Patch by Gael Guennebaud: unify fixed-size and dynamic-size Block

expressions, update documentation.

Eigen/src/Core/Block.h

@@ -27,19 +27,21 @@
 
 /** \class Block
   *
-  * \brief Expression of a dynamic-size block
+  * \brief Expression of a fixed-size or dynamic-size block
   *
   * \param MatrixType the type of the object in which we are taking a block
+  * \param BlockRows the number of rows of the block we are taking at compile time (optional)
+  * \param BlockCols the number of columns of the block we are taking at compile time (optional)
   *
-  * This class represents an expression of a dynamic-size block. It is the return
-  * type of MatrixBase::block(int,int,int,int) and most of the time this is the only way it
-  * is used.
+  * This class represents an expression of either a fixed-size or dynamic-size block. It is the return
+  * type of MatrixBase::block(int,int,int,int) and MatrixBase::block<int,int>(int,int) and
+  * most of the time this is the only way it is used.
   *
-  * However, if you want to directly maniputate dynamic-size block expressions,
+  * However, if you want to directly maniputate 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 this:
+  * Here is an example illustrating the dynamic case:
   * \include class_Block.cpp
   * Output: \verbinclude class_Block.out
   *
@@ -47,10 +49,16 @@
   * has fixed size, this expression inherits a fixed maximal size which means that evaluating
   * it does not cause a dynamic memory allocation.
   *
-  * \sa MatrixBase::block(int,int,int,int), class VectorBlock
+  * Here is an example illustrating the fixed-size case:
+  * \include class_FixedBlock.cpp
+  * Output: \verbinclude class_FixedBlock.out
+  *
+  * \sa MatrixBase::block(int,int,int,int), MatrixBase::block(int,int), class VectorBlock
   */
-template<typename MatrixType> class Block
-  : public MatrixBase<typename MatrixType::Scalar, Block<MatrixType> >
+template<typename MatrixType,
+    int BlockRows/*=Dynamic*/, int BlockCols/*=Dynamic*/> class Block
+  : public MatrixBase<typename MatrixType::Scalar,
+                      Block<MatrixType, BlockRows, BlockCols> >
 {
   public:
     typedef typename MatrixType::Scalar Scalar;
@@ -58,12 +66,26 @@ template<typename MatrixType> class Block
     friend class MatrixBase<Scalar, Block>;
     typedef MatrixBase<Scalar, Block> Base;
 
+    /** Fixed-size constructor
+      */
+    Block(const MatRef& matrix, int startRow, int startCol)
+      : m_matrix(matrix), m_startRow(startRow), m_startCol(startCol)
+    {
+      assert(RowsAtCompileTime!=Dynamic && RowsAtCompileTime!=Dynamic);
+      assert(startRow >= 0 && BlockRows >= 1 && startRow + BlockRows <= matrix.rows()
+          && startCol >= 0 && BlockCols >= 1 && startCol + BlockCols <= matrix.cols());
+    }
+    
+    /** Dynamic-size constructor
+      */
     Block(const MatRef& matrix,
           int startRow, int startCol,
           int blockRows, int blockCols)
       : m_matrix(matrix), m_startRow(startRow), m_startCol(startCol),
                           m_blockRows(blockRows), m_blockCols(blockCols)
     {
+      assert((RowsAtCompileTime==Dynamic || RowsAtCompileTime==1)
+          && (ColsAtCompileTime==Dynamic || ColsAtCompileTime==1));
       assert(startRow >= 0 && blockRows >= 1 && startRow + blockRows <= matrix.rows()
           && startCol >= 0 && blockCols >= 1 && startCol + blockCols <= matrix.cols());
     }
@@ -71,11 +93,13 @@ template<typename MatrixType> class Block
     EIGEN_INHERIT_ASSIGNMENT_OPERATORS(Block)
     
   private:
-    enum {
-      RowsAtCompileTime = MatrixType::Traits::RowsAtCompileTime == 1 ? 1 : Dynamic,
-      ColsAtCompileTime = MatrixType::Traits::ColsAtCompileTime == 1 ? 1 : Dynamic,
-      MaxRowsAtCompileTime = RowsAtCompileTime == 1 ? 1 : MatrixType::Traits::MaxRowsAtCompileTime,
-      MaxColsAtCompileTime = ColsAtCompileTime == 1 ? 1 : MatrixType::Traits::MaxColsAtCompileTime
+    enum{
+      RowsAtCompileTime = MatrixType::Traits::RowsAtCompileTime == 1 ? 1 : BlockRows,
+      ColsAtCompileTime = MatrixType::Traits::ColsAtCompileTime == 1 ? 1 : BlockCols,
+      MaxRowsAtCompileTime = RowsAtCompileTime == 1 ? 1
+        : (BlockRows==Dynamic ? MatrixType::Traits::MaxRowsAtCompileTime : BlockRows),
+      MaxColsAtCompileTime = ColsAtCompileTime == 1 ? 1
+        : (BlockCols==Dynamic ? MatrixType::Traits::MaxColsAtCompileTime : BlockCols)
     };
 
     const Block& _ref() const { return *this; }
@@ -93,11 +117,10 @@ template<typename MatrixType> class Block
     }
     
   protected:
+
     MatRef m_matrix;
-    IntAtRunTimeIfDynamic<MatrixType::Traits::RowsAtCompileTime == 1 ? 0 : Dynamic>
-      m_startRow;
-    IntAtRunTimeIfDynamic<MatrixType::Traits::ColsAtCompileTime == 1 ? 0 : Dynamic>
-      m_startCol;
+    IntAtRunTimeIfDynamic<MatrixType::Traits::RowsAtCompileTime == 1 ? 0 : Dynamic> m_startRow;
+    IntAtRunTimeIfDynamic<MatrixType::Traits::ColsAtCompileTime == 1 ? 0 : Dynamic> m_startCol;
     IntAtRunTimeIfDynamic<RowsAtCompileTime> m_blockRows;
     IntAtRunTimeIfDynamic<ColsAtCompileTime> m_blockCols;
 };
@@ -116,7 +139,7 @@ template<typename MatrixType> class Block
   * when it is applied to a fixed-size matrix, it inherits a fixed maximal size,
   * which means that evaluating it does not cause a dynamic memory allocation.
   *
-  * \sa class Block, fixedBlock(int,int)
+  * \sa class Block, block(int,int)
   */
 template<typename Scalar, typename Derived>
 Block<Derived> MatrixBase<Scalar, Derived>
@@ -147,7 +170,7 @@ const Block<Derived> MatrixBase<Scalar, Derived>
   * when it is applied to a fixed-size vector, it inherits a fixed maximal size,
   * which means that evaluating it does not cause a dynamic memory allocation.
   *
-  * \sa class Block, fixedBlock(int)
+  * \sa class Block, block(int)
   */
 template<typename Scalar, typename Derived>
 Block<Derived> MatrixBase<Scalar, Derived>
@@ -293,4 +316,34 @@ const Block<Derived> MatrixBase<Scalar, Derived>
     return Block<Derived>(ref(), rows() - cRows, cols() - cCols, cRows, cCols);
 }
 
+/** \returns a fixed-size expression of a block in *this.
+  *
+  * The template parameters \a BlockRows and \a BlockCols are the number of
+  * rows and columns in the block.
+  *
+  * \param startRow the first row in the block
+  * \param startCol the first column in the block
+  *
+  * Example: \include MatrixBase_block_int_int.cpp
+  * Output: \verbinclude MatrixBase_block_int_int.out
+  *
+  * \sa class Block, block(int,int,int,int)
+  */
+template<typename Scalar, typename Derived>
+template<int BlockRows, int BlockCols>
+Block<Derived, BlockRows, BlockCols> MatrixBase<Scalar, Derived>
+  ::block(int startRow, int startCol)
+{
+  return Block<Derived, BlockRows, BlockCols>(ref(), startRow, startCol);
+}
+
+/** This is the const version of block<>(int, int). */
+template<typename Scalar, typename Derived>
+template<int BlockRows, int BlockCols>
+const Block<Derived, BlockRows, BlockCols> MatrixBase<Scalar, Derived>
+  ::block(int startRow, int startCol) const
+{
+  return Block<Derived, BlockRows, BlockCols>(ref(), startRow, startCol);
+}
+
 #endif // EIGEN_BLOCK_H

Eigen/src/Core/ForwardDeclarations.h

@@ -31,8 +31,7 @@ template<typename NewScalar, typename MatrixType> class Cast;
 template<typename MatrixType> class Row;
 template<typename MatrixType> class Column;
 template<typename MatrixType> class Minor;
-template<typename MatrixType> class Block;
-template<typename MatrixType, int BlockRows, int BlockCols> class FixedBlock;
+template<typename MatrixType, int BlockRows=Dynamic, int BlockCols=Dynamic> class Block;
 template<typename MatrixType> class Transpose;
 template<typename MatrixType> class Conjugate;
 template<typename MatrixType> class Opposite;

Eigen/src/Core/MatrixBase.h

@@ -200,9 +200,9 @@ template<typename Scalar, typename Derived> class MatrixBase
     const Block<Derived> corner(CornerType type, int cRows, int cCols) const;
 
     template<int BlockRows, int BlockCols>
-    FixedBlock<Derived, BlockRows, BlockCols> fixedBlock(int startRow, int startCol);
+    Block<Derived, BlockRows, BlockCols> block(int startRow, int startCol);
     template<int BlockRows, int BlockCols>
-    const FixedBlock<Derived, BlockRows, BlockCols> fixedBlock(int startRow, int startCol) const;
+    const Block<Derived, BlockRows, BlockCols> block(int startRow, int startCol) const;
 
     Transpose<Derived> transpose();
     const Transpose<Derived> transpose() const;