seqan3::detail::random_access_iterator_base< range_type, derived_t_template, args_t > Class Template Reference

A CRTP base template for creating random access iterators. More...

#include <seqan3/core/range/detail/random_access_iterator.hpp>

Inheritance diagram for seqan3::detail::random_access_iterator_base< range_type, derived_t_template, args_t >:

Public Types
using	const_reference = typename range_type::const_reference
	Use const reference type provided by container.
using	difference_type = typename range_type::difference_type
	Type for distances between iterators.
using	iterator_category = std::random_access_iterator_tag
	Tag this class as a random access iterator.
using	pointer = value_type *
	Pointer type is pointer of container element type.
using	reference = std::conditional_t< std::is_const_v< range_type >, typename range_type::const_reference, typename range_type::reference >
	Use reference type defined by container.
using	value_type = typename range_type::value_type
	Value type of container elements.

Public Member Functions
Constructors/Destructors
constexpr	random_access_iterator_base ()=default
	Default constructor.
constexpr	random_access_iterator_base (random_access_iterator_base const &)=default
	Copy constructor.
constexpr random_access_iterator_base &	operator= (random_access_iterator_base const &)=default
	Copy construction via assignment.
constexpr	random_access_iterator_base (random_access_iterator_base &&)=default
	Move constructor.
constexpr random_access_iterator_base &	operator= (random_access_iterator_base &&)=default
	Move assignment.
	~random_access_iterator_base ()=default
	Use default deconstructor.
constexpr	random_access_iterator_base (range_type &host) noexcept
	Construct by host, default position pointer with 0.
constexpr	random_access_iterator_base (range_type &host, position_type const pos) noexcept
	Construct by host and explicit position.
template<typename range_type2 > requires std::is_const_v<range_type> && (!std::is_const_v<range_type2>) && std::is_same_v<std::remove_const_t<range_type>, range_type2>
constexpr	random_access_iterator_base (random_access_iterator_base< range_type2, derived_t_template > const &rhs) noexcept
	Constructor for const version from non-const version.
Comparison operators
Compare iterators by position. seqan3::detail::random_access_iterator_base operators are used unless specialised in derived type.
template<typename range_type2 > requires std::is_same_v<std::remove_const_t<range_type>, std::remove_const_t<range_type2>>
constexpr bool	operator== (random_access_iterator_base< range_type2, derived_t_template > const &rhs) const noexcept
	Checks whether *this is equal to rhs.
template<typename range_type2 > requires std::is_same_v<std::remove_const_t<range_type>, std::remove_const_t<range_type2>>
constexpr bool	operator!= (random_access_iterator_base< range_type2, derived_t_template > const &rhs) const noexcept
	Checks whether *this is not equal to rhs.
template<typename range_type2 > requires std::is_same_v<std::remove_const_t<range_type>, std::remove_const_t<range_type2>>
constexpr bool	operator< (random_access_iterator_base< range_type2, derived_t_template > const &rhs) const noexcept
	Checks whether *this is less than rhs.
template<typename range_type2 > requires std::is_same_v<std::remove_const_t<range_type>, std::remove_const_t<range_type2>>
constexpr bool	operator> (random_access_iterator_base< range_type2, derived_t_template > const &rhs) const noexcept
	Checks whether *this is greater than rhs.
template<typename range_type2 > requires std::is_same_v<std::remove_const_t<range_type>, std::remove_const_t<range_type2>>
constexpr bool	operator<= (random_access_iterator_base< range_type2, derived_t_template > const &rhs) const noexcept
	Checks whether *this is less than or equal to rhs.
template<typename range_type2 > requires std::is_same_v<std::remove_const_t<range_type>, std::remove_const_t<range_type2>>
constexpr bool	operator>= (random_access_iterator_base< range_type2, derived_t_template > const &rhs) const noexcept
	Checks whether *this is greater than or equal to rhs.
Reference/Dereference operators
seqan3::detail::random_access_iterator_base operators are used unless specialised in derived type.
constexpr reference	operator* () const noexcept(noexcept((*host)[pos]))
	Dereference operator returns element currently pointed at.
constexpr pointer	operator-> () const noexcept(noexcept((&host)[pos]))
	Return pointer to this iterator.
constexpr reference	operator[] (position_type const n) const noexcept(noexcept((*host)[pos+n]))
	Return underlying container value currently pointed at.

Protected Types
using	derived_t = derived_t_template< range_type >
	Because this is CRTP, we know the full derived type:
using	position_type = std::make_unsigned_t< typename range_type::difference_type >
	Use container's size_type as a position.

Protected Attributes
std::add_pointer_t< range_type >	host {nullptr}
	Iterator stores pointer to underlying container structure.
position_type	pos {static_cast<position_type>(0)}
	Store position index for container.

Private Member Functions
constexpr derived_t *	this_derived ()
	Cast this to derived type.
constexpr derived_t const *	this_derived () const
	Cast this to derived type.

Friends
template<typename range_type2 , template< typename... > typename derived_t_template2, typename... args2_t>
class	random_access_iterator_base
	This friend declaration is required to allow non-const to const-construction.

Arithmetic operators
seqan3::detail::random_access_iterator_base operators are used unless specialised in derived type.
constexpr friend derived_t	operator+ (difference_type const skip, derived_t const &it) noexcept
	Non-member operator+ delegates to non-friend operator+.
constexpr friend derived_t	operator- (difference_type const skip, derived_t const &it) noexcept
	Non-member operator- delegates to non-friend operator-.
constexpr friend difference_type	operator- (derived_t const &lhs, derived_t const &rhs) noexcept
	Return offset between this and remote iterator's position.
constexpr derived_t &	operator++ () noexcept
	Pre-increment, return updated iterator.
constexpr derived_t	operator++ (int) noexcept
	Post-increment, return previous iterator state.
constexpr derived_t &	operator-- () noexcept
	Pre-decrement, return updated iterator.
constexpr derived_t	operator-- (int) noexcept
	Post-decrement, return previous iterator state.
constexpr derived_t &	operator+= (difference_type const skip) noexcept
	Forward this iterator.
constexpr derived_t	operator+ (difference_type const skip) const noexcept
	Forward copy of this iterator.
constexpr derived_t &	operator-= (difference_type const skip) noexcept
	Decrement iterator by skip.
constexpr derived_t	operator- (difference_type const skip) const noexcept
	Return decremented copy of this iterator.

Detailed Description

template<typename range_type, template< typename... > typename derived_t_template, typename... args_t>
class seqan3::detail::random_access_iterator_base< range_type, derived_t_template, args_t >

A CRTP base template for creating random access iterators.

Template Parameters

range_type	The data structure on which the iterator operates, e.g. std::vector<int>.
derived_t_template	The derived type template, see below.

The iterator makes certain assumptions on the range_type, but does not formally require it to satisfy the std::ranges::random_access_range, because the iterator itself may be a requirement for this.

Actual functionality of this iterator is realised via the host range's [] operator and member type definitions, i.e. you need to implement these in the range before you can make use of this iterator.

Since the CRTP parameter is in fact a template template, CRTP instantiation looks a little different, e.g.:

// SPDX-FileCopyrightText: 2006-2025 Knut Reinert & Freie Universität Berlin
// SPDX-FileCopyrightText: 2016-2025 Knut Reinert & MPI für molekulare Genetik
// SPDX-License-Identifier: CC0-1.0
 
#include <seqan3/core/range/detail/random_access_iterator.hpp>
 
template <typename range_type>
class my_random_access_iterator :
    public seqan3::detail::random_access_iterator_base<range_type, seqan3::detail::random_access_iterator>
{
    //...
};
 
int main()
{}

Member Function Documentation

this_derived()

template<typename range_type , template< typename... > typename derived_t_template, typename... args_t>

constexpr derived_t const * seqan3::detail::random_access_iterator_base< range_type, derived_t_template, args_t >::this_derived ( ) const

inlineconstexprprivate

Cast this to derived type.

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

• random_access_iterator.hpp