///////////////////////////////////////////////////////////////////////////////////////////////
public static IList <IList <string> > Permute(
IList <string> list,
ListTransformCallback callback
)
{
IList <IList <string> > result = null;
if (list != null)
{
IList <string> localList = new StringList(list); /* COPY */
HandlePermuteResult(callback, localList, ref result);
int count = localList.Count;
int[] indexes = new int[count + 1];
int index1 = 1;
while (index1 < count)
{
if (indexes[index1] < index1)
{
int index2 = index1 % 2 * indexes[index1];
string temporary = localList[index2];
localList[index2] = localList[index1];
localList[index1] = temporary;
HandlePermuteResult(callback, localList, ref result);
indexes[index1]++;
index1 = 1;
}
else
{
indexes[index1] = 0;
index1++;
}
}
}
return(result);
}
///////////////////////////////////////////////////////////////////////////////////////////////
private static void HandlePermuteResult(
ListTransformCallback callback, /* in */
IList <string> list, /* in */
ref IList <IList <string> > result /* in, out */
)
{
if (list == null)
{
return;
}
if ((callback == null) || callback(list))
{
if (result == null)
{
result = new List <IList <string> >();
}
result.Add(new StringList(list)); /* COPY */
}
}
