Method: Ariel::Learner#add_new_landmarks

Defined in:
lib/ariel/learner.rb

#add_new_landmarks(landmark, index) ⇒ Object

Implements topology refinements - new landmarks are added to the current rule.

  • Takes a landmark and its index in the current rule.

  • Applies the rule consisting of all landmarks up to and including the current landmark to find where it matches.

  • Only tokens between the label_index and the position at which the partial rule matches are considered.

  • Tokens before the rule match location will have no effect, as adding new landmarks before or after the current landmark will not make the rule match any earlier.

  • For every token in this slice of the TokenStream, a new potential rule is created by adding a new landmark consisting of that token. This is also done for each of that token’s matching wildcards.



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# File 'lib/ariel/learner.rb', line 226

def add_new_landmarks(landmark, index)
  topology_refs=[]
  start_pos = current_rule.partial(0..index).closest_match(current_seed, :early)
  end_pos = current_seed.label_index #No point adding tokens that occur after the label_index
  current_seed.tokens[start_pos...end_pos].each do |token|
      r=current_rule.deep_clone
      r.landmarks.insert(index+1, [token.text])
      topology_refs << r
      topology_refs.concat r.generalise_feature(index+1)
  end
Log.debug "Topology refinements before uniq! #{topology_refs.size}"
topology_refs.uniq!
@candidates.concat topology_refs
Log.debug "#{topology_refs.size} topology refinements generated"
return topology_refs.size
end