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std::ranges::all_of, std::ranges::any_of, std::ranges::none_of - cppreference.com

在标头 <algorithm> 定义

调用签名

 
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 all_of( I first, S last, Pred pred, Proj proj = {} );
(1) (C++20 起) 
template< ranges::input_range R, class Proj = std::identity,
          std::indirect_unary_predicate
              <std::projected<ranges::iterator_t<R>, Proj>> Pred >
constexpr bool all_of( R&& r, Pred pred, Proj proj = {} );
(2) (C++20 起) 
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 any_of( I first, S last, Pred pred, Proj proj = {} );
(3) (C++20 起) 
template< ranges::input_range R, class Proj = std::identity,
          std::indirect_unary_predicate
              <std::projected<ranges::iterator_t<R>, Proj>> Pred >
constexpr bool any_of( R&& r, Pred pred, Proj proj = {} );
(4) (C++20 起) 
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 none_of( I first, S last, Pred pred, Proj proj = {} );
(5) (C++20 起) 
template< ranges::input_range R, class Proj = std::identity,
          std::indirect_unary_predicate
              <std::projected<ranges::iterator_t<R>, Proj>> Pred >
constexpr bool none_of( R&& r, Pred pred, Proj proj = {} );
(6) (C++20 起) 
template< /*execution-policy*/ Ep, std::random_access_iterator I,
          std::sized_sentinel_for<I> S, class Proj = std::identity,
          std::indirect_unary_predicate<std::projected<I, Proj>> Pred >
bool all_of( Ep&& policy, I first, S last, Pred pred, Proj proj = {} );
(7) (C++26 起) 
template< /*execution-policy*/ Ep,
          /*sized-random-access-range*/ R, class Proj = std::identity,
          std::indirect_unary_predicate
              <std::projected<ranges::iterator_t<R>, Proj>> Pred >
bool all_of( Ep&& policy, R&& r, Pred pred, Proj proj = {} );
(8) (C++26 起) 
template< /*execution-policy*/ Ep, std::random_access_iterator I,
          std::sized_sentinel_for<I> S, class Proj = std::identity,
          std::indirect_unary_predicate<std::projected<I, Proj>> Pred >
bool any_of( Ep&& policy, I first, S last, Pred pred, Proj proj = {} );
(9) (C++26 起) 
template< /*execution-policy*/ Ep,
          /*sized-random-access-range*/ R, class Proj = std::identity,
          std::indirect_unary_predicate
              <std::projected<ranges::iterator_t<R>, Proj>> Pred >
bool any_of( Ep&& policy, R&& r, Pred pred, Proj proj = {} );
(10) (C++26 起) 
template< /*execution-policy*/ Ep, std::random_access_iterator I,
          std::sized_sentinel_for<I> S, class Proj = std::identity,
          std::indirect_unary_predicate<std::projected<I, Proj>> Pred >
bool none_of( Ep&& policy, I first, S last, Pred pred, Proj proj = {} );
(11) (C++26 起) 
template< /*execution-policy*/ Ep,
          /*sized-random-access-range*/ R, class Proj = std::identity,
          std::indirect_unary_predicate
              <std::projected<ranges::iterator_t<R>, Proj>> Pred >
bool none_of( Ep&& policy, R&& r, Pred pred, Proj proj = {} );
(12) (C++26 起)

/*execution-policy*/ 的定义见此页；/*sized-random-access-range*/ 的定义见此页。

1,2) 检查一元谓词 pred 是否对范围 [first, last) 或 r 中至少一个（以 proj 投影后的）元素返回 false。

3,4) 检查一元谓词 pred 是否对范围 [first, last) 或 r 中至少一个（以 proj 投影后的）元素返回 true。

5,6) 检查一元谓词 pred 是否不对范围 [first, last) 或 r 中任何（以 proj 投影后的）元素返回 true。

7-12) 同 (1-6)，但按照 policy 执行。

此页面上描述的函数式实体是算法函数对象（非正式地称为 niebloid），即：

参数

first, last - 表示要检验的元素范围的迭代器-哨位对
r - 要检验的元素范围
pred - 会应用到（投影后的）元素的谓词
proj - 会应用到元素的投影
policy - 所用的执行策略

返回值

范围中含有 true 元素 是 否
 范围中含有 false 元素  是 否 是     否[1]
all_of false true false true
any_of true true   false     false  
none_of   false     false   true true
  1. ↑ 此情况下范围为空。

复杂度

最多应用 range::distance(first, last) 或 range::distance(r) 次 pred 和 proj。

异常

可能的实现

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));
    }
    
    template<ranges::forward_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::next(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));
    }
    
    template<ranges::forward_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::next(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));
    }
    
    template<ranges::forward_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::next(ranges::begin(r), ranges::end(r)),
                          std::ref(pred), std::ref(proj));
    }
};

inline constexpr none_of_fn none_of;

示例

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

namespace ranges = std::ranges;

constexpr bool some_of(auto&& r, auto&& pred) // 一些但非全部
{
    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 << "这些数中：";
    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 << "全部都是偶数\n";
    
    if (ranges::none_of(v, std::bind(std::modulus<int>(), std::placeholders::_1, 2)))
        std::cout << "没有奇数\n";
    
    auto DivisibleBy = [](int d)
    {
        return [d](int m) { return m % d == 0; };
    };
    
    if (ranges::any_of(v, DivisibleBy(7)))
        std::cout << "至少一个数可被 7 整除\n";
}

输出： 

这些数中：2 4 6 8 10 12 14 16 18 20
全部都是偶数
没有奇数
至少一个数可被 7 整除

参阅