module Graphviz

option　options　String

:format ('pdf') The output format (e.g. pdf).

option　options　String

:path The output path, if not specified data is returned.

option　options　String

:dot ('dot') The +dot+ executable to use.

def self.output(graph, path: nil, format: "pdf", dot: "dot")
	output_format = format
	
	if path
		# Grab the output format from the file name:
		if path =~ /\.(.*?)$/
			output_format ||= $1
		end
	end
	
	output, input = IO.pipe
	pipeline = Process::Pipeline.(dot, "-T#{output_format}")
	
	writer = Thread.new do
		graph.dump_graph(input)
		
		input.close
	end
	
	if path
		pipeline.write(path, input: output)
	else
		return pipeline.read(input: output)
	end
ensure
	writer.join
end