Difference between revisions of "cpp/memory/ranges/destroy"
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{{cpp/memory/navbar}} | {{cpp/memory/navbar}} | ||
{{dcl begin}} | {{dcl begin}} | ||
| − | {{dcl header | memory}} | + | {{dcl header|memory}} |
| − | {{dcl h | Call signature}} | + | {{dcl h|Call signature}} |
| − | {{dcl | since=c++20 | num=1 | | + | {{dcl|since=c++20|num=1| |
template< no-throw-input-iterator I, no-throw-sentinel-for<I> S > | template< no-throw-input-iterator I, no-throw-sentinel-for<I> S > | ||
requires std::destructible<std::iter_value_t<I>> | requires std::destructible<std::iter_value_t<I>> | ||
constexpr I destroy( I first, S last ) noexcept; | constexpr I destroy( I first, S last ) noexcept; | ||
}} | }} | ||
| − | {{dcl | since=c++20 | num=2 | | + | {{dcl|since=c++20|num=2| |
template< no-throw-input-range R > | template< no-throw-input-range R > | ||
requires std::destructible<ranges::range_value_t<R>> | requires std::destructible<ranges::range_value_t<R>> | ||
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{{dcl end}} | {{dcl end}} | ||
| − | @1@ Destroys the objects in the range {{ | + | @1@ Destroys the objects in the range {{range|first|last}}, as if by |
{{source|1= | {{source|1= | ||
for (; first != last; ++first) | for (; first != last; ++first) | ||
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}} | }} | ||
| − | @2@ Same as {{v|1}}, but uses {{ | + | @2@ Same as {{v|1}}, but uses {{c|r}} as the source range, as if using {{c|ranges::begin(r)}} as {{c|first}} and {{c|ranges::end(r)}} as {{c|last}}. |
{{cpp/ranges/niebloid}} | {{cpp/ranges/niebloid}} | ||
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===Parameters=== | ===Parameters=== | ||
{{par begin}} | {{par begin}} | ||
| − | {{par | first, last | iterator-sentinel pair denoting the range of elements to destroy}} | + | {{par|first, last|iterator-sentinel pair denoting the range of elements to destroy}} |
| − | {{par | r | the range to destroy}} | + | {{par|r|the range to destroy}} |
{{par end}} | {{par end}} | ||
===Return value=== | ===Return value=== | ||
| − | An iterator compares equal to {{ | + | An iterator compares equal to {{c|last}}. |
===Complexity=== | ===Complexity=== | ||
| − | Linear in the distance between {{ | + | Linear in the distance between {{c|first}} and {{c|last}}. |
===Possible implementation=== | ===Possible implementation=== | ||
| − | {{eq fun | 1= | + | {{eq fun|1= |
| − | struct destroy_fn { | + | struct destroy_fn |
| − | + | { | |
| − | + | template<no-throw-input-iterator I, no-throw-sentinel-for<I> S> | |
| − | + | requires std::destructible<std::iter_value_t<I>> | |
| − | + | constexpr I operator()(I first, S last) const noexcept | |
| − | + | { | |
| − | + | for (; first != last; ++first) | |
| − | + | std::ranges::destroy_at(std::addressof(*first)); | |
| − | + | return first; | |
| + | } | ||
| − | + | template<no-throw-input-range R> | |
| − | + | requires std::destructible<std::ranges::range_value_t<R>> | |
| − | + | constexpr std::ranges::borrowed_iterator_t<R> operator()(R&& r) const noexcept | |
| − | + | { | |
| − | + | return operator()(std::ranges::begin(r), std::ranges::end(r)); | |
| − | + | } | |
}; | }; | ||
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===See also=== | ===See also=== | ||
{{dsc begin}} | {{dsc begin}} | ||
| − | {{dsc inc | cpp/memory/ranges/dsc destroy_n}} | + | {{dsc inc|cpp/memory/ranges/dsc destroy_n}} |
| − | {{dsc inc | cpp/memory/ranges/dsc destroy_at}} | + | {{dsc inc|cpp/memory/ranges/dsc destroy_at}} |
| − | {{dsc inc | cpp/memory/dsc destroy}} | + | {{dsc inc|cpp/memory/dsc destroy}} |
{{dsc end}} | {{dsc end}} | ||
| − | {{langlinks|es|ja|zh}} | + | {{langlinks|es|ja|ru|zh}} |
Latest revision as of 21:24, 13 July 2023
| Defined in header <memory>
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| Call signature |
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| template< no-throw-input-iterator I, no-throw-sentinel-for<I> S > requires std::destructible<std::iter_value_t<I>> |
(1) | (since C++20) |
| template< no-throw-input-range R > requires std::destructible<ranges::range_value_t<R>> |
(2) | (since C++20) |
1) Destroys the objects in the range
[first, last), as if by
for (; first != last; ++first) std::ranges::destroy_at(std::addressof(*first)); return first;
2) Same as (1), but uses r as the source range, as if using ranges::begin(r) as first and ranges::end(r) as last.
The function-like entities described on this page are niebloids, that is:
- Explicit template argument lists cannot be specified when calling any of them.
- None of them are visible to argument-dependent lookup.
- When any of them are found by normal unqualified lookup as the name to the left of the function-call operator, argument-dependent lookup is inhibited.
In practice, they may be implemented as function objects, or with special compiler extensions.
Contents |
[edit] Parameters
| first, last | - | iterator-sentinel pair denoting the range of elements to destroy |
| r | - | the range to destroy |
[edit] Return value
An iterator compares equal to last.
[edit] Complexity
Linear in the distance between first and last.
[edit] Possible implementation
struct destroy_fn { template<no-throw-input-iterator I, no-throw-sentinel-for<I> S> requires std::destructible<std::iter_value_t<I>> constexpr I operator()(I first, S last) const noexcept { for (; first != last; ++first) std::ranges::destroy_at(std::addressof(*first)); return first; } template<no-throw-input-range R> requires std::destructible<std::ranges::range_value_t<R>> constexpr std::ranges::borrowed_iterator_t<R> operator()(R&& r) const noexcept { return operator()(std::ranges::begin(r), std::ranges::end(r)); } }; inline constexpr destroy_fn destroy{}; |
[edit] Example
The following example demonstrates how to use ranges::destroy to destroy a contiguous sequence of elements.
Run this code
#include <iostream> #include <memory> #include <new> struct Tracer { int value; ~Tracer() { std::cout << value << " destructed\n"; } }; int main() { alignas(Tracer) unsigned char buffer[sizeof(Tracer) * 8]; for (int i = 0; i < 8; ++i) new(buffer + sizeof(Tracer) * i) Tracer{i}; //manually construct objects auto ptr = std::launder(reinterpret_cast<Tracer*>(buffer)); std::ranges::destroy(ptr, ptr + 8); }
Output:
0 destructed 1 destructed 2 destructed 3 destructed 4 destructed 5 destructed 6 destructed 7 destructed
[edit] See also
| (C++20) |
destroys a number of objects in a range (niebloid) |
| (C++20) |
destroys an object at a given address (niebloid) |
| (C++17) |
destroys a range of objects (function template) |
