added overload for std::less<value_t> #486

MSVC needs this overload to compile code containing a std::map that
uses nlohmann::detail::operator as key.
parent 758c4add
...@@ -13025,6 +13025,22 @@ struct hash<nlohmann::json> ...@@ -13025,6 +13025,22 @@ struct hash<nlohmann::json>
return h(j.dump()); return h(j.dump());
} }
}; };
/// specialization for std::less<value_t>
template <>
struct less<::nlohmann::detail::value_t>
{
/*!
@brief compare two value_t enum values
@since version 3.0.0
*/
bool operator()(nlohmann::detail::value_t lhs,
nlohmann::detail::value_t rhs) const noexcept
{
return nlohmann::detail::operator<(lhs, rhs);
}
};
} // namespace std } // namespace std
/*! /*!
......
...@@ -12059,6 +12059,22 @@ struct hash<nlohmann::json> ...@@ -12059,6 +12059,22 @@ struct hash<nlohmann::json>
return h(j.dump()); return h(j.dump());
} }
}; };
/// specialization for std::less<value_t>
template <>
struct less<::nlohmann::detail::value_t>
{
/*!
@brief compare two value_t enum values
@since version 3.0.0
*/
bool operator()(nlohmann::detail::value_t lhs,
nlohmann::detail::value_t rhs) const noexcept
{
return nlohmann::detail::operator<(lhs, rhs);
}
};
} // namespace std } // namespace std
/*! /*!
......
...@@ -795,4 +795,11 @@ TEST_CASE("regression tests") ...@@ -795,4 +795,11 @@ TEST_CASE("regression tests")
std::string s2 = j2.dump(); std::string s2 = j2.dump();
CHECK(s1 == s2); CHECK(s1 == s2);
} }
SECTION("issue #486 - json::value_t can't be a map's key type in VC++ 2015")
{
// the code below must compile with MSVC
std::map<json::value_t, std::string> jsonTypes ;
jsonTypes[json::value_t::array] = "array";
}
} }
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