输入一个DO-WHILE的语句,进行词法分析,词法分析器利用超前搜索,状态转换等方法,将源程序转化成为一个一个的单词符号二元式,如果词法分析无误,则进入语法分析部分,使用简单优先法进行文法分析,为每个终极符与非终极符之间定义优先关系,利用优先关系进行移进-规约,如果能规约到文法的开始符,则文法分析成功,输出四元式.-importation of a DO-WHILE statements, lexical analysis, lexical analyzer using advanced search, the transformation of the state, will be turned into a source of a binary symbols-words, if the lexical analysis accurate. it may enter the syntax analysis, the use of simple grammar priority method, Ultimate website for each non-whitespace between the ultimate definition of priorities, the use of priority relations Shift-Statute If the statute can begin to address the grammar, grammar analysis of successful export-4 yuan.