Allow map and unordered_map with any template parameters.

[verri]

Similar to #12, but it works for the other template parameters as well.
I also provided some test cases and did the same thing for std::map.

[Habbie]

Thank you for this!

When I add tests/map.cpp to add_executable(tests and rebuild, this happens:

In file included from /Users/peter/projects/powerdns/luawrapper/tests/maps.cpp:1:
In file included from /Users/peter/projects/powerdns/luawrapper/include/LuaContext.hpp:31:
In file included from /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/algorithm:637:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/type_traits:1464:38: error: implicit instantiation of undefined template 'std::__1::hash<boost::variant<std::__1::basic_string<char>, int> >'
    : public integral_constant<bool, __is_empty(_Tp)> {};
                                     ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/unordered_map:383:18: note: in instantiation of template class 'std::__1::is_empty<std::__1::hash<boost::variant<std::__1::basic_string<char>, int> > >' requested here
          bool = is_empty<_Hash>::value && !__libcpp_is_final<_Hash>::value
                 ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/unordered_map:765:13: note: in instantiation of default argument for '__unordered_map_hasher<boost::variant<std::__1::basic_string<char>, int>, std::__1::__hash_value_type<boost::variant<std::__1::basic_string<char>, int>, int>, std::__1::hash<boost::variant<std::__1::basic_string<char>, int> > >' required here
    typedef __unordered_map_hasher<key_type, __value_type, hasher>   __hasher;
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/peter/projects/powerdns/luawrapper/tests/maps.cpp:54:28: note: in instantiation of template class 'std::__1::unordered_map<boost::variant<std::__1::basic_string<char>, int>, int, std::__1::hash<boost::variant<std::__1::basic_string<char>, int> >, std::__1::equal_to<boost::variant<std::__1::basic_string<char>, int> >, std::__1::allocator<std::__1::pair<const boost::variant<std::__1::basic_string<char>, int>, int> > >' requested here
    const auto b = context.readVariable<std::unordered_map<boost::variant<std::string, int>, int>>("a");
                           ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/type_traits:397:50: note: template is declared here
template <class _Tp> struct _LIBCPP_TEMPLATE_VIS hash;
                                                 ^
In file included from /Users/peter/projects/powerdns/luawrapper/tests/maps.cpp:1:
In file included from /Users/peter/projects/powerdns/luawrapper/include/LuaContext.hpp:48:
In file included from /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/unordered_map:369:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/__hash_table:1952:21: error: called object type 'hasher' (aka 'int') is not a function or function pointer
    size_t __hash = hash_function()(__k);
                    ^~~~~~~~~~~~~~~
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/__hash_table:1079:14: note: in instantiation of function template specialization 'std::__1::__hash_table<std::__1::__hash_value_type<boost::variant<std::__1::basic_string<char>, int>, int>, int, std::__1::__unordered_map_equal<boost::variant<std::__1::basic_string<char>, int>, std::__1::__hash_value_type<boost::variant<std::__1::basic_string<char>, int>, int>, std::__1::equal_to<boost::variant<std::__1::basic_string<char>, int> >, true>, std::__1::allocator<std::__1::__hash_value_type<boost::variant<std::__1::basic_string<char>, int>, int> > >::__emplace_unique_key_args<boost::variant<std::__1::basic_string<char>, int>, std::__1::pair<const boost::variant<std::__1::basic_string<char>, int>, int> >' requested here
      return __emplace_unique_key_args(_NodeTypes::__get_key(__x), _VSTD::move(__x));
             ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/unordered_map:944:26: note: in instantiation of member function 'std::__1::__hash_table<std::__1::__hash_value_type<boost::variant<std::__1::basic_string<char>, int>, int>, int, std::__1::__unordered_map_equal<boost::variant<std::__1::basic_string<char>, int>, std::__1::__hash_value_type<boost::variant<std::__1::basic_string<char>, int>, int>, std::__1::equal_to<boost::variant<std::__1::basic_string<char>, int> >, true>, std::__1::allocator<std::__1::__hash_value_type<boost::variant<std::__1::basic_string<char>, int>, int> > >::__insert_unique' requested here
        {return __table_.__insert_unique(_VSTD::move(__x));}
                         ^
/Users/peter/projects/powerdns/luawrapper/include/LuaContext.hpp:2753:24: note: in instantiation of member function 'std::__1::unordered_map<boost::variant<std::__1::basic_string<char>, int>, int, std::__1::hash<boost::variant<std::__1::basic_string<char>, int> >, std::__1::equal_to<boost::variant<std::__1::basic_string<char>, int> >, std::__1::allocator<std::__1::pair<const boost::variant<std::__1::basic_string<char>, int>, int> > >::insert' requested here
                result.insert({ key.get(), value.get() });
                       ^
/Users/peter/projects/powerdns/luawrapper/include/LuaContext.hpp:1069:68: note: in instantiation of member function 'LuaContext::Reader<std::__1::unordered_map<boost::variant<std::__1::basic_string<char>, int>, int, std::__1::hash<boost::variant<std::__1::basic_string<char>, int> >, std::__1::equal_to<boost::variant<std::__1::basic_string<char>, int> >, std::__1::allocator<std::__1::pair<const boost::variant<std::__1::basic_string<char>, int>, int> > >, void>::read' requested here
        auto val = Reader<typename std::decay<TReturnType>::type>::read(state, -object.getNum());
                                                                   ^
/Users/peter/projects/powerdns/luawrapper/include/LuaContext.hpp:672:16: note: in instantiation of function template specialization 'LuaContext::readTopAndPop<std::__1::unordered_map<boost::variant<std::__1::basic_string<char>, int>, int, std::__1::hash<boost::variant<std::__1::basic_string<char>, int> >, std::__1::equal_to<boost::variant<std::__1::basic_string<char>, int> >, std::__1::allocator<std::__1::pair<const boost::variant<std::__1::basic_string<char>, int>, int> > > >' requested here
        return readTopAndPop<TType>(mState, PushedObject{mState, 1});
               ^
/Users/peter/projects/powerdns/luawrapper/tests/maps.cpp:54:28: note: in instantiation of function template specialization 'LuaContext::readVariable<std::__1::unordered_map<boost::variant<std::__1::basic_string<char>, int>, int, std::__1::hash<boost::variant<std::__1::basic_string<char>, int> >, std::__1::equal_to<boost::variant<std::__1::basic_string<char>, int> >, std::__1::allocator<std::__1::pair<const boost::variant<std::__1::basic_string<char>, int>, int> > >>' requested here
    const auto b = context.readVariable<std::unordered_map<boost::variant<std::string, int>, int>>("a");
                           ^
In file included from /Users/peter/projects/powerdns/luawrapper/tests/maps.cpp:1:
In file included from /Users/peter/projects/powerdns/luawrapper/include/LuaContext.hpp:48:
In file included from /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/unordered_map:369:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/__hash_table:1952:21: error: called object type 'hasher' (aka 'int') is not a function or function pointer
    size_t __hash = hash_function()(__k);
                    ^~~~~~~~~~~~~~~
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/__hash_table:1113:16: note: in instantiation of function template specialization 'std::__1::__hash_table<std::__1::__hash_value_type<boost::variant<std::__1::basic_string<char>, int>, int>, int, std::__1::__unordered_map_equal<boost::variant<std::__1::basic_string<char>, int>, std::__1::__hash_value_type<boost::variant<std::__1::basic_string<char>, int>, int>, std::__1::equal_to<boost::variant<std::__1::basic_string<char>, int> >, true>, std::__1::allocator<std::__1::__hash_value_type<boost::variant<std::__1::basic_string<char>, int>, int> > >::__emplace_unique_key_args<boost::variant<std::__1::basic_string<char>, int>, const std::__1::pair<const boost::variant<std::__1::basic_string<char>, int>, int> &>' requested here
        return __emplace_unique_key_args(_NodeTypes::__get_key(__x), __x);
               ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/unordered_map:1414:18: note: in instantiation of member function 'std::__1::__hash_table<std::__1::__hash_value_type<boost::variant<std::__1::basic_string<char>, int>, int>, int, std::__1::__unordered_map_equal<boost::variant<std::__1::basic_string<char>, int>, std::__1::__hash_value_type<boost::variant<std::__1::basic_string<char>, int>, int>, std::__1::equal_to<boost::variant<std::__1::basic_string<char>, int> >, true>, std::__1::allocator<std::__1::__hash_value_type<boost::variant<std::__1::basic_string<char>, int>, int> > >::__insert_unique' requested here
        __table_.__insert_unique(*__first);
                 ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/unordered_map:1269:5: note: in instantiation of function template specialization 'std::__1::unordered_map<boost::variant<std::__1::basic_string<char>, int>, int, std::__1::hash<boost::variant<std::__1::basic_string<char>, int> >, std::__1::equal_to<boost::variant<std::__1::basic_string<char>, int> >, std::__1::allocator<std::__1::pair<const boost::variant<std::__1::basic_string<char>, int>, int> > >::insert<std::__1::__hash_map_const_iterator<std::__1::__hash_const_iterator<std::__1::__hash_node<std::__1::__hash_value_type<boost::variant<std::__1::basic_string<char>, int>, int>, void *> *> > >' requested here
    insert(__u.begin(), __u.end());
    ^
/Users/peter/projects/powerdns/luawrapper/include/LuaContext.hpp:1072:16: note: in instantiation of member function 'std::__1::unordered_map<boost::variant<std::__1::basic_string<char>, int>, int, std::__1::hash<boost::variant<std::__1::basic_string<char>, int> >, std::__1::equal_to<boost::variant<std::__1::basic_string<char>, int> >, std::__1::allocator<std::__1::pair<const boost::variant<std::__1::basic_string<char>, int>, int> > >::unordered_map' requested here
        return val.get();
               ^
/Users/peter/projects/powerdns/luawrapper/include/LuaContext.hpp:672:16: note: in instantiation of function template specialization 'LuaContext::readTopAndPop<std::__1::unordered_map<boost::variant<std::__1::basic_string<char>, int>, int, std::__1::hash<boost::variant<std::__1::basic_string<char>, int> >, std::__1::equal_to<boost::variant<std::__1::basic_string<char>, int> >, std::__1::allocator<std::__1::pair<const boost::variant<std::__1::basic_string<char>, int>, int> > > >' requested here
        return readTopAndPop<TType>(mState, PushedObject{mState, 1});
               ^
/Users/peter/projects/powerdns/luawrapper/tests/maps.cpp:54:28: note: in instantiation of function template specialization 'LuaContext::readVariable<std::__1::unordered_map<boost::variant<std::__1::basic_string<char>, int>, int, std::__1::hash<boost::variant<std::__1::basic_string<char>, int> >, std::__1::equal_to<boost::variant<std::__1::basic_string<char>, int> >, std::__1::allocator<std::__1::pair<const boost::variant<std::__1::basic_string<char>, int>, int> > >>' requested here
    const auto b = context.readVariable<std::unordered_map<boost::variant<std::string, int>, int>>("a");
                           ^
3 errors generated.
make[2]: *** [CMakeFiles/tests.dir/tests/maps.cpp.o] Error 1
make[1]: *** [CMakeFiles/tests.dir/all] Error 2
make: *** [all] Error 2

[verri]

I'll check that.

[verri]

The problem was an unrelated limitation. The code

context.writeVariable("a", std::map<boost::variant<std::string, int>, int>{ /* ... */ });
context.readVariable<std::map<boost::variant<std::string, int>, int>>("a");

never works. Do you have any idea why that happens?

[verri]

In fact, the compilation error was because I forgot the boost::hash<...> stuff.

Then, after fixing that, I realized that writeVariable works when keys are boost::variant, but lua_atpanic is triggered if I try to read the variable back with readVariable.

[Habbie]

Hello! Assuming you still care, do you want to rebase this now that I finally merged #38?

[verri]

Hello @Habbie!
Done.