std::owner_less
Defined in header <memory>
.
template<>
struct owner_less<void>;
std::owner_less<>
is a specialization of std::owner_less with parameter types deduced.
Member types
Member type | Definition |
---|---|
is_transparent | /* unspecified */ |
Notes
The member type is_transparent indicates to the caller that this function object is a transparent function object:
it accepts arguments of arbitrary types and uses perfect forwarding, which avoids unnecessary copying and conversion when the function object is used in heterogeneous context,
or with rvalue arguments. In particular, template functions such as std::set::find
and std::set::lower_bound
make use of this member type on their Compare types.
Feature-test macro |
---|
__cpp_lib_transparent_operators |
Member functions
pub | operator() | compares its arguments using owner-based semantics (function) |
std::owner_less<void>::operator()
template<class T, class U>
bool operator()( const std::shared_ptr<T>& lhs,
const std::shared_ptr<U>& rhs ) const noexcept; // (since C++11)
template<class T, class U>
bool operator()( const std::shared_ptr<T>& lhs,
const std::weak_ptr<U>& rhs ) const noexcept; // (since C++11)
template<class T, class U>
bool operator()( const std::weak_ptr<T>& lhs,
const std::shared_ptr<U>& rhs ) const noexcept; // (since C++11)
template<class T, class U>
bool operator()( const std::weak_ptr<T>& lhs,
const std::weak_ptr<U>& rhs ) const noexcept; // (since C++11)
Compares lhs
and rhs
using owner-based semantics. Effectively calls lhs.owner_before(rhs)
.
The ordering is strict weak ordering relation.
lhs
and rhs
are equivalent only if they are both empty or share ownership.
Parameters
lhs
, rhs
- shared-ownership pointers to compare
Return value
true
if lhs
is less than rhs
as determined by the owner-based ordering.