编写一个LEX输入文件，使之生成可计算文本文件的字符、单词和行数且能报告这些数字的程序。单词为不带标点或空格的字母和/数字的序列。标点和空白格不计算为单词。(Write a LEX input file to generate programs that can calculate characters, words and rows of text files, and can report these numbers. Words are sequences of letters and numbers without punctuation or blanks. Punctuation and blank spaces are not counted as words.)