NodeVisitor allows you to define callbacks based on node type, then visit the AST nodes.

Add this line to your application's Gemfile:

gem 'node_visitor'

And then execute:

$ bundle

Or install it yourself as:

$ gem install node_visitor

1. initialize the visitor

visitor = NodeVisitor.new(adapter: 'prism')

2. add callbacks

# this will be triggered when it starts to visit class_node
visitor.add_callback(:class_node, at: 'start') do |node|
  node.name # get the name of class node
end

# this will be triggered after it finishes to visit class_node
visitor.add_callback(:class_node, at: 'end') do |node|
  node.name # get the name of class node
end

There is a special node type, :all, which is triggered before or after visiting all nodes.

# this will be triggered after it finishes to visit all nodes
visitor.add_callback(:class_node, at: 'end') do
end

3. visit the AST node

visitor.visit(node)

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/synvert-hq/node_visitor.