std::ranges::all_of,std::ranges::any_of,std::ranges::none_of (3) - Linux Manuals

std::ranges::all_of,std::ranges::any_of,std::ranges::none_of: std::ranges::all_of,std::ranges::any_of,std::ranges::none_of

Command to display std::ranges::all_of,std::ranges::any_of,std::ranges::none_of manual in Linux: $ man 3 std::ranges::all_of,std::ranges::any_of,std::ranges::none_of

NAME

std::ranges::all_of,std::ranges::any_of,std::ranges::none_of - std::ranges::all_of,std::ranges::any_of,std::ranges::none_of

Synopsis

Defined in header <algorithm>
Call signature
template< InputIterator I, Sentinel S, class Proj = std::identity,
IndirectUnaryPredicate<projected<I, Proj>> Pred > (1) (since C++20)
bool all_of( I first, S last, Pred pred, Proj proj = {} );
template< InputRange R, class Proj = std::identity,
IndirectUnaryPredicate<projected<ranges::iterator_t<R>, Proj>> Pred > (2) (since C++20)
bool all_of( R&& r, Pred pred, Proj proj = {} );
template< InputIterator I, Sentinel S, class Proj = std::identity,
IndirectUnaryPredicate<projected<I, Proj>> Pred > (3) (since C++20)
bool any_of( I first, S last, Pred pred, Proj proj = {} );
template< InputRange R, class Proj = std::identity,
IndirectUnaryPredicate<projected<ranges::iterator_t<R>, Proj>> Pred > (4) (since C++20)
bool any_of( R&& r, Pred pred, Proj proj = {} );
template< InputIterator I, Sentinel S, class Proj = std::identity,
IndirectUnaryPredicate<projected<I, Proj>> Pred > (5) (since C++20)
bool none_of( I first, S last, Pred pred, Proj proj = {} );
template< InputRange R, class Proj = std::identity,
IndirectUnaryPredicate<projected<ranges::iterator_t<R>, Proj>> Pred > (6) (since C++20)
bool none_of( R&& r, Pred pred, Proj proj = {} );

1) Checks if unary predicate pred returns true for all elements in the range [first, last) (after projecting with the projection proj).
3) Checks if unary predicate pred returns true for at least one element in the range [first, last) (after projecting with the projection proj).
5) Checks if unary predicate pred returns true for no elements in the range [first, last) (after projecting with the projection proj).
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.
The function-like entities described on this page are niebloids, that is:

* Explicit template argument lists may not be specified when calling any of them.
* None of them is visible to argument-dependent_lookup.
* When one of them is found by normal_unqualified_lookup for the name to the left of the function-call operator, it inhibits argument-dependent_lookup.

In practice, they may be implemented as function objects, or with special compiler extensions.

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

Return value

1-2) true if std::invoke(pred, std::invoke(proj, *i)) != false for every iterator i in the range, false otherwise. Returns true if the range is empty.
3-4) true if std::invoke(pred, std::invoke(proj, *i)) != false for at least one iterator i in the range, false otherwise. Returns false if the range is empty.
5-6) true if std::invoke(pred, std::invoke(proj, *i)) == false for every iterator i in the range, false otherwise. Returns true if the range is empty.

Complexity

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

Possible implementation

First version

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

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

inline constexpr all_of_fn all_of;

Second version

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

inline constexpr any_of_fn any_of;

Third version

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

inline constexpr none_of_fn none_of;

Example

// Run this code

#include <vector>
 #include <numeric>
 #include <algorithm>
 #include <iterator>
 #include <iterator>
 #include <iostream>
 #include <functional>

namespace ranges = std::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, std::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