private HashSet <NodeReference> findRemainingNodes(ConstraintPoolRule rule)
{
var pool = new ContextPool(Graph);
//TODO optimize filling the pool
pool.Insert(_originalRemainingNodes.ToArray());
rule.Execute(pool);
//take only those remaining nodes which have been selected
var remainingNodes = new HashSet <NodeReference>(pool.ActiveNodes);
return(remainingNodes);
}
private ConstraintPoolRule[] combineRules(ConstraintPoolRule[] combinationRule, ConstraintPoolRule[] ruleToCombine)
{
var result = new ConstraintPoolRule[combinationRule.Length + ruleToCombine.Length];
for (var i = 0; i < combinationRule.Length; ++i)
{
result[i] = combinationRule[i];
}
for (var i = 0; i < ruleToCombine.Length; ++i)
{
result[i + combinationRule.Length] = ruleToCombine[i];
}
return(result);
}
private bool tryFindNextConstraint()
{
var wasFirst = _isFirst;
_isFirst = false;
if (_originalRemainingNodes.Count == 0 || !_factory.HasNextPath)
{
//there is no need for other than empty rule
if (!wasFirst)
{
IsEnd = true;
}
return(wasFirst);
}
var lastCompleteRuleCount = _completeRules.Count;
if (_combinationIndex < 1)
{
//create new rule from next constraint path
var pathSegment = _factory.GetNextSegment();
if (pathSegment == null)
{
return(false);
}
var constraint = createConstraint(pathSegment);
var newRule = new ConstraintPoolRule[] { constraint };
var remainingNodes = findRemainingNodes(constraint);
var isTrivialRule = remainingNodes.Count == _originalRemainingNodes.Count;
if (isTrivialRule || Graph.ContainsLoop(new[] { _factory.StartingNode }, pathSegment.GetReversedEdges()))
{
//we don't need any trivial rule
return(false);
}
_factory.Enqueue(pathSegment);
addRule(newRule, remainingNodes);
//set combination for next rules
_combinationIndex = _incompleteRuleSequence.Count - 1;
_combinationRule = newRule;
_combinationNodes = remainingNodes;
}
else
{
--_combinationIndex;
//combine with previous rule
var ruleToCombine = _incompleteRuleSequence[_combinationIndex];
var nodesToCombine = _remainingNodes[_combinationIndex];
var combinedRule = combineRules(_combinationRule, ruleToCombine);
var combinedNodes = combineNodes(_combinationNodes, nodesToCombine);
var isTrivialExtension = combinedNodes.Count == _combinationNodes.Count || combinedNodes.Count == nodesToCombine.Count;
if (!isTrivialExtension)
{
addRule(combinedRule, combinedNodes);
}
}
//detect whether new complete rule has been found
return(_completeRules.Count > lastCompleteRuleCount);
}