densematrix.h

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#pragma once
#include <vector>
#include "predicate.h"
 
namespace dg
{
 
// The rationale for having this class is so that a std::vector of pointers
// is recognised as a matrix type rather than a recursive vector
// in blas2 functions
 
template<class ContainerType>
struct DenseMatrix
{
    using container_type = ContainerType;
    DenseMatrix() = default;
    DenseMatrix( const std::vector<const ContainerType*>& columns) :
        m_matrix( columns), m_num_cols(columns.size()) {}
    DenseMatrix( const std::vector<const ContainerType*>& columns, unsigned num_cols) :
        m_matrix( columns), m_num_cols(num_cols) {}
 
    unsigned num_cols() const{
        return m_num_cols;
    }
    const ContainerType * operator[] ( unsigned idx) const
    {
        return m_matrix[idx];
    }
    const std::vector<const ContainerType*>& get() const{ return m_matrix;}
    // Should we delte copy and assignment ?
 
    private:
    const std::vector<const ContainerType*>& m_matrix;
    unsigned m_num_cols;
};
template <class Container>
struct TensorTraits<DenseMatrix<Container> >
{
    using value_type  = get_value_type<Container>;
    using execution_policy = get_execution_policy<Container>;
    using tensor_category = DenseMatrixTag;
};
 
 
template<class ContainerType>
auto asDenseMatrix( const std::vector<const ContainerType*>& in)
{
    // TODO could be marked deprecated because with C++17 the compiler can figure out the type of DenseMatrix
    return DenseMatrix<ContainerType>(in);
}
 
 
template<class ContainerType>
auto asDenseMatrix( const std::vector<const ContainerType*>& in, unsigned size)
{
    // TODO could be marked deprecated because with C++17 the compiler can figure out the type of DenseMatrix
    return DenseMatrix<ContainerType>(in, size);
}
 
template<class ContainerType>
std::vector<const ContainerType*> asPointers( const std::vector<ContainerType>& in)
{
    std::vector<const ContainerType*> ptrs( in.size(), nullptr);
    for( unsigned i=0; i<ptrs.size(); i++)
        ptrs[i] = &in[i];
    return ptrs;
}
 
} // namespace dg