计算机编译原理习作——ll(1)语法分析器.txt

* VC6.0下运行通过 此程序为本人苦心所做

     }
     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");
 }
}
/*=================主控程序=====================*/
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");
 
 step = 0;
 current = 0; /*符号串指示器*/
 printf("%d\t",step);
 ShowStack();
 printf("\t\t%c\t\t- -\n", st[current]);

 while('#' != st[current])
 {
  if(100 > analyseStack[topAnalyse]) /*当为终结符时*/
  {
   if(analyseStack[topAnalyse] == IndexCh(st[current]))
   {
    /*匹配出栈，指示器后移*/
    Pop();
    current++;
    step++;
    printf("%d\t", step);
    ShowStack();
    printf("\t\t%c\t\t出栈、后移\n", st[current]);
   }
   else
   {
    printf("%c-%c不匹配！", analyseStack[topAnalyse], st[current]);
    printf("此串不是此文法的句子！\n");
    return;
   }
  }
  else /*当为非终结符时*/
  {
   r = analyseTable[analyseStack[topAnalyse] - 100][IndexCh(st[current])];
   if(-1 != r)
   {
    Push(r); /*产生式右部代替左部，指示器不移动*/
    step++;
    printf("%d\t", step);
    ShowStack();
    printf("\t\t%c\t\t%d\n", st[current], r);
   }
   else
   {
    printf("无可用产生式，此串不是此文法的句子！\n");
    return;
   }
  }
 }
 if('#' == st[current])
 {

  if(0 == topAnalyse && '#' == st[current])
  {
   step++;
   printf("%d\t", step);
   ShowStack();
   printf("\t\t%c\t\t分析成功！\n", st[current]);
   printf("%s是给定文法的句子！\n", st);
  }
  else
  {
   while(topAnalyse > 0)
   {
    if(100 > analyseStack[topAnalyse]) /*当为终结符时*/
    {
     printf("无可用产生式，此串不是此文法的句子！\n");
     return;
    }
    else
    {
     r = analyseTable[analyseStack[topAnalyse] - 100][vtNum];
     if(-1 != r)
     {
      Push(r); /*产生式右部代替左部，指示器不移动*/
      step++;
      printf("%d\t", step);
      ShowStack();
      if(0 == topAnalyse && '#' == st[current])
      {
       printf("\t\t%c\t\t分析成功！\n", st[current]);
       printf("%s是给定文法的句子！\n", st);
      }
      else      
       printf("\t\t%c\t\t%d\n", st[current], r);
     }
     else
     {
      printf("无可用产生式，此串不是此文法的句子！\n");
      return;
     }
    }
   }
  }
 }
}
/*初始化栈及符号串*/
void InitStack()
{
 int i;
 /*分析栈的初始化*/
 for(i = 0; i < MaxStLength; i++)
  st[i] = '\0';
 analyseStack[0] = -1; /*#(-1)入栈*/
 analyseStack[1] = 100; /*初始符入栈*/
 topAnalyse = 1;
}
/*显示符号栈中内容*/
void ShowStack()
{
 int i;
 for(i = 0; i <= topAnalyse; i++)
 {
  if(100 <= analyseStack[i])
   printf("%c", Vn[analyseStack[i] - 100]);
  else
  {
   if(-1 != analyseStack[i])
    printf("%c", Vt[analyseStack[i]]);
   else 
    printf("#");
  }
 }
}
/*栈顶出栈*/
void Pop()
{
 topAnalyse--;
}
/*使用产生式入栈操作*/
void Push(int r)
{
 int i;
 struct pRNode *pt;
 Pop();
 pt = P[r].rHead;
 if(-1 == pt->rCursor) /*为空产生式时*/
  return;
 topAnalyse += P[r].rLength;
 for(i = 0; i < P[r].rLength; i++)
 {
  /*不为空产生式时*/
  analyseStack[topAnalyse - i] = pt->rCursor;/*逆序入栈*/
  pt = pt->next;
 }/*循环未完时pt为空，则说明rLength记录等出错*/
}