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

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.

llvm-svn: 264989
This commit is contained in:
Eric Fiselier 2016-03-31 03:13:37 +00:00
parent 851b33a0b1
commit 54f0cda625
3 changed files with 109 additions and 72 deletions
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109
libcxx/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&

43
libcxx/test/std/containers/associative/map/map.access/index_key.pass.cpp
View File

@ -16,8 +16,13 @@
#include <map>
#include <cassert>
#include "test_macros.h"
#include "count_new.hpp"
#include "min_allocator.h"
#include "private_constructor.hpp"
#if TEST_STD_VER >= 11
#include "container_test_types.h"
#endif
int main()
{
@ -46,7 +51,7 @@ int main()
assert(m[6] == 6.5);
assert(m.size() == 8);
}
#if __cplusplus >= 201103L
#if TEST_STD_VER >= 11
{
typedef std::pair<const int, double> V;
V ar[] =
@ -73,8 +78,42 @@ int main()
assert(m[6] == 6.5);
assert(m.size() == 8);
}
{
// Use "container_test_types.h" to check what arguments get passed
// to the allocator for operator[]
using Container = TCT::map<>;
using Key = Container::key_type;
using MappedType = Container::mapped_type;
using ValueTp = Container::value_type;
ConstructController* cc = getConstructController();
cc->reset();
{
Container c;
const Key k(1);
cc->expect<std::piecewise_construct_t const&, std::tuple<Key const&>&&, std::tuple<>&&>();
MappedType& mref = c[k];
assert(!cc->unchecked());
{
DisableAllocationGuard g;
MappedType& mref2 = c[k];
assert(&mref == &mref2);
}
}
{
Container c;
Key k(1);
cc->expect<std::piecewise_construct_t const&, std::tuple<Key const&>&&, std::tuple<>&&>();
MappedType& mref = c[k];
assert(!cc->unchecked());
{
DisableAllocationGuard g;
MappedType& mref2 = c[k];
assert(&mref == &mref2);
}
}
}
#endif
#if _LIBCPP_STD_VER > 11
#if TEST_STD_VER > 11
{
typedef std::pair<const int, double> V;
V ar[] =

29
libcxx/test/std/containers/associative/map/map.access/index_rv_key.pass.cpp
View File

@ -7,6 +7,8 @@
//
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++98, c++03
// <map>
// class map
@ -17,12 +19,13 @@
#include <cassert>
#include "test_macros.h"
#include "count_new.hpp"
#include "MoveOnly.h"
#include "min_allocator.h"
#include "container_test_types.h"
int main()
{
#if TEST_STD_VER >= 11
{
std::map<MoveOnly, double> m;
assert(m.size() == 0);
@ -52,5 +55,27 @@ int main()
assert(m[6] == 6.5);
assert(m.size() == 2);
}
#endif
{
// Use "container_test_types.h" to check what arguments get passed
// to the allocator for operator[]
using Container = TCT::map<>;
using Key = Container::key_type;
using MappedType = Container::mapped_type;
using ValueTp = Container::value_type;
ConstructController* cc = getConstructController();
cc->reset();
{
Container c;
Key k(1);
cc->expect<std::piecewise_construct_t const&, std::tuple<Key &&>&&, std::tuple<>&&>();
MappedType& mref = c[std::move(k)];
assert(!cc->unchecked());
{
Key k2(1);
DisableAllocationGuard g;
MappedType& mref2 = c[std::move(k2)];
assert(&mref == &mref2);
}
}
}
}