private ShuffleInfo ExtractShuffleInfo(AType left, AType right)
{
ShuffleInfo info =
new ShuffleInfo(ExtractInteger(left), ExtractInteger(right));
if (info.ItemCount > info.MaxValue)
{
throw new Error.Domain(DomainErrorText);
}
return(info);
}
private ShuffleInfo ExtractShuffleInfo(AType left, AType right)
{
ShuffleInfo info =
new ShuffleInfo(ExtractInteger(left), ExtractInteger(right));
if (info.ItemCount > info.MaxValue)
{
throw new Error.Domain(DomainErrorText);
}
return info;
}
/// <summary>
/// Shuffle the items with a given seed.
/// </summary>
/// <param name="seed"></param>
/// <param name="info">Information for shuffling.</param>
/// <remarks>
/// An implementation of "modified" Durstenfeld's algorithm.
/// http://en.wikipedia.org/wiki/Fisher-Yates_shuffle
/// </remarks>
/// <returns></returns>
private AType Shuffle(int seed, ShuffleInfo info)
{
AType result = AArray.Create(ATypes.AInteger);
int[] randomList = Enumerable.Range(0, info.MaxValue).ToArray();
Random random = (seed != -1) ? new Random(seed) : new Random();
int currentIndex;
for (int i = info.MaxValue - 1; i >= info.MaxValue - info.ItemCount; i--)
{
currentIndex = random.Next(i);
result.AddWithNoUpdate(AInteger.Create(randomList[currentIndex]));
randomList[currentIndex] = randomList[i];
}
result.Length = info.ItemCount;
result.Shape = new List <int>()
{
info.ItemCount
};
result.Rank = 1;
return(result);
}
public override AType Execute(AType right, AType left, Aplus environment)
{
ShuffleInfo info = ExtractShuffleInfo(left, right);
return(Shuffle(GetSeed(environment), info));
}
/// <summary>
/// Shuffle the items with a given seed.
/// </summary>
/// <param name="seed"></param>
/// <param name="info">Information for shuffling.</param>
/// <remarks>
/// An implementation of "modified" Durstenfeld's algorithm.
/// http://en.wikipedia.org/wiki/Fisher-Yates_shuffle
/// </remarks>
/// <returns></returns>
private AType Shuffle(int seed, ShuffleInfo info)
{
AType result = AArray.Create(ATypes.AInteger);
int[] randomList = Enumerable.Range(0, info.MaxValue).ToArray();
Random random = (seed != -1) ? new Random(seed) : new Random();
int currentIndex;
for (int i = info.MaxValue - 1; i >= info.MaxValue - info.ItemCount; i--)
{
currentIndex = random.Next(i);
result.AddWithNoUpdate(AInteger.Create(randomList[currentIndex]));
randomList[currentIndex] = randomList[i];
}
result.Length = info.ItemCount;
result.Shape = new List<int>() { info.ItemCount };
result.Rank = 1;
return result;
}
