public static IEnumerable <Tuple <T, IEnumerable <T> > > RecursivelyDescendHelper <T>(
this T seed,
IEnumerable <T> initAccumulator,
AccumulatorInclusion accumulatorTerminalInclusion,
Func <T, bool> terminateOnDescendent,
Func <T, IEnumerable <T> > getDescendents)
where T : class
{
// ideally a linked arraylist would be used here.
if (terminateOnDescendent(seed))
{
if (accumulatorTerminalInclusion == AccumulatorInclusion.Include)
{
return(new Tuple <T, IEnumerable <T> >(seed, initAccumulator.Concat(seed)).Wrap());
}
else
{
return(new Tuple <T, IEnumerable <T> >(seed, initAccumulator).Wrap());
}
}
else //seed is intermediate
{
initAccumulator = initAccumulator.Concat(seed);
var descendents = getDescendents(seed);
var results = descendents.Select(
(d) => RecursivelyDescendHelper(
d,
initAccumulator,
accumulatorTerminalInclusion,
terminateOnDescendent,
getDescendents
)
).SelectMany(r => r);
return(results);
}
}
public static IEnumerable <Tuple <T, IEnumerable <T> > > RecursivelyDescend <T>(
this T seed,
IEnumerable <T> initAccumulator,
AccumulatorInclusion accumulatorSeedInclusion,
AccumulatorInclusion accumulatorTerminalInclusion,
Func <T, bool> terminateOnDescendent,
Func <T, IEnumerable <T> > getDescendents)
where T : class
{
if (accumulatorSeedInclusion == AccumulatorInclusion.Include)
{
initAccumulator = initAccumulator.Concat(seed);
}
return(getDescendents(seed).Select(
descendent => RecursivelyDescendHelper(
descendent,
initAccumulator,
accumulatorTerminalInclusion,
terminateOnDescendent,
getDescendents
)
).SelectMany(many => many));
}
