/// <summary>
        /// Trim excessive inaccessible text.
        /// </summary>
        private static void TrimInaccessibleText(ArrayBuilder <SourceText> segments)
        {
            int length, size;

            ComputeLengthAndStorageSize(segments, out length, out size);

            // if more than half of the storage is unused, compress into a single new segment
            if (length < size / 2)
            {
                var writer = SourceTextWriter.Create(length);
                foreach (var segment in segments)
                {
                    segment.Write(writer);
                }

                segments.Clear();
                segments.Add(writer.ToSourceText());
            }
        }
        /// <summary>
        /// Combines contiguous segments with lengths that are each less than or equal to the specified segment size.
        /// </summary>
        private static void CombineSegments(ArrayBuilder <SourceText> segments, int segmentSize)
        {
            for (int i = 0; i < segments.Count - 1; i++)
            {
                if (segments[i].Length <= segmentSize)
                {
                    int combinedLength = segments[i].Length;

                    // count how many contiguous segments are reducible
                    int count = 1;
                    for (int j = i + 1; j < segments.Count; j++)
                    {
                        if (segments[j].Length <= segmentSize)
                        {
                            count++;
                            combinedLength += segments[j].Length;
                        }
                    }

                    // if we've got at least two, then combine them into a single text
                    if (count > 1)
                    {
                        var writer = SourceTextWriter.Create(combinedLength);

                        while (count > 0)
                        {
                            segments[i].Write(writer);
                            segments.RemoveAt(i);
                            count--;
                        }

                        var newText = writer.ToSourceText();

                        segments.Insert(i, newText);
                    }
                }
            }
        }