You are currently viewing Write a C program for implementing the functionalities of predictive parser for the mini language
implementing the functionalities of predictive parser

Write a C program for implementing the functionalities of predictive parser for the mini language

3.4
(18)

Write a C program for implementing the functionalities of predictive parser for the mini-language.

This example explains the C program for implementing the functionalities of the predictive parser.

#include<stdio.h>
#include<conio.h>
#include<string.h>
char prol[7][10]={"S","A","A","B","B","C","C"};
char pror[7][10]={"A","Bb","Cd","aB","@","Cc","@"};
char prod[7][10]={"S->A","A->Bb","A->Cd","B->aB","B->@","C->Cc","C->@"}; char first[7][10]={"abcd","ab","cd","a@","@","c@","@"}; char follow[7][10]={"$","$","$","a$","b$","c$","d$"};
char table[5][6][10];
int numr(char c)
{
switch(c){
case 'S': return 0;
case 'A': return 1;
case 'B': return 2;
case 'C': return 3;
case 'a': return 0;
case 'b': return 1;
case 'c': return 2;
case 'd': return 3;
case '$': return 4;
}
return(2);
}
void main()
{
int i,j,k;
clrscr();
for(i=0;i<5;i++)
for(j=0;j<6;j++)
strcpy(table[i][j]," ");
printf("\nThe following is the predictive parsing table for the following grammar:\n"); for(i=0;i<7;i++)
printf("%s\n",prod[i]);
printf("\nPredictive parsing table is\n");
fflush(stdin);
for(i=0;i<7;i++){
k=strlen(first[i]);
for(j=0;j<10;j++)
if(first[i][j]!='@')
strcpy(table[numr(prol[i][0])+1][numr(first[i][j])+1],prod[i]);
}
for(i=0;i<7;i++){
if(strlen(pror[i])==1)
{
if(pror[i][0]=='@')
{
k=strlen(follow[i]);
for(j=0;j<k;j++)
strcpy(table[numr(prol[i][0])+1][numr(follow[i][j])+1],prod[i]); 
}
}
}
strcpy(table[0][0]," ");
strcpy(table[0][1],"a");
strcpy(table[0][2],"b");
strcpy(table[0][3],"c");
strcpy(table[0][4],"d");
strcpy(table[0][5],"$");
strcpy(table[1][0],"S");
strcpy(table[2][0],"A");
strcpy(table[3][0],"B");
strcpy(table[4][0],"C");
printf("\n--------------------------------------------------------\n");
for(i=0;i<5;i++)
for(j=0;j<6;j++){
printf("%-10s",table[i][j]);
if(j==5)
printf("\n--------------------------------------------------------\n");
}
getch();
}

Output:

The following is the predictive parsing table for the following grammar:

S->A
A->Bb
A->Cd
B->aB
B->@
C->Cc
C->@
Predictive parsing table is
--------------------------------------------------------
          a         b         c         d         $         
--------------------------------------------------------
S         S->A      S->A      S->A      S->A                
--------------------------------------------------------
A         A->Bb     A->Bb     A->Cd     A->Cd               
--------------------------------------------------------
B         B->aB     B->@      B->@        B->@      
--------------------------------------------------------
C                             C->@      C->@      C->@      
--------------------------------------------------------

Want to learn more about predictive parser? Please visit this link: Recursive descent parser

How useful was this post?

Click on a star to rate it!

Average rating 3.4 / 5. Vote count: 18

No votes so far! Be the first to rate this post.

As you found this post useful...

Share this post on social media!

We are sorry that this post was not useful for you!

Let us improve this post!

Tell us how we can improve this post?