Difference between revisions of "cpp/ranges/split view"
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===Example=== | ===Example=== | ||
{{example | {{example | ||
| − | |||
|code= | |code= | ||
#include <iostream> | #include <iostream> | ||
| Line 78: | Line 77: | ||
int main() { | int main() { | ||
| − | constexpr std::string_view words{"Hello | + | constexpr std::string_view words{"Hello^_^C++^_^20^_^!"}; |
| − | constexpr std::string_view delim{" | + | constexpr std::string_view delim{"^_^"}; |
for (const auto word : std::views::split(words, delim)) { | for (const auto word : std::views::split(words, delim)) { | ||
std::cout << std::quoted(std::string_view(word.begin(), word.end())) << ' '; | std::cout << std::quoted(std::string_view(word.begin(), word.end())) << ' '; | ||
} | } | ||
} | } | ||
| − | | output= | + | |output="Hello" "C++" "20" "!" |
| − | "Hello" "C++" "20" "!" | + | |
}} | }} | ||
Revision as of 14:32, 15 September 2022
| Defined in header <ranges>
|
||
| template< ranges::forward_range V, ranges::forward_range Pattern > requires ranges::view<V> && ranges::view<Pattern> && |
(1) | (since C++20) |
| namespace views { inline constexpr /*unspecified*/ split = /*unspecified*/; |
(2) | (since C++20) |
| Call signature |
||
| template< ranges::viewable_range R, class Pattern > requires /* see below */ |
(since C++20) | |
| template< class Pattern > constexpr /*range adaptor closure*/ split( Pattern&& pattern ); |
(since C++20) | |
split_view models the concepts forward_range, and common_range when the underlying view V models respective concepts.
The inner range (ranges::range_reference_t<split_view>) is a ranges::subrange<ranges::iterator_t<V>>, which models common_range, models sized_range when ranges::iterator_t<V> models std::sized_sentinel_for<ranges::iterator_t<V>>, and models contiguous_range, random_access_range, bidirectional_range, and forward_range when V models respective concepts.
Contents |
Expression-equivalent
Expression e is expression-equivalent to expression f, if
- e and f have the same effects, and
- either both are constant subexpressions or else neither is a constant subexpression, and
- either both are potentially-throwing or else neither is potentially-throwing (i.e. noexcept(e) == noexcept(f)).
Data members
Typical implementations of split_view hold three non-static data members:
- the underlying
viewof typeV(shown here asbase_for exposition only), and - the pattern (shown here as
pattern_for exposition only) that is used as a delimiter to split the underlyingview. - an object equivalent to std::optional<ranges::subrange<ranges::iterator_t<V>>> (shown here as
cached_begin_for exposition only) that caches the result of a first call tobegin().
Member functions
constructs a split_view (public member function) | |
| returns a copy of the underlying (adapted) view (public member function) | |
| returns an iterator to the beginning (public member function) | |
| returns an iterator or a sentinel to the end (public member function) | |
| (C++20) |
searches for the next occurrence of the pattern (exposition-only member function*) |
Inherited from std::ranges::view_interface | |
returns whether the derived view is empty. Provided if it satisfies sized_range or forward_range. (public member function of std::ranges::view_interface<D>)
| |
| (C++23) |
returns a constant iterator to the beginning of the range. (public member function of std::ranges::view_interface<D>)
|
| (C++23) |
returns a sentinel for the constant iterator of the range. (public member function of std::ranges::view_interface<D>)
|
| returns whether the derived view is not empty. Provided if ranges::empty is applicable to it. (public member function of std::ranges::view_interface<D>)
| |
returns the first element in the derived view. Provided if it satisfies forward_range. (public member function of std::ranges::view_interface<D>)
| |
Nested classes
| (C++20) |
the iterator type (exposition-only member class*) |
| (C++20) |
the sentinel type (exposition-only member class*) |
Deduction guides
Notes
Before P2210R2, split_view used a lazy mechanism for splitting, and thus could not keep the bidirectional, random access, or contiguous properties of the underlying view, or make the iterator type of the inner range same as that of the underlying view. Consequently, it is redesigned by P2210R2, and the lazy mechanism is moved to lazy_split_view.
Example
#include <iostream> #include <iomanip> #include <ranges> #include <string_view> int main() { constexpr std::string_view words{"Hello^_^C++^_^20^_^!"}; constexpr std::string_view delim{"^_^"}; for (const auto word : std::views::split(words, delim)) { std::cout << std::quoted(std::string_view(word.begin(), word.end())) << ' '; } }
Output:
"Hello" "C++" "20" "!"
Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| P2210R2 | C++20 | the old split_view was too lazy to be easily used
|
it is redesigned |
See also
a view over the subranges obtained from splitting another view using a delimiter(class template) (range adaptor object) | |
| (C++20) |
a view consisting of the sequence obtained from flattening a view of ranges(class template) (range adaptor object) |
