Annotations from idl parser

[joakimono]

The eprosima::xtypes::Member has support for id, key and optional annotations, which can be set using the xtypes API. Currently, it seems the IDL parser do not parse annotations. Is it possible to slightly extend the grammar or the IDL parser implementation, so that the three annotations above are recognized when parsing IDL files?

  std::string my_idl = R"~~~(
    struct Inner
    {
        @key uint32 my_uint32;
        @optional boolean yes;
    };
  )~~~";

  eprosima::xtypes::idl::Context context = eprosima::xtypes::idl::parse(my_idl);

  // Create struct same with xtypes API
  eprosima::xtypes::StructType inner2 =
   eprosima::xtypes::StructType("Inner")
   .add_member(eprosima::xtypes::Member("my_uint32", eprosima::xtypes::primitive_type<uint32_t>()).key())
   .add_member(eprosima::xtypes::Member("yes", eprosima::xtypes::primitive_type<bool>()).optional());

  auto inner = context.module().structure("Inner");

  EXPECT_EQ(inner.member(0).is_key(), inner2.member(0).is_key());           // false, true
  EXPECT_EQ(inner.member(1).is_optional(), inner2.member(1).is_optional()); // false, true