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RuboCop AST

Gem Version CI Test Coverage Maintainability

Contains the classes needed by RuboCop to deal with Ruby's AST, in particular:

  • RuboCop::AST::Node (doc)
  • RuboCop::AST::NodePattern (doc)

This gem may be used independently from the main RuboCop gem. It was extracted from RuboCop in version 0.84 and its only dependency is the parser gem, which rubocop-ast extends.


Just install the rubocop-ast gem

gem install rubocop-ast

or if you use bundler put this in your Gemfile

gem 'rubocop-ast'


Refer to the documentation of RuboCop::AST::Node and RuboCop::AST::NodePattern

See the docs site for more details.

Parser compatibility switches

This gem, by default, uses most legacy AST output from parser, except for the following which are set to true:

  • emit_forward_arg
  • emit_match_pattern

The main RuboCop gem uses these defaults (and is currently only compatible with these), but this gem can be used separately from RuboCop and is meant to be compatible with all settings. For example, to have -> { ... } emitted as LambdaNode instead of SendNode:

RuboCop::AST::Builder.emit_lambda = true


Checkout the contribution guidelines.


rubocop-ast is MIT licensed. See the accompanying file for the full text.