Do some refactor with multiple left associative operators

smnp/ast/node/relation.py

@@ -1,5 +1,5 @@
 from smnp.ast.node.expression import ExpressionNode
-from smnp.ast.node.ignore import IgnoredNode
+from smnp.ast.node.none import NoneNode
 from smnp.ast.parser import Parser
 from smnp.token.type import TokenType
 
@@ -7,7 +7,7 @@ from smnp.token.type import TokenType
 class RelationOperatorNode(ExpressionNode):
     def __init__(self, pos):
         super().__init__(pos)
-        self.children.append(IgnoredNode(pos))
+        self.children = [ NoneNode(), NoneNode(), NoneNode()]
 
     @property
     def left(self):
@@ -18,33 +18,42 @@ class RelationOperatorNode(ExpressionNode):
         self[0] = value
 
     @property
-    def right(self):
+    def operator(self):
         return self[1]
 
+    @operator.setter
+    def operator(self, value):
+        self[1] = value
+
+    @property
+    def right(self):
+        return self[2]
+
     @right.setter
     def right(self, value):
-        self[1] = value
+        self[2] = value
 
     @classmethod
     def relationParser(cls):
-        def createNode(left, right):
+        def createNode(left, operator, right):
             node = RelationOperatorNode(right.pos)
             node.left = left
+            node.operator = operator
             node.right = right
             return node
 
         return Parser.leftAssociativeOperatorParser(
-            cls._relationLiteralParser(),
+            cls._relationLhs(),
             TokenType.EQUAL,
-            cls._parseRelationProperty(),
+            cls._relationRhs(),
             createNode=createNode
         )
 
     @classmethod
-    def _relationLiteralParser(cls):
-        raise RuntimeError(f"_relationLiteralParser() is not implemented in {cls.__name__} class")
+    def _relationLhs(cls):
+        raise RuntimeError(f"_relationLhs() is not implemented in {cls.__name__} class")
 
     @staticmethod
-    def _parseRelationProperty():
+    def _relationRhs():
         # TODO doAssert
         return ExpressionNode.parse