Separate multiple inherited interfaces with &

[cjoudrey]

This pull request modifies the parser and language printer to support separating multiple inherited interfaces with & as per graphql/graphql-js#1169 and graphql/graphql-spec#90.

This replaces:

type Foo implements Bar, Baz { field: Type }

With:

type Foo implements Bar & Baz { field: Type }

With no changes to the common case of implementing a single interface.

In order to preserve backwards compatibility, the parser temporarily supports the old syntax. The language printer only prints the new syntax though.

Note: We need to revert 27ac21c and generate the parser before merging this as the version of ragel on brew is not as recent as the version used here.

[rmosolgo]

Wow, I didn't realize this change was in the final draft, interesting. It definitely makes the tokenization easier, I bet atom-language-graphql could finally be fixed.

For compatibility, how about we continue to accept , as well as &? That way, anyone who's building the schema from SDL won't be disrupted. (I know there are a few). But we can always dump the latest (&), so I think that's good as is. Does that sound fair?

[rmosolgo]

ragel

Oh my, I should build a Ragel API 😆 I'm pretty sure it's a violation of Ragel's license. (Or... maybe I'd just have to release it GPL or something ...)

[cjoudrey]

For compatibility, how about we continue to accept , as well as &?

Sounds good 👍, I'll make that change tonight.

[cjoudrey]

bb4cf6f adds backwards compatibility.

[rmosolgo]

Ok, I rebuilt the lexer, I'll merge when it's green

[rmosolgo]

Thanks for taking care of this!