# A mean to save and load a Neo4j graph.
abstract class GraphStore
	super Trackable

	# The graph to save or load.
	var graph: NeoGraph

	# Can we save the graph without conflict?
	fun isolated_save: Bool is abstract

	# Load the graph (or a part of it).
	#
	# Do not reset the graph.
	fun load is abstract

	# Save the graph.
	fun save do save_part(graph.nodes, graph.edges)

	# Save the specified part of the graph.
	#
	# Assume that for each relationship specified, both ends are already saved
	# or are specified in the same call to this method.
	fun save_part(nodes: Collection[NeoNode],
			edges: Collection[NeoEdge]) is abstract
end