Difference between revisions of "cpp/ranges/lazy split view"
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The exposition-only concept {{c|/*tiny-range*/<Pattern>}} is satisfied if {{c|Pattern}} satisfies {{lconcept|sized_range}}, {{c|Pattern::size()}} is a constant expression, and the value of {{c|Pattern::size()}} is less than or equal to {{tt|1}}.<!-- The standard uses `std::remove_reference_t<R>::size()`, but since `Pattern` is a `view`, it cannot be a reference. --> Notably, {{rlpt|empty_view}} and {{rlpt|single_view}} satisfy this concept. | The exposition-only concept {{c|/*tiny-range*/<Pattern>}} is satisfied if {{c|Pattern}} satisfies {{lconcept|sized_range}}, {{c|Pattern::size()}} is a constant expression, and the value of {{c|Pattern::size()}} is less than or equal to {{tt|1}}.<!-- The standard uses `std::remove_reference_t<R>::size()`, but since `Pattern` is a `view`, it cannot be a reference. --> Notably, {{rlpt|empty_view}} and {{rlpt|single_view}} satisfy this concept. | ||
| − | @2@ The expression {{c|views::lazy_split(e, f)}} is ''expression-equivalent'' to {{c|lazy_split_view(e, f)}}<!-- LWG 3524 -->. | + | @2@ A [[cpp/ranges#Range adaptor objects|range adaptor object]]. The expression {{c|views::lazy_split(e, f)}} is ''expression-equivalent'' to {{c|lazy_split_view(e, f)}}<!-- LWG 3524 -->. |
===Member functions=== | ===Member functions=== | ||
Revision as of 09:30, 29 July 2021
| Defined in header <ranges>
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| template< ranges::input_range V, ranges::forward_range Pattern > requires ranges::view<V> && ranges::view<Pattern> && |
(1) | (since C++20) |
| namespace views { inline constexpr /*unspecified*/ lazy_split = /*unspecified*/; |
(2) | (since C++20) |
1)
lazy_split_view takes a view and a delimiter, and splits the view into subranges on the delimiter.
Two major scenarios are supported:
- The view is a
input_range, the delimiter is a single element (wrapped in asingle_view). - The view is a
forward_range, the delimiter is aviewof elements.
sized_range, Pattern::size() is a constant expression, and the value of Pattern::size() is less than or equal to 1. Notably, empty_view and single_view satisfy this concept.2) A range adaptor object. The expression views::lazy_split(e, f) is expression-equivalent to lazy_split_view(e, f).
Contents |
Member functions
constructs a lazy_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) | |
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>)
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| (C++23) |
returns a sentinel for the constant iterator of the range. (public member function of std::ranges::view_interface<D>)
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| 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
| the iterator type (public member class) | |
| the iterator type of the inner range (public member class) |
Deduction guides
Example
Run this code
#include <algorithm> #include <iostream> #include <ranges> #include <string_view> // P2210R2: a temporary patch until online g++ >= 12 #define lazy_split_view split_view #define lazy_split split auto print = [](auto const& view) { // `view` is a std::views::lazy_split_view::/*outer-iterator*/::value_type for (std::cout << "{ "; const auto element : view) std::cout << element << ' '; std::cout << "} "; }; int main() { constexpr static auto source = { 0, 1,0, 2,3,0, 4,5,6,0, 7,8,9 }; constexpr int delimiter {0}; constexpr std::ranges::lazy_split_view lazy_split_view {source, delimiter}; std::cout << "splits[" << std::ranges::distance(lazy_split_view) << "]: "; for (auto const& lazy_split: lazy_split_view) print(lazy_split); constexpr std::string_view hello { "Hello C++ 20 !" }; std::cout << "\n" "substrings: "; std::ranges::for_each(hello | std::views::lazy_split(' '), print); constexpr std::string_view text { "Hello-+-C++-+-20-+-!" }; constexpr std::string_view delim { "-+-" }; std::cout << "\n" "substrings: "; std::ranges::for_each(text | std::views::lazy_split(delim), print); }
Output:
splits[5]: { } { 1 } { 2 3 } { 4 5 6 } { 7 8 9 }
substrings: { H e l l o } { C + + } { 2 0 } { ! }
substrings: { H e l l o } { C + + } { 2 0 } { ! }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) |
