namespace std::ranges {
template <input_iterator I1,
sentinel_for<I1> S1,
input_iterator I2,
sentinel_for<I2> S2,
class Pred = ranges::equal_to,
class Proj1 = identity,
class Proj2 = identity>
requires (forward_iterator<I1> || sized_sentinel_for<S1, I1>) &&
(forward_iterator<I2> || sized_sentinel_for<S2, I2>) &&
indirectly_comparable<I1, I2, Pred, Proj1, Proj2>
constexpr bool
ends_with(I1 first1,
S1 last1,
I2 first2,
S2 last2,
Pred pred = {},
Proj1 proj1 = {},
Proj2 proj2 = {}); // (1) C++23
template <input_range R1,
input_range R2,
class Pred = ranges::equal_to,
class Proj1 = identity,
class Proj2 = identity>
requires (forward_range<R1> || sized_range<R1>) &&
(forward_range<R2> || sized_range<R2>) &&
indirectly_comparable<iterator_t<R1>, iterator_t<R2>, Pred, Proj1, Proj2>
constexpr bool
ends_with(R1&& r1,
R2&& r2,
Pred pred = {},
Proj1 proj1 = {},
Proj2 proj2 = {}); // (2) C++23
}
概要
シーケンスの末尾が指定されたシーケンスと一致するかを調べる
- (1): イテレータ範囲を指定する
- (2): Rangeを直接指定する
戻り値
- (1):
N1 = last1 - first1,N2 = last2 - first2とする。N1 < N2のとき、false- それ以外のとき、
ranges::equal(std::move(first1) + (N1 - N2), last1,std::move(first2), last2, pred, proj1, proj2)
- (2):
N1 =ranges::distance(r1),N2 =ranges::distance(r2)とする。N1 < N2のとき、false- それ以外のとき、
ranges::equal(ranges::drop_view(ranges::ref_view(r1), N1 - N2), r2, pred, proj1, proj2)
計算量
最大で N2 回の対応する述語が適用される。
例
#include <algorithm>
#include <iostream>
#include <vector>
int main() {
const std::vector v = { 1,2,3,4,5,6 };
const std::vector v1 = { 1,2,3 };
const std::vector v2 = { 4,5,6 };
std::cout << std::ranges::ends_with(v1, v) << std::endl;
std::cout << std::ranges::ends_with(v, v1) << std::endl;
std::cout << std::ranges::ends_with(v, v2) << std::endl;
}
14
#include <algorithm>#include <iostream>#include <vector>int main() { const std::vector v = { 1,2,3,4,5,6 }; const std::vector v1 = { 1,2,3 }; const std::vector v2 = { 4,5,6 }; std::cout << std::ranges::ends_with(v1, v) << std::endl; std::cout << std::ranges::ends_with(v, v1) << std::endl; std::cout << std::ranges::ends_with(v, v2) << std::endl;}出力
0
0
1
実装例
struct ends_with_impl {
template<input_iterator I1, sentinel_for<I1> S1, input_iterator I2, sentinel_for<I2> S2, class Pred = ranges::equal_to, class Proj1 = identity, class Proj2 = identity>
requires (forward_iterator<I1> || sized_sentinel_for<S1, I1>) &&
(forward_iterator<I2> || sized_sentinel_for<S2, I2>) &&
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 {
const auto N1 = distance(first1, last1);
const auto N2 = distance(first2, last2);
return N1 < N2 ? false :
equal(move(first1) + (N1 - N2), last1, move(first2), last2, pred, proj1, proj2);
}
template<input_range R1, input_range R2, class Pred = ranges::equal_to, class Proj1 = identity, class Proj2 = identity>
requires (forward_range<R1> || sized_range<R1>) &&
(forward_range<R2> || sized_range<R2>) &&
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 {
const auto N1 = distance(r1);
const auto N2 = distance(r2);
return N1 < N2 ? false :
equal(drop_view(ref_view(r1), N1 - N2), r2, pred, proj1, proj2);
}
};
inline constexpr ends_with_impl ends_with;
バージョン
言語
- C++23
処理系
- Clang: ??
- GCC: ??
- ICC: ??
- Visual C++: ??