add: GrammarBuilder

Canon.Core/Enums/GrammarEnums.cs

@@ -2,6 +2,10 @@
 
 public enum NonTerminatorType
 {
+    /// <summary>
+    /// 拓广文法
+    /// </summary>
+    StartNonTerminator,
     ProgramStruct,
     ProgramHead,
     ProgramBody,

Canon.Core/Enums/SemanticEnums.cs

@@ -8,6 +8,10 @@ public enum SemanticTokenType
     Delimiter,
     Identifier,
     Character,
+    /// <summary>
+    /// 语法分析中的栈底符号
+    /// </summary>
+    End
 }
 
 public enum DelimiterType