语法分析器实验报告

1、南京信息工程大学实验（实习）报告实验（实习）名称 LL（1）文法语法分析设计 实验（实习）日期 11月28日 得分 指导教师 林美华 系 计算机 专业 计算机科学与技术 年级 2011 班次 计科3班 姓名 王欣 学号 20112308915 一 实验目的1熟悉判断LL（1）文法的方法及对某一输入串的分析过程。2学会构造表达式文法的预测分析表。二 实验内容编写一个语法分析程序，对于给定的输入串，能够判断识别该串是否为给定文法的句型。三 实验步骤从键盘读入输入串，并判断正误；若无误，由程序自动构造FIRST、FOLLOW集以及SELECT集合，判断是否为LL（1）文法；若符合LL（1）文法，由程

2、序自动构造LL（1）分析表；由算法判断输入符号串是否为该文法的句型【源代码】#include "stdio.h"#include "stdlib.h"#define MaxRuleNum 8#define MaxVnNum 5#define MaxVtNum 5#define MaxStackDepth 20#define MaxPLength 20#define MaxStLength 50struct pRNode /*产生式右部结构*/ int rCursor; /*右部序号*/ struct pRNode

3、*next;struct pNode /*产生式结点结构*/ int lCursor; /*左部符号序号*/ int rLength; /*右部长度*/ /*注当rLength = 1 时，rCursor = -1为空产生式*/ struct pRNode *rHead; /*右部结点头指针*/;char VnMaxVnNum + 1; /*非终结符集*/int vnNum;char VtMaxVtNum + 1; /*终结符集*/int vtNum;struct pNode PMaxRuleN

4、um; /*产生式*/int PNum; /*产生式实际个数*/char bufferMaxPLength + 1;char ch; /*符号或string ch;*/char stMaxStLength; /*要分析的符号串*/struct collectNode /*集合元素结点结构*/ int nVt; /*在终结符集中的下标*/ struct collectNode *next;struct collectNode* firstMaxVnNum + 1; /*first集*/struct collectNo

5、de* followMaxVnNum + 1; /*follow集*/int analyseTableMaxVnNum + 1MaxVtNum + 1 + 1;/*预测分析表存放为产生式的编号，+1用于存放结束符，多+1用于存放#(-1)*/int analyseStackMaxStackDepth + 1; /*分析栈*/int topAnalyse; /*分析栈顶*/*int reverseStackMaxStackDepth + 1; /*颠倒顺序栈*/*int topReverse; /*倒叙栈顶*/void Init();/*初始化*

6、/int IndexCh(char ch);/*返回Vn在Vn表中的位置+100、Vt在Vt表中的位置，-1表示未找到*/void InputVt(); /*输入终结符*/void InputVn();/*输入非终结符*/void ShowChArray(char* collect, int num);/*输出Vn或Vt的内容*/void InputP();/*产生式输入*/bool CheckP(char * st);/*判断产生式正确性*/void First(int U);/*计算first集,U->xx.*/void AddFirst(int U, int nCh);&

7、#160;/*加入first集*/bool HaveEmpty(int nVn); /*判断first集中是否有空(-1)*/void Follow(int V);/*计算follow集*/void AddFollow(int V, int nCh, int kind);/*加入follow集， kind = 0表加入follow集，kind = 1加入first集*/void ShowCollect(struct collectNode *collect);/*输出first或follow集*/void FirstFollow();/*计算first和follow*/void Cr

8、eateAT();/*构造预测分析表*/void ShowAT();/*输出分析表*/void Identify(char *st);/*主控程序,为操作方便*/*分析过程显示操作为本行变换所用，与教程的显示方式不同*/void InitStack();/*初始化栈及符号串*/void ShowStack();/*显示符号栈中内容*/void Pop();/*栈顶出栈*/void Push(int r);/*使用产生式入栈操作*/#include "LL1.h"void main(void) char todo,ch;  Init();

9、0;InputVn(); InputVt(); InputP(); getchar(); FirstFollow(); printf("所得first集为："); ShowCollect(first); printf("所得follow集为："); ShowCollect(follow); CreateAT(); ShowAT(); todo = 'y' while('y' = todo) &#

10、160; printf("n是否继续进行句型分析？(y / n):");  todo = getchar();  while('y' != todo && 'n' != todo)     printf("n(y / n)? ");   todo = getchar();    if('y' = todo) 

11、60;   int i;   InitStack();   printf("请输入符号串(以#结束) : ");   ch = getchar();   i = 0;   while('#' != ch && i < MaxStLength)       if(' ' !=

12、ch && 'n' != ch)         sti+ = ch;        ch = getchar();      if('#' = ch && i < MaxStLength)       sti = ch;

13、0;   Identify(st);      else     printf("输入出错！n");    getchar();void Init() int i,j; vnNum = 0; vtNum = 0; PNum = 0; for(i = 0; i <= MaxVnNum; i+)  Vni = '0'&#

14、160;for(i = 0; i <= MaxVtNum; i+)  Vti = '0' for(i = 0; i < MaxRuleNum; i+)   Pi.lCursor = NULL;  Pi.rHead = NULL;  Pi.rLength = 0;  PNum = 0; for(i = 0; i <= MaxPLength; i+)  bufferi = '0' for(i

15、 = 0; i < MaxVnNum; i+)   firsti = NULL;  followi = NULL;  for(i = 0; i <= MaxVnNum; i+)   for(j = 0; j <= MaxVnNum + 1; j+)   analyseTableij = -1; /*返回Vn在Vn表中的位置+100、Vt在Vt表中的位置，-1表示未找到*/int IndexCh(char ch)  in

16、t n; n = 0; /*is Vn?*/ while(ch != Vnn && '0' != Vnn)  n+; if('0' != Vnn)  return 100 + n; n = 0; /*is Vt?*/ while(ch != Vtn && '0' != Vtn)  n+; if('0' != Vtn)  return n;&#

17、160;return -1;/*输出Vn或Vt的内容*/void ShowChArray(char* collect) int k = 0; while('0' != collectk)   printf(" %c ", collectk+);  printf("n");/*输入非终结符*/void InputVn() int inErr = 1; int n,k; char ch; while(inErr)  

18、; printf("n请输入所有的非终结符，注意：");  printf("请将开始符放在第一位，并以#号结束:n");   ch = ' '  n = 0;  /*初始化数组*/  while(n < MaxVnNum)     Vnn+ = '0'    n = 0;  while(&#

19、39;#' != ch) && (n < MaxVnNum)     if(' ' != ch && 'n' != ch && -1 = IndexCh(ch)       Vnn+ = ch;    vnNum+;      ch = getchar();  &#

20、160; Vnn = '#' /*以“#”标志结束用于判断长度是否合法*/  k = n; /*k用于记录n以便改Vnn='0'*/  if('#' != ch)     if( '#' != (ch = getchar()       while('#' != (ch = getchar()   

21、      printf("n符号数目超过限制！n");    inErr = 1;    continue;       /*正确性确认，正确则，执行下下面，否则重新输入*/  Vnk = '0'  ShowChArray(Vn);  ch = ' '  

22、while('y' != ch && 'n' != ch)     if('n' != ch)       printf("输入正确确认?(y/n):");      scanf("%c", &ch);    if('n' = ch) 

23、60;   printf("录入错误重新输入！n");   inErr = 1;    else     inErr = 0;   /*输入终结符*/void InputVt() int inErr = 1; int n,k; char ch; while(inErr)   printf("n请输入所有的终结符，注意：

24、");  printf("以#号结束:n");   ch = ' '  n = 0;  /*初始化数组*/  while(n < MaxVtNum)     Vtn+ = '0'    n = 0;  while('#' != ch) && (n < MaxVtNum)&#

25、160;    if(' '!= ch && 'n' != ch && -1 = IndexCh(ch)       Vtn+ = ch;    vtNum+;      ch = getchar();    Vtn = '#' /*以“#”标志结束*/

26、60; k = n; /*k用于记录n以便改Vtn='0'*/  if('#' != ch)     if( '#' != (ch = getchar()       while('#' != (ch = getchar()        printf("n符号数目超过限制！n&quo

27、t;);    inErr = 1;    continue;       /*正确性确认，正确则，执行下下面，否则重新输入*/  Vtk = '0'  ShowChArray(Vt);  ch =' '  while('y' != ch && 'n' != ch)  

28、   if('n' != ch)       printf("输入正确确认?(y/n):");      scanf("%c", &ch);    if('n' = ch)     printf("录入错误重新输入！n");  &

29、#160;inErr = 1;    else     inErr = 0;   /*产生式输入*/void InputP() char ch; int i = 0, n,num; printf("请输入文法产生式的个数："); scanf("%d", &num); PNum = num; getchar(); /*消除回车符*/ printf(&q

30、uot;n请输入文法的%d个产生式,并以回车分隔每个产生式：", num); printf("n"); while(i < num)   printf("第%d个：", i);  /*初始化*/  for(n =0; n < MaxPLength; n+)   buffern = '0'  /*输入产生式串*/  ch = ' ' &

31、#160;n = 0;  while('n' != (ch = getchar() && n < MaxPLength)     if(' ' != ch)    buffern+ = ch;        buffern = '0'/*  printf("%s", buffer);*/ 

32、 if(CheckP(buffer)     /*填写入产生式结构体*/   pRNode *pt, *qt;   Pi.lCursor = IndexCh(buffer0);   pt = (pRNode*)malloc(sizeof(pRNode);   pt->rCursor = IndexCh(buffer3);   pt->next = NULL; 

33、60; Pi.rHead = pt;   n = 4;   while('0' != buffern)       qt = (pRNode*)malloc(sizeof(pRNode);    qt->rCursor = IndexCh(buffern);    qt->next = NULL;    pt-

34、>next = qt;    pt = qt;    n+;      Pi.rLength = n - 3;   i+;   /*调试时使用*/    else   printf("输入符号含非法在成分，请重新输入！n"); /*判断产生式正确性*/bool CheckP(char * st

35、) int n; if(100 > IndexCh(st0)  return false; if('-' != st1)  return false; if('>' != st2)  return false; for(n = 3; '0' != stn; n +)   if(-1 = IndexCh(stn)   return false;  r

36、eturn true;/*=first & follow=*/*计算first集,U->xx.*/void First(int U) int i,j; for(i = 0; i < PNum; i+)   if(Pi.lCursor = U)     struct pRNode* pt;   pt = Pi.rHead;   j = 0;   while(j < Pi.rLengt

37、h)       if(100 > pt->rCursor)         /*注:此处因编程出错,使空产生式时     rlength同样是1,故此处同样可处理空产生式*/     AddFirst(U, pt->rCursor);     break; &

38、#160;      else         if(NULL = firstpt->rCursor - 100)           First(pt->rCursor);             

39、;  AddFirst(U, pt->rCursor);     if(!HaveEmpty(pt->rCursor)           break;          else          

40、0;pt = pt->next;             j+;      if(j >= Pi.rLength) /*当产生式右部都能推出空时*/    AddFirst(U, -1);   /*加入first集*/void AddFirst(int U, int nCh) /*当数值小于100时nCh为

41、Vt*/*当处理非终结符时,AddFirst不添加空项(-1)*/ struct collectNode *pt, *qt; int ch; /*用于处理Vn*/ pt = NULL; qt = NULL; if(nCh < 100)   pt = firstU - 100;  while(NULL != pt)     if(pt->nVt = nCh)    break; 

42、;  else       qt = pt;    pt = pt->next;       if(NULL = pt)     pt = (struct collectNode *)malloc(sizeof(struct collectNode);   pt->nVt = nCh;  

43、; pt->next = NULL;   if(NULL = firstU - 100)       firstU - 100 = pt;      else       qt->next = pt; /*qt指向first集的最后一个元素*/      pt = pt->

44、;next;    else   pt = firstnCh - 100;  while(NULL != pt)     ch = pt->nVt;   if(-1 != ch)       AddFirst(U, ch);      pt = pt->next;  

45、 /*判断first集中是否有空(-1)*/bool HaveEmpty(int nVn)  if(nVn < 100) /*为终结符时(含-1)，在follow集中用到*/  return false; struct collectNode *pt; pt = firstnVn - 100; while(NULL != pt)   if(-1 = pt->nVt)   return true;  pt = pt-

46、>next;  return false;/*计算follow集,例：U->xVy,U->xV.(注：初始符必含#"-1")*/void Follow(int V) int i; struct pRNode *pt  if(100 = V) /*当为初始符时*/  AddFollow(V, -1, 0 ); for(i = 0; i < PNum; i+)   pt = Pi.rHead;  while

47、(NULL != pt && pt->rCursor != V) /*注此不能处理：U->xVyVz的情况*/   pt = pt->next;  if(NULL != pt)     pt = pt->next; /*V右侧的符号*/   if(NULL = pt) /*当V后为空时V->xV，将左符的follow集并入V的follow集中*/    

48、0;  if(NULL = followPi.lCursor - 100 && Pi.lCursor != V)         Follow(Pi.lCursor);        AddFollow(V, Pi.lCursor, 0);      else /*不为空时V->xVy,(注意：y->)，调用A

49、ddFollow加入Vt或y的first集*/       while(NULL != pt && HaveEmpty(pt->rCursor)    AddFollow(V, pt->rCursor, 1); /*y的前缀中有空时，加如first集*/     pt = pt->next;        if(N

50、ULL = pt) /*当后面的字符可以推出空时*/         if(NULL = followPi.lCursor - 100 && Pi.lCursor != V)           Follow(Pi.lCursor);          AddFollow(

51、V, Pi.lCursor, 0);        else /*发现不为空的字符时*/         AddFollow(V, pt->rCursor, 1);           /*当数值小于100时nCh为Vt*/*#用-1表示,kind用于区分是并入符号的first集，还是follow集ki

52、nd = 0表加入follow集，kind = 1加入first集*/void AddFollow(int V, int nCh, int kind) struct collectNode *pt, *qt; int ch; /*用于处理Vn*/ pt = NULL; qt = NULL; if(nCh < 100) /*为终结符时*/   pt = followV - 100;  while(NULL != pt)    

53、60;if(pt->nVt = nCh)    break;   else       qt = pt;    pt = pt->next;       if(NULL = pt)     pt = (struct collectNode *)malloc(sizeof(struct c

54、ollectNode);   pt->nVt = nCh;   pt->next = NULL;   if(NULL = followV - 100)       followV - 100 = pt;      else       qt->next = pt; /*qt指向fo

55、llow集的最后一个元素*/      pt = pt->next;    else /*为非终结符时，要区分是加first还是follow*/   if(0 = kind)     pt = follownCh - 100;   while(NULL != pt)       ch = pt->

56、nVt;    AddFollow(V, ch, 0);    pt = pt->next;       else     pt = firstnCh - 100;   while(NULL != pt)       ch = pt->nVt;   

57、0;if(-1 != ch)         AddFollow(V, ch, 1);        pt = pt->next;      /*输出first或follow集*/void ShowCollect(struct collectNode *collect) int i; struct collectNode *pt; 

58、i = 0; while(NULL != collecti)   pt = collecti;  printf("n%c:t", Vni);  while(NULL != pt)     if(-1 != pt->nVt)       printf(" %c", Vtpt->nVt);     &

59、#160;else    printf(" #");   pt = pt->next;    i+;  printf("n");/*计算first和follow*/void FirstFollow() int i; i = 0; while('0' != Vni)   if(NULL = firsti)   Firs

60、t(100 + i);  i+;  i = 0; while('0' != Vni)   if(NULL = followi)   Follow(100 + i);  i+; /*=构造预测分析表,例：U:xyz=*/void CreateAT() int i; struct pRNode *pt; struct collectNode *ct; for(i = 0; i < PNum; i+)

61、   pt = Pi.rHead;  while(NULL != pt && HaveEmpty(pt->rCursor)      /*处理非终结符，当为终结符时，定含空为假跳出*/   ct = firstpt->rCursor - 100;   while(NULL != ct)       if(-1 != ct->

62、nVt)     analyseTablePi.lCursor - 100ct->nVt = i;    ct = ct->next;      pt = pt->next;    if(NULL = pt)     /*NULL = pt，说明xyz->,用到follow中的符号*/   ct = fo

63、llowPi.lCursor - 100;   while(NULL != ct)       if(-1 != ct->nVt)     analyseTablePi.lCursor - 100ct->nVt = i;    else /*当含有#号时*/     analyseTablePi.lCursor - 100vtNum =

64、 i;    ct = ct->next;       else     if(100 <= pt->rCursor) /*不含空的非终结符*/       ct = firstpt->rCursor - 100;    while(NULL != ct)   &#

65、160;     analyseTablePi.lCursor - 100ct->nVt = i;     ct = ct->next;          else /*终结符或者空*/       if(-1 = pt->rCursor) /*-1为空产生式时*/  &

66、#160;      ct = followPi.lCursor - 100;     while(NULL != ct)           if(-1 != ct->nVt)       analyseTablePi.lCursor - 100ct->nVt = i;  &

67、#160;   else /*当含有#号时*/       analyseTablePi.lCursor - 100vtNum = i;      ct = ct->next;             else /*为终结符*/    

68、0;    analyseTablePi.lCursor - 100pt->rCursor = i;          /*输出分析表*/void ShowAT() int i,j;1  printf("构造预测分析表如下：n"); printf("t|t"); for(i = 0; i < vtNum; i+)   printf(&q

69、uot;%ct", Vti);  printf("#tn");2  printf("- - -t|- - -t"); for(i = 0; i <= vtNum; i+)  printf("- - -t"); printf("n");3  for(i = 0; i < vnNum; i+)   printf("%ct|t", Vni);  for

70、(j = 0; j <= vtNum; j+)     if(-1 != analyseTableij)    printf("R(%d)t", analyseTableij);   else    printf("errort");    printf("n"); /*=主控程序=*/void Identify(char

71、 *st) int current,step,r; /*r表使用的产生式的序号*/ printf("n%s的分析过程：n", st); printf("步骤t分析符号栈t当前指示字符t使用产生式序号n");  step = 0; current = 0; /*符号串指示器*/ printf("%dt",step); ShowStack(); printf("tt%ctt- -n", stcurrent);4

72、  while('#' != stcurrent)   if(100 > analyseStacktopAnalyse) /*当为终结符时*/     if(analyseStacktopAnalyse = IndexCh(stcurrent)       /*匹配出栈，指示器后移*/    Pop();    current

73、+;    step+;    printf("%dt", step);    ShowStack();    printf("tt%ctt出栈、后移n", stcurrent);      else       printf("%c-%c不匹配！"

74、, analyseStacktopAnalyse, stcurrent);    printf("此串不是此文法的句子！n");    return;       else /*当为非终结符时*/     r = analyseTableanalyseStacktopAnalyse - 100IndexCh(stcurrent);   i

75、f(-1 != r)       Push(r); /*产生式右部代替左部，指示器不移动*/    step+;    printf("%dt", step);    ShowStack();    printf("tt%ctt%dn", stcurrent, r);    &#

76、160; else       printf("无可用产生式，此串不是此文法的句子！n");    return;       if('#' = stcurrent) 5   if(0 = topAnalyse && '#' = stcurrent)     s

77、tep+;   printf("%dt", step);   ShowStack();   printf("tt%ctt分析成功！n", stcurrent);   printf("%s是给定文法的句子！n", st);    else     while(topAnalyse > 0)       if(100 > analyseStacktopAnalyse) /*当为终结符时*/