_ptr(&xpr.coeffRef(startRow,startCol))), m_xpr(xpr)
    288     {
    289       eigen_assert(startRow >= 0 && BlockRows >= 1 && startRow + BlockRows <= xpr.rows()
    290              && startCol >= 0 && BlockCols >= 1 && startCol + BlockCols <= xpr.cols());
    291       init();
    292     }
    293 
    294     /** Dynamic-size constructor
    295       */
    296     inline Block(XprType& xpr,
    297           Index startRow, Index startCol,
    298           Index blockRows, Index blockCols)
    299       : Base(internal::const_cast_ptr(&xpr.coeffRef(startRow,startCol)), blockRows, blockCols),
    300         m_xpr(xpr)
    301     {
    302       eigen_assert((RowsAtCompileTime==Dynamic || RowsAtCompileTime==blockRows)
    303              && (ColsAtCompileTime==Dynamic || ColsAtCompileTime==blockCols));
    304       eigen_assert(startRow >= 0 && blockRows >= 0 && startRow + blockRows <= xpr.rows()
    305              && startCol >= 0 && blockCols >= 0 && startCol + blockCols <= xpr.cols());
    306       init();
    307     }
    308 
    309     const typename internal::remove_all<typename XprType::Nested>::type& nestedExpression() const
    310     {
    311       return m_xpr;
    312     }
    313 
    314     /** \sa MapBase::innerStride() */
    315     inline Index innerStride() const
    316     {
    317       return internal::traits<Block>::HasSameStorageOrderAsXprType
    318              ? m_xpr.innerStride()
    319              : m_xpr.outerStride();
    320     }
    321 
    322     /** \sa MapBase::outerStride() */
    323     inline Index outerStride() const
    324     {
    325       return m_outerStride;
    326     }
    327 
    328   #ifndef __SUNPRO_CC
    329   // FIXME sunstudio is not friendly with the above friend...
    330   // META-FIXME there is no 'friend' keyword around here. Is this obsolete?
    331   protected:
    332   #endif
    333 
    334     #ifndef EIGEN_PARSED_BY_DOXYGEN
    335     /** \internal used by allowAligned() */
    336     inline Block(XprType& xpr, const Scalar* data, Index blockRows, Index blockCols)
    337       : Base(data, blockRows, blockCols), m_xpr(xpr)
    338     {
    339       init();
    340     }
    341     #endif
    342 
    343   protected:
    344     void init()
    345     {
    346       m_outerStride = internal::traits<Block>::HasSameStorageOrderAsXprType
    347                     ? m_xpr.outerStride()
    348                     : m_xpr.innerStride();
    349     }
    350 
    351     typename XprType::Nested m_xpr;
    352     Index m_outerStride;
    353 };
    354 
    355 } // end namespace Eigen
    356 
    357 #endif // EIGEN_BLOCK_H
    358