Question

构造算符优先分析器能够实现：输入文法,判断是否是算符文法!输出每个非终结符的FRISTVT集和LASTVT集!构造算符优

Answer 1

#include

#include

//

void error()

{

x09printf("error!n");

x09exit(1);

}

char judge(char x,char y)

{

x09int col;x09x09//分析表中的y所在的列号

x09switch (y)

x09{

x09case '+':

x09x09col=0;

x09x09break;

x09case '*':

x09x09col=1;

x09x09break;

x09case 'i':

x09x09col=2;

x09x09break;

x09case '(':

x09x09col=3;

x09x09break;

x09case ')':

x09x09col=4;

x09x09break;

x09case '#':

x09x09col=5;

x09x09break;

x09default:

x09x09printf("y isn't in the analysis List!");

x09}

x09switch(x)

x09{

x09case '+':

x09x09return ConstList[0][col];

x09case '*':

x09x09return ConstList[1][col];

x09case 'i':

x09x09return ConstList[2][col];

x09case '(':

x09x09return ConstList[3][col];

x09case ')':

x09x09return ConstList[4][col];

x09case '#':

x09x09return ConstList[5][col];

x09default:

x09x09printf(" x isn't in the analysis List!");

x09}

x09return '$';//错误信息

x09

}

char POP(struct stack *s)

{

x09char ch;

x09struct linkList *p;

x09if(0==s->num)

x09{

x09x09printf("pop error!n");

x09x09return 0;

x09}

x09else

x09{

x09x09s->num--;

x09x09ch=s->top->data;

x09x09p=s->top;

x09x09s->top=s->top->next;

x09x09free(p);

x09x09return ch;

x09x09

x09}

}

void PUSH(struct stack *s,char ch)

{

x09struct linkList *p;

x09if(NULL==s->top)

x09{

x09x09s->top=(struct linkList *)malloc (sizeof(struct linkList ));

x09x09s->top->data=ch;

x09x09s->top->next=NULL;

x09x09s->num=1;

x09}

x09else

x09{

x09x09p=(struct linkList *)malloc (sizeof(struct linkList ));

x09x09p->data=ch;

x09x09p->next=s->top;

x09x09s->top=p;

x09x09s->num++;

x09}

}

char head(struct stack *s)x09x09x09//取栈顶元素

{

x09if (s->num>0)

x09{

x09x09return s->top->data;

x09}

x09else

x09x09return 0;

}

void enStack_Queue(struct stack *s,char ch)x09x09//按入队方式入栈

{

x09struct linkList *p;

x09if (NULL==s->top)

x09{

x09x09s->top=(struct linkList *)malloc (sizeof(struct linkList ));

x09x09s->top->data=ch;

x09x09s->top->next=NULL;

x09x09s->num=1;

x09x09

x09}

x09else

x09{

x09x09p=s->top;

x09x09while (NULL!=p->next)

x09x09{

x09x09x09p=p->next;

x09x09}

x09x09p->next=(struct linkList *)malloc (sizeof(struct linkList ));

x09x09p->next->data=ch;

x09x09p->next->next=NULL;

x09x09s->num++;

x09x09

x09}

}

char getStack(struct stack *s,int j)

{

x09struct linkList *p;

x09int c;

x09int i=s->num-j;

x09if (s->num>=j)

x09{

x09x09p=s->top;

x09x09for (c=0;cnext;

x09x09}

x09x09return p->data;

x09}

x09else

x09x09return 0;

}

int isVT(char ch)x09x09x09//是否是终极符

{

x09int i;

x09for(i=0;inum;i>0;i--)

x09{

x09x09p=s->top;

x09x09for (c=0;cnext;

x09x09}

x09x09printf("%c",p->data);

x09}

x09printf("t");

x09

}

void showInput(struct stack *s)

{

x09struct linkList *p;

x09int i,c;

x09for (i=0;inum;i++)

x09{

x09x09p=s->top;

x09x09for (c=0;cnext;

x09x09}

x09x09printf("%c",p->data);

x09}

}

void main()

{

x09char ch;

x09char a,Q;

x09int k,j,pop_c,i,flag=0;

x09int relation=0;

x09struct stack *s_in=(struct stack *)malloc (sizeof(struct stack ));

x09struct stack *s_an=(struct stack *)malloc (sizeof(struct stack ));

x09s_an->top=NULL;

x09s_in->top=NULL;

x09printf("please input the string:");

x09

x09do

x09{x09

x09x09ch=getchar();

x09x09enStack_Queue(s_in,ch);

x09}while ('#'!=ch);

x09k=1;

x09PUSH(s_an,'#');

x09printf("栈t当前符号t剩余输入符t优先关系t移进或规约n");

x09do

x09{

x09x09a=POP(s_in);x09x09//当前输入符读入ax09x09

x09x09do

x09x09{

x09x09x09

x09x09x09showAnalysis(s_an);

x09x09x09printf("%ctt",a);

x09x09x09showInput(s_in);

x09x09x09if (isVT(getStack(s_an,k)))

x09x09x09{

x09x09x09x09j=k;

x09x09x09}

x09x09x09else

x09x09x09x09j=k-1;

x09x09x09if ('>'==judge(getStack(s_an,j),a))x09x09//s[j]>a

x09x09x09{

x09x09x09x09printf("tt%c",'>');

x09x09x09x09printf("tt规约n");

x09x09x09x09do

x09x09x09x09{

x09x09x09x09x09Q=getStack(s_an,j);

x09x09x09x09x09if (isVT(getStack(s_an,j-1)))

x09x09x09x09x09{

x09x09x09x09x09x09j--;

x09x09x09x09x09}

x09x09x09x09x09else

x09x09x09x09x09x09j=j-2;

x09x09x09x09} while (!('