public void Generate(StructureDefinition structure)
{
if (structure.Differential == null) throw Error.Argument("structure", "structure does not contain a differential specification");
if (!structure.IsConstraint) throw Error.Argument("structure", "structure is not a constraint or extension");
if(structure.Base == null) throw Error.Argument("structure", "structure is a constraint, but no base has been specified");
var differential = structure.Differential;
var baseStructure = _resolver.GetStructureDefinition(structure.Base);
if (baseStructure == null) throw Error.InvalidOperation("Could not locate the base StructureDefinition for url " + structure.Base);
if (baseStructure.Snapshot == null) throw Error.InvalidOperation("Snapshot generator required the base at {0} to have a snapshot representation", structure.Base);
var snapshot = (StructureDefinition.SnapshotComponent)baseStructure.Snapshot.DeepCopy();
generateBaseElements(snapshot.Element);
var snapNav = new ElementNavigator(snapshot.Element);
// Fill out the gaps (mostly missing parents) in the differential representation
var fullDifferential = new DifferentialTreeConstructor(differential.Element).MakeTree();
var diffNav = new ElementNavigator(fullDifferential);
merge(snapNav, diffNav);
structure.Snapshot = new StructureDefinition.SnapshotComponent() { Element = snapNav.ToListOfElements() };
}