Module: JSON::LD::StreamingWriter

Included in:
Writer
Defined in:
lib/json/ld/streaming_writer.rb

Overview

Streaming writer interface.

Writes an array of statements serialized in expanded JSON-LD. No provision for turning rdf:first/rest into @list encodings.

Author:

Instance Method Summary collapse

Instance Method Details

#stream_epilogue ⇒ void

This method returns an undefined value.

Complete open statements



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# File 'lib/json/ld/streaming_writer.rb', line 78

def stream_epilogue
  # log_debug("epilogue") {"state: #{@state.inspect}"}
  end_graph
  if context
    @output.puts "\n]}"
  else
    @output.puts "\n]"
  end
  self
end

#stream_prologue ⇒ void

This method returns an undefined value.

Write out array start, and note not to prepend node-separating ‘,’



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# File 'lib/json/ld/streaming_writer.rb', line 14

def stream_prologue
  # If we were provided a context, or prefixes, use them to compact the output
  @context = case @options[:context]
  when nil then nil
  when Context then @options[:context]
  else Context.parse(@options[:context])
  end

  # log_debug("prologue") {"context: #{context.inspect}"}
  if context
    @output.puts %({"@context": #{context.serialize['@context'].to_json}, "@graph": [)
  else
    @output.puts "["
  end
  self
end

#stream_statement(statement) ⇒ void

This method returns an undefined value.

Write a statement, creating a current node definition, if necessary.

Once a new/first statement is seen, terminate the current node definition and compact if provided a context.

Also expects all statements in the same context to be contained in a block including all subjects in a block (except for list elements)

Note that if list elements are not received in order using the same subject and property, this may cause a bad serialization.



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# File 'lib/json/ld/streaming_writer.rb', line 41

def stream_statement(statement)
  # log_debug("ss") {"state: #{@state.inspect}, stmt: #{statement}"}
  if @current_graph != statement.graph_name
    end_graph
    start_graph(statement.graph_name)
  end

  # If we're writing a list
  @current_node_def ||= { '@id' => statement.subject.to_s }

  if statement.subject.to_s != @current_node_def['@id']
    end_node
    @current_node_def = { '@id' => statement.subject.to_s }
  end

  if statement.predicate == RDF.type
    (@current_node_def['@type'] ||= []) << statement.object.to_s
  else
    pd = (@current_node_def[statement.predicate.to_s] ||= [])

    pd << if statement.object.resource?
      { '@id' => statement.object.to_s }
    elsif statement.object.datatype == RDF_JSON
      { "@value" => MultiJson.load(statement.object.to_s), "@type" => "@json" }
    else
      lit = { "@value" => statement.object.to_s }
      lit["@type"] = statement.object.datatype.to_s if statement.object.datatype?
      lit["@language"] = statement.object.language.to_s if statement.object.language?
      lit
    end
  end
  self
end