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< std::input_iterator I, std::sentinel_for S,

class Proj = std::identity,
std::indirect_unary_predicate<std::projected<I, Proj>> Pred > (1) (since C++20)

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

std::indirect_unary_predicate< (2) (since C++20)
std::projected<ranges::iterator_t<R>,Proj>> Pred >

constexpr bool all_of( R&& r, Pred pred, Proj proj = {} );
template< std::input_iterator I, std::sentinel_for S,

class Proj = std::identity,
std::indirect_unary_predicate<std::projected<I, Proj>> Pred > (3) (since C++20)

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

std::indirect_unary_predicate< (4) (since C++20)
std::projected<ranges::iterator_t<R>,Proj>> Pred >

constexpr bool any_of( R&& r, Pred pred, Proj proj = {} );
template< std::input_iterator I, std::sentinel_for S,

class Proj = std::identity,
std::indirect_unary_predicate<std::projected<I, Proj>> Pred > (5) (since C++20)

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

std::indirect_unary_predicate< (6) (since C++20)
std::projected<ranges::iterator_t<R>,Proj>> Pred >

constexpr 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

Complexity

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

Possible implementation

First version

struct all_of_fn {
template< std::input_iterator I, std::sentinel_for S, class Proj = std::identity,
std::indirect_unary_predicate<std::projected<I, Proj>> Pred >
constexpr 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< ranges::input_range R, class Proj = std::identity,
std::indirect_unary_predicate<
std::projected<ranges::iterator_t<R>,Proj>> Pred >
constexpr 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< std::input_iterator I, std::sentinel_for S, class Proj = std::identity,
std::indirect_unary_predicate<std::projected<I, Proj>> Pred >
constexpr bool operator()( I first, S last, Pred pred, Proj proj = {} ) const
{
return ranges::find_if(first, last, std::ref(pred), std::ref(proj)) != last;
}

template< ranges::input_range R, class Proj = std::identity,
std::indirect_unary_predicate<
std::projected<ranges::iterator_t<R>,Proj>> Pred >
constexpr 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 any_of_fn any_of;
Third version
struct none_of_fn {
template< std::input_iterator I, std::sentinel_for S, class Proj = std::identity,
std::indirect_unary_predicate<std::projected<I, Proj>> Pred >
constexpr bool operator()( I first, S last, Pred pred, Proj proj = {} ) const
{
return ranges::find_if(first, last, std::ref(pred), std::ref(proj)) == last;
}

template< ranges::input_range R, class Proj = std::identity,
std::indirect_unary_predicate<
std::projected<ranges::iterator_t<R>,Proj>> Pred >
constexpr 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 none_of_fn none_of;

Notes

The return value represented in the form of the Truth table is:

input range contains
all true, some true, none true, none true,
none false some false all false none false
(empty range)
1–2) all_of true false false true
3–4) any_of true true false false
5–6) none_of false false true true

Example

// Run this code

#include <vector>
#include <numeric>
#include <algorithm>
#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";
}

auto DivisibleBy = [](int d)
{
return [d](int m) { return m % 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