重新设计了@get 表达式，修改了 Workbench后台长时间运行时，重新切换到前台会产生参数连接线错误显示的问题

Library/Utils/SereinExpression/SereinExpressionExtension.cs

@@ -0,0 +1,57 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Serein.Library.Utils.SereinExpression
+{
+    internal class SereinExpressionExtension
+    {
+        /// <summary>
+        /// 尝试获取类型
+        /// </summary>
+        /// <param name="context"></param>
+        /// <param name="elementName"></param>
+        /// <param name="type"></param>
+        /// <returns></returns>
+        public static bool TryGetType(string context, out string elementName , out Type type)
+        {
+            int startIndex = context.IndexOf('<');
+            int endIndex = context.IndexOf('>');
+            if (startIndex < 0 || endIndex < 0 || startIndex > endIndex)
+            {
+                type = null;
+                elementName = null;
+                return false;
+            }
+            elementName = context.Substring(0,startIndex);
+            type = context.Substring(startIndex + 1, endIndex - startIndex - 1).ToTypeOfString();
+            return true;
+
+        }
+
+        /// <summary>
+        /// 尝试获取下标
+        /// </summary>
+        /// <param name="context"></param>
+        /// <param name="strIndexKey">文本形式的key/索引</param>
+        /// <returns></returns>
+        public static bool TryGetIndex(string context,out string elementName,  out string strIndexKey)
+        {
+            int startIndex = context.IndexOf('[');
+            int endIndex = context.IndexOf(']');
+            if (startIndex < 0 || endIndex < 0 || startIndex > endIndex)
+            {
+                strIndexKey = null;
+                elementName = null;
+                return false;
+            }
+
+            elementName = context.Substring(0,startIndex);
+            strIndexKey = context.Substring(startIndex + 1, endIndex - startIndex - 1);
+            return true;
+
+        }
+    }
+}