预测分析法（LL(1)方法）的基本思想是：从文法开始符S出发，从左到右扫描源程序，每次通过向前查看 1 个字符，选择合适的产生式，生成中间推导过程以及句子的最左推导。本程序可以输入预测分析表，输出最左推导和中间过程。(The basic idea of prediction analysis method (LL (1)) is to start from the grammar start symbol S, and scan the source program from left to right. Every time we look at 1 characters forward, we choose the right generation to generate the middle derivation process and the left-hand inference of the sentence. The program can input the prediction analysis table to output the most left and middle process.)