the science of programming BNF范式的优先级

标签：bnf范式 优先级

  1. <expr>:=<expr_imp>
  2.		|<exper>-<expr_imp>
  3. <expr_imp>:=<factor>
  4.		|<expr_imp>*<factor>
  5. <facotr>:=(<expr>)
  6.		|<identifer>

  matchExpr(){

	 while(testNext()=EOF){

		matchExper_imp() 
		if ! matchMinus()
		   return 
	 }
	 mathcExper_imp()
  }

  matchExpr_imp(){

	 while(testNext()=EOF){

		matchFactor() 
		if ! matchMulti()
			return
	 }
	 mathcFactor()
  }

 matchFactor(){
 
	 if test()=="("
		 matchLeftPar()
		 matchExpr()
		 mathcRightPar()
	 else if test() == number
		 matchIdenti()
	 else 
		 error
 
 }

the science of programming BNF范式的优先级

标签：bnf范式 优先级

原文地址：http://blog.csdn.net/dexter_morgan/article/details/41513723