node_matcher.rb

#!/usr/bin/env ruby

require 'pathname'
require 'optparse'

$LOAD_PATH.unshift(Pathname(__dir__).join('../lib/').realpath)
require 'rubocop'

pattern, ruby, version = ARGV.options do |opt|
  version = RUBY_VERSION
  opt.on('-v VERSION') { |v| version = v }
  [*opt.parse!, version]
end

source = RuboCop::ProcessedSource.new(ruby, version.to_f)

mod = Module.new do
  extend RuboCop::NodePattern::Macros
  extend self
  def_node_matcher :match, pattern
end

p mod.match(source.ast)