std::experi...es::any_of,(3)

okay bestie, we're in the C++ Standard Libary manual and today's page is std::experi...es::any_of,(3) — yes, the title is doing the absolute most, but we're gonna get through it together 💖

💖 NAME 💖

std::experimental::ranges::all_of,std::experimental::ranges::any_of, - std::experimental::ranges::all_of,std::experimental::ranges::any_of,

periodt. that's the name section, and it's chaotic but iconic.

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✨ Synopsis ✨

okay so this is defined in the header <experimental/ranges/algorithm>, and the whole overload lineup is giving major ranges TS energy. here's the exact synopsis, bestie:

          Defined in header <experimental/ranges/algorithm>
          template< InputIterator I, Sentinel<I> S, class Proj =
          ranges::identity,
                                                                               (1)
       (ranges TS)
                    IndirectUnaryPredicate<projected<I, Proj>> Pred >

          bool all_of( I first, S last, Pred pred, Proj proj = Proj{} );
          template< InputRange R, class Proj = ranges::identity,

                    IndirectUnaryPredicate<projected<ranges::iterator_t<R>,
       (2) (ranges TS)
          Proj>> Pred >

          bool all_of( R&& r, Pred pred, Proj proj = Proj{} );
          template< InputIterator I, Sentinel<I> S, class Proj =
          ranges::identity,
                                                                               (3)
       (ranges TS)
                    IndirectUnaryPredicate<projected<I, Proj>> Pred >

          bool any_of( I first, S last, Pred pred, Proj proj = Proj{} );
          template< InputRange R, class Proj = ranges::identity,

                    IndirectUnaryPredicate<projected<ranges::iterator_t<R>,
       (4) (ranges TS)
          Proj>> Pred >

          bool any_of( R&& r, Pred pred, Proj proj = Proj{} );
          template< InputIterator I, Sentinel<I> S, class Proj = identity,

                    IndirectUnaryPredicate<projected<I, Proj>> Pred >
       (5) (ranges TS)

          bool none_of( I first, S last, Pred pred, Proj proj = Proj{} );
          template< InputRange R, class Proj = ranges::identity,

                    IndirectUnaryPredicate<projected<ranges::iterator_t<R>,
       (6) (ranges TS)
          Proj>> Pred >

          bool none_of( R&& r, Pred pred, Proj proj = Proj{} );

the little (1)–(6) tags are literally part of the synopsis, so don't lose them. same with every (ranges TS) note — they're lowkey important.

1. Checks if unary predicate pred returns true for all elements in the range [first, last).
3. Checks if unary predicate pred returns true for at least one element in the range [first, last).
5. Checks if unary predicate pred returns true for no elements in the range [first, last).

2,4,6) Same as (1,3,5), but uses r as the source range, as if using ranges::begin(r) as first and ranges::end(r) as last.

Notwithstanding the declarations depicted above, the actual number and order of template parameters for algorithm declarations is unspecified. Thus, if explicit template arguments are used when calling an algorithm, the program is probably non-portable.

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🌸 Parameters 🌸

• first, last — the range of the elements to examine
• r — the range of the elements to examine
• pred — predicate to apply to the projected elements
• proj — projection to apply to the elements

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🦋 Return value 🦋

• 1,2) true if pred returns true for all elements in the range, false otherwise. Returns true if the range is empty.
• 3,4) true if pred returns true for at least one element in the range, false otherwise. Returns false if the range is empty.
• 5,6) true if pred returns true for no elements in the range, false otherwise. Returns true if the range is empty.

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🎀 Complexity 🎀

1-6) At most last - first applications of the predicate and last - first applications of the projection.

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🧚 Possible implementation 🧚

First version

          template<InputIterator I, Sentinel<I> S, class Proj =
       ranges::identity,
                   IndirectUnaryPredicate<projected<I, Proj>> Pred>
          bool all_of(I first, S last, Pred pred, Proj proj = Proj{})
          {
              return ranges::find_if_not(first, last, std::ref(pred),
       std::ref(proj)) == last;
          }

          template<InputRange R, class Proj = ranges::identity,
                   IndirectUnaryPredicate<projected<ranges::iterator_t<R>,
       Proj>> Pred>
          bool all_of(R&& r, Pred pred, Proj proj = Proj{})
          {
              return ranges::all_of(ranges::begin(r), ranges::end(r),
                                    std::ref(pred), std::ref(proj));
          }

Second version

          template<InputIterator I, Sentinel<I> S, class Proj =
       ranges::identity,
                   IndirectUnaryPredicate<projected<I, Proj>> Pred>
          bool any_of(I first, S last, Pred pred, Proj proj = Proj{})
          {
              return ranges::find_if(first, last, std::ref(pred),
       std::ref(proj)) != last;
          }

          template<InputRange R, class Proj = ranges::identity,
                   IndirectUnaryPredicate<projected<ranges::iterator_t<R>,
       Proj>> Pred>
          bool any_of(R&& r, Pred pred, Proj proj = Proj{})
          {
              return ranges::any_of(ranges::begin(r), ranges::end(r),
                                    std::ref(pred), std::ref(proj));
          }

Third version

          template<InputIterator I, Sentinel<I> S, class Proj = identity,
                   IndirectUnaryPredicate<projected<I, Proj>> Pred>
          bool none_of(I first, S last, Pred pred, Proj proj = Proj{})
          {
              return ranges::find_if(first, last, std::ref(pred),
       std::ref(proj)) == last;
          }

          template<InputRange R, class Proj = ranges::identity,
                   IndirectUnaryPredicate<projected<ranges::iterator_t<R>,
       Proj>> Pred>
          bool none_of(R&& r, Pred pred, Proj proj = Proj{})
          {
              return ranges::none_of(ranges::begin(r), ranges::end(r),
                                     std::ref(pred), std::ref(proj));
          }

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🌈 Example 🌈

       // Run this code

        #include <experimental/ranges/algorithm>
        #include <experimental/ranges/iterator>
        #include <functional>
        #include <iostream>
        #include <iterator>
        #include <numeric>
        #include <vector>

        namespace ranges = std::experimental::ranges;

        int main()
        {
            std::vector<int> v(10, 2);
            std::partial_sum(v.cbegin(), v.cend(), v.begin());
            std::cout << "Among the numbers: ";
            ranges::copy(v, ranges::ostream_iterator<int>(std::cout, " "));
            std::cout << '\n';

            if (ranges::all_of(v.cbegin(), v.cend(), [](int i) { return i % 2
       == 0; }))
                std::cout << "All numbers are even\n";
            if (ranges::none_of(v, std::bind(std::modulus<int>(),
       std::placeholders::_1, 2)))
                std::cout << "None of them are odd\n";

            struct DivisibleBy
            {
                const int d;
                DivisibleBy(int n) : d(n) {}
                bool operator()(int n) const { return n % d == 0; }
            };

            if (ranges::any_of(v, DivisibleBy(7)))
                std::cout << "At least one number is divisible by 7\n";
        }

Output:

Among the numbers: 2 4 6 8 10 12 14 16 18 20
All numbers are even
None of them are odd
At least one number is divisible by 7

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⭐ See also ⭐

• all_of
• any_of
• none_of — checks if a predicate is true for all, any or none of the elements in a range
• (C++11) (function template)
• (C++11)
• (C++11)

okay bye bestie 🫶 — source: http://cppreference.com, version/date: 2024.06.10, page: std::experi...es::any_of,(3) ✨