Have you considered sending a PR to angel-dart/graphql?

[thosakwe]

The functionality in graphql_ast_visitor seems useful, and I believe a lot of people would be able to benefit from something like it. It may be worthwhile to potentially send in a patch that adds visitors to package:graphql_parser.

[Brooooooklyn]

@thosakwe apologize for my late reply, I was just notice this issue in this morning.
For now graphql_ast_visitor is just providing functionality which meet my projects need.
I will enhance this project (APIs, tests, documents...) in sometime later and send pull request to package:graphql_parser. It's too rough now.