boost :: uuids :: uuid作为关键在std :: unordered_map? [英] boost::uuids::uuid as a key in std::unordered_map?
问题描述
我在Mac OS X上使用clang(CXX ='clang ++ -std = c ++ 11 -stdlib = libc ++'),使用boost 1.53.0。
I'm using clang (CXX='clang++ -std=c++11 -stdlib=libc++') on Mac OS X, with boost 1.53.0.
我想在unordered_map中使用uuid作为键,但会收到以下错误:
I want to use uuid as keys in unordered_map, but getting the following errors:
/usr/bin/../lib/c++/v1/type_traits:748:38: error: implicit instantiation of undefined template
'std::__1::hash<boost::uuids::uuid>'
: public integral_constant<bool, __is_empty(_Tp)> {};
^
/usr/bin/../lib/c++/v1/unordered_map:327:54: note: in instantiation of template class
'std::__1::is_empty<std::__1::hash<boost::uuids::uuid> >' requested here
template <class _Key, class _Tp, class _Hash, bool = is_empty<_Hash>::value
...
/usr/bin/../lib/c++/v1/unordered_map:327:71: error: no member named 'value' in
'std::__1::is_empty<std::__1::hash<boost::uuids::uuid> >'
template <class _Key, class _Tp, class _Hash, bool = is_empty<_Hash>::value
~~~~~~~~~~~~~~~~~^
...
- Boost中的一个错误,这使它与我的C ++ lib不兼容?或者我做错了什么?任何解决方法?
What is it - a bug in Boost, which makes it incompatible with my C++ lib? Or I am doing something wrong? Any workarounds?
推荐答案
您应该专门为 std :: hash 模板 boost :: uuid
。
#include <boost/functional/hash.hpp>
namespace std
{
template<>
struct hash<boost::uuids::uuid>
{
size_t operator () (const boost::uuids::uuid& uid)
{
return boost::hash<boost::uuids::uuid>()(uid);
}
};
}
或者,只需创建 unordered_map
与 boost :: hash
par
or, simply create unordered_map
with boost::hash
par
std::unordered_map<boost::uuids::uuid, T, boost::hash<boost::uuids::uuid>>
或提供 hash
函子 std :: hash
(感谢Praetorian)。
or provide hash
functor that satisfies requirements of std::hash
(thanks to Praetorian).
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