C求文法的first和follow集合

本文格式为Word版，下载可任意编辑——C求文法的first和follow集合1.#include\2.#include\3.#include\4.

5.#ifdef_DEBUG6.#undefTHIS_FILE

7.staticcharTHIS_FILE[]=__FILE__;8.#definenewDEBUG_NEW9.#endif

10.//调试部分使用的代码

11.CStringMLR1::GetFirst(inti){

12.if(i=GetIdentNum())return\;

13.returnFirstSet5(m_first[i].Fi,m_first[i].flag14.}

15.CStringMLR1::GetFollow(inti){

16.if(i=GetIdentNum())return\;

17.returnFollowSet1(m_first[i].Fo,m_first[i].flag18.}

19.//构造部分20.MLR1::MLR1(){21.}

22.MLR1::~MLR1(){23.}

24.voidMLR1::ReSet(FILE*pf){25.//使用文件指针pf来重新驱动程序26.inti;27.p_file=pf;

28.list_Express.RemoveAll();29.list_Ident.RemoveAll();

30.for(i=0;i=(char*)m_first;p--)31.*p=0;32.Lex3();33.FirstSet6();34.//FollowSet3();35.}

36.//输入分析部分37.boolMLR1::Lex1(){

38.//截取一个分号段到tocken中39.//功能字符取其负数40.charch=0;41.boolend=false;42.token_len=0;

43.if(feof(p_file))returnfalse;

44.while(!end46.if(fread(47.if(ch':53.case'=':54.ch=-ch;55.break;56.case'\\\\':

57.fread(58.if(ch')return0;79.if(t==0)return0;80.ident[t]=0;

81.for(t=list_Ident.GetSize()-1;t>=0;t--)82.if(list_Ident[t]==(CString)ident)break;83.if(t=MAX_IDENT)returnfalse;85.list_Ident.Add((CString)ident);86.t=list_Ident.GetSize()-1;

87.if(isUse)bit_map[t/8]|=1=符号表;95.registerchar*s,*d;96.char*end;97.inti;98.s=d=token;

99.end=100.if(i=Lex2_1(s))*d++=-i;101.elsereturnfalse;

102.if(*s++!=-'=')returnfalse;

103.while(s=1){104.returnfalse;105.}else{

106.if(*p==*X)returnfalse;107.if(!FirstSet2(*p))108.returnfalse;109.}110.p++;111.}

112.returntrue;113.}

114.boolMLR1::FirstSet2(constcharX){115.//判断非终结符X能否推出LR_NULL116.CStringtemp;

117.if(m_first[-X-1].flag118.if(m_first[-X-1].flag120.m_first[-X-1].flag|=0x40;

121.for(inti=list_Express.GetSize();i>0;i--){122.temp=list_Express.GetAt(i-1);123.if(temp[0]==X){

124.if(FirstSet1((LPCSTR)temp)){125.m_first[-X-1].flag|=3;126.returntrue;127.}128.}129.}

130.m_first[-X-1].flag|=1;131.m_first[-X-1].flag^=0x40;132.returnfalse;133.}

134.boolMLR1::FirstSet3(constchar*X,char*Fi){

135.//求产生式X的First集放在F中,假使LR_NULL在First集中则返回true136.//假使要求符号串的First集,就将X[0]设为0137.//假设X中不出现LR_NULL,LR_EOF和LR_EOS138.//假设F的长度为MAP_SIZE,有128b139.constchar*p=X;140.X++;

141.while(*X!=0){142.if(*X>=1){

143.Fi[(*X)/8]|=10;i--){165.temp=list_Express.GetAt(i-1);166.if(temp[0]==X)

167.FirstSet3((LPCSTR)temp,m_first[-X-1].Fi);

168.}

169.m_first[-X-1].flag|=4;170.m_first[-X-1].flag^=0x40;171.}

172.if(Fi!=m_first[-X-1].Fi){

173.for(inti=0;i0;i--){174.if((m_first[i-1].flag176.}

177.for(i=list_Ident.GetSize();i>0;i--){178.if((m_first[i-1].flag180.}181.}

182.CStringMLR1::FollowSet1(constchar*Fo,boolhas_eof){183.//将集合表示的Follow变为字符串式184.chart[128];185.char*p=t;186.inti,j;

187.for(i=0;i0;i--){194.sprintf(temp,list_Express.GetAt(i-1));195.flag=false;196.p=temp+1;197.while(*p!=0){198.if(!flag){

199.if(*p==X){

200.//表达式中出现了符号X201.flag=true;}202.}else{

203.if(*p>0){

204.//规则2:X后碰上终结符205.flag=false;

206.Fo[*p/8]|=1199.