std::ranges::includes
| 定义在头文件 <algorithm> 中 |
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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, |
(1) | (自 C++20) |
| template< ranges::input_range R1, ranges::input_range R2, class Proj1 = std::identity, class Proj2 = std::identity, |
(2) | (自 C++20) |
两个范围必须使用给定的比较函数 comp 进行排序。子序列不必是连续的。
此页面上描述的类函数实体是 *niebloids*，即
实际上，它们可以用函数对象实现，或者使用特殊的编译器扩展。
内容 |
[edit] 参数
| first1, last1 | - | 要检查的已排序元素范围 |
| r1 | - | 要检查的已排序元素范围 |
| first2, last2 | - | 要搜索的已排序元素范围 |
| r2 | - | 要搜索的已排序元素范围 |
| comp | - | 要应用于投影元素的比较函数 |
| proj1 | - | 要应用于第一个范围中元素的投影 |
| proj2 | - | 要应用于第二个范围中元素的投影 |
[edit] 返回值
如果 [first2, last2) 是 [first1, last1) 的子序列；否则为 false。
[edit] 复杂度
最多 2·(N1+N2-1) 次比较，其中 N1 是 ranges::distance(r1) 且 N2 是 ranges::distance(r2)。
[edit] 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 {}; |
[edit] 示例
#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[edit] 参见
| (C++20) |
计算两个集合之间的差集 (niebloid) |
| (C++20) |
搜索元素范围的第一次出现 (niebloid) |
| (C++23)(C++23) |
检查范围是否包含给定元素或子范围 (niebloid) |
| 如果一个序列是另一个序列的子序列，则返回 true (函数模板) |
