util::TensorIndices< RANK > Class Template Reference

Converts a tensor element specification into a linear index. More...

#include <TensorIndices.h>

Public Types
using	Index_t = Base_t::Index_t
	Type of a single index in the tensor. More...
using	DimSize_t = Base_t::DimSize_t
	Type for the specification of a dimension size. More...
using	LinIndex_t = Base_t::LinIndex_t
	Type of the linear index. More...
using	MinorTensor_t = TensorIndices< rank()-1 >
	Type of the tensor indices with rank smaller by one. More...

Public Member Functions
template<typename... OTHERDIMS>
	TensorIndices (DimSize_t first, OTHERDIMS...others)
	Constructor: initialises the dimension of the tensor. More...
template<typename ITER , typename = std::enable_if_t <std::is_convertible<decltype(*(ITER())), DimSize_t>::value, void>>
	TensorIndices (ITER dimIter)
	Constructor: initialises the dimension of the tensor. More...
template<typename... OTHERINDICES>
LinIndex_t	operator() (Index_t first, OTHERINDICES...others) const
	Returns the linear index corresponding to the tensor indices. More...
template<typename ITER >
std::enable_if_t < std::is_convertible < decltype(*(ITER())), DimSize_t >::value, LinIndex_t >	operator() (ITER indexIter) const
	Returns the linear index corresponding to the tensor indices. More...
template<typename... OTHERINDICES>
LinIndex_t	at (Index_t first, OTHERINDICES...others) const
	Returns the linear index corresponding to the tensor indices. More...
template<typename ITER >
std::enable_if_t < std::is_convertible < decltype(*(ITER())), DimSize_t >::value, LinIndex_t >	at (ITER indexIter) const
	Returns the linear index corresponding to the tensor indices. More...
template<typename... OTHERINDICES>
bool	has (Index_t first, OTHERINDICES...others) const
	Returns whether the specified set of indices is valid. More...
template<typename ITER >
std::enable_if_t < std::is_convertible < decltype(*(ITER())), DimSize_t >::value, bool >	has (ITER indexIter) const
	Returns whether the specified set of indices is valid. More...
template<unsigned int DIM>
DimSize_t	dim () const
	Returns the size of the specified dimension. More...
template<unsigned int DIM>
bool	hasIndex (Index_t index) const
	Returns whether a index is valid within a specified dimension. More...
template<unsigned int DIM = 0>
DimSize_t	size () const
	Returns the size of the minor tensor. More...
bool	hasLinIndex (LinIndex_t linIndex) const
	Returns whether the specified linear index is valid in this tensor. More...
MinorTensor_t const &	minorTensor () const
bool	operator== (TensorIndices< RANK > const &t) const
	Returns whether all sizes of the tensor t are the same as this one. More...
bool	operator!= (TensorIndices< RANK > const &t) const
	Returns whether any size of the tensor t is different from this one. More...

Static Public Member Functions
static constexpr unsigned int	rank ()
	Rank of this tensor. More...

Protected Member Functions
DimSize_t	totalSize () const
	Returns the total size of this tensor (the same as size()) More...

Protected Attributes
MinorTensor_t	m
	the rest of the tensor indices More...
DimSize_t	totSize
	size of this tensor More...

Private Types
using	Base_t = TensorIndices< 1U >
	type of base class More...

Friends
template<unsigned int R, unsigned int D>
struct	details::ExtractTensorDimension

Detailed Description

template<unsigned int RANK>
class util::TensorIndices< RANK >

Converts a tensor element specification into a linear index.

Example to use a 6 x 3 x 2 x 4 tensor of rank 4:

TensorIndices<4> indices(6, 3, 2, 4);

std::vector<double> v(indices.size(), 0.);
std::cout << v[indices(4, 1, 1, 0)] << std::endl;

This will map the content of the vector v as a tensor of rank 4.

Definition at line 46 of file TensorIndices.h.

Member Typedef Documentation

template<unsigned int RANK>

using util::TensorIndices< RANK >::Base_t = TensorIndices<1U>

private

type of base class

Definition at line 177 of file TensorIndices.h.

template<unsigned int RANK>

using util::TensorIndices< RANK >::DimSize_t = Base_t::DimSize_t

Type for the specification of a dimension size.

Definition at line 185 of file TensorIndices.h.

template<unsigned int RANK>

using util::TensorIndices< RANK >::Index_t = Base_t::Index_t

Type of a single index in the tensor.

Definition at line 182 of file TensorIndices.h.

template<unsigned int RANK>

using util::TensorIndices< RANK >::LinIndex_t = Base_t::LinIndex_t

Type of the linear index.

Definition at line 188 of file TensorIndices.h.

template<unsigned int RANK>

using util::TensorIndices< RANK >::MinorTensor_t = TensorIndices<rank() - 1>

Type of the tensor indices with rank smaller by one.

Definition at line 195 of file TensorIndices.h.

Constructor & Destructor Documentation

template<unsigned int RANK>

template<typename... OTHERDIMS>

util::TensorIndices< RANK >::TensorIndices ( DimSize_t  first, OTHERDIMS...  others  )

inline

Constructor: initialises the dimension of the tensor.

Template Parameters

OTHERINDICES

types of the other index values

Parameters

first	the size of the first dimension
others	size of each of the other dimensions

Example to initialise indices for a 6 x 3 x 2 x 4 tensor of rank 4:

TensorIndices<4> indices(6, 3, 2, 4);

Definition at line 211 of file TensorIndices.h.

      : Base_t(first), m(others...), totSize(dim0() * m.size()) {}

template<unsigned int RANK>

template<typename ITER , typename = std::enable_if_t <std::is_convertible<decltype(*(ITER())), DimSize_t>::value, void>>

util::TensorIndices< RANK >::TensorIndices ( ITER  dimIter )

inline

Constructor: initialises the dimension of the tensor.

Template Parameters

ITER	type of iterator to dimension sizes

Parameters

dimIter

iterator pointing to the first dimension size

Dimensions are initialised from the values pointed by the specified iterator. The iterator is required to be a forward iterator pointing to a type convertible to a DimSize_t type. The iterator must be valid when increased up to rank() - 1 times, so that all the rank() dimensions can be extracted.

Example to initialise indices for a 6 x 3 x 2 x 4 tensor of rank 4:

std::array<size_t, 4> dims { 6, 3, 2, 4 };
TensorIndices<4> indices(dims.begin());

Note that no end iterator is required.

Definition at line 240 of file TensorIndices.h.

      : Base_t(dimIter), m(++dimIter), totSize(dim0() * m.size()) {}

Member Function Documentation

template<unsigned int RANK>

template<typename... OTHERINDICES>

LinIndex_t util::TensorIndices< RANK >::at ( Index_t  first, OTHERINDICES...  others  ) const

inline

Returns the linear index corresponding to the tensor indices.

Template Parameters

OTHERINDICES

types of the other index values

Parameters

first	the index of the first dimension
others	the indices of the other dimensions

Exceptions

std::out_of_range

if any of the indices is not valid

Returns

the offset of the specified element with respect to the first one

See Also

operator()(), has()

If any of the index values is not in the valid index range, an exception is thrown.

Use it as:

TensorIndices<4> indices(6, 3, 2, 4);
auto validIndex = indices.at(4, 2, 0, 1);
auto invalidIndex = indices.at(4, 3, 2, 1); // throws std::out_of_range

(in the example, note that the last line has two indices out of range and an exception will be thrown).

Definition at line 321 of file TensorIndices.h.

      {
        return Base_t::checkOuterIndex(first) * minorTensor().size()
          + minorTensor().at(others...);
      }

template<unsigned int RANK>

template<typename ITER >

std::enable_if_t<std::is_convertible<decltype(*(ITER())), DimSize_t>::value, LinIndex_t> util::TensorIndices< RANK >::at ( ITER  indexIter ) const

inline

Returns the linear index corresponding to the tensor indices.

Template Parameters

ITER	type of iterator to dimension sizes

Parameters

indexIter

iterator pointing to the first dimension size

Exceptions

std::out_of_range

if any of the indices is not valid

Returns

the offset of the specified element with respect to the first one

See Also

operator()(), has()

If any of the index values is not in the valid index range, an exception is thrown.

Use it as:

TensorIndices<4> indices(6, 3, 2, 4);
std::array<int, 4> ix { 4, 2, 0, 1 };
auto validIndex = indices.at(ix.begin());

The behaviour is the same as in at()(Index_t first, OTHERINDICES... others).

Definition at line 351 of file TensorIndices.h.

      {
        auto const baseSize
          = Base_t::checkOuterIndex(*indexIter) * minorTensor().size();
        return baseSize + minorTensor()(++indexIter);
      }

template<unsigned int RANK>

template<unsigned int DIM>

DimSize_t util::TensorIndices< RANK >::dim ( ) const

inline

Returns the size of the specified dimension.

Template Parameters

DIM	the dimension (0 is the first one)

Returns

the size of the specified dimension

Code won't compile for DIM larger than the tensor rank.

Definition at line 424 of file TensorIndices.h.

      { return details::ExtractTensorDimension<rank(), DIM>::dim(*this); }

template<unsigned int RANK>

template<typename... OTHERINDICES>

bool util::TensorIndices< RANK >::has ( Index_t  first, OTHERINDICES...  others  ) const

inline

Returns whether the specified set of indices is valid.

Template Parameters

OTHERINDICES

types of the other index values

Parameters

first	the index of the first dimension
others	the indices of the other dimensions

Returns

whether the specified set of indices is valid

See Also

operator(), at()

If any of the index values is not in the valid index range, an exception is thrown.

Use it as:

TensorIndices<4> indices(6, 3, 2, 4);
if (indices.has(4, 2, 0, 1)) {
  // ...
}
if (indices.has(4, 3, 2, 1)) {
  // ... (won't be executed)
}

(in the example, note that the last line has two indices out of range and an exception will be thrown).

Definition at line 384 of file TensorIndices.h.

      { return Base_t::has(first) && minorTensor().has(others...); }

template<unsigned int RANK>

template<typename ITER >

std::enable_if_t<std::is_convertible<decltype(*(ITER())), DimSize_t>::value, bool> util::TensorIndices< RANK >::has ( ITER  indexIter ) const

inline

Returns whether the specified set of indices is valid.

Template Parameters

ITER	type of iterator to dimension sizes

Parameters

indexIter

iterator pointing to the first dimension size

Returns

whether the specified set of indices is valid

See Also

operator(), at()

If any of the index values is not in the valid index range, an exception is thrown.

Use it as:

TensorIndices<4> indices(6, 3, 2, 4);
std::array<int, 4> ix { 4, 2, 0, 1 };
if (indices.has(ix.begin())) {
  // ...
}

The behaviour is the same as in has()(Index_t first, OTHERINDICES... others).

Definition at line 412 of file TensorIndices.h.

      { return Base_t::has(*indexIter)? minorTensor().has(++indexIter): false; }

template<unsigned int RANK>

template<unsigned int DIM>

bool util::TensorIndices< RANK >::hasIndex ( Index_t  index ) const

inline

Returns whether a index is valid within a specified dimension.

Template Parameters

DIM	the dimension (0 is the first one)

Parameters

index

the value of the index to be tested

Returns

whether a index is valid within a specified dimension

Use it as:

TensorIndices<4> indices(6, 3, 2, 4);
if (indices.hasIndex<0>(2)) { // dimension #0 has 6 indices, [ 0 ; 5 ]
  // ... (will be executed)
}
if (indices.hasIndex<0>(6)) {
  // ... (will not be executed)
}
if (indices.hasIndex<2>(0)) { // dimension #2 has 2 indices, { 0 , 1 }
  // ... (will be executed)
}
if (indices.hasIndex<3>(6)) {// dimension #3 has 4 indices, [ 0 ; 3 ]
  // ... (will not be executed)
}

Definition at line 453 of file TensorIndices.h.

      { return (index >= 0U) && ((DimSize_t) index < dim<DIM>()); }

template<unsigned int RANK>

bool util::TensorIndices< RANK >::hasLinIndex ( LinIndex_t  linIndex ) const

inline

Returns whether the specified linear index is valid in this tensor.

Definition at line 478 of file TensorIndices.h.

      { return (linIndex >= 0U) && ((DimSize_t) linIndex < size()); }

template<unsigned int RANK>

MinorTensor_t const& util::TensorIndices< RANK >::minorTensor ( ) const

inline

Returns the tensor of rank Rank-1 from stripping the first dimension Note that the minorTensor variable was previously named "minor". However, minor is also defined in sys/types.h to mean something completely different.

Definition at line 485 of file TensorIndices.h.

{ return m; }

template<unsigned int RANK>

bool util::TensorIndices< RANK >::operator!= ( TensorIndices< RANK > const &  t ) const

inline

Returns whether any size of the tensor t is different from this one.

Definition at line 492 of file TensorIndices.h.

      { return Base_t::operator!=(t) || (minorTensor() != t.minorTensor()); }

template<unsigned int RANK>

template<typename... OTHERINDICES>

LinIndex_t util::TensorIndices< RANK >::operator() ( Index_t  first, OTHERINDICES...  others  ) const

inline

Returns the linear index corresponding to the tensor indices.

Template Parameters

OTHERINDICES

types of the other index values

Parameters

first	the index of the first dimension
others	the indices of the other dimensions

Returns

the offset of the specified element with respect to the first one

See Also

at(), has()

No check is performed on the validity of the indices (that is, whether they fall within the dimension range).

Use it as:

TensorIndices<4> indices(6, 3, 2, 4);
auto validIndex = indices(4, 2, 0, 1);
auto invalidIndex = indices(4, 3, 2, 1); // invalid index is returned!

(in the example, note that the last line has two indices out of range and the return value will not be valid!).

Definition at line 265 of file TensorIndices.h.

      { return first * minorTensor().size() + minorTensor()(others...); }

template<unsigned int RANK>

template<typename ITER >

std::enable_if_t<std::is_convertible<decltype(*(ITER())), DimSize_t>::value, LinIndex_t> util::TensorIndices< RANK >::operator() ( ITER  indexIter ) const

inline

Returns the linear index corresponding to the tensor indices.

Template Parameters

ITER	type of iterator to dimension sizes

Parameters

indexIter

iterator pointing to the first dimension size

Returns

the offset of the specified element with respect to the first one

See Also

at(), has()

No check is performed on the validity of the indices (that is, whether they fall within the dimension range).

Use it as:

TensorIndices<4> indices(6, 3, 2, 4);
std::array<int, 4> ix { 4, 2, 0, 1 };
auto validIndex = indices(ix.begin());

The behaviour is the same as in operator()(Index_t first, OTHERINDICES... others).

Definition at line 291 of file TensorIndices.h.

      {
        auto const baseSize = (*indexIter) * minorTensor().size();
        return baseSize + minorTensor()(++indexIter);
      }

template<unsigned int RANK>

bool util::TensorIndices< RANK >::operator== ( TensorIndices< RANK > const &  t ) const

inline

Returns whether all sizes of the tensor t are the same as this one.

Definition at line 488 of file TensorIndices.h.

      { return Base_t::operator==(t) && (minorTensor() == t.minorTensor()); }

template<unsigned int RANK>

static constexpr unsigned int util::TensorIndices< RANK >::rank ( )

inlinestatic

Rank of this tensor.

Definition at line 192 of file TensorIndices.h.

{ return RANK; }

template<unsigned int RANK>

template<unsigned int DIM = 0>

DimSize_t util::TensorIndices< RANK >::size ( ) const

inline

Returns the size of the minor tensor.

Template Parameters

DIM	the index of the outer dimension of the minor tensor

Returns

the size of the specified tensor

The total size of the tensor obtained after stripping the DIM most outer dimensions if returned. Therefore, size<0>() is the size of the full tensor, while size<1>() is the size of the tensor obtained by stripping the first dimension (that is, the tensor returned by minor()), and so on.

Code won't compile for DIM larger than the tensor rank.

Definition at line 471 of file TensorIndices.h.

      {
        return (DIM == 0)? totalSize():
          details::ExtractTensorDimension<rank(), DIM>::size(*this);
      }

template<unsigned int RANK>

DimSize_t util::TensorIndices< RANK >::totalSize ( ) const

inlineprotected

Returns the total size of this tensor (the same as size())

Definition at line 506 of file TensorIndices.h.

{ return totSize; }

Friends And Related Function Documentation

template<unsigned int RANK>

template<unsigned int R, unsigned int D>

friend struct details::ExtractTensorDimension

friend

Definition at line 500 of file TensorIndices.h.

Member Data Documentation

template<unsigned int RANK>

MinorTensor_t util::TensorIndices< RANK >::m

protected

the rest of the tensor indices

Definition at line 502 of file TensorIndices.h.

template<unsigned int RANK>

DimSize_t util::TensorIndices< RANK >::totSize

protected

size of this tensor

Definition at line 503 of file TensorIndices.h.

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The documentation for this class was generated from the following file:

• TensorIndices.h