The syntax tree is gained during parsing web resources by means of using heap and stack .

在解析网页资源的过程中，通过使用 堆栈来进行相关的操作，得到了所需的 语法树。

As input a sentence if the sentence is lawful sentence corresponding output syntax tree to the output of the process every step of the sign changes in the stack .

如输入一个句子，如果该句子合法则输出与句子对应的 语法树；能够输出分析过程中每一步符号 栈的变化情况。