lib/rdf/mixin/indexable.rb
module RDF
##
# A mixin that can be used to mark RDF repository implementations as
# indexable.
#
# @since 0.3.0
module Indexable
##
# Returns `true` if `self` is indexed at present.
#
# @abstract
# @return [Boolean]
def indexed?
false
end
##
# Indexes `self`.
#
# @abstract
# @return [self]
def index!
raise NotImplementedError, "#{self.class}#index!"
end
end # Indexable
end # RDF