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调用签名
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template< std::input_iterator I, std::sentinel_for<I> S, class T1, class T2,
std::output_iterator<const T2&> O, class Proj = std::identity >
requires std::indirectly_copyable<I, O> &&
std::indirect_binary_predicate<ranges::equal_to, std::projected<I,
Proj>,
const T1*>
constexpr replace_copy_result<I, O>
replace_copy( I first, S last, O
result, const T1&
old_value, const T2& new_value,
Proj proj = {} );
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(1) |
(C++20 起) |
template< ranges::input_range R, class T1,
class T2,
std::output_iterator<const T2&> O, class Proj = std::identity >
requires std::indirectly_copyable<ranges::iterator_t<R>, O> &&
std::indirect_binary_predicate<ranges::equal_to,
std::projected<ranges::iterator_t<R>, Proj>, const T1*>
constexpr replace_copy_result<ranges::borrowed_iterator_t<R>, O>
replace_copy( R&& r, O result, const T1& old_value,
const T2&
new_value,
Proj proj = {} );
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(2) |
(C++20 起) |
template< std::input_iterator I, std::sentinel_for<I> S, class T,
std::output_iterator<const T&> O,
class Proj =
std::identity,
std::indirect_unary_predicate<
std::projected<I,
Proj>> Pred >
requires std::indirectly_copyable<I, O>
constexpr replace_copy_if_result<I, O>
replace_copy_if( I first, S last, O
result, Pred pred, const T& new_value,
Proj proj = {} );
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(3) |
(C++20 起) |
template< ranges::input_range R, class T,
std::output_iterator<const T&> O,
class Proj =
std::identity,
std::indirect_unary_predicate<std::projected<ranges::iterator_t<R>, Proj>> Pred >
requires std::indirectly_copyable<ranges::iterator_t<R>, O>
constexpr replace_copy_if_result<ranges::borrowed_iterator_t<R>, O>
replace_copy_if( R&& r, O result, Pred pred, const T&
new_value,
Proj proj = {} );
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(4) |
(C++20 起) |
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辅助类型
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template< class I, class O >
using replace_copy_result = ranges::in_out_result<I, O>;
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(5) |
(C++20 起) |
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template< class I, class O >
using replace_copy_if_result = ranges::in_out_result<I, O>;
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(6) |
(C++20 起) |
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从源范围 [first, last) 复制元素到始于 result 的目标范围，以 new_value
替换所欲满足特定标准的元素。若源范围与目标范围重叠则行为未定义。
1) 替换所有等于
old_value 的元素，用
std::invoke(proj, *(first + (i - result))) == old_value 比较。
2,4) 同 (1,3) ，但以
r 为源范围，如同以 ranges::begin(r) 为 first 并以 ranges::end(r) 为 last 。
此页面上描述的仿函数实体是 niebloid，即：
实际上，它们能以函数对象，或者某些特殊编译器扩展实现。
参数
| first, last
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要复制的元素范围
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| r
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要复制的元素范围
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| result
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目标范围的起始
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| old_value
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要替换的元素的值
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| new_value
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用作替换品的值
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| pred
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应用到投影后元素的谓词
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| proj
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应用到元素的投影
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返回值
{last, result
+ N} ，其中
1,3) N = ranges::distance(first, last) ；
2,4) N = ranges::distance(r) 。
复杂度
准确应用 N 次对应的谓词
comp 与投影 proj 。
可能的实现
| 版本一
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struct replace_copy_fn {
template <std::input_iterator I, std::sentinel_for<I> S, class T1, class T2,
std::output_iterator<const T2&> O, class Proj = std::identity>
requires std::indirectly_copyable<I, O> &&
std::indirect_binary_predicate<ranges::equal_to, std::projected<I, Proj>,
const T1*>
constexpr ranges::replace_copy_result<I, O>
operator()( I first, S last, O result, const T1& old_value, const T2& new_value,
Proj proj = {} ) const {
for (; first != last; ++first, ++result) {
*result = (std::invoke(proj, *first) == old_value) ? new_value : *first;
}
return {std::move(first), std::move(result)};
}
template <ranges::input_range R, class T1, class T2,
std::output_iterator<const T2&> O, class Proj = std::identity>
requires std::indirectly_copyable<ranges::iterator_t<R>, O> &&
std::indirect_binary_predicate<ranges::equal_to,
std::projected<ranges::iterator_t<R>, Proj>, const T1*>
constexpr ranges::replace_copy_result<ranges::borrowed_iterator_t<R>, O>
operator()( R&& r, O result, const T1& old_value, const T2& new_value,
Proj proj = {} ) const {
return (*this)(ranges::begin(r), ranges::end(r), std::move(result),
old_value, new_value, std::move(proj));
}
};
inline constexpr replace_copy_fn replace_copy{};
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| 版本二
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struct replace_copy_if_fn {
template <std::input_iterator I, std::sentinel_for<I> S, class T,
std::output_iterator<const T&> O,
class Proj = std::identity, std::indirect_unary_predicate<
std::projected<I, Proj>> Pred>
requires std::indirectly_copyable<I, O>
constexpr ranges::replace_copy_if_result<I, O>
operator()( I first, S last, O result, Pred pred, const T& new_value,
Proj proj = {} ) const {
for (; first != last; ++first, ++result) {
*result = std::invoke(pred, std::invoke(proj, *first)) ? new_value : *first;
}
return {std::move(first), std::move(result)};
}
template <ranges::input_range R, class T, std::output_iterator<const T&> O,
class Proj = std::identity,
std::indirect_unary_predicate<std::projected<ranges::iterator_t<R>, Proj>> Pred>
requires std::indirectly_copyable<ranges::iterator_t<R>, O>
constexpr ranges::replace_copy_if_result<ranges::borrowed_iterator_t<R>, O>
operator()( R&& r, O result, Pred pred, const T& new_value,
Proj proj = {} ) const {
return (*this)(ranges::begin(r), ranges::end(r), std::move(result),
std::move(pred), new_value, std::move(proj));
}
};
inline constexpr replace_copy_if_fn replace_copy_if{};
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示例
#include <algorithm>
#include <array>
#include <iostream>
#include <vector>
int main()
{
auto print = [](const auto rem, const auto& v) {
for (std::cout << rem << ": "; const auto& e : v)
std::cout << e << ' ';
std::cout << '\n';
};
std::vector<int> o;
std::array p{1, 6, 1, 6, 1, 6};
o.resize(p.size());
print("p", p);
std::ranges::replace_copy(p, o.begin(), 6, 9);
print("o", o);
std::array q{1, 2, 3, 6, 7, 8, 4, 5};
o.resize(q.size());
print("q", q);
std::ranges::replace_copy_if(q, o.begin(), [](int x){ return 5 < x; }, 5);
print("o", o);
}
输出：
p: 1 6 1 6 1 6
o: 1 9 1 9 1 9
q: 1 2 3 6 7 8 4 5
o: 1 2 3 5 5 5 4 5
参阅
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将所有满足特定判别标准的值替换为另一个值
(niebloid) |
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复制一个范围内的元素，并将满足特定判别标准的元素替换为另一个值
(函数模板) |