Fix LWG issue 2469 - Use piecewise construction in unordered_map::operator[].
unordered_map's allocator may only be used to construct objects of 'value_type',
or in this case 'pair<const Key, Value>'. In order to respect this requirement
in operator[], which requires default constructing the 'mapped_type', we have
to use pair's piecewise constructor with '(tuple<Kep>, tuple<>)'.
Unfortunately we still need to provide a fallback implementation for C++03
since we don't have <tuple>. Even worse this fallback is the last remaining
user of '__hash_map_node_destructor' and '__construct_node_with_key'.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@260601 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/unordered_map b/include/unordered_map
index 7e84f74..372868a 100644
--- a/include/unordered_map
+++ b/include/unordered_map
@@ -369,6 +369,7 @@
#include <__hash_table>
#include <functional>
#include <stdexcept>
+#include <tuple>
#include <__debug>
@@ -1128,7 +1129,7 @@
{return __table_.__equal_range_unique(__k);}
mapped_type& operator[](const key_type& __k);
-#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+#ifndef _LIBCPP_CXX03_LANG
mapped_type& operator[](key_type&& __k);
#endif
@@ -1184,10 +1185,10 @@
#endif // _LIBCPP_DEBUG_LEVEL >= 2
private:
-#ifndef _LIBCPP_CXX03_LANG
- __node_holder __construct_node_with_key(key_type&& __k);
-#endif // _LIBCPP_CXX03_LANG
+
+#ifdef _LIBCPP_CXX03_LANG
__node_holder __construct_node_with_key(const key_type& __k);
+#endif
};
template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
@@ -1394,23 +1395,7 @@
#endif // _LIBCPP_HAS_NO_GENERALIZED_INITIALIZERS
-#ifndef _LIBCPP_CXX03_LANG
-
-template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
-typename unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::__node_holder
-unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::__construct_node_with_key(key_type&& __k)
-{
- __node_allocator& __na = __table_.__node_alloc();
- __node_holder __h(__node_traits::allocate(__na, 1), _Dp(__na));
- __node_traits::construct(__na, _VSTD::addressof(__h->__value_.__cc.first), _VSTD::move(__k));
- __h.get_deleter().__first_constructed = true;
- __node_traits::construct(__na, _VSTD::addressof(__h->__value_.__cc.second));
- __h.get_deleter().__second_constructed = true;
- return __h;
-}
-
-#endif
-
+#ifdef _LIBCPP_CXX03_LANG
template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
typename unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::__node_holder
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::__construct_node_with_key(const key_type& __k)
@@ -1423,6 +1408,7 @@
__h.get_deleter().__second_constructed = true;
return _LIBCPP_EXPLICIT_MOVE(__h); // explicitly moved for C++03
}
+#endif
template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
template <class _InputIterator>
@@ -1435,6 +1421,7 @@
__table_.__insert_unique(*__first);
}
+#ifdef _LIBCPP_CXX03_LANG
template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
_Tp&
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::operator[](const key_type& __k)
@@ -1447,23 +1434,27 @@
__h.release();
return __r.first->second;
}
+#else
-#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
+template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
+_Tp&
+unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::operator[](const key_type& __k)
+{
+ return __table_.__emplace_unique_key_args(__k,
+ std::piecewise_construct, std::forward_as_tuple(__k),
+ std::forward_as_tuple()).first->__cc.second;
+}
template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
_Tp&
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::operator[](key_type&& __k)
{
- iterator __i = find(__k);
- if (__i != end())
- return __i->second;
- __node_holder __h = __construct_node_with_key(_VSTD::move(__k));
- pair<iterator, bool> __r = __table_.__node_insert_unique(__h.get());
- __h.release();
- return __r.first->second;
+ return __table_.__emplace_unique_key_args(__k,
+ std::piecewise_construct, std::forward_as_tuple(std::move(__k)),
+ std::forward_as_tuple()).first->__cc.second;
}
-#endif // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+#endif // !_LIBCPP_CXX03_MODE
template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
_Tp&