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Fix LWG issue 2469 - Use piecewise construction in map::operator[].

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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'.

This patch also switches try_emplace over to __tree.__emplace_unique_key_args.


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@264989 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Eric Fiselier
2016-03-31 03:13:37 +00:00
parent db21506d13
commit d2864678e0
3 changed files with 109 additions and 72 deletions
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109
include/map
View File

@@ -1026,7 +1026,7 @@ public:
size_type max_size() const _NOEXCEPT {return __tree_.max_size();}
mapped_type& operator[](const key_type& __k);
#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
#ifndef _LIBCPP_CXX03_LANG
mapped_type& operator[](key_type&& __k);
#endif
@@ -1105,62 +1105,45 @@ public:
#endif // _LIBCPP_HAS_NO_GENERALIZED_INITIALIZERS
#if _LIBCPP_STD_VER > 14
#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
#ifndef _LIBCPP_HAS_NO_VARIADICS
template <class... _Args>
_LIBCPP_INLINE_VISIBILITY
pair<iterator, bool> try_emplace(const key_type& __k, _Args&&... __args)
{
iterator __p = lower_bound(__k);
if ( __p != end() && !key_comp()(__k, __p->first))
return _VSTD::make_pair(__p, false);
else
return _VSTD::make_pair(
emplace_hint(__p,
_VSTD::piecewise_construct, _VSTD::forward_as_tuple(__k),
_VSTD::forward_as_tuple(_VSTD::forward<_Args>(__args)...)),
true);
return __tree_.__emplace_unique_key_args(__k,
_VSTD::piecewise_construct,
_VSTD::forward_as_tuple(__k),
_VSTD::forward_as_tuple(_VSTD::forward<_Args>(__args)...));
}
template <class... _Args>
_LIBCPP_INLINE_VISIBILITY
pair<iterator, bool> try_emplace(key_type&& __k, _Args&&... __args)
{
iterator __p = lower_bound(__k);
if ( __p != end() && !key_comp()(__k, __p->first))
return _VSTD::make_pair(__p, false);
else
return _VSTD::make_pair(
emplace_hint(__p,
_VSTD::piecewise_construct, _VSTD::forward_as_tuple(_VSTD::move(__k)),
_VSTD::forward_as_tuple(_VSTD::forward<_Args>(__args)...)),
true);
return __tree_.__emplace_unique_key_args(__k,
_VSTD::piecewise_construct,
_VSTD::forward_as_tuple(_VSTD::move(__k)),
_VSTD::forward_as_tuple(_VSTD::forward<_Args>(__args)...));
}
template <class... _Args>
_LIBCPP_INLINE_VISIBILITY
iterator try_emplace(const_iterator __h, const key_type& __k, _Args&&... __args)
{
iterator __p = lower_bound(__k);
if ( __p != end() && !key_comp()(__k, __p->first))
return __p;
else
return emplace_hint(__p,
_VSTD::piecewise_construct, _VSTD::forward_as_tuple(__k),
_VSTD::forward_as_tuple(_VSTD::forward<_Args>(__args)...));
return __tree_.__emplace_hint_unique_key_args(__h.__i_, __k,
_VSTD::piecewise_construct,
_VSTD::forward_as_tuple(__k),
_VSTD::forward_as_tuple(_VSTD::forward<_Args>(__args)...));
}
template <class... _Args>
_LIBCPP_INLINE_VISIBILITY
iterator try_emplace(const_iterator __h, key_type&& __k, _Args&&... __args)
{
iterator __p = lower_bound(__k);
if ( __p != end() && !key_comp()(__k, __p->first))
return __p;
else
return emplace_hint(__p,
_VSTD::piecewise_construct, _VSTD::forward_as_tuple(_VSTD::move(__k)),
_VSTD::forward_as_tuple(_VSTD::forward<_Args>(__args)...));
return __tree_.__emplace_hint_unique_key_args(__h.__i_, __k,
_VSTD::piecewise_construct,
_VSTD::forward_as_tuple(_VSTD::move(__k)),
_VSTD::forward_as_tuple(_VSTD::forward<_Args>(__args)...));
}
template <class _Vp>
@@ -1175,7 +1158,7 @@ public:
}
return _VSTD::make_pair(emplace_hint(__p, __k, _VSTD::forward<_Vp>(__v)), true);
}
template <class _Vp>
_LIBCPP_INLINE_VISIBILITY
pair<iterator, bool> insert_or_assign(key_type&& __k, _Vp&& __v)
@@ -1214,8 +1197,7 @@ public:
}
return emplace_hint(__h, _VSTD::move(__k), _VSTD::forward<_Vp>(__v));
}
#endif
#endif
#endif
_LIBCPP_INLINE_VISIBILITY
@@ -1321,11 +1303,9 @@ private:
typedef __map_node_destructor<__node_allocator> _Dp;
typedef unique_ptr<__node, _Dp> __node_holder;
#ifndef _LIBCPP_CXX03_LANG
__node_holder __construct_node_with_key(key_type&& __k);
#endif
#ifdef _LIBCPP_CXX03_LANG
__node_holder __construct_node_with_key(const key_type& __k);
#endif
__node_base_pointer const&
__find_equal_key(__node_base_pointer& __parent, const key_type& __k) const;
@@ -1400,22 +1380,11 @@ map<_Key, _Tp, _Compare, _Allocator>::map(map&& __m, const allocator_type& __a)
}
}
template <class _Key, class _Tp, class _Compare, class _Allocator>
typename map<_Key, _Tp, _Compare, _Allocator>::__node_holder
map<_Key, _Tp, _Compare, _Allocator>::__construct_node_with_key(key_type&& __k)
{
__node_allocator& __na = __tree_.__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 // !_LIBCPP_CXX03_LANG
#ifdef _LIBCPP_CXX03_LANG
template <class _Key, class _Tp, class _Compare, class _Allocator>
typename map<_Key, _Tp, _Compare, _Allocator>::__node_holder
map<_Key, _Tp, _Compare, _Allocator>::__construct_node_with_key(const key_type& __k)
@@ -1445,25 +1414,29 @@ map<_Key, _Tp, _Compare, _Allocator>::operator[](const key_type& __k)
return __r->__value_.__cc.second;
}
#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
#else
template <class _Key, class _Tp, class _Compare, class _Allocator>
_Tp&
map<_Key, _Tp, _Compare, _Allocator>::operator[](const key_type& __k)
{
return __tree_.__emplace_unique_key_args(__k,
_VSTD::piecewise_construct,
_VSTD::forward_as_tuple(__k),
_VSTD::forward_as_tuple()).first->__cc.second;
}
template <class _Key, class _Tp, class _Compare, class _Allocator>
_Tp&
map<_Key, _Tp, _Compare, _Allocator>::operator[](key_type&& __k)
{
__node_base_pointer __parent;
__node_base_pointer& __child = __find_equal_key(__parent, __k);
__node_pointer __r = static_cast<__node_pointer>(__child);
if (__child == nullptr)
{
__node_holder __h = __construct_node_with_key(_VSTD::move(__k));
__tree_.__insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__h.get()));
__r = __h.release();
}
return __r->__value_.__cc.second;
return __tree_.__emplace_unique_key_args(__k,
_VSTD::piecewise_construct,
_VSTD::forward_as_tuple(_VSTD::move(__k)),
_VSTD::forward_as_tuple()).first->__cc.second;
}
#endif // _LIBCPP_HAS_NO_RVALUE_REFERENCES
#endif // !_LIBCPP_CXX03_LANG
template <class _Key, class _Tp, class _Compare, class _Allocator>
_Tp&