该文档主要讲解了如何用lex和yacc组建一个编译器。并描述了如何做一个复杂的计算器。Thisdocumentexplainshowtoconstructacompilerusinglexandyacc.Lexandyaccaretoolsusedtogeneratelexicalanalyzersandparsers.IassumeyoucanprograminC,andunderstanddatastructuressuchaslinked-listsandtrees.Theintroductiondescribesthebasicbuildingblocks