private static ISet <ITreeProgram <TOutput> > GetSubOffspring(
ITreeProgram <TOutput> subProg1, ITreeProgram <TOutput> subProg2)
{
var offspring = new HashSet <ITreeProgram <TOutput> > {
subProg1, subProg2
};
// check if children differ (different sub-structure) or no children -> nothing to do in this branch
if (subProg1.Input == null || subProg2.Input == null ||
subProg1.Input.Count != subProg2.Input.Count || subProg1.Input.Count == 0)
{
return(offspring);
}
// programs have same number of children, iterate recursively to get possible children in each sub-branch
var numChildren = subProg1.Input.Count;
var subChildren = new List <IEnumerable <ITreeProgram <TOutput> > >(numChildren);
for (var i = 0; i < numChildren; i++)
{
subChildren.Add(GetSubOffspring(subProg1.Input[i], subProg2.Input[i]).ToList());
}
// gets all combinations of possible sub-branches
var childrenCombinations = subChildren.GetAllCombinations().ToList();
var subOffspring = new HashSet <ITreeProgram <TOutput> >();
// if sub-programs are the same function, we only need one of them
if (subProg1.GetType() == subProg2.GetType())
{
offspring.Remove(subProg2);
}
// for each sub-program, creates new sub-programs for each combination
foreach (var subProg in offspring)
{
foreach (var childCombination in childrenCombinations)
{
subOffspring.Add(subProg.CreateNew(childCombination));
}
}
return(subOffspring);
}