First round of argument ripper

argument_ripper.rb

# Based on: https://twitter.com/josh_cheek/status/1079827841095749632

require 'method_source'
require 'parser/ruby25'

module ArgRipper
  class << self
    def get_args(meth)
      Parser::Ruby25
        .parse(meth.source)
        .then(&method(:extract_args))
        .children
        .select { |arg| arg.type == :kwoptarg }
        .map(&method(:expression_source))
        .to_h
    end

    private def extract_args(ast)
      return nil unless ast.is_a?(Parser::AST::Node)
      return ast if ast.type == :args

      ast.children.find { |child| extract_args(child) }
    end

    private def expression_source(argument)
      name, value = argument.children

      [name, value.location.expression.source]
    end
  end
end

def part1(before:, after:, instruction: [_op, a, b, c])
  [1, 2, 3].map &transform||:to_s
end

def part2(instruction: { a: { b: { c: 2 }}}) end
def part3(instruction: OpenStruct.new(a: { b: { c: 2 }})) end

p ArgRipper.get_args(method(:part1))
# => {:instruction=>"[_op, a, b, c]"}

p ArgRipper.get_args(method(:part2))
# => {:instruction=>"{ a: { b: { c: 2 }}}"}

p ArgRipper.get_args(method(:part3))
# => {:instruction=>"OpenStruct.new(a: { b: { c: 2 }})"}