seqan3::detail::pairwise_combine_view< underlying_range_type >::basic_iterator< range_type > Class Template Reference

The forward declared iterator type for pairwise_combine_view. More...

#include <seqan3/utility/views/pairwise_combine.hpp>

Inheritance diagram for seqan3::detail::pairwise_combine_view< underlying_range_type >::basic_iterator< range_type >:

Public Types
Associated types
using	difference_type = std::ptrdiff_t
	The difference type.
using	value_type = std::tuple< underlying_val_t, underlying_val_t >
	The value type.
using	reference = common_tuple< underlying_ref_t, underlying_ref_t >
	The reference type.
using	pointer = void
	The pointer type.
using	iterator_concept = detail::iterator_concept_tag_t< underlying_iterator_type >
	The iterator concept tag.
Public Types inherited from seqan3::detail::maybe_iterator_category< std::ranges::iterator_t< range_type > >
using	iterator_category = MAYBE_PRESENT(std::iterator_traits< std::ranges::iterator_t< range_type > >::iterator_category)
	The iterator category tag. (not always present!)

Public Member Functions
Constructors, destructor and assignment
	basic_iterator ()=default
	Defaulted.
	basic_iterator (basic_iterator const &)=default
	Defaulted.
	basic_iterator (basic_iterator &&)=default
	Defaulted.
basic_iterator &	operator= (basic_iterator const &)=default
	Defaulted.
basic_iterator &	operator= (basic_iterator &&)=default
	Defaulted.
	~basic_iterator ()=default
	Defaulted.
constexpr	basic_iterator (underlying_iterator_type iter, underlying_iterator_type begin_it, underlying_iterator_type end_it) noexcept
	Constructs the iterator from the current underlying iterator and the end iterator of the underlying range.
template<typename other_range_type > requires std::convertible_to<other_range_type, range_type &> && std::same_as<std::remove_const_t<other_range_type>, std::remove_const_t<range_type>>
constexpr	basic_iterator (basic_iterator< other_range_type > other) noexcept
	Constructs const iterator from non-const iterator.
Accessors
constexpr reference	operator* () const noexcept(noexcept(*std::declval< underlying_iterator_type >()))
	Accesses the pointed-to element.
constexpr reference	operator[] (size_t const index) const noexcept(noexcept(std::declval< basic_iterator & >().from_index(1)))
	Access the element at the given index.
Comparison operators
These operators are available if the underlying_iterator_type models std::equality_comparable or std::totally_ordered respectively.
template<typename other_range_type > requires std::equality_comparable_with<underlying_iterator_type, std::ranges::iterator_t<other_range_type>> && std::same_as<std::remove_const_t<range_type>, std::remove_const_t<other_range_type>>
constexpr bool	operator== (basic_iterator< other_range_type > const &rhs) const noexcept(noexcept(std::declval< underlying_iterator_type & >()==std::declval< underlying_iterator_type & >()))
	Checks whether *this is equal to rhs.
template<typename other_range_type > requires std::equality_comparable_with<underlying_iterator_type, std::ranges::iterator_t<other_range_type>> && std::same_as<std::remove_const_t<range_type>, std::remove_const_t<other_range_type>>
constexpr bool	operator!= (basic_iterator< other_range_type > const &rhs) const noexcept(noexcept(std::declval< underlying_iterator_type & >() !=std::declval< underlying_iterator_type & >()))
	Checks whether *this is not equal to rhs.
template<typename other_range_type > requires std::totally_ordered_with<underlying_iterator_type, std::ranges::iterator_t<other_range_type>> && std::same_as<std::remove_const_t<range_type>, std::remove_const_t<other_range_type>>
constexpr bool	operator< (basic_iterator< other_range_type > const &rhs) const noexcept(noexcept(std::declval< underlying_iterator_type & >()< std::declval< underlying_iterator_type & >()))
	Checks whether *this is less than rhs.
template<typename other_range_type > requires std::totally_ordered_with<underlying_iterator_type, std::ranges::iterator_t<other_range_type>> && std::same_as<std::remove_const_t<range_type>, std::remove_const_t<other_range_type>>
constexpr bool	operator> (basic_iterator< other_range_type > const &rhs) const noexcept(noexcept(std::declval< underlying_iterator_type & >() > std::declval< underlying_iterator_type & >()))
	Checks whether *this is greater than rhs.
template<typename other_range_type > requires std::totally_ordered_with<underlying_iterator_type, std::ranges::iterator_t<other_range_type>> && std::same_as<std::remove_const_t<range_type>, std::remove_const_t<other_range_type>>
constexpr bool	operator<= (basic_iterator< other_range_type > const &rhs) const noexcept(noexcept(std::declval< underlying_iterator_type & >()<=std::declval< underlying_iterator_type & >()))
	Checks whether *this is less than or equal to rhs.
template<typename other_range_type > requires std::totally_ordered_with<underlying_iterator_type, std::ranges::iterator_t<other_range_type>> && std::same_as<std::remove_const_t<range_type>, std::remove_const_t<other_range_type>>
constexpr bool	operator>= (basic_iterator< other_range_type > const &rhs) const noexcept(noexcept(std::declval< underlying_iterator_type & >() >=std::declval< underlying_iterator_type & >()))
	Checks whether *this is greater than or equal to rhs.

Private Types
using	underlying_iterator_type = std::ranges::iterator_t< range_type >
	Alias type for the iterator over the passed range type.
using	underlying_ref_t = std::iter_reference_t< underlying_iterator_type >
	Alias for the reference type of the underlying iterator type.
using	underlying_val_t = std::iter_value_t< underlying_iterator_type >
	Alias for the value type of the underlying iterator type.

Private Member Functions
constexpr void	from_index (size_t const index) noexcept(noexcept(std::declval< underlying_iterator_type & >() - std::declval< underlying_iterator_type & >()) &&noexcept(std::declval< underlying_iterator_type & >()+1))
	Sets the iterator to the given index.
constexpr size_t	to_index () const noexcept(noexcept(std::declval< underlying_iterator_type & >() - std::declval< underlying_iterator_type & >()))
	Returns the index for the current iterator position.

Private Attributes
underlying_iterator_type	begin_it {}
	The begin of the underlying range.
underlying_iterator_type	end_it {}
	The end of the underlying range.
underlying_iterator_type	first_it {}
	The iterator pointing to the first element of the pairwise combination.
underlying_iterator_type	second_it {}
	The iterator pointing to the second element of the pairwise combination.

Friends
template<typename other_range_type >
class	basic_iterator
	Friend declaration for iterator with different range const-ness.

Arithmetic operators
constexpr friend basic_iterator	operator+ (difference_type const offset, basic_iterator iter) noexcept(noexcept(std::declval< basic_iterator< range_type > & >().from_index(1)))
	Advances the iterator by the given offset; underlying_iterator_type must model \ std::random_access_iterator.
constexpr basic_iterator &	operator++ () noexcept(noexcept(++std::declval< underlying_iterator_type & >()))
	Pre-increment operator.
constexpr basic_iterator	operator++ (int) noexcept(noexcept(std::declval< underlying_iterator_type & >()++))
	Post-increment operator.
constexpr basic_iterator &	operator-- () noexcept(noexcept(--std::declval< underlying_iterator_type & >()))
	Pre-decrement operator; underlying_iterator_type must model std::bidirectional_iterator.
constexpr basic_iterator	operator-- (int) noexcept(noexcept(std::declval< underlying_iterator_type & >() --))
	Post-decrement operator; underlying_iterator_type must model std::bidirectional_iterator.
constexpr basic_iterator &	operator+= (difference_type const offset) noexcept(noexcept(std::declval< basic_iterator & >().from_index(1)))
	Advances the iterator by the given offset; underlying_iterator_type must model \ std::random_access_iterator.
constexpr basic_iterator	operator+ (difference_type const offset) const noexcept(noexcept(std::declval< basic_iterator & >()+=1))
	Advances the iterator by the given offset; underlying_iterator_type must model \ std::random_access_iterator.
constexpr basic_iterator &	operator-= (difference_type const offset) noexcept(noexcept(std::declval< basic_iterator & >().from_index(1)))
	Decrements the iterator by the given offset; underlying_iterator_type must model \ std::random_access_iterator.
constexpr basic_iterator	operator- (difference_type const offset) const noexcept(noexcept(std::declval< basic_iterator & >() -=1))
	Decrements the iterator by the given offset; underlying_iterator_type must model \ std::random_access_iterator.
template<typename other_range_type > requires std::random_access_iterator<underlying_iterator_type> && std::same_as<std::remove_const_t<range_type>, std::remove_const_t<other_range_type>>
constexpr difference_type	operator- (basic_iterator< other_range_type > const &rhs) const noexcept(noexcept(std::declval< basic_iterator & >().to_index()))
	Computes the distance between two iterators; underlying_iterator_type must model \ std::random_access_iterator.

Detailed Descriptionno-api

template<std::ranges::view underlying_range_type>
template<typename range_type>
requires std::ranges::forward_range<underlying_range_type> && std::ranges::common_range<underlying_range_type>
class seqan3::detail::pairwise_combine_view< underlying_range_type >::basic_iterator< range_type >

The forward declared iterator type for pairwise_combine_view.

The internal iterator type for pairwise_combine_view.

Template Parameters

range_type

The type of the range this iterator is operating on.

This iterator models the iterator category of the underlying_iterator_type. It maintains a pair of iterators on the underlying range that move over all pairwise combinations of elements. The end is reached, when the second iterator points to the end of the underlying range and the first iterator to the last element of the range. Also note that this iterator does not model Cpp17Iterator, since it does not return a reference to the represented type but a prvalue. Thus this iterator might not be usable with some legacy algorithms of the STL. But it is guaranteed to work with the ranges algorithms.

Constructor & Destructor Documentation

basic_iterator() [1/2] [no-api]

template<std::ranges::view underlying_range_type>

template<typename range_type >

constexpr seqan3::detail::pairwise_combine_view< underlying_range_type >::basic_iterator< range_type >::basic_iterator ( underlying_iterator_type  iter, underlying_iterator_type  begin_it, underlying_iterator_type  end_it  )

no-apiinlineconstexprnoexcept

Constructs the iterator from the current underlying iterator and the end iterator of the underlying range.

Parameters

[in]	iter	The iterator pointing to current element within the underlying range.
[in]	begin_it	The iterator pointing to begin of the underlying range. Only needed if underlying_iterator_type models std::random_access_iterator.
[in]	end_it	The iterator pointing to end of the underlying range.

Constructs the iterator by caching the end of the underlying range and setting the first iterator to the given position and the second to the first incremented by one.

basic_iterator() [2/2] [no-api]

template<std::ranges::view underlying_range_type>

template<typename range_type >

template<typename other_range_type >
requires std::convertible_to<other_range_type, range_type &> && std::same_as<std::remove_const_t<other_range_type>, std::remove_const_t<range_type>>

constexpr seqan3::detail::pairwise_combine_view< underlying_range_type >::basic_iterator< range_type >::basic_iterator ( basic_iterator< other_range_type >  other )

no-apiinlineconstexprnoexcept

Constructs const iterator from non-const iterator.

Parameters

[in]

other

The non-const iterator to construct from.

Allows construction of a const iterator (operating on a const range) from a non-const iterator. This special constructor is needed as it is not covered by the standard copy and move constructors.

Member Function Documentation

from_index() [no-api]

template<std::ranges::view underlying_range_type>

template<typename range_type >

constexpr void seqan3::detail::pairwise_combine_view< underlying_range_type >::basic_iterator< range_type >::from_index ( size_t const  index )

no-apiinlineconstexprprivatenoexcept

Sets the iterator to the given index.

Parameters

[in]

index

The index to set the iterator to.

The pairwise combination can also be seen as a triangular matrix, where given a size n the corresponding matrix has values in [0, 1], [0, 2], ... , [0, n - 1], [1, 2], ..., [1, n - 1], ... [n - 2, n - 1] and all other entries are empty. Using this scheme one can use the properties of triangular numbers, where the diagonal index of this matrix can be computed using triangular roots (see https://stackoverflow.com/questions/27086195/linear-index-upper-triangular-matrix). Given these properties, one can compute the matrix index (i, j) from the linearised matrix index and vice versa.

operator[]() [no-api]

template<std::ranges::view underlying_range_type>

template<typename range_type >

constexpr reference seqan3::detail::pairwise_combine_view< underlying_range_type >::basic_iterator< range_type >::operator[] ( size_t const  index ) const

no-apiinlineconstexprnoexcept

Access the element at the given index.

Parameters

[in]

index

The index of the element to be returned.

to_index() [no-api]

template<std::ranges::view underlying_range_type>

template<typename range_type >

constexpr size_t seqan3::detail::pairwise_combine_view< underlying_range_type >::basic_iterator< range_type >::to_index ( ) const

no-apiinlineconstexprprivatenoexcept

Returns the index for the current iterator position.

The pairwise combination can also be seen as a triangular matrix, where given a size n the corresponding matrix has values in [0, 1], [0, 2], ... , [0, n - 1], [1, 2], ..., [1, n - 1], ... [n - 2, n - 1] and all other entries are empty. Using this scheme one can use the properties of triangular numbers, where the diagonal index of this matrix can be computed using triangular roots (see https://stackoverflow.com/questions/27086195/linear-index-upper-triangular-matrix). Given these properties, one can compute the matrix index (i, j) from the linearised matrix index and vice versa.

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

• pairwise_combine.hpp