grub-lexer

Grub::Lexer

Convert Grub boot loader configuration into tokens that can be fed into the parser.

Installation

Install the gem and add to the application's Gemfile by executing:

bundle add grub-lexer

If bundler is not being used to manage dependencies, install the gem by executing:

gem install grub-lexer

Usage

Basic example

require "grub/lexer"
lexer = Grub::Lexer.new
lexer.parse "sleep 1"
lexer.next_token   # => [:WORD, "sleep"]
lexer.next_token   # => [:WORD, "1"]
lexer.next_token   # => nil

Loading configuration from file

require "grub/lexer"
lexer = Grub::Lexer.new
lexer.parse_file "/boot/grub/grub.cfg"

Variables expansion

require "grub/lexer"
expander = ->(var) { var == :greeting ? "hello" : "awesome" }
lexer = Grub::Lexer.new expander
lexer.parse %{echo "$greeting ${adjective} world!"\n}
lexer.next_token   # => [:WORD, "echo"]
lexer.next_token   # => [:WORD, "hello awesome world!"]
lexer.next_token   # => [:SEPARATOR, "\n"]

Variables detection and per-call expanders

require "grub/lexer"
lexer = Grub::Lexer.new ->(_) { "same" }
lexer.parse '$var1 text "$var2 text"'
token = lexer.next_token                 # => [:WORD, "same"]
token[1].expandable?                     # => true
token = lexer.next_token                 # => [:WORD, "text"]
token[1].expandable?                     # => false
token = lexer.next_token                 # => [:WORD, "same text"]
token[1].to_s(->(v) { v.to_s.upcase })   # => "VAR2 text"

Limitations

Only Grub 2 is supported. Grub Legacy may work, but hasn't been tested.

The gem doesn't support Grub translations. I18n strings ($"translation key") are treated like normal strings in double quotes.

Only subset of metacharacters are recognized as distinct token types. However, implementation of missing metacharacter types is trivial.

Development

After checking out the repo, run bin/setup to install dependencies. Then, run bundle exec 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 the created tag, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/phantom-node/grub-lexer. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.

Author

My name is Paweł Pokrywka and I'm the author of grub-lexer.

If you want to contact me or get to know me better, check out my blog.

Thank you for your interest in this project :)

License

The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the Grub project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.