etl/docs/iterators/Iterator.md
John Wellbelove 4a88884b39
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---------

Co-authored-by: Roland Reichwein <Roland.Reichwein@bmw.de>
Co-authored-by: John Wellbelove <john.wellbelove@etlcpp.com>
Co-authored-by: John Wellbelove <john.wellbelove@etlcpp.co.uk>
2026-06-06 13:12:44 +01:00

10 KiB

title
iterator

{{< callout type="info">}} Header: iterator.h
Since: TBC
{{< /callout >}}

A set of templates to more easily determine the properties of iterator types.

Input iterators

is_input_iterator<T>::value

Description
Is T an input iterator?


is_input_iterator_concept<T>::value

Description
Can T be used as an input iterator?

Output iterators

is_output_iterator<T>::value

Description
Is T an output iterator?


is_output_iterator_concept<T>::value

Description
Can T be used as an output iterator?

Forward iterators

is_forward_iterator<T>::value

Description
Is T a forward iterator?


is_forward_iterator_concept<T>::value

Description
Can T be used as an forward iterator?

Bidirectional iterators

is_bidirectional_iterator<T>::value

Description
Is T a bidirectional iterator?


is_bidirectional_iterator_concept<T>::value

Description
Can T be used as a bidirectional iterator?

Random iterators

is_random_iterator<T>::value

Description
Is T a random iterator?

is_random_iterator_concept<T>::value

Description
Can T be used as a random iterator?

Iterator tags

struct input_iterator_tag
struct output_iterator_tag
struct forward_iterator_tag
struct bidirectional_iterator_tag
struct random_access_iterator_tag

Iterator traits

template <typename TIterator>
struct iterator_traits

Defined types

iterator_category
value_type
difference_type
pointer
reference

advance

template <typename TIterator, typename TDistance>
ETL_CONSTEXPR17 void advance(TIterator& itr, TDistance n)

prev

template<typename TIterator>
ETL_CONSTEXPR17 TIterator prev(TIterator itr, 
                               typename etl::iterator_traits<TIterator>::difference_type n = 1)

next

template<typename TIterator>
ETL_CONSTEXPR17 TIterator next(TIterator itr, 
                               typename etl::iterator_traits<TIterator>::difference_type n = 1)

distance

template<typename TIterator>
ETL_CONSTEXPR17 typename std::iterator_traits<TIterator>::difference_type 
 distance(TIterator first, TIterator last)

iterator

A base class provided to simplify definitions of the required types for iterators. https://en.cppreference.com/w/cpp/iterator/iterator

template <typename TCategory,
          typename T, 
          typename TDistance = ptrdiff_t, 
          typename TPointer = T* , 
          typename TReference = T&>
struct iterator

Defined types

value_type
difference_type
pointer
reference
iterator_category

reverse_iterator

An iterator adaptor that reverses the direction of a given iterator

template <typename TIterator>
class reverse_iterator

Defined types

iterator_category
value_type
iterator_type
difference_type
pointer
reference

move_iterator

An iterator adaptor that converts the value returned by the underlying iterator into an rvalue. C++11 or above.

template <typename TIterator>
class move_iterator

Defined types

iterator_category
value_type
iterator_type
difference_type
pointer
reference

back_insert_iterator

Inserts using push_back.

template <typename TContainer>
class back_insert_iterator

template <typename TContainer>
ETL_NODISCARD 
ETL_CONSTEXPR14 
etl::back_insert_iterator<TContainer> back_inserter(TContainer& container)

front_insert_iterator

Inserts using push_front.

template <typename TContainer>
class front_insert_iterator

template <typename TContainer>
ETL_NODISCARD
ETL_CONSTEXPR14
etl::front_insert_iterator<TContainer> front_inserter(TContainer& container)

push_insert_iterator

Inserts using push.

template <typename TContainer>
class push_insert_iterator

template <typename TContainer>
ETL_NODISCARD
ETL_CONSTEXPR14
etl::push_insert_iterator<TContainer> push_inserter(TContainer& container)

begin

template <typename TContainer>
ETL_CONSTEXPR typename TContainer::iterator begin(TContainer& container)
Get the 'begin' iterator of `container`.

Enabled if ETL_NOT_USING_STL or ETL_CPP11_NOT_SUPPORTED.


template <typename TContainer>
ETL_CONSTEXPR typename TContainer::const_iterator begin(const TContainer& container)

Get the begin const_iterator of container.
Enabled if ETL_NOT_USING_STL or ETL_CPP11_NOT_SUPPORTED.


template <typename TContainer>
ETL_CONSTEXPR typename TContainer::const_iterator cbegin(const TContainer& container)

Get the begin const_iterator of container.
Enabled if ETL_NOT_USING_STL or ETL_CPP11_NOT_SUPPORTED.


template <typename TValue, size_t Array_Size>
ETL_CONSTEXPR TValue* begin(TValue(&data)[Array_Size])

Get the begin pointer for an array.
Enabled if ETL_NOT_USING_STL or ETL_CPP11_NOT_SUPPORTED.


template <typename TValue, size_t Array_Size>
ETL_CONSTEXPR const TValue* begin(const TValue(&data)[Array_Size])

Get the begin const pointer for an array.
Enabled if ETL_NOT_USING_STL or ETL_CPP11_NOT_SUPPORTED.


template <typename TValue, size_t Array_Size>
ETL_CONSTEXPR const TValue* cbegin(const TValue(&data)[Array_Size])

Get the begin const pointer for an array.
Enabled if ETL_NOT_USING_STL or ETL_CPP11_NOT_SUPPORTED.


template <typename TContainer>
ETL_CONSTEXPR typename TContainer::reverse_iterator rbegin(TContainer& container)

Get the begin reverse_iterator of container.
Enabled if ETL_NOT_USING_STL or ETL_CPP14_NOT_SUPPORTED.


template <typename TContainer>
ETL_CONSTEXPR typename TContainer::const_reverse_iterator rbegin(const TContainer& container)

Get the begin const_reverse_iterator of container.
Enabled if ETL_NOT_USING_STL or ETL_CPP14_NOT_SUPPORTED.


template <typename TContainer>
ETL_CONSTEXPR typename TContainer::const_reverse_iterator crbegin(const TContainer& container)

Get the begin' const_reverse_iterator of container.
Enabled if ETL_NOT_USING_STL or ETL_CPP14_NOT_SUPPORTED.


template <typename TValue, size_t Array_Size>
ETL_OR_STD::reverse_iterator<TValue*> rbegin(TValue(&data)[Array_Size])

Get the begin reverse_iterator for an array.
Enabled if ETL_NOT_USING_STL or ETL_CPP14_NOT_SUPPORTED.


template <typename TValue, size_t Array_Size>
ETL_CONSTEXPR ETL_OR_STD::reverse_iterator<const TValue*> crbegin(const TValue(&data)[Array_Size])

Get the begin const_reverse_iterator for an array.
Enabled if ETL_NOT_USING_STL or ETL_CPP14_NOT_SUPPORTED.

end

template <typename TContainer>
ETL_CONSTEXPR typename TContainer::iterator end(TContainer& container)

Get the end iterator of container.
Enabled if ETL_NOT_USING_STL or ETL_CPP11_NOT_SUPPORTED.


template <typename TContainer>
ETL_CONSTEXPR typename TContainer::const_iterator end(const TContainer& container)

Get the end const_iterator of container.
Enabled if ETL_NOT_USING_STL or ETL_CPP11_NOT_SUPPORTED.


template <typename TContainer>
ETL_CONSTEXPR typename TContainer::const_iterator cend(const TContainer& container)

Get the end const_iterator of container.
Enabled if ETL_NOT_USING_STL or ETL_CPP11_NOT_SUPPORTED.


template <typename TValue, size_t Array_Size>
ETL_CONSTEXPR TValue* end(TValue(&data)[Array_Size])

Get the end pointer for an array.
Enabled if ETL_NOT_USING_STL or ETL_CPP11_NOT_SUPPORTED.


template <typename TValue, size_t Array_Size>
ETL_CONSTEXPR const TValue* end(const TValue(&data)[Array_Size])

Get the end const pointer of an array.
Enabled if ETL_NOT_USING_STL or ETL_CPP11_NOT_SUPPORTED.


template <typename TValue, size_t Array_Size>
ETL_CONSTEXPR const TValue* cend(const TValue(&data)[Array_Size])

Get the end const pointer of an array.
Enabled if ETL_NOT_USING_STL or ETL_CPP11_NOT_SUPPORTED.


template <typename TContainer>
ETL_CONSTEXPR typename TContainer::reverse_iterator rend(TContainer& container)

Get the end reverse_iterator of container.
Enabled if ETL_NOT_USING_STL or ETL_CPP14_NOT_SUPPORTED.


template <typename TContainer>
ETL_CONSTEXPR typename TContainer::const_reverse_iterator rend(TContainer& container)

Get the end const_reverse_iterator of container. Enabled if ETL_NOT_USING_STL or ETL_CPP14_NOT_SUPPORTED.


template <typename TContainer>
ETL_CONSTEXPR typename TContainer::const_reverse_iterator crend(const TContainer& container)

Get the end const_reverse_iterator of container.
Enabled if ETL_NOT_USING_STL or ETL_CPP14_NOT_SUPPORTED.


template <typename TValue, size_t Array_Size>
ETL_CONSTEXPR ETL_OR_STD::reverse_iterator<TValue*> rend(TValue(&data)[Array_Size])

Get the end reverse_iterator for an array.
Enabled if ETL_NOT_USING_STL or ETL_CPP14_NOT_SUPPORTED.


template <typename TValue, size_t Array_Size>
ETL_CONSTEXPR ETL_OR_STD::reverse_iterator<const TValue*> crend(const TValue(&data)[Array_Size])

Get the end const_reverse_iterator for an array.
Enabled if ETL_NOT_USING_STL or ETL_CPP14_NOT_SUPPORTED.

size

template <typename TContainer>
ETL_CONSTEXPR typename TContainer::size_type size(const TContainer& container)

Get the size of a container.
Expects the container to have defined size_type.
Enabled if ETL_NOT_USING_STL or ETL_CPP17_NOT_SUPPORTED.


template <typename TValue, size_t Array_Size>
ETL_CONSTEXPR size_t size(TValue(&)[Array_Size])

Get the size of an array in elements at run time, or compile time if C++11 or above.
Enabled if ETL_NOT_USING_STL or ETL_CPP17_NOT_SUPPORTED.


template <typename T, size_t Array_Size>
char(&array_size(T(&array)[Array_Size]))[Array_Size];

Get the size of an array in elements at compile time for C++03
Usage:- sizeof(array_size(array))
Enabled if ETL_NOT_USING_STL or ETL_CPP17_NOT_SUPPORTED.


ETL_ARRAY_SIZE(a) calls sizeof(etl::array_size(a))