std::ranges:: includes

From cppreference.net

定义于头文件 `<algorithm>`
调用约定
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)

1) 若已排序范围

first2

last2

的投影构成已排序范围

first1

last1

投影的子序列，则返回 true 。

2) 与 (1) 相同，但使用 r1 和 r2 作为源范围，如同分别使用 ranges:: begin ( r1 ) 和 ranges:: begin ( r2 ) 作为 first1 和 first2 ，以及 ranges:: end ( r1 ) 和 ranges:: end ( r2 ) 作为 last1 和 last2 。

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。

本页面描述的函数式实体是 算法函数对象 （非正式称为 niebloids ），即：

在调用其中任何一个时，都不能指定显式模板实参列表。
它们对实参依赖查找均不可见。
当通过常规非限定查找将其中任何一个作为函数调用运算符左侧的名称找到时，会抑制实参依赖查找。

first1, last1	-	定义待检验元素有序范围的迭代器-哨位对
r1	-	待检验元素的有序范围
first2, last2	-	定义待查找元素有序范围的迭代器-哨位对
r2	-	待查找元素的有序范围
comp	-	应用于投影元素的比较函数
proj1	-	应用于第一范围元素的投影
proj2	-	应用于第二范围元素的投影

返回值

当 [ first2 , last2 ) 是 [ first1 , last1 ) 的子序列时返回 true ；否则返回 false 。

复杂度

最多 $2\cdot(N 1 +N 2 -1)$ 次比较，其中 $\scriptsize N_1$ $N 1$ 为 ranges:: distance ( r1 ) ， $\scriptsize N_2$ $N 2$ 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 {};

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

参见

ranges::set_difference (C++20)	计算两个集合的差集 (算法函数对象)
ranges::search (C++20)	搜索元素范围的首次出现 (算法函数对象)
ranges::contains ranges::contains_subrange (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)
includes	若一个序列是另一个序列的子序列则返回 true (函数模板)

Compiler support
Freestanding and hosted
Language
Standard library
Standard library headers
Named requirements
Feature test macros (C++20)
Language support library
Concepts library (C++20)
Diagnostics library
Memory management library
Metaprogramming library (C++11)
General utilities library
Containers library
Iterators library
Ranges library (C++20)
Algorithms library
Strings library
Text processing library
Numerics library
Date and time library
Input/output library
Filesystem library (C++17)
Concurrency support library (C++11)
Execution control library (C++26)
Technical specifications
Symbols index
External libraries

cppreference.net

Namespaces

Variants

std::ranges:: includes

目录

参数

返回值

复杂度

可能的实现

示例

参见