Support itblock for Prism::Translation::Parser

[koic]

Summary

itblock node is added to support the it block parameter syntax introduced in Ruby 3.4.

$ ruby -Ilib -rprism -rprism/translation/parser34 -e 'buffer = Parser::Source::Buffer.new("path"); buffer.source = "proc { it }"; \
                                                      p Prism::Translation::Parser34.new.tokenize(buffer)[0]'
s(:itblock,
  s(:send, nil, :proc), :it,
  s(:lvar, :it))

This node design is similar to the numblock node, which was introduced for the numbered parameter syntax in Ruby 2.7.

$ ruby -Ilib -rprism -rprism/translation/parser34 -e 'buffer = Parser::Source::Buffer.new("path"); buffer.source = "proc { _1 }"; \
                                                      p Prism::Translation::Parser34.new.tokenize(buffer)[0]'
s(:numblock,
  s(:send, nil, :proc), 1,
  s(:lvar, :_1))

The difference is that while numbered parameters can have multiple parameters, the it block parameter syntax allows only a single parameter.

In Ruby 3.3, the conventional node prior to the it block parameter syntax is returned.

$ ruby -Ilib -rprism -rprism/translation/parser33 -e 'buffer = Parser::Source::Buffer.new("path"); buffer.source = "proc { it }"; \
                                                      p Prism::Translation::Parser33.new.tokenize(buffer)[0]'
s(:block,
  s(:send, nil, :proc),
  s(:args),
  s(:send, nil, :it))

Development Note

The Parser gem does not yet support the it block parameter syntax. This is the first case where Prism's node design precedes that of the Parser gem. When implementing whitequark/parser#962, this node design will need to be taken into consideration.

cc @whitequark @iliabylich

[Earlopain]

This code is actually not really tested, only Parser33 is run in the test suite. I thought about it a bit before, and probably a separate directory for new syntax would make sense (or something along those lines).

You probably need to assert specifically against the ast anyways, as it only compares to the parser gem, and there is nothing to compare against in this case.

[koic]

For now, I've added a test to check the :itblock node type, which is currently provided only by Prism::Translation::Parser. Since it is essentially an extension of the Parser gem, I've added it to parser_test.rb.

Additionally, I've implemented a mechanism to compare node compatibility with the Parser::Ruby34, but since the Parser gem doesn't yet support the it block parameter, it is currently skipped.

[Earlopain]

It's doubtful if parser will ever support 3.4 and this seems highly specific. It also only works because this is valid syntax to the parser gem, if some new syntax gets added you can't test this via this mechanism.

I think I would just add new specific tests for this syntax. If the parser gem does end up supporting it, then these test cases can just be imported. Something like this:

# Pseudo-code like
def test_it_syntax
  parser = Prism:Parser::Translator::Ruby34.new
  expected = s(:itblock, s(:begin, s(:itarg)))
  assert_equal(expected, parser.tokenize(it_fixture)[0].to_sexp)
end

Then, you can extend the existing it.txt (stuff in fixtures/whitequark is pulled from upstream) and explicitly assert against it. What do you think?