实验名称：实验任务：对下述描述算符表达式的算符优先文法GE,给出算符优先分析的实验结果;实验内容：有上下无关文法如下：E->E+T|E-T|TT->TF|T/F|FF->E|i说明：优先关系矩阵的构造过程：1 = 关系由产生式 F->E 知‘’=‘’FIRSTVT集及LASTVT集FIRSTVTE={ +,-,,/,,i }FIRSTVTF={ ,i }FIRSTVTT={ ,/,,i }LASTVTE={ +,-,,/,,i }LASTVTF={ ,i }LASTVTT={ ,/,,i }2 < 关系+T 则有：+ < FIRSTVTT-T 则有：- < FIRSTVTTF 则有： < FIRSTVTF/F 则有：/ < FIRSTVTFE 则有： < FIRSTVTE3 > 关系E+ 则有： LASTVTE > +E- 则有： LASTVTE > -T 则有： LASTVTT >T/ 则有： LASTVTT > /E 则有： LASTVTE >4请大家画出优先关系矩阵终结符之间的优先关系是唯一的,所以该文法是算符优先文法; 程序的功能描述：程序由文件读入字符串以结束,然后进行算符优先分析,分析过程中如有错误,则终止程序并报告错误位置,最终向屏幕输出移近——规约过程;5依据文法和求出的相应FirstVT和 LastVT 集生成算符优先分析表; 算法描述如下：for 每个形如 P->X1X2…Xn的产生式dofor i =1 to n-1 dobeginif Xi和Xi+1都是终结符 thenXi = Xi+1if i<= n-2, Xi和Xi+2 是终结符, 但Xi+1 为非终结符thenXi = Xi+2if Xi为终结符, Xi+1为非终结符 thenfor FirstVT 中的每个元素 a doXi < aif Xi为非终结符, Xi+1为终结符 thenfor LastVT 中的每个元素 a doa > Xi+1end6构造总控程序算法描述如下：stack S; k = 1; //符号栈S的使用深度Sk = ‘’REPEAT把下一个输入符号读进a中；If Sk VT thenj = kelsej = k-1;While Sj > a doBeginRepeatQ = Sj;if Sj-1 VT thenj = j-1elsej = j-2until Sj < Q;把Sj+1…Sk归约为某个N,并输出归约为哪个符号；K = j+1;Sk = N;end of whileif Sj < a or Sj = a thenbegin k = k+1; Sk = a endelse error //调用出错诊察程序until a = ‘’7代码如下：include ""include ""include ""char data2020; //算符优先关系char s100; //模拟符号栈schar lable20; //文法终极符集char input100; //文法输入符号串char string2010; //用于输入串的分析int k;char a;int j;char q;int r; //文法规则个数int r1; //转化后文法规则个数char st1030; //用来存储文法规则char first1010; //文法非终结符FIRSTVT集char last1010; //文法非终结符LASTVT集int fflag10={0}; //标志第i个非终结符的FIRSTVT集是否已求出int lflag10={0}; //标志第i个非终结符的LASTVT集是否已求出int deal; //对输入串的分析int zhongjiechar c; //判断字符c是否是终极符int xiabiaochar c; //求字符c在算符优先关系表中的下标void outint j,int k,char s; //打印s栈void firstvtchar c; //求非终结符c的FIRSTVT集void lastvtchar c; //求非终结符c的LASTVT集void table; //创建文法优先关系表void main{int i,j,k=0;printf"请输入文法规则数：";scanf"%d",&r;printf"请输入文法规则：\n";fori=0;i<r;i++{scanf"%s",sti; //存储文法规则,初始化FIRSTVT集和LASTVT集/firsti0=0; /firsti0和lasti0分别表示sti0非终极符的FIRSTVT集和LASTVT集中元素的个数/lasti0=0;}fori=0;i<r;i++ //判断文法是否合法{forj=0;stij='\0';j++{ifsti0<'A'||sti0>'Z'{printf"不是算符文法\n";exit-1;}ifstij>='A'&&stij<='Z'{ifstij+1>='A'&&stij+1<='Z'{printf"不是算符文法\n";exit-1;}}}}fori=0;i<r;i++{forj=0;stij='\0';j++{ifstij<'A'||stij>'Z'&&stij='-'&&stij='>'&&stij='|'lablek++=stij;}}lablek='';lablek+1='\0';table;printf"每个非终结符的FIRSTVT集为：\n"; //输出每个非终结符的FIRSTVT集fori=0;i<r;i++{printf"%c: ",sti0;forj=0;j<firsti0;j++{printf"%c ",firstij+1;}printf"\n";}printf"每个非终结符的LASTVT集为：\n"; //输出每个非终结符的LASTVT集fori=0;i<r;i++{printf"%c: ",sti0;forj=0;j<lasti0;j++{printf"%c ",lastij+1;}printf"\n";}printf"算符优先分析表如下:\n";fori=0;lablei='\0';i++printf"\t%c",lablei;printf"\n";fori=0;i<k+1;i++{printf"%c\t",lablei;forj=0;j<k+1;j++{printf"%c\t",dataij;}printf"\n";}printf"请输入文法输入符号串以结束:";scanf"%s",input;deal;}void table{char text2010;int i,j,k,t,l,x=0,y=0;int m,n;x=0;fori=0;i<r;i++{firstvtsti0;lastvtsti0;}fori=0;i<r;i++{textxy=sti0;y++;forj=1;stij='\0';j++{ifstij=='|'{textxy='\0';x++;y=0;textxy=sti0;y++;textxy++='-';textxy++='>';}else{textxy=stij;y++;}}textxy='\0';x++;y=0;}r1=x;printf"转化后的文法为:\n";fori=0;i<x;i++ //输出转化后的文法规则串{printf"%s\n",texti;}fori=0;i<x;i++ /求每个终结符的推导结果去掉"->"后的转化文法,用于最后的规约/ {stringi0=texti0;forj=3,l=1;textij='\0';j++,l++stringil=textij;stringil='\0';}fori=0;i<x;i++{forj=1;textij+1='\0';j++{ifzhongjietextij&&zhongjietextij+1{m=xiabiaotextij;n=xiabiaotextij+1;datamn='=';}iftextij+2='\0'&&zhongjietextij&&zhongjietextij+2&&zhongjietextij+1{m=xiabiaotextij;n=xiabiaotextij+2;datamn='=';}ifzhongjietextij&&zhongjietextij+1{fork=0;k<r;k++{ifstk0==textij+1break;}m=xiabiaotextij;fort=0;t<firstk0;t++{n=xiabiaofirstkt+1;datamn='<';}}ifzhongjietextij&&zhongjietextij+1{fork=0;k<r;k++{ifstk0==textijbreak;}n=xiabiaotextij+1;fort=0;t<lastk0;t++{m=xiabiaolastkt+1;datamn='>';}}}}m=xiabiao'';fort=0;t<first00;t++{n=xiabiaofirst0t+1;datamn='<';}n=xiabiao'';fort=0;t<last00;t++{m=xiabiaolast0t+1;datamn='>';}datann='=';}void firstvtchar c //求FIRSTVT集{int i,j,k,m,n;fori=0;i<r;i++{ifsti0==cbreak;}iffflagi==0{n=firsti0+1;m=0;do{ifm==2||stim=='|'{ifzhongjiestim+1{firstin=stim+1;n++;}else{ifzhongjiestim+2{firstin=stim+2;n++;}ifstim+1=c{firstvtstim+1;forj=0;j<r;j++{ifstj0==stim+1break;}fork=0;k<firstj0;k++{int t;fort=0;t<n;t++{iffirstit==firstjk+1break;}ift==n{firstin=firstjk+1;n++;}}}}}m++;}whilestim='\0';firstin='\0';firsti0=--n;fflagi=1;}}void lastvtchar c //求LASTVT集{int i,j,k,m,n;fori=0;i<r;i++{ifsti0==cbreak;}iflflagi==0{n=lasti0+1;m=0;do{ifstim+1=='\0'||stim+1=='|'{ifzhongjiestim{lastin=stim;n++;}else{ifzhongjiestim-1{lastin=stim-1;n++;}ifstim=c{lastvtstim;forj=0;j<r;j++{ifstj0==stimbreak;}fork=0;k<lastj0;k++{int t;fort=0;t<n;t++{iflastit==lastjk+1break;}ift==n{lastin=lastjk+1;n++;}}}}}m++;}whilestim='\0';lastin='\0';lasti0=--n;lflagi=1;}}int deal{int i,j;int x,y;int z; //输入串的长度k=1;sk=''; //栈置初值fori=0;inputi='\0';i++; //计算输入串的长度z=i--;i=0;whilea=inputi='\0'{ifzhongjieskj=k;elsej=k-1;x=xiabiaosj;y=xiabiaoa;ifdataxy=='>'{out1,k,s;printf"%c",a;outi+1,z,input;printf"规约\n";do{q=sj;ifzhongjiesj-1j=j-1;else j=j-2;x=xiabiaosj;y=xiabiaoq;}whiledataxy='<';int m,n,N;form=j+1;m<=k;m++{forN=0;N<r1;N++forn=1;stringNn='\0';n++{ifzhongjiesm&&zhongjiestringNn{ifzhongjiesm+1&&zhongjiestringNn+1&&sm+1==stringNn+1{sj+1=stringN0;break;}}elseifzhongjiesmifsm==stringNn{sj+1=stringN0;break;}}}k=j+1;ifk==2&&a==''{out1,k,s;printf"%c",a;outi+1,z,input;printf"结束\n";printf"输入串符合文法的定义\n";return 1; //输入串符合文法的定义}}elseifdataxy=='<'||dataxy=='='{ //移进out1,k,s;printf"%c",a;outi+1,z,input;printf"移进\n";k++;sk=a;i++;}else{printf"\nflase";return 0;}}printf"\nflase";return 0;}void outint j,int k,char s{int n=0;int i;fori=j;i<=k;i++{printf"%c",si;n++;}for;n<15;n++{printf" ";}}int xiabiaochar c //求字符c在算符优先关系表中的下标{int i;fori=0;lablei='\0';i++{ifc==lableireturn i;}return -1;}int zhongjiechar c //判断字符c是否是终极符{int i;fori=0;lablei='\0';i++{ifc==lableireturn 1;}return 0;}实验结果：。
