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Defined in header <ranges> | ||
template<ranges::forward_range V,std::indirect_binary_predicate<iterator_t<V>, ranges::iterator_t<V>> Pred> | (1) | (since C++23) |
namespace views{ inlineconstexpr/* unspecified */ chunk_by=/* unspecified */; | (2) | (since C++23) |
Call signature | ||
template<ranges::viewable_range R,class Pred> requires/* see below */ | (since C++23) | |
template<class Pred> constexpr/*range adaptor closure*/ chunk_by( Pred&& pred); | (since C++23) | |
chunk_by_view is a range adaptor that takes aview and an invocable objectpred (the binary predicate), and produces aview of subranges (chunks), by splitting the underlying view between each pair of adjacent elements for whichpred returnsfalse. The first element of each such pair belongs to the previous chunk, and the second element belongs to the next chunk.chunk_by_view always modelsforward_range, and modelsbidirectional_range and/orcommon_range, if adaptedview type models the corresponding concepts.chunk_by_view never modelsborrowed_range orsized_range.
Contents |
| Member | Definition |
Vbase_ | the underlyingview(exposition-only member object*) |
movable-box<Pred>pred_ | an object that wraps the predicate used to split the elements ofbase_(exposition-only member object*) |
non-propagating-cache<iterator>begin_ | an object that caches the iterator to the first element (exposition-only member object*) |
constructs achunk_by_view(public member function)[edit] | |
| returns a copy of the underlying (adapted) view (public member function)[edit] | |
| returns a reference to the stored predicate (public member function)[edit] | |
| returns an iterator to the beginning (public member function)[edit] | |
| returns an iterator or a sentinel to the end (public member function)[edit] | |
| returns an iterator to the begin of the next subrange (exposition-only member function*) | |
| returns an iterator to the begin of the previous subrange (exposition-only member function*) | |
Inherited fromstd::ranges::view_interface | |
returns whether the derived view is empty, provided only if it satisfiessized_range orforward_range(public member function of std::ranges::view_interface<D>)[edit] | |
(C++23) | returns a constant iterator to the beginning of the range (public member function of std::ranges::view_interface<D>)[edit] |
(C++23) | returns a sentinel for the constant iterator of the range (public member function of std::ranges::view_interface<D>)[edit] |
| returns whether the derived view is not empty, provided only ifranges::empty is applicable to it (public member function of std::ranges::view_interface<D>)[edit] | |
returns the first element in the derived view, provided if it satisfiesforward_range(public member function of std::ranges::view_interface<D>)[edit] | |
returns the last element in the derived view, provided only if it satisfiesbidirectional_range andcommon_range(public member function of std::ranges::view_interface<D>)[edit] | |
| the iterator type (exposition-only member class template*) |
In order to provide the amortized constant time complexity required by therange concept, the result ofbegin() is cached within thechunk_by_view object. If the underlying range is modified after the first call tobegin(), subsequent uses of thechunk_by_view object might have unintuitive behavior.
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_ranges_chunk_by | 202202L | (C++23) | std::ranges::chunk_by_view |
#include <functional>#include <iostream>#include <ranges>#include <string_view> void print_chunks(auto view,std::string_view separator=", "){for(autoconst subrange: view){std::cout<<'[';for(std::string_view prefix;autoconst& elem: subrange)std::cout<< prefix<< elem, prefix= separator;std::cout<<"] ";}std::cout<<'\n';} int main(){std::initializer_list v1={1,2,3,1,2,3,3,3,1,2,3};auto fn1= std::ranges::less{};auto view1= v1| std::views::chunk_by(fn1); print_chunks(view1); std::initializer_list v2={1,2,3,4,4,0,2,3,3,3,2,1};auto fn2= std::ranges::not_equal_to{};auto view2= v2| std::views::chunk_by(fn2); print_chunks(view2); std::string_view v3="__cpp_lib_ranges_chunk_by";auto fn3=[](auto x,auto y){return not(x=='_' or y=='_');};auto view3= v3| std::views::chunk_by(fn3); print_chunks(view3,""); std::string_view v4="\u007a\u00df\u6c34\u{1f34c}";// "zß水🍌"auto fn4=[](auto,auto ß){return128==((128+64)& ß);};auto view4= v4| std::views::chunk_by(fn4); print_chunks(view4,"");}
Output:
[1, 2, 3] [1, 2, 3] [3] [3] [1, 2, 3] [1, 2, 3, 4] [4, 0, 2, 3] [3] [3, 2, 1] [_] [_] [cpp] [_] [lib] [_] [ranges] [_] [chunk] [_] [by][z] [ß] [水] [🍌]
a range ofviews that areN-sized non-overlapping successive chunks of the elements of anotherview(class template)(range adaptor object)[edit] | |
aview whose Mth element is aview over the Mth through (M + N - 1)th elements of anotherview(class template)(range adaptor object)[edit] | |
aview consisting of elements of anotherview, advancing over N elements at a time(class template)(range adaptor object)[edit] |
