private INode InsertShortNode(
ShortNode shortNode,
ImmutableArray <byte> prefix,
ImmutableArray <byte> key,
INode value)
{
int CommonPrefixLen(ImmutableArray <byte> a, ImmutableArray <byte> b)
{
var length = Math.Min(a.Length, b.Length);
foreach (var i in Enumerable.Range(0, length))
{
if (a[i] != b[i])
{
return(i);
}
}
return(length);
}
int commonPrefixLength = CommonPrefixLen(shortNode.Key, key);
if (commonPrefixLength == shortNode.Key.Length)
{
var nn = Insert(
shortNode.Value,
prefix.AddRange(key.Take(commonPrefixLength)),
key.Skip(commonPrefixLength).ToImmutableArray(),
value);
return(new ShortNode(shortNode.Key, nn));
}
var branch = new FullNode();
branch = branch.SetChild(
key[commonPrefixLength],
Insert(
null,
prefix.AddRange(key.Take(commonPrefixLength + 1)),
key.Skip(commonPrefixLength + 1).ToImmutableArray(),
value));
branch = branch.SetChild(
shortNode.Key[commonPrefixLength],
Insert(
null,
prefix.AddRange(shortNode.Key.Take(commonPrefixLength + 1)),
shortNode.Key.Skip(commonPrefixLength + 1).ToImmutableArray(),
shortNode.Value !));
if (commonPrefixLength == 0)
{
return(branch);
}
// extension node
return(new ShortNode(key.Take(commonPrefixLength).ToArray(), branch));
}