/usr/include/dune/geometry/typeindex.hh is in libdune-geometry-dev 2.5.1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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// vi: set et ts=4 sw=2 sts=2:
#ifndef DUNE_GEOMETRY_TYPEINDEX_HH
#define DUNE_GEOMETRY_TYPEINDEX_HH
/**
* \file
* \brief Helper classes to provide indices for geometrytypes for use in a
* vector
*/
#include <cstddef>
#include "type.hh"
namespace Dune
{
//! Compute per-dimension indices for geometry types
class LocalGeometryTypeIndex
{
/**
* \brief Compute the number of regular geometry types for the given dimension
*
* Regular geometry type are those which have a topologyId, i.e. "None" is
* not a regular geometry type.
*/
inline static constexpr std::size_t regular_size(std::size_t dim)
{
// The following expression is derived from the expression for
// GlobalGeometryTypeIndex::regular_offset(). Subtracting
// regular_offset(dim+1)-regular_offset(dim) we get:
//
// ((1 << dim+1) >> 1) - ((1 << dim) >> 1)
//
// We always have
//
// dim >= 0,
//
// so
//
// (1 << dim+1) >= 2 and (1 << dim+2) % 2 == 0.
//
// So if we apply a single right-shift to that, we will never lose any
// set bits, thus
//
// ((1 << dim+1) >> 1) == (1 << dim)
return (1 << dim) - ((1 << dim) >> 1);
}
public:
/**
* \brief Compute total number of geometry types for the given dimension
*
* This includes irregular geometry types such as "None".
*/
inline static constexpr std::size_t size(std::size_t dim)
{
// one for "none"
return regular_size(dim) + 1;
}
/**
* \brief Compute the index for the given geometry type within its dimension
*
* Geometry types from different dimensions my get the same index. If that
* is not what you want, maybe you should look at GlobalGeometryTypeIndex.
*/
inline static std::size_t index(const GeometryType >)
{
if(gt.isNone())
{
return regular_size(gt.dim());
}
else
{
return gt.id() >> 1;
}
}
//! compute the geometry type for the given local index and dimension
inline static GeometryType type(std::size_t dim, std::size_t index) {
if(index == regular_size(dim)) {
GeometryType gt;
gt.makeNone(dim);
return gt;
}
else {
// the cast to unsigned makes sure this is interpreted as the topology
// ID constructor
return GeometryType(unsigned(index << 1), dim);
}
}
};
//! Compute indices for geometry types, taking the dimension into account
class GlobalGeometryTypeIndex
{
/**
* \brief Compute the starting index for a given dimension ignoring
* irregular geometry types
*
* This ignores irregular geometry types so it is not useful in itself.
* Have a look at offset() which does include the irregular geometry types.
*/
inline static constexpr std::size_t regular_offset(std::size_t dim)
{
// The number of regular geometry types in a given dimension is
// 2^(dim-1). For dim==0 this would yield 1/2 geometry types (which is
// obviously bogus, dim==0 has one regular geometry type, the point).
// The following expression relies on 1 >> 1 == 0 to treat dim==0
// specially.
return (1 << dim) >> 1;
}
public:
/**
* \brief Compute the starting index for a given dimension including
* irregular geometry types
*/
inline static constexpr std::size_t offset(std::size_t dim)
{
// dim times "none"
return regular_offset(dim) + dim;
}
/**
* \brief Compute total number of geometry types up to and including the
* given dimension
*
* This includes irregular geometry types such as "None".
*/
inline static constexpr std::size_t size(std::size_t maxdim)
{
return offset(maxdim+1);
}
/**
* \brief Compute the index for the given geometry type over all dimensions
*
* Geometry types from different dimensions will get different indices,
* and lower dimensions will always have lower indices than higher
* dimensions. If that is not what you want, maybe you should look at
* LocalGeometryTypeIndex.
*/
inline static std::size_t index(const GeometryType >)
{
return offset(gt.dim()) + LocalGeometryTypeIndex::index(gt);
}
};
} // namespace Dune
#endif // DUNE_GEOMETRY_TYPEINDEX_HH
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