DOWHILE循环语句的翻译程序设计简单优先法输出四元式

1、（二）DO-WHILE循环语句的翻译程序设计（简单优先法、输出四元式）一、1.简单优先法的基本思想根据优先关系的定义，将简单优先文法中各文法符号之间的这种关系用一个矩阵表示，称作简单优先矩阵。PDA读入一个单词后，比较栈顶符号和该单词的优先级，若栈顶符号优先级低于该单词，继续读入；若栈顶符号优先级高于或等于读入符号，则找句柄进行归约，找不到句柄就继续读入。直到最后栈内只剩下开始符号，输入串读到“”为止。此时识别正确。可分点描述如下:（1）、对句型中相邻的文法符号规定优先关系，以寻找句型中的句柄;（2）、规定句柄内各相邻符号之间具有相同的优先级;（3）、规定句柄两端符号优先级要比位于句柄之外而又

2、和句柄相邻的符号的优先级高，以先归约句柄;（4）、对于文法中所有符号，只要它们可能在某个句型中相邻，就要为它们规定相应的优先关系，若某两个符号永远不可能相邻，则它们之间就无关系.2.简单优先矩阵用于表示文法符号之间的简单优先关系的矩阵。3.简单优先法的优缺点优点：技术简单,当做简单优先矩阵是要求较短。缺点：适用范围小，分析表尺寸太大。二、源代码实现：#include<iostream>#define MAX 35#include<list>#include<string>#include<fstream>using namespace std;#

3、defineTABLE_LEN8#defineSTR_LEN256int zhlen;char sTableTABLE_LEN+1 = "+-*/()i#"/顺序索引int ShipTableTABLE_LENTABLE_LEN = /优先表 1, 1,-1,-1,-1, 1,-1, 1, 1, 1,-1,-1,-1, 1,-1, 1, 1, 1, 1, 1,-1, 1,-1, 1, 1, 1, 1, 1,-1, 1,-1, 1,-1,-1,-1,-1,-1, 0,-1,-2, 1, 1, 1, 1,-2, 1,-2, 1, 1, 1, 1, 1,-2, 1,-2, 1,-

4、1,-1,-1,-1,-1,-2,-1, 0;char X,a;char VN11='K','L','P','S','E','G','T','R','F','Q','0'char VT15='i','=','<','>','+','-','*','/','(',

5、9;)','d','w','','#','0'char p186="dLwS0","SP0","SP0","0","iQE0","TG0","+TG0","-TG0","0","FR0","*FR0","/FR0","0","(E)0&quo

6、t;,"i0","=0","<0",">0"char stackMAX;char queueMAX;int sp,front;intM1014= -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,0,-1,-1,-1,1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,3,2,-1,4,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,5,-1,-1,-1,-1,-1,-

7、1,-1,5,-1,-1,-1,-1,-1,-1,-1,-1,-1,6,7,-1,-1,-1,-1,-1,8,8,8,9,-1,-1,-1,-1,-1,-1,-1,9,-1,-1,-1,-1,-1,-1,-1,-1,-1,12,12,10,11,-1,-1,-1,12,12,12,14,-1,-1,-1,-1,-1,-1,-1,13,-1,-1,-1,-1,-1,-1,15,16,17,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,;int f=0; int count=0;int c=0;char arr_iMAX;char varMAX; /表格管理int tdMAX; in

8、t t=0;int opd=-1;int opr=-1;int id=0;int d=0;char arrMAX4;/存放待输出的四元式/char keyword27="do0","while0"bool IsCharInStr(char c,char s)for(int i=0;si!='0'i+)if(si=c)return true;return false;int GetIndex(char s,char c)for(int i=0;si!='0'i+)if(c=si)return i;return -1;/str

9、ing GetSubString(char s,int from,int to)string st;for(int i=from;i<to;i+)st+=si;return st;/* 翻译赋值表达式*/void translatefuzhi(char *sInput)/栈结构的初始化char StackSTR_LEN=0;int index = 0;int top = 1;Stack0 = '#'list<char> rPolish;list<string> Num;int begin=0;while(sInputbegin!='=

10、9;)if(IsCharInStr(sInputbegin,sTable)cout<<"Equal expression is illegal!"<<endl;return ;begin+;Num.push_back(GetSubString(sInput,0,begin);int now = begin+1;int before = begin;rPolish.push_back('i');while(sInputnow!='0')if(IsCharInStr(sInputnow,sTable)char temp3=

11、0;if(now-before>1)temp0 = 'i'temp1 = sInputnow;Num.push_back(GetSubString(sInput,before+1,now);elsetemp0 = sInputnow;int i=0;while(tempi!=0)int left = GetIndex(sTable,Stackindex);int right = GetIndex(sTable,tempi);switch(ShipTableleftright)case -1:/移入Stacktop+ = tempi;index = top-1;i+;bre

12、ak;case 0:/脱括号if(Stackindex='(')Stacktop+ = ')'Stackindex = 'E'top = index+1;index-;else/规约if(top!=2)return;rPolish.push_back('=');list<char>:iterator iter;list<string>:iterator siter=Num.begin();string fuzhi256;int d=0,m;for(iter=rPolish.begin();iter!=rPo

13、lish.end();iter+)if(*iter='i')fuzhid+=*siter;siter+;elsefuzhid+=*iter;m=d;string op1,op2;int flag,xiabiao=0;for(d=0;d<m;d+)cout<<"("<<fuzhid<<","<<op1<<","<<op2<<","<<"T"<<xiabiao<&l

14、t;")"<<endl;fuzhid = "T"fuzhid+=(xiabiao+'0');xiabiao+;/cout<<fuzhid;return;i+;break;case 1:/归约if(Stackindex='i')rPolish.push_back('i');Stackindex = 'E'index-;elserPolish.push_back(Stackindex);Stackindex-1 = 'E'top = index;index

15、-=2;break; default:return;before=now;now+;int len(char str)int i=0;while(stri!='0')i+;return i;int index(char ch,char str)int i=0;while(stri!='0')if(ch!=stri)i+;else break;if(stri='0')return -1;return i;void err(int n)if(n=1)cout<<"字符不匹配"<<endl;else if(n

16、=2)cout<<"字符没有出现在产生式中"<<endl;else if(n=3)cout<<"没有找到合适的¨选产式"<<endl;else cout<<"该句子是文法语言的句子"<<endl;void print()cout<<"("if(count<10)cout<<'0'cout<<count<<")"int i;for(i=0;i<

17、;=sp;i+)cout<<stacki;for(;i<=20;i+)cout<<" "for(i=0;i<front;i+)cout<<" "for(;queuei!='#'i+)cout<<queuei;cout<<queuei;for(;i<=20;i+)cout<<" "void semantic()if(VTopr='=')arrd0='='arrd1=arr_iopd;arrd2=id;

18、arrd3='-'id+;else if(opr=-2)arrd0='='arrd1=id-1;arrd2=arr_iopd;arrd3='-'else arrd0=VTopr;arrd1=arr_iopd;arrd2=id;if(VTopr!='<'&&VTopr!='>')arrd3=id-1;else arrd3=id+1;id+;d+;void syntax()/语法分析int n;count+;print();X=stacksp;a=queuefront;if(X='#

19、'&&a='#')f=4;if(X<'A'|X>'Z')if(X=a)sp-;front+;if(a!='i')if(a!='d'&&a!='w'&&a!=''&&a!='#')opr=index(a,VT);semantic();else if(a=''|a='w'|a='#')opr=-2;semantic();cout<<

20、;'t'<<'''<<a<<"'匹配"<<endl;else opd=c;cout<<'t'<<'''<<arr_ic+<<"'匹配"<<endl;else f=1; else int tx=index(X,VN);int ta=index(a,VT);n=Mtxta;tdt+=Mtxta;if(ta=-1)f=2;cout<<a<&l

21、t;endl; else if(n=-1)f=3; else sp-;cout<<'t'<<X<<"->"if(len(pn)!=0)for(int i=len(pn)-1;i>=0;i-)stack+sp=pni;cout<<pnlen(pn)-1-i;cout<<endl;else cout<<"空串"<<endl;if(f=0)syntax();else tdt='-1'err(f);void lexical() /词法分

22、析int i,j,d;char ch;j=d=0;for(i=0;vari!='#'i+)ch=vari;if(ch='d'&&vari+1='o')cout<<"do"<<'t'<<"keword"<<endl;queuej+='d'i+=1;else if(ch='w')ch=vari+1;if(ch='h')ch=vari+2;if(ch='i')ch=var

23、i+3;if(ch='l')ch=vari+4;if(ch='e')ch=vari+5;cout<<"while"<<'t'<<"keyword"<<endl;queuej+='w'i+=4;else if(index(ch,VT)<=0)if(ch!=''&&ch!=''&&ch!='('&&ch!=')')cout<&

24、lt;ch<<'t'<<"variable:i"<<d+<<""<<endl;arr_id-1=ch;queuej+='i'else cout<<ch<<'t'<<"bound"<<endl;else if(index(ch,VT)>0)cout<<ch<<'t'<<"operator"<<e

25、ndl;queuej+=ch;queuej='#'for(i=0;queuei!='#'i+)cout<<queuei;cout<<endl;int main()int i=0,j=0;int len,length;char temp;char S='K'sp=front=0;stack0='#'sp+;stack1='K'cout<<" *"<<endl;cout<<" * DO-WHILE循环语句 *"<&

26、lt;endl;cout<<" * (简单优先法输出四元式) *"<<endl;cout<<" *"<<endl;ifstream table;table.open("dowhile.txt");if(!table)cout<<"error!"table.seekg(0,ios:end);length = table.tellg();table.seekg(0,ios:beg);while(length!=table.tellg()table.read(c

27、har*)&temp,1);vari=temp;i+;if(vari=' ')i-;if(vari='#')break;table.close();len=i;vari='0'cout<<"词法分析"<<endl;lexical();char fuzhi20;int flag1,fuzhilen;int s=0;for(i=0;i<len;i+)if(vari='')flag1=i;fuzhilen=flag1-2;for(i=3;i<flag1;i+)fuzhis+=vari;fuzhis='#'char shuru;char zh100;int kaishi=0;zh0='d'for(kaishi=1;kaishi<s+1;kaishi+)zhkaishi=fuzhikaishi-1;zhkaishi+=&