<iterator>

Backports related to Standard header <iterator>

#include <cxxomfort/iterator.hpp>
// or as part of:
#include <cxxomfort/backports.hpp>

Interfaces

Interfaces defined in this section:

• C++11 Nonmember <iterator> Accessors such as begin() , end() .
• C++14 Nonmember <iterator> Accessors such as rbegin() .
• make_reverse_iterator() (C++14).
• C++17 Nonmember <iterator> Accessors such as size() .
• contiguous_iterator_tag (C++20).

Non-backport interfaces (cxxomfort::fix):

• is_contiguous_access_iterator - A trait check for contiguous access iterators.
• cdata() accessor , to supplement std::data()
• static_next(), static_prev() for constexpr -pointer iterator (C++11 onwards).

Nonmember <iterator> Accessors

C++11 onward have introduced a number of non-member accessor functions for iterator and container elements in C++. These include global begin/end functions to access arrays, containers and sequences, and a number of accessor functions such as size() that checks for a container, array or sequence's reported size.

Begin / End accessors

begin() / end() : the invocation begin(sequence) returns:

• an automatically deduced type in C++>=11
• Sequence::iterator or T* in C++<11
• sequence.begin() when it exists
• &(sequence[0]) when sequence is a native array with type T(&)[N]

rbegin() / rend() : the invocation rbegin(sequence) returns:

• an automatically deduced type in C++>=11
• Sequence::reverse_iterator in C++<11
• sequence.rbegin() when it exists
• &(sequence[N-1]) when sequence is a native array with type Type(&)[N]

cbegin() / cend() / crbegin() / crend() : they return the const_iterator or const_pointer (or T const*) version of the above.

Container Accessors

C++17 added the following functions:

size() : the invocation size(sequence) returns:

• An automatically deduced type in C++>=11
• Sequence::size_type or size_t in C+++<11
• sequence.size() when it exists
• std:distance( sequence.begin(), sequence.end() ) when a member size does not exist (see note below)
• N when sequence is a native array with type T(&)[N]

empty() : the invocation empty(sequence) returns:

• A bool value
• sequence.empty() when it exists
• 0 for arrays

data() : the invocation data(sequence) returns:

• A T* (or T const*) pointer value
• sequence.data() when it exists
• sequence (decayed to pointer) for arrays

Note

cxxomfort provides size() for objects that define begin and end, such as forward_list. As per cppreference, "Custom overloads of size may be provided for classes and enumerations that do not expose a suitable size() member function, yet can be detected", so these overloads are permitted.

Contiguous Access Iterator Tag

Previous to C++20, cxxomfort defines, but can't use, the iterator tag contiguous_iterator_tag . This is a refinement over random_access_iterator_tag used in newer Standards to point out to iterator types that refer to contiguous memory storage (such as raw pointers).

Because it's not possible to redefine member types in std containers and iterators, at present only the following features in cxxomfort make use of the contiguous_iterator_tag type:

• cxxomfort::iterator_helper
• cxxomfort::array as the category of its iterator type
• cxxomfort::array_ref as the category of its iterator type
• basic_string_view when backported
• cxxomfort::library::fixed_vector::fixed_vector as the category of its iterator type

See Also

See also

header/iterator @ cppreference (cppreference)

iterator/begin @ cppreference iterator/end @ cppreference

cxxomfort <iterator> supplements

Member cxxomfort::cxxostd::iterator::cbegin (Seq &&)

Iterator accessor

Member cxxomfort::cxxostd::iterator::cend (Seq &&)

Iterator accessor

Member cxxomfort::fix::cdata (C const &container) -> decltype(container.data())

cdata()

Member cxxomfort::fix::static_prev (It const p) noexcept

static_prev