Namarara

Namarara is a library that parses boolean expressions, builds an binary expression tree.

Namare can also evalutes a result from a set of values corresponding the variables used within the boolean expression.

binary expression and computes a boolean result from this AST.

Installation

Add this line to your application's Gemfile:

gem 'namarara'

And then execute:

$ bundle

Or install it yourself as:

$ gem install namarara

Usage

Evaluate a single expression

require 'namarara'

# Initialize Namarara
namarara = Namarara::Parser.new(Namarara::Lexer.new)

# Prepare variables 
namarara.names = {
  this: 'true',
  that: 'false',
  other: 'false',
  something_else: 'true'
}

# Build a binary expression tree (aka BET) from string
# and inject values
exp_tree = namarara.parse('this AND (that OR other) AND something_else')

# Compute tree with variables
result = exp_tree.compute
puts result # = false

Evaluating a set of rules

require 'namarara'

# Initialize Namarara
namarara = Namarara::Parser.new(Namarara::Lexer.new)

# A set of rules i want to check 
# (in this example we are looking for sensitive personnal data)
rules = {
    vulnerable_person: 'is_adult AND is_subordinate',
    has_constraints: 'is_adult AND has_children',
    is_child: 'NOT is_adult'
    # ...
}

# A set of values i want to inject (values must be expressed as strings)
namarara.names = {
    "is_adult" => 'false', 
    "is_subordinate" => 'true',
    "has_children" => 'true'
}

results = rules.map { |rule, expr| [rule, namarara.parse(expr).compute] }

if results.select{ |rule, value| value }.empty?
    puts "Perfect! Nothing to say ;-)"
else
    puts "Warning: you are collectif sensitive personnal data !"
    results.each do |rule, value|
      puts "#{value ? '>>':'  '} #{rule}: #{value}" 
    end
end

Development

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.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/glenux/namarara

License

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

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