#region tag find function
		private string TagFind(string sourse, string left, string right, int startIndex, bool greedy)
		{
			int p = sourse.IndexOf(left, startIndex);
			if (p == -1) return string.Empty;
			int start = p + left.Length;
			int t;
			if (greedy)
				t = sourse.LastIndexOf(right);
			else
				t = sourse.IndexOf(right, start);
			if (t == -1)
				return string.Empty;
			return (sourse.Substring(start, t - start));
		}
		#endregion