Antlr4.Runtime.UnbufferedTokenStream.Seek C# (CSharp) Method

        public virtual void Seek(int index)
        {
            // seek to absolute index
            if (index == currentTokenIndex)
            {
                return;
            }
            if (index > currentTokenIndex)
            {
                Sync(index - currentTokenIndex);
                index = Math.Min(index, GetBufferStartIndex() + n - 1);
            }
            int bufferStartIndex = GetBufferStartIndex();
            int i = index - bufferStartIndex;
            if (i < 0)
            {
                throw new ArgumentException("cannot seek to negative index " + index);
            }
            else
            {
                if (i >= n)
                {
                    throw new NotSupportedException("seek to index outside buffer: " + index + " not in " + bufferStartIndex + ".." + (bufferStartIndex + n));
                }
            }
            p = i;
            currentTokenIndex = index;
            if (p == 0)
            {
                lastToken = lastTokenBufferStart;
            }
            else
            {
                lastToken = tokens[p - 1];
            }
        }