实验二LL预测分析

1、word实验二 LL(1)分析的设计与实现开课实验室： A201，A207 实验工程LL(1)分析的设计与实现实验类型设计实验学时4一、实验目的根据某一文法编制调试LL(1)分析程序，以便对任意输入的符号串进行分析。掌握LL(1)分析法的根本原理，LL(1)分析表的构造方法，LL(1)驱动程序的构造方法。二、设备与环境 1. 硬件设备：PC机一台2. 软件环境：安装Windows操作系统或者Linux操作系统，并安装相关的程序开发环境，如C C+Java 等编程语言环境。三、实验要求1. 输入文法G的非终结符、终结符和产生式；1输出非终结符的FIRST集；2输出非终结符的FOLLOW集；3构造

2、文法G的预测分析表；4对输入符号串进行分析。2、编程语言不限。四、实验原理1.程序功能流程图参考：2. 计算FIRST集合：First集合最终是对产生式右部的字符串而言的，但其关键是求出非终结符的First集合，由于终结符的First集合就是它自己，所以求出非终结符的First集合后，就可很直观地得到每个字符串的First集合。² 直接收取：对形如Ua的产生式其中a是终结符，把a收入到First(U)中² 反复传送：对形入UP的产生式其中P是非终结符，应把First(P)中的全部内容传送到First(U)中。算法描述：见教材P80) 假设XVt,那么FIRST(X)=X;&

3、#160;) 假设XVn,且有产生式X->a,aVt，那么aFIRST(X);               ) 假设XVn,X->e,那么eFIRST(X) ) 假设X,Y1,Y2,Y3,Y4Yn都Vn,而产生式X->Y1,Y2Yn.当Y1,Y2,Y3,Y4Yn都能=>e，那么FIRST(X)=并集的FIRST(Yi)- e(0<=i<=n) ) 假设Yi=>e (i=1,2,3)，那

4、么FIRST(X)=并集的FIRST(Yi)- e并上e 3. 计算FOLLOW集合：Follow集合是针对非终结符而言的，Follow(U)所表达的是句型中非终结符U所有可能的后随终结符号的集合，特别地，“#是识别符号的后随符。² 直接收取：注意产生式右部的每一个形如“Ua的组合，把a直接收入到Follow(U)中；² 直接收取：对形如“UP(P是非终结符)的组合，把First(P)直接收入到Follow(U)中；² 直接收取：假设为文法开始符号S，那么把#收入FOLLOW(S)；² 反复传送：对形如UP的产生式其中P是非终结符，应把Foll

5、ow(U)中的全部内容传送到Follow(P)中。算法描述：见教材P82) 假设为文法开始符号S，那么FOLLOW(S)=# ) 假设为文法A->aBb是一个产生式，那么把FIRSTb的非空元素参加 FOLLOW(B)中。如果b->那么把FOLLOW(A)也参加FOLLOW(B)中。4. 构造预测分析表：(1) 对于文法的每条产生式A®a，假设aÎFIRST(a)，那么MA, a = A ®a；(2) 假设eÎFIRST(a)，bÎFOLLOW(a)那么MA, b = A ®a；(3) 分析表M的其他元素均为出错标志err

6、or。5. 预测分析程序流图：见课本P93-P94五、程序源码#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; struct pRNode *next;struct pNode int lCursor; int

7、rLength; /*右部长度*/ 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 PMaxRuleNum; int PNum; char bufferMaxPLength + 1;char ch; char stMaxStLength; /*要分析的符号串*/struct collectNode int nVt; struct collectNode *next;struct collect

8、Node* firstMaxVnNum + 1; /*first集*/struct collectNode* followMaxVnNum + 1; /*follow集*/int analyseTableMaxVnNum + 1MaxVtNum + 1 + 1;int analyseStackMaxStackDepth + 1; /*分析栈*/int topAnalyse; /*分析栈顶*/void Init();/*初始化*/int IndexCh(char ch);void InputVt(); /*输入终结符*/void InputVn();/*输入非终结符*/void ShowChAr

9、ray(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);void AddFirst(int U, int nCh); /*参加first集*/bool HaveEmpty(int nVn); void Follow(int V);/*计算follow集*/void AddFollow(int V, int nCh, int kind);void ShowCollect(struct collectNode *coll

10、ect);/*输出first或follow集*/void FirstFollow();/*计算first和follow*/void CreateAT();/*构造预测分析表*/void ShowAT();/*输出分析表*/void Identify(char *st);void InitStack();void ShowStack();void Pop();void Push(int r);void main(void) char todo,ch; Init(); InputVn(); InputVt(); InputP(); getchar(); FirstFollow(); printf(

11、"所得first集为："); ShowCollect(first); printf("所得follow集为："); ShowCollect(follow); CreateAT(); ShowAT(); todo = 'y' while('y' = todo) printf("n是否继续进行句型分析？(y / n):"); todo = getchar(); while('y' != todo && 'n' != todo) printf("n(y

12、 / n) "); todo = getchar(); if('y' = todo) int i; InitStack(); printf("请输入符号串(以#结束) : "); ch = getchar(); i = 0; while('#' != ch && i < MaxStLength) if(' ' != ch && 'n' != ch) sti+ = ch; ch = getchar(); if('#' = ch &&

13、i < MaxStLength) sti = ch; 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' for(i = 0; i <= MaxVtNum; i+) Vti = '0' for(i = 0; i < MaxRuleNum; i+) Pi.lCursor = NULL; Pi.rH

14、ead = NULL; Pi.rLength = 0; PNum = 0; for(i = 0; i <= MaxPLength; i+) bufferi = '0' for(i = 0; i < MaxVnNum; i+) firsti = NULL; followi = NULL; for(i = 0; i <= MaxVnNum; i+) for(j = 0; j <= MaxVnNum + 1; j+) analyseTableij = -1; int IndexCh(char ch) int n; n = 0; /*is Vn*/ while(

15、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; return -1;/*输出Vn或Vt的内容*/void ShowChArray(char* collect) int k = 0; while('0' != collectk) printf(" %c

16、", collectk+); printf("n");/*输入非终结符*/void InputVn() int inErr = 1; int n,k; char ch; while(inErr) 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('#' != ch) &

17、amp;& (n < MaxVnNum) if(' ' != ch && 'n' != ch && -1 = IndexCh(ch) Vnn+ = ch; vnNum+; ch = getchar(); Vnn = '#' /*以“#标志结束用于判断长度是否合法*/ k = n; if('#' != ch) if( '#' != (ch = getchar() while('#' != (ch = getchar() ; printf("n符号

18、数目超过限制！n"); inErr = 1; continue; /*正确性确认，正确那么，执行下下面，否那么重新输入*/ Vnk = '0' ShowChArray(Vn); ch = ' ' while('y' != ch && 'n' != ch) if('n' != ch) printf("输入正确确认(y/n):"); scanf("%c", &ch); if('n' = ch) printf("录入错误重

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

20、t; MaxVtNum) if(' ' != ch && 'n' != ch && -1 = IndexCh(ch) Vtn+ = ch; vtNum+; ch = getchar(); Vtn = '#' k = n; if('#' != ch) if( '#' != (ch = getchar() while('#' != (ch = getchar() ; printf("n符号数目超过限制！n"); inErr = 1; continue;

21、 Vtk = '0' ShowChArray(Vt); ch = ' ' while('y' != ch && 'n' != ch) 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"); inErr = 1; else inErr = 0; /*产生式输入*/void InputP() ch

22、ar 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("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 =

23、'0' /*输入产生式串*/ ch = ' ' n = 0; while('n' != (ch = getchar() && n < MaxPLength) if(' ' != ch) buffern+ = ch; buffern = '0' if(CheckP(buffer) pRNode *pt, *qt; Pi.lCursor = IndexCh(buffer0); pt = (pRNode*)malloc(sizeof(pRNode); pt->rCursor = IndexCh

24、(buffer3); pt->next = NULL; Pi.rHead = pt; n = 4; while('0' != buffern) qt = (pRNode*)malloc(sizeof(pRNode); qt->rCursor = IndexCh(buffern); qt->next = NULL; pt->next = qt; pt = qt; n+; Pi.rLength = n - 3; i+; 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(c

25、har * st) 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; return true;void First(int U) int i,j; for(i = 0; i < PNum; i+) if(Pi.lCursor = U) struct pRN

26、ode* pt; pt = Pi.rHead; j = 0; while(j < Pi.rLength) if(100 > pt->rCursor) AddFirst(U, pt->rCursor); break; else if(NULL = firstpt->rCursor - 100) First(pt->rCursor); AddFirst(U, pt->rCursor); if(!HaveEmpty(pt->rCursor) break; else pt = pt->next; j+; if(j >= Pi.rLength)

27、 /*当产生式右部都能推出空时*/ AddFirst(U, -1); /*参加first集*/void AddFirst(int U, int nCh) 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; else qt = pt; pt = pt->next; if(NULL = pt) pt = (struct collectNode

28、*)malloc(sizeof(struct collectNode); pt->nVt = nCh; 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->next; else pt = firstnCh - 100; while(NULL != pt) ch = pt->nVt; if(-1 != ch) AddFirst(U, ch); pt = pt->next; bool HaveE

29、mpty(int nVn) if(nVn < 100) return false; struct collectNode *pt; pt = firstnVn - 100; while(NULL != pt) if(-1 = pt->nVt) return true; pt = pt->next; return false;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.r

30、Head; while(NULL != pt && pt->rCursor != V) pt = pt->next; if(NULL != pt) pt = pt->next; if(NULL = pt) if(NULL = followPi.lCursor - 100 && Pi.lCursor != V) Follow(Pi.lCursor); AddFollow(V, Pi.lCursor, 0); else while(NULL != pt && HaveEmpty(pt->rCursor) AddFollow(V

31、, pt->rCursor, 1); pt = pt->next; if(NULL = pt) if(NULL = followPi.lCursor - 100 && Pi.lCursor != V) Follow(Pi.lCursor); AddFollow(V, Pi.lCursor, 0); else AddFollow(V, pt->rCursor, 1); void AddFollow(int V, int nCh, int kind) struct collectNode *pt, *qt; int ch; pt = NULL; qt = NULL

32、; if(nCh < 100) /*为终结符时*/ pt = followV - 100; while(NULL != pt) if(pt->nVt = nCh) break; else qt = pt; pt = pt->next; if(NULL = pt) pt = (struct collectNode *)malloc(sizeof(struct collectNode); pt->nVt = nCh; pt->next = NULL; if(NULL = followV - 100) followV - 100 = pt; else qt->ne

33、xt = pt; /*qt指向follow集的最后一个元素*/ pt = pt->next; else if(0 = kind) pt = follownCh - 100; while(NULL != pt) ch = pt->nVt; AddFollow(V, ch, 0); pt = pt->next; else pt = firstnCh - 100; while(NULL != pt) ch = pt->nVt; if(-1 != ch) AddFollow(V, ch, 1); pt = pt->next; /*输出first或follow集*/void

34、 ShowCollect(struct collectNode *collect) int i; struct collectNode *pt; i = 0; while(NULL != collecti) pt = collecti; printf("n%c:t", Vni); while(NULL != pt) if(-1 != pt->nVt) printf(" %c", Vtpt->nVt); else printf(" #"); pt = pt->next; i+; printf("n"

35、);/*计算first和follow*/void FirstFollow() int i; i = 0; while('0' != Vni) if(NULL = firsti) First(100 + i); i+; i = 0; while('0' != Vni) if(NULL = followi) Follow(100 + i); i+; /*构造预测分析表*/void CreateAT() int i; struct pRNode *pt; struct collectNode *ct; for(i = 0; i < PNum; i+) pt =

36、Pi.rHead; while(NULL != pt && HaveEmpty(pt->rCursor) ct = firstpt->rCursor - 100; while(NULL != ct) if(-1 != ct->nVt) analyseTablePi.lCursor - 100ct->nVt = i; ct = ct->next; pt = pt->next; if(NULL = pt) ct = followPi.lCursor - 100; while(NULL != ct) if(-1 != ct->nVt) ana

37、lyseTablePi.lCursor - 100ct->nVt = i; else analyseTablePi.lCursor - 100vtNum = i; ct = ct->next; else if(100 <= pt->rCursor) /*不含空的非终结符*/ ct = firstpt->rCursor - 100; while(NULL != ct) analyseTablePi.lCursor - 100ct->nVt = i; ct = ct->next; else /*终结符或者空*/ if(-1 = pt->rCursor

38、) ct = followPi.lCursor - 100; while(NULL != ct) if(-1 != ct->nVt) analyseTablePi.lCursor - 100ct->nVt = i; else /*当含有#号时*/ analyseTablePi.lCursor - 100vtNum = i; ct = ct->next; else /*为终结符*/ analyseTablePi.lCursor - 100pt->rCursor = i; /*输出分析表*/void ShowAT() int i,j; printf("构造预测分析

39、表如下：n"); printf("t|t"); for(i = 0; i < vtNum; i+) printf("%ct", Vti); printf("#tn"); printf("- - -t|- - -t"); for(i = 0; i <= vtNum; i+) printf("- - -t"); printf("n"); for(i = 0; i < vnNum; i+) printf("%ct|t", Vni);

40、for(j = 0; j <= vtNum; j+) if(-1 != analyseTableij) printf("R(%d)t", analyseTableij); else printf("errort"); printf("n"); void Identify(char *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"); ste

41、p = 0; current = 0; printf("%dt",step); ShowStack(); printf("tt%ctt- -n", stcurrent); while('#' != stcurrent) if(100 > analyseStacktopAnalyse) if(analyseStacktopAnalyse = IndexCh(stcurrent) Pop(); current+; step+; printf("%dt", step); ShowStack(); printf(&quo

42、t;tt%ctt出栈、后移n", stcurrent); else printf("%c-%c不匹配！", 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); if(-1 != r) Push(r); step+; printf("%dt", step); ShowStack(); printf("tt%ctt%dn", stcurrent, r); else printf("此串不是此文法的句子！n"); return; if('#' = stcurrent) if(0 = topAnalyse && '#' = stcurrent) step+; printf(&quo