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std::ranges::slide_view<V>::begin

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< cpp‎ | ranges‎ | slide view
 
 
Ranges library
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(C++23)
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constexpr auto begin()
    requires (!(__simple_view<V> && __slide_caches_nothing<const V>));
(1) (since C++23)
constexpr auto begin() const
    requires __slide_caches_nothing<const V>;
(2) (since C++23)

Returns an iterator to the first element of the slide_view.

1) If V models __slide_caches_first, equivalent to:

return iterator<false>(
           ranges::begin(base_),
           ranges::next(ranges::begin(base_), n_ - 1, ranges::end(base_)),
           n_
       );

Otherwise, equivalent to: return iterator<false>(ranges::begin(base_), n_);.
If V models __slide_caches_first this function caches the result within the slide_view::cached_begin_ for use on subsequent calls. This is necessary to provide the amortized constant-time complexity required by the range.
2) Equivalent to: return iterator<true>(ranges::begin(base_), n_);.

Contents

[edit] Parameters

(none)

[edit] Return value

An iterator to the first element of slide_view, which points to the n_-sized subrange of the possibly const-qualified underlying view type – V for overload (1) or const V for overload (2).

[edit] Example

A link to test: Compiler Explorer

#include <ranges>
#include <iostream>
#include <string_view>
using namespace std::literals;
 
int main()
{
    static constexpr auto source = {"∀x"sv, "∃y"sv, "ε"sv, "δ"sv};
    auto view {std::ranges::slide_view(source, 2)};
    const auto subrange {*(view.begin())};
    for (std::string_view const s: subrange)
        std::cout << s << ' ';
}

Output:

∀x ∃y

[edit] See also

(C++23)
returns an iterator or a sentinel to the end
(public member function) [edit]
compares a sentinel with an iterator returned from slide_view::begin
(function) [edit]