| Permutation operations |
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| Fold operations |
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| Operations on uninitialized storage |
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| Return types |
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1) Checks if unary predicate pred returns false for at least one element 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 none of the 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 algorithm function objects (informally known as niebloids), that is:
[edit] Parameters
first, last
-
the iterator-sentinel pair defining the
range of 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
[edit] 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.
| Range has some true element
|
Yes
|
No
|
| Range has some false element
|
Yes
|
No
|
Yes
|
No[1]
|
all_of
|
false
|
true
|
false
|
true
|
any_of
|
true
|
true
|
false
|
false
|
none_of
|
false
|
false
|
true
|
true
|
- ↑ The range is empty in this case.
[edit] Complexity
At most last - first applications of the predicate and the projection.
[edit] Possible implementation
| all_of (1,2)
|
struct all_of_fn
{
template<std::input_iterator I, std::sentinel_for <I> 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; |
| any_of (3,4)
|
struct any_of_fn
{
template<std::input_iterator I, std::sentinel_for <I> 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; |
| none_of (5,6)
|
struct none_of_fn
{
template<std::input_iterator I, std::sentinel_for <I> 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; |
[edit] Example
#include <algorithm>
#include <functional>
#include <iostream>
#include <iterator>
#include <numeric>
#include <vector>
namespace ranges = std::ranges;
constexpr bool some_of(auto&& r, auto&& pred) // some but not all
{
return not (ranges::all_of (r, pred) or ranges::none_of (r, pred));
}
constexpr auto w = {1, 2, 3};
static_assert(!some_of(w, [](int x) { return x < 1; }));
static_assert( some_of(w, [](int x) { return x < 2; }));
static_assert(!some_of(w, [](int x) { return x < 4; }));
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
[edit] See also
checks if a predicate is
true for all, any or none of the elements in a range
(function template) [edit]