yufa.cpp

语法分析器(C++)源代码＋其详细的课程设计报告 输入的文法可以消除左递归并提取公共左因子求出文法的非终结集合——FIRST和FOLLOW集并对输入的算符优先文法

#include "LL1.h"

void main(void)
{
 char todo,ch;
 printf("********************************************************************\n");
 printf("******************         语法器分析器           *******************\n");
 printf("*********************************************************************\n\n");

 Init();
 InputVn();
 InputVt();
 InputP();
 getchar();
 FirstFollow();
 printf("所得first集为：");
 ShowCollect(first);
 printf("所得follow集为：");
 ShowCollect(follow);
 CreateAT();
 ShowAT();
 printf("所得firstvt集为：");
 ShowCollect(first);
 printf("所得followvt集为：");
 ShowCollect(follow);

 
 printf("\n\n\n是否继续进行句型分析？(y / n):\n");
 todo = getchar();
 while('y' == todo)
 {

  
  while('y' != todo && 'n' != todo)
  {
   printf("\n(y / n)? ");
   todo = getchar();
  }
  if('y' == todo)
  {
   int i;
   printf("请输入符号串(以#结束) : ");
   getchar();
   i=0;
   while('#' != ch && i < MaxStLength)
   {
    if( ' ' != ch && '\n' != ch)
    {
     st[i++] = ch;
    }
    ch = getchar();
   }
   if('#' == ch && i < MaxStLength)
   {
    st[i] = ch;
    //Identify(st);
   }
   else 
    printf("输入出错！\n");
  }
 }
 getchar();
}



/*---------------function definition------------------*/
void Init()
{
 int i,j;
 vnNum = 0;
 vtNum = 0;
 PNum = 0;
 for(i = 0; i <= MaxVnNum; i++)
  Vn[i] = '\0';
 for(i = 0; i <= MaxVtNum; i++)
  Vt[i] = '\0';
 for(i = 0; i < MaxRuleNum; i++)
 {
  P[i].lCursor = NULL;
  P[i].rHead = NULL;
  P[i].rLength = 0;
 }
 PNum = 0;
 for(i = 0; i <= MaxPLength; i++)
  buffer[i] = '\0';
 for(i = 0; i < MaxVnNum; i++)
 {
  first[i] = NULL;
  follow[i] = NULL;
 }
 for(i = 0; i <= MaxVnNum; i++)
 {
  for(j = 0; j <= MaxVnNum + 1; j++)
   analyseTable[i][j] = -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) 
{
 int n;
 n = 0; /*is Vn?*/
 while(ch != Vn[n] && '\0' != Vn[n])
  n++;
 if('\0' != Vn[n])
 {

  return 100 + n;
 }
 n = 0; /*is Vt?*/
 while(ch != Vt[n] && '\0' != Vt[n])
  n++;
 if('\0' != Vt[n])
	 return n;
 return -1;
}
/*输出Vn或Vt的内容*/
void ShowChArray(char* collect)
{
 int k = 0;
 while('\0'!= collect[k])
 {
  printf(" %c ", collect[k++]);
 }
 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,并以#号结束.");
  printf("注：将开始符放在第一位.:\n"); 
   scanf("%c", &ch);
  n = 0;
  /*初始化数组*/
  while(n < MaxVnNum)
  {
   Vn[n++] = '\0';
  }
  n = 0;
  while(('#' != ch) && (n < MaxVnNum))
  {
   if( ' '!= ch && '\n' != ch && -1 == IndexCh(ch))
   {
    Vn[n++] = ch;
    vnNum++;
   }
  ch = getchar();
  }
  Vn[n] = '#';  /*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Vn[n]=\0*/
  if('#' != ch)
  {
   if( '#' != (ch = getchar()))
   {
    while('#' != (ch = getchar()))
     ;
    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*/
  Vn[k] = '\0';
  printf("\n非终结符为:");
  ShowChArray(Vn);
  //ch=getchar();
  while('y' != ch && 'n' != ch)
  {
   if('\n' != ch)
   {
    printf("\n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;
  }
 }
}

/*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=getchar();
  n = 0;
  /*初始化数组*/
  while(n < MaxVtNum)
  {
   Vt[n++] = '\0';
  }
  n = 0;
  while(('#' != ch) && (n < MaxVtNum))
  {
  if(' '!= ch && '\n'!= ch && -1 == IndexCh(ch))
   {
    Vt[n++] = ch;
    vtNum++;
   }
   ch=getchar();
  }
  Vt[n] = '#'; /*以"#"标志结束*/
  k = n; /*k用于记录n以便改Vt[n]=\0*/
  if('#' != ch)
  {
   if( '#' != (ch = getchar()))
   {
    while('#' != (ch = getchar()))
     ;
    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*/
  Vt[k] ='\0';
  printf("\n终结符为:");
  ShowChArray(Vt);
 
  while('y' != ch && 'n' != ch)
  {
   if('\n' != ch)
   {
    printf("\n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()
{
 char ch;
 int i = 0, n,num;
 printf("\n请输入文法产生式的个数：");
 scanf("%d", &num);//cin>>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：", num);
 printf("\n");
 while(i < num)
 {
  printf("第%d个：", i);
  /*初始化*/
  for(n =0; n < MaxPLength; n++)
  
  buffer[n] = '\0';
  /*输入产生式串*/
  ch =getchar(); 
  n = 0;
  while('\n' != ch && n < MaxPLength)
  {
   if(' ' != ch)
    buffer[n++] = ch; 
   ch =getchar();
  }
  buffer[n] ='\0';
  
  if(CheckP(buffer))
  { cout<<"********";
   /*填写入产生式结构体*/
   pRNode *pt, *qt;
   P[i].lCursor = IndexCh(buffer[0]);
   pt = (pRNode*)malloc(sizeof(pRNode));
   pt->rCursor = IndexCh(buffer[3]);
   pt->next = NULL;
   P[i].rHead = pt;
   n = 4;
   while('\0' != buffer[n])
   {
    qt = (pRNode*)malloc(sizeof(pRNode));
    qt->rCursor = IndexCh(buffer[n]);
    qt->next = NULL;
    pt->next = qt;
    pt = qt;
    n++;
   }
   P[i].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)
{
 int n;
 if(100 > IndexCh(st[0]))
  return false;
 if('-'!= st[1])
  return false;
 if('>'!= st[2])
  return false;
 for(n = 3; '\0' != st[n]; n ++)
 {
  if(-1 == IndexCh(st[n]))
   return false;
 }
 return true;
}
/*====================first & follow======================*/

void First(int U)
{
 int i,j;
 for(i = 0; i < PNum; i++)
 {
  if(P[i].lCursor == U)
  {
   struct pRNode* pt;
   pt = P[i].rHead;
   j = 0;
   while(j < P[i].rLength)
   {
    if(100 > pt->rCursor)
    {
     
     AddFirst(U, pt->rCursor);
     break;
    }
    else
    {
     if(NULL == first[pt->rCursor - 100])
     {
      First(pt->rCursor);
     }     
     AddFirst(U, pt->rCursor);
     if(!HaveEmpty(pt->rCursor))
     {
      break;
     }
     else
     {
      pt = pt->next;
     }
    }
    j++;
   }
   if(j >= P[i].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 = first[U - 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 == first[U - 100])
   {
    first[U - 100] = pt;
   }
   else
   {
    qt->next = pt; /*qt指向first集的最后一个元素*/
   }
   pt = pt->next;
  }
 }
 else
 {
  pt = first[nCh - 100];
  while(NULL != pt)
  {
   ch = pt->nVt;
   if(-1 != ch)
   {
    AddFirst(U, ch);
   }
   pt = pt->next;
  }
 }
}
/*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 = first[nVn - 100];
 while(NULL != pt)
 {
  if(-1 == pt->nVt)
   return true;
  pt = pt->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 = P[i].rHead;
  while(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*/
   {
    if(NULL == follow[P[i].lCursor - 100] && P[i].lCursor != V)
    {
     Follow(P[i].lCursor);
    }
    AddFollow(V, P[i].lCursor, 0);
   }
   else /*不为空时V->xVy,(注意：y->)，调用AddFollow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(NULL == pt) /*当后面的字符可以推出空时*/
    {
     if(NULL == follow[P[i].lCursor - 100] && P[i].lCursor != V)
     {
      Follow(P[i].lCursor);
     }
     AddFollow(V, P[i].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
kind = 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 = follow[V - 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 == follow[V - 100])
   {
    follow[V - 100] = pt;
   }
   else
   {
    qt->next = pt; /*qt指向follow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 = follow[nCh - 100];
   while(NULL != pt)
   {
    ch = pt->nVt;
    AddFollow(V, ch, 0);
    pt = pt->next;
   }
  }
  else
  {
   pt = first[nCh - 100];
   while(NULL != pt)
   {
    ch = pt->nVt;
    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;
 i = 0;
 while(NULL != collect[i])
 {
  pt = collect[i];
  printf("\n%c:\t", Vn[i]);
  while(NULL != pt)
  {
   if(-1 != pt->nVt)
   {
    printf(" %c", Vt[pt->nVt]);
   }
   else
    printf(" #");
   pt = pt->next;
  }
  i++;
 }
 printf("\n");
}
/*计算first和follow*/
void FirstFollow()
{
 int i;
 i = 0;
 while('\0' != Vn[i])
 {
  if(NULL == first[i])
   First(100 + i);
  i++;
 }
 i = 0;
 while('\0' != Vn[i])
 {
  if(NULL == follow[i])
   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++)
 {
  pt = P[i].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 = first[pt->rCursor - 100];
   while(NULL != ct)
   {
    if(-1 != ct->nVt)
     analyseTable[P[i].lCursor - 100][ct->nVt] = i;
    ct = ct->next;
   }
   pt = pt->next;
  }
  if(NULL == pt)
  {
   /*NULL == pt，说明xyz->,用到follow中的符号*/
   ct = follow[P[i].lCursor - 100];
   while(NULL != ct)
   {
    if(-1 != ct->nVt)
     analyseTable[P[i].lCursor - 100][ct->nVt] = i;
    else /*当含有#号时*/
     analyseTable[P[i].lCursor - 100][vtNum] = i;
    ct = ct->next;
   }
  }
  else
  {
   if(100 <= pt->rCursor) /*不含空的非终结符*/
   {
    ct = first[pt->rCursor - 100];
    while(NULL != ct)
    {
     analyseTable[P[i].lCursor - 100][ct->nVt] = i;
     ct = ct->next;
    }
   }
   else /*终结符或者空*/
   {
    if(-1 == pt->rCursor) /*-1为空产生式时*/
    {
     ct = follow[P[i].lCursor - 100];
     while(NULL != ct)
     {
      if(-1 != ct->nVt)
       analyseTable[P[i].lCursor - 100][ct->nVt] = i;
      else /*当含有#号时*/
       analyseTable[P[i].lCursor - 100][vtNum] = i;
      ct = ct->next;
     }
    }
    else /*为终结符*/
    {
     analyseTable[P[i].lCursor - 100][pt->rCursor] = i;
    }
   }
  }
 }
}
/*输出分析表*/
void ShowAT()
{
 int i,j;
 printf("构造预测分析表如下：\n");
 printf("\t|\t");
 for(i = 0; i < vtNum; i++)
 {
  printf("%c\t", Vt[i]);
 }
 printf("#\t\n");
 printf("- - -\t|- - -\t");
 for(i = 0; i <= vtNum; i++)
  printf("- - -\t");
 printf("\n");
 for(i = 0; i < vnNum; i++)
 {
  printf("%c\t|\t", Vn[i]);
  for(j = 0; j <= vtNum; j++)
  {
   if(-1 != analyseTable[i][j])
    printf("R(%d)\t", analyseTable[i][j]);
   else
    printf("error\t");
  }
  printf("\n");
 }
}