语法分析器，实现pascal语言的分析，对源程序从左到右进行扫描，对组成源程序的字符串拼接成为单词；并把其并把其转换成属性字输出,并管理符号表，处理词法错误。-Parser to realize pascal language analysis, source code is scanned from left to right, to the composition of a string of source code splicing into words and its properti