Class: Triannon::LdpToOaMapper

Inherits:
Object
  • Object
show all
Defined in:
app/services/triannon/ldp_to_oa_mapper.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(ldp_anno) ⇒ LdpToOaMapper

Returns a new instance of LdpToOaMapper.



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# File 'app/services/triannon/ldp_to_oa_mapper.rb', line 15

def initialize ldp_anno
  @ldp_anno = ldp_anno
  @ldp_anno_graph = ldp_anno.stripped_graph
  g = RDF::Graph.new
  @oa_graph = Triannon::Graph.new g
end

Instance Attribute Details

#id ⇒ Object

Returns the value of attribute id.



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# File 'app/services/triannon/ldp_to_oa_mapper.rb', line 13

def id
  @id
end

#oa_graph ⇒ Object

Returns the value of attribute oa_graph.



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# File 'app/services/triannon/ldp_to_oa_mapper.rb', line 13

def oa_graph
  @oa_graph
end

Class Method Details

.ldp_to_oa(ldp_anno) ⇒ Object

maps an AnnotationLdp to an OA RDF::Graph



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# File 'app/services/triannon/ldp_to_oa_mapper.rb', line 5

def self.ldp_to_oa ldp_anno
  mapper = Triannon::LdpToOaMapper.new ldp_anno
  mapper.extract_base
  mapper.extract_bodies
  mapper.extract_targets
  mapper.oa_graph
end

Instance Method Details

#extract_base ⇒ Object 



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# File 'app/services/triannon/ldp_to_oa_mapper.rb', line 22

def extract_base
  root_subject_solns = @ldp_anno_graph.query Triannon::Graph.anno_query
  if root_subject_solns.count == 1
    @id = root_subject_solns[0].s.to_s.split('/').last
    base_url = Triannon.config[:triannon_base_url]
    base_url.strip!
    base_url.chop! if base_url[-1] == '/'
    @root_uri = RDF::URI.new(base_url + "/#{@id}")
  end
  
  @ldp_anno_graph.each_statement do |stmnt|
    if stmnt.predicate == RDF.type && stmnt.object == RDF::OpenAnnotation.Annotation
      @oa_graph << [@root_uri, RDF.type, RDF::OpenAnnotation.Annotation]
    elsif stmnt.predicate == RDF::OpenAnnotation.motivatedBy
      @oa_graph << [@root_uri, stmnt.predicate, stmnt.object]
    elsif stmnt.predicate == RDF::OpenAnnotation.annotatedAt
      @oa_graph << [@root_uri, stmnt.predicate, stmnt.object]
    end
  end
end

#extract_bodies ⇒ Object 



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# File 'app/services/triannon/ldp_to_oa_mapper.rb', line 43

def extract_bodies
  @ldp_anno.body_uris.each { |body_uri|
    if !map_external_ref(body_uri, RDF::OpenAnnotation.hasBody) &&
        !map_content_as_text(body_uri, RDF::OpenAnnotation.hasBody) &&
        !map_specific_resource(body_uri, RDF::OpenAnnotation.hasBody)
      map_choice(body_uri, RDF::OpenAnnotation.hasBody)
    end
  }
end

#extract_targets ⇒ Object 



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# File 'app/services/triannon/ldp_to_oa_mapper.rb', line 53

def extract_targets
  @ldp_anno.target_uris.each { |target_uri| 
    if !map_external_ref(target_uri, RDF::OpenAnnotation.hasTarget) &&
        !map_specific_resource(target_uri, RDF::OpenAnnotation.hasTarget)
      map_choice(target_uri, RDF::OpenAnnotation.hasTarget)
    end
  }
end

#map_choice(uri_obj, predicate) ⇒ Boolean

if uri_obj has a type of RDF::OpenAnnotation.Choice, then this is a skolemized blank node;

add appropriate statements to @oa_graph to represent the blank node and its contents and return true

to be added to @oa_graph, e.g. RDF::OpenAnnotation.hasTarget

Parameters:

  • uri_obj (RDF::URI) —

    the object that may have type RDF::OpenAnnotation.Choice

  • predicate (RDF::URI) —

    the predicate for [@root_uri, predicate, (choice)] statement

Returns:

  • (Boolean) —

    true if it adds statements to @oa_graph, false otherwise



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# File 'app/services/triannon/ldp_to_oa_mapper.rb', line 174

def map_choice uri_obj, predicate
  solns = @ldp_anno_graph.query [uri_obj, RDF.type, RDF::OpenAnnotation.Choice]
  if solns.count > 0
    blank_node = RDF::Node.new
    @oa_graph << [@root_uri, predicate, blank_node]
    
    default_obj = nil
    item_objs = []
    choice_stmts = Triannon::Graph.subject_statements(uri_obj, @ldp_anno_graph)
    choice_stmts.each { |stmt|
      if stmt.predicate == RDF::OpenAnnotation.default
        default_obj = stmt.object
        # assume it is either ContentAsText or external ref
        if !map_content_as_text(default_obj, RDF::OpenAnnotation.default, blank_node)
          map_external_ref(default_obj, RDF::OpenAnnotation.default, blank_node)
        end
      elsif stmt.predicate == RDF::OpenAnnotation.item
        item_objs << stmt.object
        # assume it is either ContentAsText or external ref
        if !map_content_as_text(stmt.object, RDF::OpenAnnotation.item, blank_node)
          map_external_ref(stmt.object, RDF::OpenAnnotation.item, blank_node)
        end
      end
    }
    
    # We can't know we'll hit item and default statements in graph first, 
    # so we must do another pass through the statements to get that information
    choice_stmts.each { |stmt| 
      if stmt.subject == uri_obj && stmt.object != default_obj && !item_objs.include?(stmt.object)
        @oa_graph << [blank_node, stmt.predicate, stmt.object]
      # there shouldn't be any other unmapped statements present
      end
    }
    true
  else
    false
  end
end

#map_content_as_text(uri_obj, predicate, subject_obj = @root_uri) ⇒ Boolean

if uri_obj has a type of RDF::Content.ContentAsText, then this is a skolemized blank node;

add appropriate statements to @oa_graph to represent the blank node and its contents and return true

to be added to @oa_graph, e.g. RDF::OpenAnnotation.hasTarget

Parameters:

  • uri_obj (RDF::URI) —

    the object that may type RDF::Content.ContentAsText

  • predicate (RDF::URI) —

    the predicate for [subject_obj, predicate, (ext_url)] statement

  • subject_obj (RDF::URI) (defaults to: @root_uri) —

    the subject object to get the predicate statement; defaults to @root_uri

Returns:

  • (Boolean) —

    true if it adds statements to @oa_graph, false otherwise



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# File 'app/services/triannon/ldp_to_oa_mapper.rb', line 95

def map_content_as_text uri_obj, predicate, subject_obj = @root_uri
  solns = @ldp_anno_graph.query [uri_obj, RDF.type, RDF::Content.ContentAsText]
  if solns.count > 0
    blank_node = RDF::Node.new
    @oa_graph << [subject_obj, predicate, blank_node]
    
    Triannon::Graph.subject_statements(uri_obj, @ldp_anno_graph).each { |stmt|
      if stmt.subject == uri_obj
        @oa_graph << [blank_node, stmt.predicate, stmt.object]
      else
        # it is a descendant statment - take as is
        @oa_graph << stmt
      end
    }
    true
  else
    false
  end
end

#map_external_ref(uri_obj, predicate, subject_obj = @root_uri) ⇒ Boolean

if uri_obj is the subject of a Triannon.externalReference then add appropriate

statements to @oa_graph and return true

to be added to @oa_graph, e.g. RDF::OpenAnnotation.hasTarget

Parameters:

  • uri_obj (RDF::URI) —

    the object that may have RDF::Triannon.externalReference

  • predicate (RDF::URI) —

    the predicate for [subject_obj, predicate, (ext_url)] statement

  • subject_obj (RDF::URI) (defaults to: @root_uri) —

    the subject object to get the predicate statement; defaults to @root_uri

Returns:

  • (Boolean) —

    true if it adds statements to @oa_graph, false otherwise



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# File 'app/services/triannon/ldp_to_oa_mapper.rb', line 69

def map_external_ref uri_obj, predicate, subject_obj = @root_uri
  solns = @ldp_anno_graph.query [uri_obj, RDF::Triannon.externalReference, nil]
  if solns.count > 0
    external_uri = solns.first.object
    @oa_graph << [subject_obj, predicate, external_uri]
    
    Triannon::Graph.subject_statements(uri_obj, @ldp_anno_graph).each { |stmt|
      if stmt.subject == uri_obj && stmt.predicate != RDF::Triannon.externalReference
        @oa_graph << [external_uri, stmt.predicate, stmt.object]
      else
        # we should never get here for external references ...
      end
    }
    true
  else
    false
  end
end

#map_specific_resource(uri_obj, predicate) ⇒ Boolean

if uri_obj has a type of RDF::OpenAnnotation.SpecificResource, then this is a skolemized blank node;

add appropriate statements to @oa_graph to represent the blank node and its contents and return true

to be added to @oa_graph, e.g. RDF::OpenAnnotation.hasTarget

Parameters:

  • uri_obj (RDF::URI) —

    the object that may have type RDF::OpenAnnotation.SpecificResource

  • predicate (RDF::URI) —

    the predicate for [@root_uri, predicate, (sel_res)] statement

Returns:

  • (Boolean) —

    true if it adds statements to @oa_graph, false otherwise



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# File 'app/services/triannon/ldp_to_oa_mapper.rb', line 121

def map_specific_resource uri_obj, predicate
  solns = @ldp_anno_graph.query [uri_obj, RDF.type, RDF::OpenAnnotation.SpecificResource]
  if solns.count > 0
    blank_node = RDF::Node.new
    @oa_graph << [@root_uri, predicate, blank_node]
    
    source_obj = nil
    selector_obj = nil
    selector_blank_node = nil
    specific_res_stmts = Triannon::Graph.subject_statements(uri_obj, @ldp_anno_graph)
    specific_res_stmts.each { |stmt|
      if stmt.predicate == RDF::OpenAnnotation.hasSource
        # expecting a hash URI
        source_obj = stmt.object
        if source_obj.to_s.match("#{uri_obj.to_s}#source")
          source_has_ext_uri = map_external_ref source_obj, RDF::OpenAnnotation.hasSource, blank_node
        end
      elsif stmt.predicate == RDF::OpenAnnotation.hasSelector
        # this becomes a blank node.  Per http://www.openannotation.org/spec/core/specific.html#Selectors
        # "Typically if all of the information needed to resolve the Selector (or other Specifier)
        #  is present within the graph, such as is the case for the 
        # FragmentSelector, TextQuoteSelector, TextPositionSelector and DataPositionSelector classes, 
        # then there is no need to have a resolvable resource that provides the same information."
        selector_obj = stmt.object
        selector_blank_node = RDF::Node.new
        @oa_graph << [blank_node, RDF::OpenAnnotation.hasSelector, selector_blank_node]
      end
    }
    
    # We can't know we'll hit hasSource and hasSelector statements in graph first, 
    # so we must do another pass through the statements to get that information
    specific_res_stmts.each { |stmt| 
      if stmt.subject == uri_obj && stmt.object != source_obj && stmt.object != selector_obj
        @oa_graph << [blank_node, stmt.predicate, stmt.object]
      elsif stmt.subject != source_obj
        if selector_blank_node && stmt.subject == selector_obj
          @oa_graph << [selector_blank_node, stmt.predicate, stmt.object]
        end
      # there shouldn't be any other statements present
      end
    }
    true
  else
    false
  end
end