Class: BioInterchange::Writer

Inherits:
Object
  • Object
show all
Defined in:
lib/biointerchange/writer.rb

Instance Method Summary collapse

Constructor Details

#initialize(ostream) ⇒ Writer

Creates a new instance of a writer that will use the provided output stream to serialize object model instances.

When you override this method, please make sure that the parameter ‘ostream` is assigned to the instance variable `@ostream`. The instance variable `@ostream` will be used by the serialization helper-method `create_triple`.

ostream

instance of IO or derivative class

Raises:



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# File 'lib/biointerchange/writer.rb', line 12

def initialize(ostream)
  raise BioInterchange::Exceptions::ImplementationWriterError, 'The output stream is not an instance of IO or its subclasses.' unless ostream.kind_of?(IO)
  @ostream = ostream
  @prefixes = {
    '<http://purl.org/dc/terms/'                   => 'dc:',
    '<http://www.w3.org/1999/02/22-rdf-syntax-ns#' => 'rdf:',
    '<http://www.w3.org/2000/01/rdf-schema#'       => 'rdfs:',
    '<http://www.w3.org/2002/07/owl#'              => 'owl:',
    '<http://www.w3.org/2001/XMLSchema#'           => 'xsd:'
  }
end

Instance Method Details

#add_prefix(uri_prefix, abbreviation_prefix) ⇒ Object

Adds a URI prefix that should be abbreviated when serializing triples in Turtle.



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# File 'lib/biointerchange/writer.rb', line 94

def add_prefix(uri_prefix, abbreviation_prefix)
  @prefixes["<#{uri_prefix}"] = "#{abbreviation_prefix}:"
end

#close ⇒ Object

Finishes serializing triples.



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# File 'lib/biointerchange/writer.rb', line 82

def close
  if BioInterchange::format == :turtle then
    serialize_turtle()
  end
end

#create_triple(subject, predicate, object, datatype = nil) ⇒ Object

Creates a new triple and serializes it.

subject

a string or RDF::URI instance denoting the subject of the triple

predicate

a string or RDF::URI instance denoting the predicate of the triple

object

RDF::URI instance for URIs or other Ruby class for literals

datatype

optional datatype describing literal types



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# File 'lib/biointerchange/writer.rb', line 38

def create_triple(subject, predicate, object, datatype = nil)
  subject_uri = subject
  subject_uri = subject_uri.to_s unless subject_uri.instance_of?(String)
  subject_uri = "<#{subject_uri}>".sub(/\s/, '%20')

  predicate_uri = predicate
  predicate_uri = predicate_uri.to_s unless predicate_uri.instance_of?(String)
  predicate_uri = "<#{predicate_uri}>".sub(/\s/, '%20')

  object_representation = nil
  if object.kind_of?(RDF::URI) then
    object_uri = object.to_s
    object_representation = "<#{object_uri}>".sub(/\s/, '%20')
  elsif object.kind_of?(Integer) then
    object_representation = object.to_s
  elsif object.kind_of?(Float) then
    object_representation = object.to_s
  elsif object.instance_of?(TrueClass) or object.instance_of?(FalseClass) then
    object_representation = object.to_s
  else
    if datatype then
      object_representation = "\"#{object.to_s}\"^^<#{datatype.to_s}>"
    else
      object_representation = "\"#{object.to_s}\""
    end
  end

  begin
    if BioInterchange::format == :turtle then
      serialize_turtle(subject_uri, predicate_uri, object_representation)
    else
      @ostream.puts("#{subject_uri} #{predicate_uri} #{object_representation} .")
    end
  rescue Errno::EPIPE
    # Whenever an output pipe disappears, then the user may be happy with what he/she
    # has seen and hit Ctrl-C, or, piped the output through a UNIX command line tool
    # such as "head".
    exit 0
  end

  subject
end

#serialize(model, uri_prefix = nil) ⇒ Object

Serializes an object model instance.

model

an object model instance

uri_prefix

optional URI prefix that should be used in the RDFization of individuals/class instances

Raises:



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# File 'lib/biointerchange/writer.rb', line 28

def serialize(model, uri_prefix = nil)
  raise BioInterchange::Exceptions::ImplementationWriterError, 'You must implement this method, which takes an object model and serializes it into the output stream provided as constructor (\'initialize\') argument.'
end

#set_base(uri_prefix) ⇒ Object

Sets the base URI prefix that is output/used when serializing triples in Turtle.



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# File 'lib/biointerchange/writer.rb', line 89

def set_base(uri_prefix)
  @prefixes["<#{uri_prefix}"] = '<'
end