System.Text.Utf8.Utf8Encoder.TryFindEncodedCodePointBytesCountGoingBackwards C# (CSharp) Метод

        private static bool TryFindEncodedCodePointBytesCountGoingBackwards(Span<byte> buffer, out int encodedBytes)
        {
            encodedBytes = 1;
            Span<byte> it = buffer;
            // TODO: Should we have something like: Span<byte>.(Slice from the back)
            for (; encodedBytes <= UnicodeConstants.Utf8MaxCodeUnitsPerCodePoint; encodedBytes++, it = it.Slice(0, it.Length - 1))
            {
                if (it.Length == 0)
                {
                    encodedBytes = default(int);
                    return false;
                }

                // TODO: Should we have Span<byte>.Last?
                if (Utf8CodeUnit.IsFirstCodeUnitInEncodedCodePoint((Utf8CodeUnit)it[it.Length - 1]))
                {
                    // output: encodedBytes
                    return true;
                }
            }

            // Invalid unicode character or stream prematurely ended (which is still invalid character in that stream)
            encodedBytes = default(int);
            return false;
        }