#include"stdio.h"
#include"stdlib.h"
#include"string.h"
char ip_sym[15],stack[15];
int ip_ptr=0,st_ptr=0,len,i;
char temp[2],temp2[2];
char act[15];
void check();
void main()
{
printf("\n\t\t SHIFT REDUCE PARSER\n");
printf("\n GRAMMER\n");
printf("\n E->E+E\n E->E/E");
printf("\n E->E*E\n E->a/b");
printf("\n enter the input symbol:\t");
gets(ip_sym);
printf("\n\t stack implementation table");
printf("\n stack\t\t input symbol\t\t action");
printf("\n______\t\t ____________\t\t ______\n");
printf("\n $\t\t%s$\t\t\t--",ip_sym);
strcpy(act,"shift ");
temp[0]=ip_sym[ip_ptr];
temp[1]='\0';
strcat(act,temp);
len=strlen(ip_sym);
for(i=0;i<=len-1;i++)
{
stack[st_ptr]=ip_sym[ip_ptr];
stack[st_ptr+1]='\0';
ip_sym[ip_ptr]=' ';
ip_ptr++;
printf("\n $%s\t\t%s$\t\t\t%s",stack,ip_sym,act);
strcpy(act,"shift ");
temp[0]=ip_sym[ip_ptr];
temp[1]='\0';
strcat(act,temp);
check();
st_ptr++;
}
check();
}
void check()
{
int flag=0;
temp2[0]=stack[st_ptr];
temp2[1]='\0';
if((isalpha(temp2[0])))
{
stack[st_ptr]='E';
printf("\n $%s\t\t%s$\t\t\tE->%s",stack,ip_sym,temp2);
flag=1;
}
if((!strcmp(temp2,"+"))||(!strcmp(temp2,"*"))||(!strcmp(temp2,"/")))
{
flag=1;
}
if((!strcmp(stack,"E+E"))||(!strcmp(stack,"E/E"))||(!strcmp(stack,"E*E")))
{
if(!strcmp(stack,"E+E"))
{
strcpy(stack,"E");
printf("\n $%s\t\t%s$\t\t\tE->E+E",stack,ip_sym);
}
else if(!strcmp(stack,"E/E"))
{
strcpy(stack,"E");
printf("\n $%s\t\t %s$\t\t\tE->E/E",stack,ip_sym);
}
else
{
strcpy(stack,"E");
printf("\n $%s\t\t%s$\t\t\tE->E*E",stack,ip_sym);
}
flag=1;
st_ptr=0;
}
if(!strcmp(stack,"E")&&ip_ptr==len)
{
printf("\n $%s\t\t%s$\t\t\tACCEPT",stack,ip_sym);
exit(0);
}
if(flag==0)
{
printf("\n $%s\t\t%s$\t\t\tReject",stack,ip_sym);
exit(0);
}
return;
}
OUTPUT:
1)
SHIFT REDUCE PARSER GRAMMER
E->E+E
E->E/E
E->E*E
E->E-E
E->id
enter the input symbol: a+b*c
stack implementation table
stack input symbol action
______ ____________ ______
$ a+b*c$ --
$a +b*c$ shift a
$E +b*c$ E->a
$E+ b *c$ shift +
$E+b *c$ shift b
$E+E *c$ E->b
$E *c$ E->E+E
$E* c$ shift *
$E*c $ shift c
$E*E $ E->c
$E $ E->E*E
$E $ ACCEPT
