/// <summary>
/// Template method, which can be configured by overriding the three
/// primitive operations below.
/// </summary>
/// <param name="csp"></param>
/// <param name="assignment"></param>
/// <returns></returns>
private Assignment RecursiveBackTrackingSearch(CSProblem csp,
Assignment assignment)
{
Assignment result = null;
if (assignment.IsComplete(csp.Variables))
{
result = assignment;
}
else
{
Variable var = this.SelectUnassignedVariable(assignment, csp);
foreach (object value in this.OrderDomainValues(var, assignment, csp))
{
assignment.SetAssignment(var, value);
this.FireStateChanged(assignment, csp);
if (assignment.IsConsistent(csp.GetConstraints(var)))
{
DomainRestoreInfo info = this.Inference(var, assignment, csp);
if (!info.IsEmpty())
{
this.FireStateChanged(csp);
}
if (!info.IsEmptyDomainFound())
{
result = this.RecursiveBackTrackingSearch(csp, assignment);
if (result != null)
{
break;
}
}
csp.RestoreDomains(info);
}
assignment.RemoveAssignment(var);
}
}
return(result);
}