最終更新日時(UTC): 2026年02月05日 04時53分18秒
Akira Takahashi が更新

履歴 編集

function template
<algorithm>

# std::ranges::contains_subrange(C++23)

    namespace std::ranges {
      // (1) C++23
      template<forward_iterator I1, sentinel_for<I1> S1,
               forward_iterator I2, sentinel_for<I2> S2,
               class Pred = ranges::equal_to, class Proj1 = identity, class Proj2 = identity>
      requires indirectly_comparable<I1, I2, Pred, Proj1, Proj2>
      constexpr bool ranges::contains_subrange(I1 first1, S1 last1, I2 first2, S2 last2,
                                               Pred pred = {}, Proj1 proj1 = {}, Proj2 proj2 = {});

      // (2) C++23
      template<forward_range R1, forward_range R2,
               class Pred = ranges::equal_to, class Proj1 = identity, class Proj2 = identity>
      requires indirectly_comparable<iterator_t<R1>, iterator_t<R2>, Pred, Proj1, Proj2>
      constexpr bool ranges::contains_subrange(R1&& r1, R2&& r2, Pred pred = {},
                                               Proj1 proj1 = {}, Proj2 proj2 = {});

      // (3) C++26
      template<execution-policy Ep,
               random_access_iterator I1, sized_sentinel_for<I1> S1,
               random_access_iterator I2, sized_sentinel_for<I2> S2,
               class Pred = ranges::equal_to, class Proj1 = identity, class Proj2 = identity>
      requires indirectly_comparable<I1, I2, Pred, Proj1, Proj2>
      bool ranges::contains_subrange(Ep&& exec, I1 first1, S1 last1, I2 first2, S2 last2,
                                     Pred pred = {}, Proj1 proj1 = {}, Proj2 proj2 = {});

      // (4) C++26
      template<execution-policy Ep,
               sized-random-access-range R1, sized-random-access-range R2,
               class Pred = ranges::equal_to, class Proj1 = identity, class Proj2 = identity>
      requires indirectly_comparable<iterator_t<R1>, iterator_t<R2>, Pred, Proj1, Proj2>
      bool ranges::contains_subrange(Ep&& exec, R1&& r1, R2&& r2, Pred pred = {},
                                     Proj1 proj1 = {}, Proj2 proj2 = {});
    }

## 概要

あるシーケンスの中に、特定のサブシーケンスが含まれるか調べる。

- (1): イテレータ範囲を指定する
- (2): Rangeを直接指定する
- (3): (1)の並列アルゴリズム版。実行ポリシーを指定する
- (4): (2)の並列アルゴリズム版。実行ポリシーを指定する

サブシーケンスが空の場合は、常に`true`を返す。

## 戻り値

    first2 == last2 || !ranges::search(first1, last1, first2, last2, pred, proj1, proj2).empty()

## 計算量

最大で `(last1 - first1) * (last2 - first2)` 回の、対応する比較もしくは述語が適用される

## 例

### 基本的な使い方

    #include <algorithm>
    #include <print>
    #include <vector>
    #include <list>

    int main() {
      std::vector<int> v = { 1,2,1,2,3 };
      std::list<int> ls = { 1,2 };

      if (std::ranges::contains_subrange(v, ls)) {
        std::println("found");
      } else {
        std::println("not found");
      }
    }

#### 出力

    found

### 並列アルゴリズムの例 (C++26)

    #include <algorithm>
    #include <execution>
    #include <iostream>
    #include <vector>

    int main() {
      std::vector<int> v = {1, 2, 3, 4, 5};
      std::vector<int> sub = {2, 3, 4};

      std::cout << std::boolalpha;

      // 並列にサブ範囲が含まれるかを判定
      bool result = std::ranges::contains_subrange(
        std::execution::par, v, sub);
      std::cout << result << std::endl;
    }

#### 出力

    true

## 実装例

    struct contains_subrange_impl {
      template<forward_iterator I1, sentinel_for<I1> S1,
               forward_iterator I2, sentinel_for<I2> S2,
               class Pred = ranges::equal_to, class Proj1 = identity, class Proj2 = identity>
      requires indirectly_comparable<I1, I2, Pred, Proj1, Proj2>
      constexpr bool operator()(I1 first1, S1 last1, I2 first2, S2 last2, Pred pred = {}, Proj1 proj1 = {}, Proj2 proj2 = {}) const {
        return first2 == last2 || !ranges::search(first1, last1, first2, last2, pred, proj1, proj2).empty();
      }

      template<forward_range R1, forward_range R2,
               class Pred = ranges::equal_to, class Proj1 = identity, class Proj2 = identity>
      requires indirectly_comparable<iterator_t<R1>, iterator_t<R2>, Pred, Proj1, Proj2>
      constexpr bool operator()(R1&& r1, R2&& r2, Pred pred = {}, Proj1 proj1 = {}, Proj2 proj2 = {}) const {
        return ranges::empty(r2) || !ranges::search(std::forward(r1), std::forward(r2), pred, proj1, proj2).empty();
      }
    };

    inline constexpr contains_subrange_impl contains_subrange;

## バージョン

### 言語

- C++23

### 処理系

- Clang: ??
- GCC: ??
- ICC: ??
- Visual C++: ??

## 参照

- N4950 27 Algorithms library
- P3179R9 C++ parallel range algorithms