public override FTree <TChild> AddFirst(TChild item, Lineage lineage)
{
FTree <TChild> ret;
#if ASSERTS
var expected = Measure + item.Measure;
#endif
if (CenterDigit.Size < 4)
{
ret = MutateOrCreate(CenterDigit.AddFirst(item, lineage), lineage);
}
else
{
var leftmost = new Digit(item, CenterDigit.First, lineage);
var rightmost = CenterDigit.RemoveFirst(lineage);
ret = new Compound(leftmost, FTree <Digit> .Empty, rightmost, lineage);
}
#if ASSERTS
ret.Measure.AssertEqual(expected);
ret.Left.AssertEqual(item);
#endif
return(ret);
}
public override FTree <TChild> AddFirst(TChild item, Lineage lineage)
{
FTree <TChild> ret;
#if ASSERTS
var expectedSize = Measure + item.Measure;
#endif
if (LeftDigit.Size < 4)
{
ret = MutateOrCreate(LeftDigit.AddFirst(item, lineage), DeepTree, RightDigit, lineage);
}
else
{
var leftmost = new Digit(item, LeftDigit.First, lineage);
var rightmost = LeftDigit.RemoveFirst(lineage);
var newDeep = DeepTree.AddFirst(rightmost, lineage);
ret = MutateOrCreate(leftmost, newDeep, RightDigit, lineage);
}
#if ASSERTS
ret.Measure.AssertEqual(expectedSize);
ret.Left.AssertEqual(item);
#endif
return(ret);
}