private int _evaluatePositionForToad(EvaluationData <FrogsAndToadsPosition> evaluationData)
{
(Maybe <EvaluationRecord> toad, Maybe <EvaluationRecord> frog)cached
= _cache.Lookup(evaluationData.Position);
if (cached.toad.HasValue && cached.toad.Value.IsComplete)
{
return(cached.toad.Value.Value);
}
MoveRecord moveRecord = new MoveRecord(
evaluationData.Position.GetLeftMoves().Select(x => x as FrogsAndToadsMove),
int.MinValue,
cached.toad);
if (moveRecord.NoPossibleMoves)
{
return(EvaluateEndPositionForRight(evaluationData.Position));
}
EvaluationRecord record = _updateEvaluation(
evaluationData,
moveRecord,
_evaluatePositionForFrog,
(x, y) => Math.Max(x, y),
x => (Math.Min(evaluationData.BestToad, x), evaluationData.BestFrog));
_cache.Store(evaluationData.Position, (record.ToMaybe(), cached.frog));
return(record.Value);
}
private EvaluationRecord _updateEvaluation(
EvaluationData <FrogsAndToadsPosition> evaluationData,
MoveRecord moveRecord,
_evaluator nextEvaluator,
_bestValueUpdater bestValueUpdater,
_bestPairUpdater bestPairUpdater)
{
FrogsAndToadsPosition resultingPosition;
EvaluationData <FrogsAndToadsPosition> resultingEvaluationData;
int bestToad = evaluationData.BestToad;
int bestFrog = evaluationData.BestFrog;
int moveEvaluationcount = 0;
int bestValue = moveRecord.BestValueSoFar;
List <FrogsAndToadsMove> evaluatedMoves =
moveRecord.EvaluatedMoves;
foreach (FrogsAndToadsMove move in moveRecord.MovesToEvaluate)
{
moveEvaluationcount++;
evaluatedMoves.Add(move);
resultingPosition = evaluationData.Position.PlayMove(move);
resultingEvaluationData = new EvaluationData <FrogsAndToadsPosition>(
resultingPosition,
evaluationData.Depth + 1,
evaluationData.BestToad,
evaluationData.BestFrog);
bestValue =
bestValueUpdater(
bestValue,
nextEvaluator(resultingEvaluationData));
(bestToad, bestFrog) = bestPairUpdater(bestValue);
if (bestToad > bestFrog)
{
break;
}
}
return
(moveEvaluationcount == moveRecord.MovesToEvaluate.Count
? new EvaluationRecord(bestValue)
: new EvaluationRecord(bestValue, evaluatedMoves));
}
