Reference documentation for deal.II version GIT relicensing-43-g3fc2fae7c3 2024-03-03 21:10:02+00:00
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Public Types | Public Member Functions | Protected Attributes | List of all members
SparsityPatternIterators::Iterator Class Reference

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

Inheritance diagram for SparsityPatternIterators::Iterator:
Inheritance graph
[legend]

Public Types

using size_type = types::global_dof_index
 
using container_pointer_type = SparsityPattern *
 
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 SparsityPattern *sp, const std::size_t linear_index)
 
 Iterator (const Accessor &accessor)
 
Iteratoroperator++ ()
 
Iterator operator++ (int)
 
Iteratoroperator-- ()
 
Iterator operator-- (int)
 
Iterator operator+ (const difference_type n) const
 
Iterator operator- (const difference_type n) const
 
difference_type operator- (const Iterator &p) const
 
Iteratoroperator+= (const difference_type n)
 
Iteratoroperator-= (const difference_type n)
 
reference operator* () const
 
pointer operator-> () const
 
std::enable_if_t< std::is_convertible_v< OtherIterator, Iterator >, booloperator== (const OtherIterator &right) const
 
std::enable_if_t< std::is_convertible_v< OtherIterator, Iterator >, booloperator!= (const OtherIterator &right) 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 SparsityPattern 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 279 of file sparsity_pattern.h.

Member Typedef Documentation

◆ size_type

Size type.

Definition at line 285 of file sparsity_pattern.h.

◆ container_pointer_type

Type of the stored pointer.

Definition at line 290 of file sparsity_pattern.h.

◆ iterator_category

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

Iterator category.

Definition at line 147 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 154 of file linear_index_iterator.h.

◆ difference_type

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

Difference type.

Definition at line 159 of file linear_index_iterator.h.

◆ reference

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

Reference type.

Definition at line 164 of file linear_index_iterator.h.

◆ pointer

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

Pointer type.

Definition at line 169 of file linear_index_iterator.h.

Constructor & Destructor Documentation

◆ Iterator() [1/2]

SparsityPatternIterators::Iterator::Iterator ( const SparsityPattern sp,
const std::size_t  linear_index 
)

Constructor. Create an iterator into the sparsity pattern sp for the given global index (i.e., the index of the given element counting from the zeroth row).

◆ Iterator() [2/2]

SparsityPatternIterators::Iterator::Iterator ( const Accessor accessor)

Constructor. Create an iterator into the sparsity pattern sp for a given accessor.

Member Function Documentation

◆ operator++() [1/2]

Iterator & LinearIndexIterator< Iterator , Accessor >::operator++ ( )
inlineinherited

Prefix increment.

Definition at line 186 of file linear_index_iterator.h.

◆ operator++() [2/2]

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

Postfix increment.

Definition at line 192 of file linear_index_iterator.h.

◆ operator--() [1/2]

Iterator & LinearIndexIterator< Iterator , Accessor >::operator-- ( )
inlineinherited

Prefix decrement.

Definition at line 198 of file linear_index_iterator.h.

◆ operator--() [2/2]

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

Postfix decrement.

Definition at line 204 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 210 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 216 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 237 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 222 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 228 of file linear_index_iterator.h.

◆ operator*()

LinearIndexIterator< Iterator , Accessor >::reference LinearIndexIterator< Iterator , Accessor >::operator* ( ) const
inlineinherited

Dereferencing operator.

Definition at line 243 of file linear_index_iterator.h.

◆ operator->()

LinearIndexIterator< Iterator , Accessor >::pointer LinearIndexIterator< Iterator , Accessor >::operator-> ( ) const
inlineinherited

Dereferencing operator.

Definition at line 249 of file linear_index_iterator.h.

◆ operator==()

std::enable_if_t< std::is_convertible_v< OtherIterator, Iterator >, bool > LinearIndexIterator< Iterator , Accessor >::operator== ( const OtherIterator &  right) const
inlineinherited

Comparison operator. Returns true if both iterators point to the same entry in the same container.

Definition at line 257 of file linear_index_iterator.h.

◆ operator!=()

std::enable_if_t< std::is_convertible_v< OtherIterator, Iterator >, bool > LinearIndexIterator< Iterator , Accessor >::operator!= ( const OtherIterator &  right) const
inlineinherited

Opposite of operator==().

Definition at line 268 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 280 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 291 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 300 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 308 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 325 of file linear_index_iterator.h.


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