public static void AddStyle(ref LinkedList <RichTextStyle> styles, RichTextStyle newSet, bool overrideOldStyle)
        {
            if (newSet.end <= newSet.start || newSet.start < 0 || !newSet.hasAnyStyle)
            {
                return;
            }
            if (styles == null)
            {
                styles = new LinkedList <RichTextStyle>();
            }
            if (styles.Count == 0)
            {
                styles.AddLast(newSet);
                return;
            }
            LinkedListNode <RichTextStyle> node = styles.First;

            while (node != null)
            {
                RichTextStyle set = node.Value;
                LinkedListNode <RichTextStyle> next = node.Next;
                if (newSet.end <= set.start)
                {
                    styles.AddBefore(node, newSet);
                    return;
                }
                else if (newSet.start >= set.end)
                {
                    node = next;
                    continue;
                }
                //newSet.end>set.Start, newSet.start<set.end
                int off0, off1;
                //左边区域
                off0 = Mathf.Min(newSet.start, set.start);
                off1 = Mathf.Max(newSet.start, set.start);
                if (off0 < off1)
                {
                    RichTextStyle insert = newSet.start < set.start ? newSet.CopyTo(off0, off1) : set.CopyTo(off0, off1);
                    styles.AddBefore(node, insert);
                    newSet.start = off1;
                    set.start    = off1;
                    node.Value   = set;
                }
                //公共区域
                off0 = off1;
                off1 = Mathf.Min(set.end, newSet.end);
                if (off0 < off1)
                {
                    RichTextStyle insert;
                    if (overrideOldStyle)
                    {
                        insert = set.CopyTo(off0, off1);
                        insert.OverrideSet(newSet);
                    }
                    else
                    {
                        insert = newSet.CopyTo(off0, off1);
                        insert.OverrideSet(set);
                    }
                    node.Value   = insert;
                    set.start    = off1;
                    newSet.start = off1;
                }
                if (newSet.start >= newSet.end)
                {
                    styles.AddAfter(node, set);
                    break;
                }
                else
                {
                    node = next;
                }
            }
            if (newSet.start < newSet.end)
            {
                styles.AddLast(newSet);
            }
        }