How to extract queried fields?

[AndrewGronin]

I'm trying to make integration with GraphQL Hive, which is a schema and field usage registry.
To push info about requests to Hive I need a way to extract queried fields in format [TypeName1.fieldName1, TypeName2.fieldName2 ...] .
After some digging my hypothesis is:

• Create FieldMiddleware.
• Extract TypeName like this (resolverContext.Selection as Selection).DeclaringType.Name.Value and FieldName like this (resolverContext.Selection as Selection).Field.Name.Value and then store it in query scoped context.
• Apply FieldMiddleware to every field with IRequestExecutorBuilder.UseField.

Is there a better way to obtain such an array of queried fields?