feat: ast structs deinitions

src/ast/ast.h

@@ -1,22 +1,37 @@
 #ifndef AST_H
 #define AST_H
 
+#include "lists.h"
 
 enum ast_type
 {
-    AST_NULL = 0,
+    AST_END = 0,
     ATS_IF,
     AST_CMD
 };
 
-union ast_union
+union ast_node
 {
+    struct ast_if;
+    struct ast_cmd;
 };
 
 struct ast
 {
     enum ast_type type;
-    union ast_union data;
+    union ast_node data;
+};
+
+struct ast_if
+{
+    struct ast* condition;  
+    struct ast* then_clause;
+    struct ast* else_clause;
+};
+
+struct ast_cmd
+{
+    struct list* cmd;
 };
 
 #endif /* ! AST_H */