Module: ActiveFedora::RdfList

Extended by:
ActiveSupport::Concern
Includes:
RdfNode
Defined in:
lib/active_fedora/rdf_list.rb

Constant Summary collapse

UNASSIGNABLE_KEYS = 
%w(_destroy )

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from RdfNode

#==, #append, #attributes=, #config_for_term_or_uri, #delete_predicate, #destroy, #find_predicate, #get_values, #mark_for_destruction, #marked_for_destruction?, #new_record=, #new_record?, #query, rdf_registry, #reset_child_cache!, #reset_rdf_subject!, #set_value, #target_class

Instance Attribute Details

#graph ⇒ Object (readonly)

Returns the value of attribute graph.



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# File 'lib/active_fedora/rdf_list.rb', line 6

def graph
  @graph
end

#subject ⇒ Object (readonly)

Returns the value of attribute subject.



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# File 'lib/active_fedora/rdf_list.rb', line 6

def subject
  @subject
end

Instance Method Details

#[](idx) ⇒ Object 



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# File 'lib/active_fedora/rdf_list.rb', line 59

def [](idx)
  idx == 0 ?  head.value : tail[idx-1]
end

#[]=(idx, value) ⇒ Object 



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# File 'lib/active_fedora/rdf_list.rb', line 63

def []=(idx, value)
  idx == 0 ?  head.value=value : tail_or_create(idx-1).value=value
end

#assign_nested_attributes_for_collection_association(association_name, attributes_collection) ⇒ Object

Override assign_nested_attributes



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# File 'lib/active_fedora/rdf_list.rb', line 25

def assign_nested_attributes_for_collection_association(association_name, attributes_collection)
  options = self.nested_attributes_options[association_name]

  # TODO
  #check_record_limit!(options[:limit], attributes_collection)

  if attributes_collection.is_a?(Hash)
    attributes_collection = attributes_collection.values
  end

  association = self.send(association_name)
  
  original_length_of_list = self.size
  attributes_collection.each_with_index do |attributes, index|
    attributes = attributes.with_indifferent_access
    minted_node = association.mint_node(attributes.except(*UNASSIGNABLE_KEYS))
    self[original_length_of_list+index] = minted_node
  end
end

#clear(first_element = true) ⇒ Object 



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# File 'lib/active_fedora/rdf_list.rb', line 67

def clear(first_element=true)
  # Remove the pointed at element
  v = graph.query([subject, RDF.first, nil]).first
  # TODO - Recursive delete
  graph.delete([v.object, nil, nil])
  
  # Remove the tail
  tail.clear(false) if tail
  # clear the cache
  @tail = nil
  graph.delete([subject, nil, nil])
  if first_element
    # Re-add first/rest predicates if its the first node
    graph.insert([subject, RDF.first, RDF.nil])
    graph.insert([subject, RDF.rest, RDF.nil])
  end
end

#each {|head.value| ... } ⇒ Object

Yields:



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# File 'lib/active_fedora/rdf_list.rb', line 85

def each &block
  yield(head.value)
  tail.each(&block) if tail
end

#empty? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_fedora/rdf_list.rb', line 100

def empty?
  !tail && graph.query([subject, RDF.first, RDF.nil]).first
end

#first ⇒ Object 



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# File 'lib/active_fedora/rdf_list.rb', line 55

def first
  self[0] 
end

#head ⇒ Object 



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# File 'lib/active_fedora/rdf_list.rb', line 139

def head
  @head ||= self.class.new(graph, subject)
end

#initialize(graph, subject) ⇒ Object

RdfList is a node of a linked list structure. The RDF.first predicate points to the contained object The RDF.rest predicate points to the next node in the list or 

RDF.nil if this is the final node.

See Also:



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# File 'lib/active_fedora/rdf_list.rb', line 13

def initialize(graph, subject)
  @graph = graph
  @subject = subject
  first = graph.query([subject, RDF.first, nil]).first
  last = graph.query([subject, RDF.rest, nil]).first
  graph.insert([subject, RDF.first, RDF.nil]) unless first
  graph.insert([subject, RDF.rest, RDF.nil]) unless last
end

#insert_child(predicate, node) ⇒ Object

Override the method from RdfNode, enabling us to insert into the list.



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# File 'lib/active_fedora/rdf_list.rb', line 47

def insert_child(predicate, node)
  self[size] = node
end

#inspect ⇒ Object 



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# File 'lib/active_fedora/rdf_list.rb', line 114

def inspect
  "[ #{value ? value.inspect : 'nil'}, #{tail.inspect}]"
end

#rdf_subject ⇒ Object 



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# File 'lib/active_fedora/rdf_list.rb', line 51

def rdf_subject
  subject
end

#size ⇒ Object 



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# File 'lib/active_fedora/rdf_list.rb', line 104

def size
  if empty?
    0
  elsif tail
    tail.size + 1
  else
    1
  end
end

#tail ⇒ Object 



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# File 'lib/active_fedora/rdf_list.rb', line 143

def tail
  return @tail if @tail
  rest = graph.query([subject, RDF.rest, nil]).first
  return if rest.object == RDF.nil
  @tail = self.class.new(graph, rest.object)
end

#tail_or_create(idx) ⇒ Object 



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# File 'lib/active_fedora/rdf_list.rb', line 150

def tail_or_create(idx)
  unless tail
    #add a tail
    graph.delete([subject, RDF.rest, RDF.nil])
    tail_node = RDF::Node.new
    graph.insert([subject, RDF.rest, tail_node])
    @tail = self.class.new(graph, tail_node)
  end

  idx == 0 ? @tail : @tail.tail_or_create(idx-1)
end

#to_ary ⇒ Object 



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# File 'lib/active_fedora/rdf_list.rb', line 90

def to_ary
  if empty?
    []
  elsif tail
    [head.value] + tail.to_ary
  else
    [head.value]
  end
end

#value ⇒ Object 



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# File 'lib/active_fedora/rdf_list.rb', line 118

def value
  v = graph.query([subject, RDF.first, nil]).first
  if v.object.uri?
    return v.object == RDF.nil ? nil : v.object
  end
  if v.object.resource?
    type = graph.query([v.object, RDF.type, nil]).first
    return ActiveFedora::RdfNode.rdf_registry[type.object].new(graph, v.object)
  end
  v
end

#value=(obj) ⇒ Object 



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# File 'lib/active_fedora/rdf_list.rb', line 130

def value=(obj)
  graph.delete([subject, RDF.first, RDF.nil])
  if obj.respond_to? :rdf_subject
    graph.insert([subject, RDF.first, obj.rdf_subject]) # an ActiveFedora::RdfObject
  else
    graph.insert([subject, RDF.first, obj])
  end
end