自顶向下 递归 if elseif else 【错误结构 不报错】

    private static final String IF = "if";
    private static final String ELSE_IF = "else if";
    private static final String ELSE = "else";
    private static final String THEN = "then";


    private class TwoTuple {
        public String token;
        public T value;
        

        private TwoTuple() {
        	
        }
        
        private TwoTuple(String token, T t) {
            this.token = token;
            this.value = t;
        }
    }
    
    private List> tokens;
    private TwoTuple