std::ranges::includes
来自cppreference.com
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| 在标头 <algorithm> 定义
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| 调用签名 |
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template< std::input_iterator I1, std::sentinel_for<I1> S1, std::input_iterator I2, std::sentinel_for<I2> S2, class Proj1 = std::identity, class Proj2 = std::identity, std::indirect_strict_weak_order< std::projected<I1, Proj1>, std::projected<I2, Proj2>> Comp = ranges::less > constexpr bool includes( I1 first1, S1 last1, I2 first2, S2 last2, Comp comp = {}, Proj1 proj1 = {}, Proj2 proj2 = {} ) |
(1) | (C++20 起) |
template< ranges::input_range R1, ranges::input_range R2, class Proj1 = std::identity, class Proj2 = std::identity, std::indirect_strict_weak_order< std::projected<ranges::iterator_t<R1>, Proj1>, std::projected<ranges::iterator_t<R2>, Proj2>> Comp = ranges::less > constexpr bool includes( R1&& r1, R2&& r2, Comp comp = {}, Proj1 proj1 = {}, Proj2 proj2 = {} ) |
(2) | (C++20 起) |
2) 同 (1)，但以
r1 与 r2 为源范围，如同分别以 ranges::begin(r1) 与 ranges::begin(r2) 为 first1 与 first2，并分别以 ranges::end(r1) 与 ranges::end(r2) 为 last1 与 last2。两个范围都必须按照给定的比较函数 comp 排序。子序列不需要连续。
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
| first1, last1 | - | 要检验的有序元素范围的迭代器-哨位对 |
| r1 | - | 要检验的有序元素范围 |
| first2, last2 | - | 要搜索的有序元素范围的迭代器-哨位对 |
| r2 | - | 要搜索的有序元素范围 |
| comp | - | 应用到投影后元素的谓词 |
| proj1 | - | 应用到第一范围中元素的投影 |
| proj2 | - | 应用到第二范围中元素的投影 |
返回值
若 [first2, last2) 是 [first1, last1) 的子序列则为 true；否则为 false。
复杂度
至多比较 2·(N1+N2-1) 次，其中 N1 为 ranges::distance(r1) 而 N2 为 ranges::distance(r2)。
可能的实现
struct includes_fn
{
template<std::input_iterator I1, std::sentinel_for<I1> S1,
std::input_iterator I2, std::sentinel_for<I2> S2,
class Proj1 = std::identity, class Proj2 = std::identity,
std::indirect_strict_weak_order<
std::projected<I1, Proj1>,
std::projected<I2, Proj2>> Comp = ranges::less>
constexpr bool operator()(I1 first1, S1 last1, I2 first2, S2 last2,
Comp comp = {}, Proj1 proj1 = {}, Proj2 proj2 = {}) const
{
for (; first2 != last2; ++first1)
{
if (first1 == last1 || comp(*first2, *first1))
return false;
if (!comp(*first1, *first2))
++first2;
}
return true;
}
template<ranges::input_range R1, ranges::input_range R2,
class Proj1 = std::identity, class Proj2 = std::identity,
std::indirect_strict_weak_order<
std::projected<ranges::iterator_t<R1>, Proj1>,
std::projected<ranges::iterator_t<R2>, Proj2>> Comp = ranges::less>
constexpr bool operator()(R1&& r1, R2&& r2, Comp comp = {},
Proj1 proj1 = {}, Proj2 proj2 = {}) const
{
return (*this)(ranges::begin(r1), ranges::end(r1),
ranges::begin(r2), ranges::end(r2),
std::ref(comp), std::ref(proj1), std::ref(proj2));
}
};
inline constexpr auto includes = includes_fn {};
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示例
运行此代码
#include <algorithm>
#include <cctype>
#include <initializer_list>
#include <iomanip>
#include <iostream>
#include <locale>
#include <string>
template<class T>
std::ostream& operator<<(std::ostream& os, std::initializer_list<T> const& list)
{
for (os << "{ "; auto const& elem : list)
os << elem << ' ';
return os << "} ";
}
struct true_false : std::numpunct<char>
{
std::string do_truename() const { return "? Yes\n"; }
std::string do_falsename() const { return "? No\n"; }
};
int main()
{
std::cout.imbue(std::locale(std::cout.getloc(), new true_false));
auto ignore_case = [](char a, char b) { return std::tolower(a) < std::tolower(b); };
const auto
a = {'a', 'b', 'c'},
b = {'a', 'c'},
c = {'a', 'a', 'b'},
d = {'g'},
e = {'a', 'c', 'g'},
f = {'A', 'B', 'C'},
z = {'a', 'b', 'c', 'f', 'h', 'x'};
std::cout
<< z << "includes\n" << std::boolalpha
<< a << std::ranges::includes(z.begin(), z.end(), a.begin(), a.end())
<< b << std::ranges::includes(z, b)
<< c << std::ranges::includes(z, c)
<< d << std::ranges::includes(z, d)
<< e << std::ranges::includes(z, e)
<< f << std::ranges::includes(z, f, ignore_case);
}
输出：
{ a b c f h x } includes
{ a b c } ? Yes
{ a c } ? Yes
{ a a b } ? No
{ g } ? No
{ a c g } ? No
{ A B C } ? Yes
参阅
(C++20) |
计算两个集合的差集 (算法函数对象) |
(C++20) |
搜索元素范围的首次出现 (算法函数对象) |
(C++23)(C++23) |
检查范围是否包含给定元素或子范围 (算法函数对象) |
当一个序列是另一个的子序列时返回 true (函数模板) |