[英]boost::uuids::uuid as a key in std::unordered_map?
I'm using clang (CXX='clang++ -std=c++11 -stdlib=libc++') on Mac OS X, with boost 1.53.0. 我在Mac OS X上使用clang(CXX ='clang ++ -std = c ++ 11 -stdlib = libc ++'),增强1.53.0。
I want to use uuid as keys in unordered_map, but getting the following errors: 我想在unordered_map中使用uuid作为键,但是会出现以下错误:
/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
~~~~~~~~~~~~~~~~~^
... ...
What is it - a bug in Boost, which makes it incompatible with my C++ lib? 它是什么 - Boost中的一个错误,它使它与我的C ++ lib不兼容? Or I am doing something wrong? 或者我做错了什么? Any workarounds? 任何解决方法?
Why bug in boost? 为什么提升中的bug? You should specialize std::hash template for boost::uuid
. 你应该专门为boost::uuid
std :: hash模板。
#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);
}
};
}
or, simply create unordered_map
with boost::hash
par 或者,只需使用boost::hash
par创建unordered_map
std::unordered_map<boost::uuids::uuid, T, boost::hash<boost::uuids::uuid>>
or provide hash
functor that satisfies requirements of std::hash
(thanks to Praetorian). 或提供满足std::hash
要求的hash
函子(感谢Praetorian)。
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