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Better rvalue emulation support in extractors

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Means that inserting rvalues into unordered_set/unordered_map won't
create a node if no insert is required.
This commit is contained in:
Daniel James
2017-05-01 21:03:11 +01:00
parent 2e14c340a8
commit 338a94e577
2 changed files with 71 additions and 11 deletions
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21
include/boost/unordered/detail/implementation.hpp
View File

@ -4267,6 +4267,11 @@ template <class ValueType> struct set_extractor
static key_type const& extract(value_type const& v) { return v; }
static key_type const& extract(BOOST_UNORDERED_RV_REF(value_type) v)
{
return v;
}
static no_key extract() { return no_key(); }
template <class Arg> static no_key extract(Arg const&) { return no_key(); }
@ -4306,6 +4311,22 @@ template <class ValueType> struct map_extractor
return v.first;
}
#if defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
template <class Second>
static key_type const& extract(
boost::rv<std::pair<key_type, Second> > const& v)
{
return v.first;
}
template <class Second>
static key_type const& extract(
boost::rv<std::pair<key_type const, Second> > const& v)
{
return v.first;
}
#endif
template <class Arg1>
static key_type const& extract(key_type const& k, Arg1 const&)
{

61
test/unordered/unnecessary_copy_tests.cpp
View File

@ -180,6 +180,53 @@ template <class T> void unnecessary_copy_insert_test(T*)
reset();
x.insert(a);
COPY_COUNT(1);
MOVE_COUNT(0);
}
template <class T> void unnecessary_copy_insert_rvalue_set_test(T*)
{
T x;
BOOST_DEDUCED_TYPENAME T::value_type a;
reset();
x.insert(boost::move(a));
COPY_COUNT(0);
MOVE_COUNT(1);
BOOST_DEDUCED_TYPENAME T::value_type a2;
reset();
x.insert(boost::move(a));
COPY_COUNT(0);
MOVE_COUNT((x.size() == 2 ? 1 : 0));
}
template <class T> void unnecessary_copy_insert_rvalue_map_test(T*)
{
// Doesn't currently try to emulate std::pair move construction,
// so std::pair's require a copy. Could try emulating it in
// construct_from_args.
T x;
BOOST_DEDUCED_TYPENAME T::value_type a;
reset();
x.insert(boost::move(a));
#if defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
COPY_COUNT(1);
MOVE_COUNT(0);
#else
COPY_COUNT(0);
MOVE_COUNT(1);
#endif
BOOST_DEDUCED_TYPENAME T::value_type a2;
reset();
x.insert(boost::move(a));
#if defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
COPY_COUNT((x.size() == 2 ? 1 : 0));
MOVE_COUNT(0);
#else
COPY_COUNT(0);
MOVE_COUNT((x.size() == 2 ? 1 : 0));
#endif
}
boost::unordered_set<count_copies>* set;
@ -188,6 +235,8 @@ boost::unordered_map<int, count_copies>* map;
boost::unordered_multimap<int, count_copies>* multimap;
UNORDERED_TEST(unnecessary_copy_insert_test, ((set)(multiset)(map)(multimap)))
UNORDERED_TEST(unnecessary_copy_insert_rvalue_set_test, ((set)(multiset)))
UNORDERED_TEST(unnecessary_copy_insert_rvalue_map_test, ((map)(multimap)))
template <class T> void unnecessary_copy_emplace_test(T*)
{
@ -315,15 +364,10 @@ UNORDERED_AUTO_TEST(unnecessary_copy_emplace_set_test)
// the existing element.
reset();
x.emplace();
#if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) || \
!defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
// source_cost doesn't make much sense here, but it seems to fit.
COPY_COUNT(1);
MOVE_COUNT(source_cost);
#else
COPY_COUNT(1);
MOVE_COUNT(1 + source_cost);
#endif
#endif
//
@ -347,13 +391,8 @@ UNORDERED_AUTO_TEST(unnecessary_copy_emplace_set_test)
// No move should take place.
reset();
x.emplace(boost::move(a));
#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
COPY_COUNT(0);
MOVE_COUNT(0);
#else
COPY_COUNT(0);
MOVE_COUNT(1);
#endif
// Use a new value for cases where a did get moved...
count_copies b;