[special.mem.concepts]

# 26 Algorithms library [[algorithms]](./#algorithms)

## 26.11 Specialized <memory> algorithms [[specialized.algorithms]](specialized.algorithms#special.mem.concepts)

### 26.11.2 Special memory concepts [special.mem.concepts]

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L13543)

Some algorithms in this subclause are constrained with the following
exposition-only concepts:

[🔗](#concept:nothrow-input-iterator)

`template<class I>
concept [nothrow-input-iterator](#concept:nothrow-input-iterator "26.11.2 Special memory concepts [special.mem.concepts]") = // exposition only
  [input_iterator](iterator.concept.input#concept:input_iterator "24.3.4.9 Concept input_­iterator [iterator.concept.input]")<I> &&
  is_lvalue_reference_v<iter_reference_t<I>> &&
  [same_as](concept.same#concept:same_as "18.4.2 Concept same_­as [concept.same]")<remove_cvref_t<iter_reference_t<I>>, iter_value_t<I>>;
`

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L13555)

A type I models [*nothrow-input-iterator*](#concept:nothrow-input-iterator "26.11.2 Special memory concepts [special.mem.concepts]") only if
no exceptions are thrown from increment,
copy construction, move construction,
copy assignment, move assignment,
or indirection through valid iterators[.](#2.sentence-1)

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L13562)

[*Note [1](#note-1)*:

This concept allows some [input_iterator](iterator.concept.input#concept:input_iterator "24.3.4.9 Concept input_­iterator [iterator.concept.input]") ([[iterator.concept.input]](iterator.concept.input "24.3.4.9 Concept input_­iterator"))
operations to throw exceptions[.](#3.sentence-1)

— *end note*]

[🔗](#concept:nothrow-sentinel-for)

`template<class S, class I>
concept [nothrow-sentinel-for](#concept:nothrow-sentinel-for "26.11.2 Special memory concepts [special.mem.concepts]") = [sentinel_for](iterator.concept.sentinel#concept:sentinel_for "24.3.4.7 Concept sentinel_­for [iterator.concept.sentinel]")<S, I>; // exposition only
`

[4](#4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L13575)

Types S and I model [*nothrow-sentinel-for*](#concept:nothrow-sentinel-for "26.11.2 Special memory concepts [special.mem.concepts]") only if no exceptions are thrown from copy construction, move construction,
copy assignment, move assignment, or comparisons between
valid values of type I and S[.](#4.sentence-1)

[5](#5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L13581)

[*Note [2](#note-2)*:

This concept allows some [sentinel_for](iterator.concept.sentinel#concept:sentinel_for "24.3.4.7 Concept sentinel_­for [iterator.concept.sentinel]") ([[iterator.concept.sentinel]](iterator.concept.sentinel "24.3.4.7 Concept sentinel_­for"))
operations to throw exceptions[.](#5.sentence-1)

— *end note*]

[🔗](#concept:nothrow-sized-sentinel-for)

`template<class S, class I>
concept [nothrow-sized-sentinel-for](#concept:nothrow-sized-sentinel-for "26.11.2 Special memory concepts [special.mem.concepts]") = // exposition only
  [nothrow-sentinel-for](#concept:nothrow-sentinel-for "26.11.2 Special memory concepts [special.mem.concepts]")<S, I> &&
  [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<S, I>;
`

[6](#6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L13596)

Types S and I model [*nothrow-sized-sentinel-for*](#concept:nothrow-sized-sentinel-for "26.11.2 Special memory concepts [special.mem.concepts]") only if no exceptions are thrown from the - operator
for valid values of type I and S[.](#6.sentence-1)

[7](#7)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L13601)

[*Note [3](#note-3)*:

This concept allows some [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]") ([[iterator.concept.sizedsentinel]](iterator.concept.sizedsentinel "24.3.4.8 Concept sized_­sentinel_­for"))
operations to throw exceptions[.](#7.sentence-1)

— *end note*]

[🔗](#concept:nothrow-input-range)

`template<class R>
concept [nothrow-input-range](#concept:nothrow-input-range "26.11.2 Special memory concepts [special.mem.concepts]") = // exposition only
  [range](range.range#concept:range "25.4.2 Ranges [range.range]")<R> &&
  [nothrow-input-iterator](#concept:nothrow-input-iterator "26.11.2 Special memory concepts [special.mem.concepts]")<iterator_t<R>> &&
  [nothrow-sentinel-for](#concept:nothrow-sentinel-for "26.11.2 Special memory concepts [special.mem.concepts]")<sentinel_t<R>, iterator_t<R>>;
`

[8](#8)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L13617)

A type R models [*nothrow-input-range*](#concept:nothrow-input-range "26.11.2 Special memory concepts [special.mem.concepts]") only if
no exceptions are thrown from calls to ranges​::​begin andranges​::​end on an object of type R[.](#8.sentence-1)

[🔗](#concept:nothrow-forward-iterator)

`template<class I>
concept [nothrow-forward-iterator](#concept:nothrow-forward-iterator "26.11.2 Special memory concepts [special.mem.concepts]") = // exposition only
  [nothrow-input-iterator](#concept:nothrow-input-iterator "26.11.2 Special memory concepts [special.mem.concepts]")<I> &&
  [forward_iterator](iterator.concept.forward#concept:forward_iterator "24.3.4.11 Concept forward_­iterator [iterator.concept.forward]")<I> &&
  [nothrow-sentinel-for](#concept:nothrow-sentinel-for "26.11.2 Special memory concepts [special.mem.concepts]")<I, I>;
`

[9](#9)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L13632)

[*Note [4](#note-4)*:

This concept allows some [forward_iterator](iterator.concept.forward#concept:forward_iterator "24.3.4.11 Concept forward_­iterator [iterator.concept.forward]") ([[iterator.concept.forward]](iterator.concept.forward "24.3.4.11 Concept forward_­iterator"))
operations to throw exceptions[.](#9.sentence-1)

— *end note*]

[🔗](#concept:nothrow-forward-range)

`template<class R>
concept [nothrow-forward-range](#concept:nothrow-forward-range "26.11.2 Special memory concepts [special.mem.concepts]") = // exposition only
  [nothrow-input-range](#concept:nothrow-input-range "26.11.2 Special memory concepts [special.mem.concepts]")<R> &&
  [nothrow-forward-iterator](#concept:nothrow-forward-iterator "26.11.2 Special memory concepts [special.mem.concepts]")<iterator_t<R>>;
`

[🔗](#concept:nothrow-bidirectional-iterator)

`template<class I>
concept [nothrow-bidirectional-iterator](#concept:nothrow-bidirectional-iterator "26.11.2 Special memory concepts [special.mem.concepts]") = // exposition only
  [nothrow-forward-iterator](#concept:nothrow-forward-iterator "26.11.2 Special memory concepts [special.mem.concepts]")<I> &&
  [bidirectional_iterator](iterator.concept.bidir#concept:bidirectional_iterator "24.3.4.12 Concept bidirectional_­iterator [iterator.concept.bidir]")<I>;
`

[10](#10)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L13654)

A type I models [*nothrow-bidirectional-iterator*](#concept:nothrow-bidirectional-iterator "26.11.2 Special memory concepts [special.mem.concepts]") only if no exceptions are thrown from decrementing valid iterators[.](#10.sentence-1)

[*Note [5](#note-5)*:

This concept allows some [bidirectional_iterator](iterator.concept.bidir#concept:bidirectional_iterator "24.3.4.12 Concept bidirectional_­iterator [iterator.concept.bidir]") ([[iterator.concept.bidir]](iterator.concept.bidir "24.3.4.12 Concept bidirectional_­iterator"))
operations to throw exceptions[.](#10.sentence-2)

— *end note*]

[🔗](#concept:nothrow-bidirectional-range)

`template<class R>
concept [nothrow-bidirectional-range](#concept:nothrow-bidirectional-range "26.11.2 Special memory concepts [special.mem.concepts]") = // exposition only
  [nothrow-forward-range](#concept:nothrow-forward-range "26.11.2 Special memory concepts [special.mem.concepts]")<R> &&
  [nothrow-bidirectional-iterator](#concept:nothrow-bidirectional-iterator "26.11.2 Special memory concepts [special.mem.concepts]")<iterator_t<R>>;
`

[🔗](#concept:nothrow-random-access-iterator)

`template<class I>
concept [nothrow-random-access-iterator](#concept:nothrow-random-access-iterator "26.11.2 Special memory concepts [special.mem.concepts]") = // exposition only
  [nothrow-bidirectional-iterator](#concept:nothrow-bidirectional-iterator "26.11.2 Special memory concepts [special.mem.concepts]")<I> &&
  [random_access_iterator](iterator.concept.random.access#concept:random_access_iterator "24.3.4.13 Concept random_­access_­iterator [iterator.concept.random.access]")<I> &&
  [nothrow-sized-sentinel-for](#concept:nothrow-sized-sentinel-for "26.11.2 Special memory concepts [special.mem.concepts]")<I, I>;
`

[11](#11)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L13679)

A type I models [*nothrow-random-access-iterator*](#concept:nothrow-random-access-iterator "26.11.2 Special memory concepts [special.mem.concepts]") only if no exceptions are thrown from comparisons of valid iterators,
or the -, +, -=, +=, [] operators
on valid values of type I and iter_difference_t<I>[.](#11.sentence-1)

[*Note [6](#note-6)*:

This concept allows some [random_access_iterator](iterator.concept.random.access#concept:random_access_iterator "24.3.4.13 Concept random_­access_­iterator [iterator.concept.random.access]") ([[iterator.concept.random.access]](iterator.concept.random.access "24.3.4.13 Concept random_­access_­iterator"))
operations to throw exceptions[.](#11.sentence-2)

— *end note*]

[🔗](#itemdecl:10)

`template<class R>
concept [nothrow-random-access-range](#concept:nothrow-random-access-range "26.11.2 Special memory concepts [special.mem.concepts]") = // exposition only
  [nothrow-bidirectional-range](#concept:nothrow-bidirectional-range "26.11.2 Special memory concepts [special.mem.concepts]")<R> &&
  [nothrow-random-access-iterator](#concept:nothrow-random-access-iterator "26.11.2 Special memory concepts [special.mem.concepts]")<iterator_t<R>>;

template<class R>
concept [nothrow-sized-random-access-range](#concept:nothrow-sized-random-access-range "26.11.2 Special memory concepts [special.mem.concepts]") = // exposition only
  [nothrow-random-access-range](#concept:nothrow-random-access-range "26.11.2 Special memory concepts [special.mem.concepts]")<R> && [sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<R>;
`

[12](#12)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L13702)

A type R models [*nothrow-sized-random-access-range*](#concept:nothrow-sized-random-access-range "26.11.2 Special memory concepts [special.mem.concepts]") only if no exceptions are thrown from the call to ranges​::​size on an object of type R[.](#12.sentence-1)