public int ReadInt()
{
Require(4);
return(_easyBuffer.ReadInt());
}
public static Options Of(params ByteString[] byteStrings)
{
if (byteStrings.Length == 0)
{
// With no choices we must always return -1. Create a trie that selects from an empty set.
return(new Options(new ByteString[0], new int[] { 0, -1 }));
}
// Sort the byte strings which is required when recursively building the trie. Map the sorted
// indexes to the caller's indexes.
List <ByteString> list = new List <ByteString>(byteStrings);
list.Sort();
List <int> indexes = new List <int>();
for (int i = 0; i < list.Count; i++)
{
indexes.Add(-1);
}
for (int i = 0; i < list.Count; i++)
{
int sortedIndex = list.BinarySearch(byteStrings[i]);
indexes[sortedIndex] = i;
}
if (list[0].Size() == 0)
{
throw new ArgumentException("the empty byte string is not a supported option");
}
// Strip elements that will never be returned because they follow their own prefixes. For
// example, if the caller provides ["abc", "abcde"] we will never return "abcde" because we
// return as soon as we encounter "abc".
for (int a = 0; a < list.Count; a++)
{
ByteString prefix = list[a];
for (int b = a + 1; b < list.Count;)
{
ByteString byteString = list[b];
if (!byteString.StartsWith(prefix))
{
break;
}
if (byteString.Size() == prefix.Size())
{
throw new ArgumentException("duplicate option: " + byteString);
}
if (indexes[b] > indexes[a])
{
list.RemoveAt(b);
indexes.Remove(b);
}
else
{
b++;
}
}
}
var trieBytes = new EasyBuffer();
BuildTrieRecursive(0L, trieBytes, 0, list, 0, list.Count, indexes);
int[] trie = new int[IntCount(trieBytes)];
for (int i = 0; i < trie.Length; i++)
{
trie[i] = trieBytes.ReadInt();
}
if (!trieBytes.Exhausted())
{
throw new AssertionException();
}
var cloneStrings = byteStrings.Clone();
return(new Options((ByteString[])cloneStrings /* Defensive copy. */, trie));
}
