Expressionist

Simple query language for tree structured data

Add this line to your application's Gemfile:

gem 'expressionist'

And then execute:

$ bundle

Or install it yourself as:

$ gem install expressionist

require 'expressionist'

context = Expressionist::Context.new

context['some.key'] = 'value'

expression = Expressionist.compile('some.key == "value" AND count(some.*) == 1')

expression.call(context) # => true

context['some.key2'] = 'value'

expression.call(context) # => false

context.export # => {"some"=>{"key"=>{"."=>"value"}, "key2"=>{"."=>"value"}}}

tmp = expression.executable # => Array

another = Expressionist.compile(tmp)

another.call(context) # => false

Context defines tree data structure that can be queried. Data can be importad from an existing Hash and can be exported using context.export.

The . is used to separate the path. There can never be two . next to each other and path can not start with a .. The . character can not be escaped.

Paths can only contain these /[A-Za-z0-9.\-_]/ characters.

ToDo: update the section, ATM check the lib/expressionist/grammar.rb and lib/expressionist/functions/*.rb files.

After checking out the repo, run bin/setup to install dependencies. Then, run rake test 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 marekjelen/expressionist.

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