Difference between revisions of "cpp/iterator/incrementable"
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{{dcl begin}} | {{dcl begin}} | ||
{{dcl header|iterator|since=c++20}} | {{dcl header|iterator|since=c++20}} | ||
| − | {{dcl | since=c++20 | 1= | + | {{dcl|since=c++20|1= |
| − | template<class I> | + | template< class I > |
concept incrementable = | concept incrementable = | ||
std::regular<I> && | std::regular<I> && | ||
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{{dcl end}} | {{dcl end}} | ||
| − | This concept specifies requirements on types that can be incremented with the pre- and post-increment operators, whose increment operations are equality-preserving, and the type is {{lc|std::equality_comparable}}. | + | This concept specifies requirements on types that can be incremented with the pre- and post-increment operators, whose increment operations are [[cpp/concepts#Equality preservation|equality-preserving]], and the type is {{lc|std::equality_comparable}}. |
Unlike with {{lc|std::weakly_incrementable}}, which only support single-pass algorithms, multi-pass one-directional algorithms can be used with types that model {{tt|std::incrementable}}. | Unlike with {{lc|std::weakly_incrementable}}, which only support single-pass algorithms, multi-pass one-directional algorithms can be used with types that model {{tt|std::incrementable}}. | ||
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===Semantic requirements=== | ===Semantic requirements=== | ||
{{tt|I}} models {{tt|std::incrementable}} only if given any two incrementable objects {{tt|a}} and {{tt|b}} of type {{tt|I}}: | {{tt|I}} models {{tt|std::incrementable}} only if given any two incrementable objects {{tt|a}} and {{tt|b}} of type {{tt|I}}: | ||
| − | * {{c|bool(a | + | * {{c|1=bool(a == b)}} implies {{c|1=bool(a++ == b)}}, and |
| − | * {{c|bool(a | + | * {{c|1=bool(a == b)}} implies {{c|1=bool(((void)a++, a) == ++b)}}. |
{{cpp/concepts/equality preservation}} | {{cpp/concepts/equality preservation}} | ||
| − | === See also === | + | ===See also=== |
{{dsc begin}} | {{dsc begin}} | ||
| − | {{dsc inc | cpp/iterator/dsc weakly_incrementable}} | + | {{dsc inc|cpp/iterator/dsc weakly_incrementable}} |
| − | {{dsc inc | cpp/concepts/dsc same_as}} | + | {{dsc inc|cpp/concepts/dsc same_as}} |
{{dsc end}} | {{dsc end}} | ||
{{langlinks|de|es|ja|ru|zh}} | {{langlinks|de|es|ja|ru|zh}} | ||
Latest revision as of 22:03, 30 September 2023
| Defined in header <iterator>
|
||
| template< class I > concept incrementable = |
(since C++20) | |
This concept specifies requirements on types that can be incremented with the pre- and post-increment operators, whose increment operations are equality-preserving, and the type is std::equality_comparable.
Unlike with std::weakly_incrementable, which only support single-pass algorithms, multi-pass one-directional algorithms can be used with types that model std::incrementable.
[edit] Semantic requirements
I models std::incrementable only if given any two incrementable objects a and b of type I:
- bool(a == b) implies bool(a++ == b), and
- bool(a == b) implies bool(((void)a++, a) == ++b).
[edit] Equality preservation
Expressions declared in requires expressions of the standard library concepts are required to be equality-preserving (except where stated otherwise).
[edit] See also
| (C++20) |
specifies that a semiregular type can be incremented with pre- and post-increment operators (concept) |
| (C++20) |
specifies that a type is the same as another type (concept) |
