etl/docs/containers/sets/const-multiset.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

7.3 KiB

title
const_multiset / const_multiset_ext

{{< callout >}} Header: const_multiset.h
Similar to: std::set {{< /callout >}}

A fixed capacity read-only set based on a sorted array.
The containers are designed to be able to be constexpr for C++14 and up.

Uses etl::less as the default key comparison method.

Internal storage

etl::const_multiset<typename TKey, size_t Size, TKeyCompare = etl::less>

Enternal storage

etl::const_multiset_ext<typename TKey, TKeyCompare = etl::less>

Inherits from etl::iconst_multiset<TKey, TMapped, TKeyCompare>. etl::iconst_multiset may be used as a Size independent pointer or reference type for any etl::const_multiset or etl::const_multiset_ext instance. Both the key type must be default constructible.

Template deduction guides

C++17 and above.

const_multiset

template <typename... TElements>
etl::const_multiset(TElements...)

Example

constexpr etl::const_multiset data{ 0, 1, 2, 3 };

Defines data as an const_multiset of int, of length 4, containing the supplied data.

const_multiset_ext

template <typename... TElements>
etl::const_multiset_ext(TElements...)

Example

constexpr etl::pair<int, int> values{ 0, 1, 2, 3 };
constexpr etl::const_multiset_ext data{ values };

Defines data as an const_multiset of int, of length 4, containing the supplied data.


constexpr values[]{ 0, 1, 2, 3 };
constexpr etl::span<int, 4> span{ values };
constexpr etl::const_multiset_ext data{ span };

Defines data as an const_multiset of int of length 4, containing the supplied data.


Member types

key_type                TKey    Must be default constructible.
value_type              key_type
size_type               std::size_t
difference_type         std::ptrdiff_t
const_reference         const T&
const_pointer           const T*
const_iterator          Constant random access iterator

Constructors

const_multiset

template <typename... TElements>
ETL_CONSTEXPR14 explicit const_multiset(TElements&&... elements) ETL_NOEXCEPT

Description
Construct a const_multiset from a variadic list of elements.
Static asserts if the elements are not of type value_type.
Static asserts if the number of elements is greater than the capacity of the const_multiset.

const_multiset_ext

ETL_CONSTEXPR14 const_multiset_ext() ETL_NOEXCEPT

Description
Default construct a const_multiset.


template <size_type Size>
ETL_CONSTEXPR14 explicit const_multiset_ext(const etl::span<const value_type, Size>& sp) ETL_NOEXCEPT

Description
Construct a const_multiset from a variadic list of elements.


template <size_type Size>
ETL_CONSTEXPR14 explicit const_multiset_ext(const value_type (&begin_)[Size]) ETL_NOEXCEPT

Description
Construct a const_multiset from an array.

Iterators

const_iterator begin() const ETL_NOEXCEPT
const_iterator cbegin() const ETL_NOEXCEPT

Description
Returns an iterator to the beginning of the set.


const_iterator end() const ETL_NOEXCEPT
const_iterator cend() const ETL_NOEXCEPT

Description
Returns an iterator to the end of the set.

Capacity

ETL_CONSTEXPR14 bool empty() const ETL_NOEXCEPT

Description
Returns true if the size of the set is zero, otherwise false.


ETL_CONSTEXPR14 bool full() const ETL_NOEXCEPT

Description
Returns true if the size of the lookup is size, otherwise false.


ETL_CONSTEXPR14 size_t size() const ETL_NOEXCEPT

Description
Returns the size of the lookup.


ETL_CONSTEXPR14 size_t max_size() const ETL_NOEXCEPT

Description
Returns the maximum possible size of the set.

Status

ETL_CONSTEXPR14 bool is_valid() const ETL_NOEXCEPT

Check that the elements are valid for a set.
The elements must be sorted and contain no duplicates.

ETL_CONSTEXPR14 const_iterator find(const key_type& key) const ETL_NOEXCEPT

Description
Find the key in the container.

Return
A const_iterator to the element, or end() if it could not be found.


ETL_CONSTEXPR14 const_iterator lower_bound(const key_type& key) const ETL_NOEXCEPT

Description
Searches for the first element after the key.

Return
A const_iterator to the element, or end() if it could not be found.


ETL_CONSTEXPR14 const_iterator upper_bound(const key_type& key) const ETL_NOEXCEPT

Description
Searches for the first element with the key.

Return
A const_iterator to the element, or end() if it could not be found.


ETL_CONSTEXPR14 pair<const_iterator, const_iterator> equal_range(const key_type& key) const ETL_NOEXCEPT

Description
The return type is either std::pair (default) or etl::pair (ETL_NO_STL)

Return
Returns a range containing all elements equivalent to key.


ETL_CONSTEXPR14 bool contains(const key_type& k) const ETL_NOEXCEPT

Description
Check if the container contains the key.

Return
true if the container contains the key, otherwise false.

Search (transparent comparators)

template <typename K>
ETL_CONSTEXPR14 const_iterator find(const K& key) const ETL_NOEXCEPT

Description
Find the key in the container.

Return
A const_iterator to the element, or end() if it could not be found.


template <typename K>
ETL_CONSTEXPR14 const_iterator lower_bound(const K& key) const ETL_NOEXCEPT

Description
Searches for the first element after the key.

Return
A const_iterator to the element, or end() if it could not be found.


template <typename K>
ETL_CONSTEXPR14 const_iterator upper_bound(const K& key) const ETL_NOEXCEPT

Description
Searches for the first element with the key.

Return
A const_iterator to the element, or end() if it could not be found.


template <typename K>
ETL_CONSTEXPR14 pair<const_iterator, const_iterator> equal_range(const K& key) const ETL_NOEXCEPT

Description
The return type is either std::pair (default) or etl::pair (ETL_NO_STL)

Return
Returns a range containing all elements equivalent to key.


template <typename K>
ETL_CONSTEXPR14 bool contains(const K& k) const ETL_NOEXCEPT

Description
Check if the container contains the key.

Return
true if the container contains the key, otherwise false.

Non-member functions

Lexicographically comparisons

operator ==

true if the contents of the sets are equal, otherwise false.


operator != 

true if the contents of the sets are not equal, otherwise false.


operator <  

true if the contents of the lhs is less-than the rhs, otherwise false.


operator <=

true if the contents of the lhs is less-than-equal the rhs, otherwise false.


operator >

true if the contents of the lhs is greater-than the rhs, otherwise false.


operator >= 

true if the contents of the lhs is greater-than-equal the rhs, otherwise false.

Technical stuff

The const set is implemented as a sorted array key/value pairs.