#
# difference.rb
#
module Puppet::Parser::Functions
  newfunction(:difference, :type => :rvalue, :doc => <<-DOC
    @summary
      This function returns the difference between two arrays.

    The returned array is a copy of the original array, removing any items that
    also appear in the second array.

    @example Example usage

      difference(["a","b","c"],["b","c","d"])
      Would return: `["a"]`

    > *Note:*
    Since Puppet 4 the minus (-) operator in the Puppet language does the same thing:
    ['a', 'b', 'c'] - ['b', 'c', 'd']
    Would return: `['a']`

    @return [Array]
      The difference between the two given arrays

    DOC
             ) do |arguments|

    # Two arguments are required
    raise(Puppet::ParseError, "difference(): 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, 'difference(): Requires 2 arrays')
    end

    result = first - second

    return result
  end
end

# vim: set ts=2 sw=2 et :