std::owner_equal
From cppreference.com
| Defined in header <memory>
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| struct owner_equal; |
(since C++26) | |
This function object provides owner-based (as opposed to value-based) mixed-type equal comparison of both std::weak_ptr and std::shared_ptr. The comparison is such that two smart pointers compare equivalent only if they are both empty or if they share ownership, even if the values of the raw pointers obtained by get() are different (e.g. because they point at different subobjects within the same object).
1) Owner-based mixed-type equal comparison is not provided for types other than std::shared_ptr and std::weak_ptr.
It is the preferred comparison predicate when building unordered associative containers with std::shared_ptr and std::weak_ptr as keys together with std::owner_hash, that is, std::unordered_map<std::shared_ptr<T>, U, std::owner_hash, std::owner_equal> or std::unordered_map<std::weak_ptr<T>, U, std::owner_hash, std::owner_equal>.
3)
std::owner_equal deduces the parameter types from the arguments.Contents |
[edit] Nested types
| Nested type | Definition |
is_transparent
|
unspecified |
[edit] Member functions
| operator() |
compares its arguments using owner-based semantics (function) |
std::owner_equal::operator()
| template< class T, class U > bool operator()( const std::shared_ptr<T>& lhs, |
(since C++26) | |
| template< class T, class U > bool operator()( const std::shared_ptr<T>& lhs, |
(since C++26) | |
| template< class T, class U > bool operator()( const std::weak_ptr<T>& lhs, |