-assignment_stmt: T_VARIABLE T_ASSIGN assign_val T_EOL { variable_add($1, $3, $2); free($1); free($3); }
+assignment_stmt: T_VARIABLE assign_op assign_val T_EOL { variable_add($1, $3, $2); free($1); free($3); }
+
+assign_op:
+ T_EQUAL { $$ = VAR_RECURSIVE; }
+ | T_COLON_EQUAL { $$ = VAR_SIMPLE; }
+ | T_PLUS_EQUAL { $$ = VAR_APPEND; }
+;