SparsityPatternIterators::Iterator Class Reference

#include <deal.II/lac/sparsity_pattern.h>

Inheritance diagram for SparsityPatternIterators::Iterator:

Public Types
using	size_type = types::global_dof_index
using	container_pointer_type = SparsityPatternBase *
using	iterator_category = std::random_access_iterator_tag
using	value_type = Accessor
using	difference_type = std::ptrdiff_t
using	reference = const value_type &
using	pointer = const value_type *

Public Member Functions
	Iterator (const SparsityPatternBase *sp, const std::size_t linear_index)
	Iterator (const Accessor &accessor)
Iterator &	operator++ ()
Iterator	operator++ (int)
Iterator &	operator-- ()
Iterator	operator-- (int)
Iterator	operator+ (const difference_type n) const
Iterator	operator- (const difference_type n) const
difference_type	operator- (const Iterator &p) const
Iterator &	operator+= (const difference_type n)
Iterator &	operator-= (const difference_type n)
reference	operator* () const
pointer	operator-> () const
bool	operator<= (const Iterator &) const
bool	operator>= (const Iterator &) const
bool	operator< (const Iterator &) const
bool	operator> (const Iterator &) const

Protected Attributes
Accessor	accessor

Detailed Description

An iterator class for walking over the elements of a sparsity pattern.

The typical use for these iterators is to iterate over the elements of a sparsity pattern (or, since they also serve as the basis for iterating over the elements of an associated matrix, over the elements of a sparse matrix), or over the elements of individual rows. There is no guarantee that the elements of a row are actually traversed in an order in which column numbers monotonically increase. See the documentation of the SparsityPattern class for more information.

Note

This class operates directly on the internal data structures of the SparsityPatternBase class. As a consequence, some operations are cheap and some are not. In particular, it is cheap to access the column index of the sparsity pattern entry pointed to. On the other hand, it is expensive to access the row index (this requires \(O(\log(N))\) operations for a matrix with \(N\) row). As a consequence, when you design algorithms that use these iterators, it is common practice to not loop over all elements of a sparsity pattern at once, but to have an outer loop over all rows and within this loop iterate over the elements of this row. This way, you only ever need to dereference the iterator to obtain the column indices whereas the (expensive) lookup of the row index can be avoided by using the loop index instead.

Definition at line 278 of file sparsity_pattern.h.

Member Typedef Documentation

iterator_category

using LinearIndexIterator< Iterator , Accessor >::iterator_category = std::random_access_iterator_tag

inherited

Iterator category.

Definition at line 145 of file linear_index_iterator.h.

value_type

using LinearIndexIterator< Iterator , Accessor >::value_type = Accessor

inherited

An alias for the type you get when you dereference an iterator of the current kind.

Definition at line 151 of file linear_index_iterator.h.

difference_type

using LinearIndexIterator< Iterator , Accessor >::difference_type = std::ptrdiff_t

inherited

Difference type.

Definition at line 156 of file linear_index_iterator.h.

reference

using LinearIndexIterator< Iterator , Accessor >::reference = const value_type &

inherited

Reference type.

Definition at line 161 of file linear_index_iterator.h.

pointer

using LinearIndexIterator< Iterator , Accessor >::pointer = const value_type *

inherited

Pointer type.

Definition at line 166 of file linear_index_iterator.h.

Member Function Documentation

operator++() [1/2]

Iterator & LinearIndexIterator< Iterator , Accessor >::operator++

inlineinherited

Prefix increment.

Definition at line 183 of file linear_index_iterator.h.

operator++() [2/2]

Iterator LinearIndexIterator< Iterator , Accessor >::operator++ ( int  )

inlineinherited

Postfix increment.

Definition at line 189 of file linear_index_iterator.h.

operator--() [1/2]

Iterator & LinearIndexIterator< Iterator , Accessor >::operator--

inlineinherited

Prefix decrement.

Definition at line 195 of file linear_index_iterator.h.

operator--() [2/2]

Iterator LinearIndexIterator< Iterator , Accessor >::operator-- ( int  )

inlineinherited

Postfix decrement.

Definition at line 201 of file linear_index_iterator.h.

operator+()

Iterator LinearIndexIterator< Iterator , Accessor >::operator+ ( const difference_type  n ) const

inlineinherited

Return an iterator that is n entries ahead of the current one.

Definition at line 207 of file linear_index_iterator.h.

operator-() [1/2]

Iterator LinearIndexIterator< Iterator , Accessor >::operator- ( const difference_type  n ) const

inlineinherited

Return an iterator that is n entries behind the current one.

Definition at line 213 of file linear_index_iterator.h.

operator-() [2/2]

LinearIndexIterator< Iterator , Accessor >::difference_type LinearIndexIterator< Iterator , Accessor >::operator- ( const Iterator &  p ) const

inlineinherited

Return the distance between the current iterator and the argument. The distance is given by how many times one has to apply operator++() to the current iterator to get the argument (for a positive return value), or operator--() (for a negative return value).

Definition at line 234 of file linear_index_iterator.h.

operator+=()

Iterator & LinearIndexIterator< Iterator , Accessor >::operator+= ( const difference_type  n )

inlineinherited

Increment the iterator position by n.

Definition at line 219 of file linear_index_iterator.h.

operator-=()

Iterator & LinearIndexIterator< Iterator , Accessor >::operator-= ( const difference_type  n )

inlineinherited

Decrement the iterator position by n.

Definition at line 225 of file linear_index_iterator.h.

operator*()

LinearIndexIterator< Iterator , Accessor >::reference LinearIndexIterator< Iterator , Accessor >::operator*

inlineinherited

Dereferencing operator.

Definition at line 239 of file linear_index_iterator.h.

operator->()

LinearIndexIterator< Iterator , Accessor >::pointer LinearIndexIterator< Iterator , Accessor >::operator->

inlineinherited

Dereferencing operator.

Definition at line 244 of file linear_index_iterator.h.

operator<=()

bool LinearIndexIterator< Iterator , Accessor >::operator<= ( const Iterator &  other ) const

inlineinherited

Comparison operator: uses the same ordering as operator<(), but also checks for equality.

This function is only valid if both iterators point into the same container.

Definition at line 279 of file linear_index_iterator.h.

operator>=()

bool LinearIndexIterator< Iterator , Accessor >::operator>= ( const Iterator &  other ) const

inlineinherited

Comparison operator: uses the same ordering as operator>(), but also checks for equality.

This function is only valid if both iterators point into the same container.

Definition at line 290 of file linear_index_iterator.h.

operator<()

bool LinearIndexIterator< Iterator , Accessor >::operator< ( const Iterator &  other ) const

inlineinherited

Comparison operator. Result is true if either the first row number is smaller or if the row numbers are equal and the first index is smaller.

This function is only valid if both iterators point into the same container.

Definition at line 299 of file linear_index_iterator.h.

operator>()

bool LinearIndexIterator< Iterator , Accessor >::operator> ( const Iterator &  other ) const

inlineinherited

Comparison operator. Works in the same way as operator<(), just the other way round.

Definition at line 307 of file linear_index_iterator.h.

Member Data Documentation

accessor

Accessor LinearIndexIterator< Iterator , Accessor >::accessor

protectedinherited

Store an object of the accessor class.

Definition at line 324 of file linear_index_iterator.h.

---

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

• include/deal.II/lac/sparsity_pattern.h