[Language::Visitor] use method-based visit handlers

[rmosolgo]

I'm thinking of stealing a page from the parser gem's book. There, the AST visitor is a class with on_* handlers for each kind of AST node. It's really easy to get going, I'd like to do the same thing in GraphQL-Ruby.

So, I tried the API on a couple of validation rules, and I'm going to try a few more. If it seems to work, I'll improve the support for that kind of API and deprecate the [node_class] << API. I think we will need to use yield or super to support [node_class].leave <<. (parser uses super). Also, I'll be interested to see the performance impact.

[arthurschreiber]

This is rad! ❤️I really love this change.

[olleolleolle]

This is a helpful change.

[rmosolgo]

I rewrote StaticValidation to use class-based visitor, I'm happy with the code and the perf is about the same

~/code/graphql-ruby $ git pom
Switched to branch 'master'
Your branch is up-to-date with 'origin/master'.
From github.com:rmosolgo/graphql-ruby
 * branch              master     -> FETCH_HEAD
Already up-to-date.
~/code/graphql-ruby $ be rake bench:validate && be rake bench:validate
Warming up --------------------------------------
validate - introspection
                        27.000  i/100ms
validate - abstract fragments
                        63.000  i/100ms
validate - abstract fragments 2
                        38.000  i/100ms
validate - big query     3.000  i/100ms
Calculating -------------------------------------
validate - introspection
                        279.931  (± 7.9%) i/s -      1.404k in   5.051684s
validate - abstract fragments
                        652.288  (± 5.1%) i/s -      3.276k in   5.035280s
validate - abstract fragments 2
                        393.109  (± 8.1%) i/s -      1.976k in   5.065726s
validate - big query     37.769  (± 5.3%) i/s -    189.000  in   5.017028s
Warming up --------------------------------------
validate - introspection
                        27.000  i/100ms
validate - abstract fragments
                        62.000  i/100ms
validate - abstract fragments 2
                        39.000  i/100ms
validate - big query     3.000  i/100ms
Calculating -------------------------------------
validate - introspection
                        278.284  (± 4.7%) i/s -      1.404k in   5.055952s
validate - abstract fragments
                        635.385  (± 5.4%) i/s -      3.224k in   5.088037s
validate - abstract fragments 2
                        388.317  (± 5.2%) i/s -      1.950k in   5.035392s
validate - big query     37.307  (± 5.4%) i/s -    189.000  in   5.079340s
~/code/graphql-ruby $ git co class-based-visitor
Switched to branch 'class-based-visitor'
~/code/graphql-ruby $ be rake bench:validate && be rake bench:validate
Warming up --------------------------------------
validate - introspection
                        28.000  i/100ms
validate - abstract fragments
                        66.000  i/100ms
validate - abstract fragments 2
                        40.000  i/100ms
validate - big query     3.000  i/100ms
Calculating -------------------------------------
validate - introspection
                        288.311  (± 4.5%) i/s -      1.456k in   5.060300s
validate - abstract fragments
                        677.300  (± 4.9%) i/s -      3.432k in   5.078672s
validate - abstract fragments 2
                        404.773  (± 4.9%) i/s -      2.040k in   5.052892s
validate - big query     37.714  (± 2.7%) i/s -    189.000  in   5.017786s
Warming up --------------------------------------
validate - introspection
                        29.000  i/100ms
validate - abstract fragments
                        68.000  i/100ms
validate - abstract fragments 2
                        42.000  i/100ms
validate - big query     3.000  i/100ms
Calculating -------------------------------------
validate - introspection
                        291.989  (± 4.1%) i/s -      1.479k in   5.074170s
validate - abstract fragments
                        684.999  (± 3.9%) i/s -      3.468k in   5.070835s
validate - abstract fragments 2
                        412.762  (± 4.8%) i/s -      2.100k in   5.098861s
validate - big query     37.823  (± 5.3%) i/s -    189.000  in   5.013675s
~/code/graphql-ruby $

[rmosolgo]

I pushed a little harder and re-wrote the remaining bits to use the new API, now it's a decent bit faster, 10% give or take.

~/code/graphql-ruby $ be rake bench:validate && be rake bench:validate
Warming up --------------------------------------
validate - introspection
                        32.000  i/100ms
validate - abstract fragments
                        76.000  i/100ms
validate - abstract fragments 2
                        46.000  i/100ms
validate - big query     4.000  i/100ms
Calculating -------------------------------------
validate - introspection
                        322.026  (± 3.7%) i/s -      1.632k in   5.075263s
validate - abstract fragments
                        744.823  (± 5.0%) i/s -      3.724k in   5.013195s
validate - abstract fragments 2
                        452.471  (± 6.0%) i/s -      2.254k in   5.000423s
validate - big query     40.256  (± 5.0%) i/s -    204.000  in   5.084613s
Warming up --------------------------------------
validate - introspection
                        32.000  i/100ms
validate - abstract fragments
                        76.000  i/100ms
validate - abstract fragments 2
                        45.000  i/100ms
validate - big query     4.000  i/100ms
Calculating -------------------------------------
validate - introspection
                        320.540  (± 4.4%) i/s -      1.600k in   5.001771s
validate - abstract fragments
                        756.113  (± 4.0%) i/s -      3.800k in   5.033471s
validate - abstract fragments 2
                        454.004  (± 5.3%) i/s -      2.295k in   5.069387s
validate - big query     39.463  (± 5.1%) i/s -    200.000  in   5.082648s

[rmosolgo]

I removed TypeStack, but I should put it back, graphql-client depends on it.

[rmosolgo]

This is almost passing. We still need one more thing out of the new visitor API, a way to modify the AST that's being iterated over. But I will add that in a later PR, this is a big step forward as-is!