ontohub/lib/triple_store.rb

	triple_store.rb revision fbba1a298e3a589aa31ff46bbe1dd7773d23f582
# A triple store
#
# Author: Daniel Couto Vale <danielvale@uni-bremen.de>
#
class TripleStore

  # A map (predicate x object) -> subject
  @subjectMap

  # A map (subject x object) -> predicate
  @predicateMap

  # A map (subject x predicate) -> object
  @objectMap

  # Constructs a triple store from an rdf file
  #
  # path_name - the path name of the rdf file to load
  #
  def load(path_name)
  end

  # Constructor
  #
  # triples - a list of triples
  #
  def initialize(triples)
    @subjectMap = Hash.new
    @predicateMap = Hash.new
    @objectMap = Hash.new
    triples.each do |triple|

      # Read triple components
      subject = triple[0].to_s
      predicate = triple[1].to_s
      object = triple[2].to_s

      # Map subject
      if @subjectMap[predicate] == nil
        @subjectMap[predicate] = Hash.new
      end
      if @subjectMap[predicate][object] == nil
        @subjectMap[predicate][object] = Array.new
      end
      @subjectMap[predicate][object].push subject

      # Map predicate
      if @predicateMap[subject] == nil
        @predicateMap[subject] = Hash.new
      end
      if @predicateMap[subject][object] == nil
        @predicateMap[subject][object] = Array.new
      end
      @predicateMap[subject][object].push predicate

      # Map object
      if @objectMap[subject] == nil
        @objectMap[subject] = Hash.new
      end
      if @objectMap[subject][predicate] == nil
        @objectMap[subject][predicate] = Array.new
      end
      @objectMap[subject][predicate].push object
    end
  end

  # Returns a list with all subjects for a given object-predicate pair
  #
  # predicate - a predicate
  # object - a range
  #
  def subjects(predicate, object)
    if @subjectMap[predicate] == nil
      return Array.new
    elsif @subjectMap[predicate][object] == nil
      return Array.new
    else
      return Array.new(@subjectMap[predicate][object])
    end
  end

  # Returns a list with all predicates for a given subject-object pair
  #
  # subject - a domain
  # object - a range
  #
  def predicates(subject, object)
    if @predicateMap[subject] == nil
      return Array.new
    elsif @predicateMap[subject][object] == nil
      return Array.new
    else
      return Array.new(@predicateMap[subject][object])
    end
  end

  # Returns a list with all objects for a given subject-predicate pair
  #
  # subject - a domain
  # predicate = a relation
  #
  def objects(subject, predicate)
    if @objectMap[subject] == nil
      return Array.new
    elsif @objectMap[subject][predicate] == nil
      return Array.new
    else
      return Array.new(@objectMap[subject][predicate])
    end
  end

end