新增赋值操作

Parsing/CustomExpressionAnalyzer.cs

@@ -589,6 +589,38 @@ namespace Flee.Parsing
             return node;
         }
 
+        public override Node ExitAssign(Token node)
+        {
+            node.AddValue("=");
+            return node;
+        }
+
+        public override Node ExitAssignmentExpression(Production node)
+        {
+            // 获取子节点：标识符和表达式
+            var children = this.GetChildValues(node);
+            if (children.Count != 3) // IDENTIFIER, ASSIGN, Expression
+            {
+                throw new InvalidOperationException("Assignment expression must have exactly 3 children");
+            }
+
+            string variableName = (string)children[0];
+            ExpressionElement valueExpression = (ExpressionElement)children[2];
+            
+            // 获取表达式上下文
+            var context = _myServices.GetService(typeof(ExpressionContext)) as ExpressionContext;
+            if (context == null)
+            {
+                throw new InvalidOperationException("ExpressionContext not found in services");
+            }
+
+            // 创建赋值表达式元素
+            var assignmentElement = new AssignmentElement(variableName, valueExpression, context);
+            node.AddValue(assignmentElement);
+            
+            return node;
+        }
+
         public override void Child(Production node, Node child)
         {
             base.Child(node, child);