我在Mac OS X上使用clang(CXX =’clang -std = c 11 -stdlib = libc’),增强1.53.0.
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,bool = is_empty<_Hash>::value
~~~~~~~~~~~~~~~~~^
…
解决方法
为什么提升中的bug？你应该专门为boost :: uuid设计
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);
}
};
}
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>>
或提供满足std :: hash要求的哈希函子(感谢Praetorian).
