puppetlabs-stdlib/lib/puppet/parser/functions/intersection.rb

#
# intersection.rb
#

module Puppet::Parser::Functions
  newfunction(:intersection, :type => :rvalue, :doc => <<-EOS
This function returns an array of the intersection of two.

*Examples:*

    intersection(["a","b","c"],["b","c","d"])  # returns ["b","c"]
    intersection(["a","b","c"],[1,2,3,4])      # returns [] (true, when evaluated as a Boolean)

    EOS
  ) do |arguments|

    # Two arguments are required
    raise(Puppet::ParseError, "intersection(): Wrong number of arguments " +
      "given (#{arguments.size} for 2)") if arguments.size != 2

    first = arguments[0]
    second = arguments[1]

    unless first.is_a?(Array) && second.is_a?(Array)
      raise(Puppet::ParseError, 'intersection(): Requires 2 arrays')
    end

    result = first & second

    return result
  end
end

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