yacc

• yacc is actually fairly straightforward to use
  yacc实际上非常易于使用。
• A yacc grammar tends to look sort of like this
  yacc语法有几分类似如下：
• Is a reasonably complete c89 grammar, done in yacc
  是一个用yacc完成的相当完整的c99语法。
• The yacc grammar file contains this grammar specification
  yacc语法文件包括这一语法规范。
• So far we ve talked about lex and yacc separately
  到目前为止我们已经分别讨论了lex和yacc。
• Lex and yacc are a matched pair of tools
  lex和yacc是一对配对工具。
• yacc then obtains the returned tokens
  于是yacc就会获得返回的标记。
• yacc files, like lex files, come in sections separated by
  类似于lex文件，yacc文件也是由使用
• If the requirement is for yacc, it may need to be downloaded
  如果需要yacc，可能得去下载它。
• Most people never need to know what lex and yacc do
  大部分人永远不需要知道lex和yacc可以做什么。