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ashishsoniii/ll1_parsing.c

Created May 6, 2024 21:29
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Write a C program to perform LL(1) parsing, including generateFirstList(), generateFollowList(), generateParsingTable(), parse(), etc. functions.
Raw
ll1_parsing.c
#include<stdio.h>
#include<stdlib.h>
#include<ctype.h>
#include<string.h>
void followfirst(char , int , int);
void findfirst(char , int , int);
void follow(char c);
int count,n=0;
char calc_first[10][100];
char calc_follow[10][100];
int m=0;
char production[10][10], first[10];
char f[10];
int k;
char ck;
int e;
int main(int argc,char **argv)
{
int jm=0;
int km=0;
int i,choice;
char c,ch;
printf("How many productions ? :");
scanf("%d",&count);
printf("\nEnter %d productions in form A=B where A and B are grammar symbols :\n\n",count);
for(i=0;i<count;i++)
{
scanf("%s%c",production[i],&ch);
}
int kay;
char done[count];
int ptr = -1;
for(k=0;k<count;k++){
for(kay=0;kay<100;kay++){
calc_first[k][kay] = '!';
}
}
int point1 = 0,point2,xxx;
for(k=0;k<count;k++)
{
c=production[k][0];
point2 = 0;
xxx = 0;
for(kay = 0; kay <= ptr; kay++)
if(c == done[kay])
xxx = 1;
if (xxx == 1)
continue;
findfirst(c,0,0);
ptr+=1;
done[ptr] = c;
printf("\n First(%c)= { ",c);
calc_first[point1][point2++] = c;
for(i=0+jm;i<n;i++){
int lark = 0,chk = 0;
for(lark=0;lark<point2;lark++){
if (first[i] == calc_first[point1][lark]){
chk = 1;
break;
}
}
if(chk == 0){
printf("%c, ",first[i]);
calc_first[point1][point2++] = first[i];
}
}
printf("}\n");
jm=n;
point1++;
}
printf("\n");
printf("-----------------------------------------------\n\n");
char donee[count];
ptr = -1;
for(k=0;k<count;k++){
for(kay=0;kay<100;kay++){
calc_follow[k][kay] = '!';
}
}
point1 = 0;
int land = 0;
for(e=0;e<count;e++)
{
ck=production[e][0];
point2 = 0;
xxx = 0;
for(kay = 0; kay <= ptr; kay++)
if(ck == donee[kay])
xxx = 1;
if (xxx == 1)
continue;
land += 1;
follow(ck);
ptr+=1;
donee[ptr] = ck;
printf(" Follow(%c) = { ",ck);
calc_follow[point1][point2++] = ck;
for(i=0+km;i<m;i++){
int lark = 0,chk = 0;
for(lark=0;lark<point2;lark++){
if (f[i] == calc_follow[point1][lark]){
chk = 1;
break;
}
}
if(chk == 0){
printf("%c, ",f[i]);
calc_follow[point1][point2++] = f[i];
}
}
printf(" }\n\n");
km=m;
point1++;
}
char ter[10];
for(k=0;k<10;k++){
ter[k] = '!';
}
int ap,vp,sid = 0;
for(k=0;k<count;k++){
for(kay=0;kay<count;kay++){
if(!isupper(production[k][kay]) && production[k][kay]!= '#' && production[k][kay] != '=' && production[k][kay] != '\0'){
vp = 0;
for(ap = 0;ap < sid; ap++){
if(production[k][kay] == ter[ap]){
vp = 1;
break;
}
}
if(vp == 0){
ter[sid] = production[k][kay];
sid ++;
}
}
}
}
ter[sid] = '$';
sid++;
printf("\n\t\t\t\t\t\t\t The LL(1) Parsing Table for the above grammer :-");
printf("\n\t\t\t\t\t\t\t^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n");
printf("\n\t\t\t=====================================================================================================================\n");
printf("\t\t\t\t|\t");
for(ap = 0;ap < sid; ap++){
printf("%c\t\t",ter[ap]);
}
printf("\n\t\t\t=====================================================================================================================\n");
char first_prod[count][sid];
for(ap=0;ap<count;ap++){
int destiny = 0;
k = 2;
int ct = 0;
char tem[100];
while(production[ap][k] != '\0'){
if(!isupper(production[ap][k])){
tem[ct++] = production[ap][k];
tem[ct++] = '_';
tem[ct++] = '\0';
k++;
break;
}
else{
int zap=0;
int tuna = 0;
for(zap=0;zap<count;zap++){
if(calc_first[zap][0] == production[ap][k]){
for(tuna=1;tuna<100;tuna++){
if(calc_first[zap][tuna] != '!'){
tem[ct++] = calc_first[zap][tuna];
}
else
break;
}
break;
}
}
tem[ct++] = '_';
}
k++;
}
int zap = 0,tuna;
for(tuna = 0;tuna<ct;tuna++){
if(tem[tuna] == '#'){
zap = 1;
}
else if(tem[tuna] == '_'){
if(zap == 1){
zap = 0;
}
else
break;
}
else{
first_prod[ap][destiny++] = tem[tuna];
}
}
}
char table[land][sid+1];
ptr = -1;
for(ap = 0; ap < land ; ap++){
for(kay = 0; kay < (sid + 1) ; kay++){
table[ap][kay] = '!';
}
}
for(ap = 0; ap < count ; ap++){
ck = production[ap][0];
xxx = 0;
for(kay = 0; kay <= ptr; kay++)
if(ck == table[kay][0])
xxx = 1;
if (xxx == 1)
continue;
else{
ptr = ptr + 1;
table[ptr][0] = ck;
}
}
for(ap = 0; ap < count ; ap++){
int tuna = 0;
while(first_prod[ap][tuna] != '\0'){
int to,ni=0;
for(to=0;to<sid;to++){
if(first_prod[ap][tuna] == ter[to]){
ni = 1;
}
}
if(ni == 1){
char xz = production[ap][0];
int cz=0;
while(table[cz][0] != xz){
cz = cz + 1;
}
int vz=0;
while(ter[vz] != first_prod[ap][tuna]){
vz = vz + 1;
}
table[cz][vz+1] = (char)(ap + 65);
}
tuna++;
}
}
for(k=0;k<sid;k++){
for(kay=0;kay<100;kay++){
if(calc_first[k][kay] == '!'){
break;
}
else if(calc_first[k][kay] == '#'){
int fz = 1;
while(calc_follow[k][fz] != '!'){
char xz = production[k][0];
int cz=0;
while(table[cz][0] != xz){
cz = cz + 1;
}
int vz=0;
while(ter[vz] != calc_follow[k][fz]){
vz = vz + 1;
}
table[k][vz+1] = '#';
fz++;
}
break;
}
}
}
for(ap = 0; ap < land ; ap++){
printf("\t\t\t %c\t|\t",table[ap][0]);
for(kay = 1; kay < (sid + 1) ; kay++){
if(table[ap][kay] == '!')
printf("\t\t");
else if(table[ap][kay] == '#')
printf("%c=#\t\t",table[ap][0]);
else{
int mum = (int)(table[ap][kay]);
mum -= 65;
printf("%s\t\t",production[mum]);
}
}
printf("\n");
printf("\t\t\t---------------------------------------------------------------------------------------------------------------------");
printf("\n");
}
int j;
printf("\n\nPlease enter the desired INPUT STRING = ");
char input[100];
scanf("%s%c",input,&ch);
printf("\n\t\t\t\t\t===========================================================================\n");
printf("\t\t\t\t\t\tStack\t\t\tInput\t\t\tAction");
printf("\n\t\t\t\t\t===========================================================================\n");
int i_ptr = 0,s_ptr = 1;
char stack[100];
stack[0] = '$';
stack[1] = table[0][0];
while(s_ptr != -1){
printf("\t\t\t\t\t\t");
int vamp = 0;
for(vamp=0;vamp<=s_ptr;vamp++){
printf("%c",stack[vamp]);
}
printf("\t\t\t");
vamp = i_ptr;
while(input[vamp] != '\0'){
printf("%c",input[vamp]);
vamp++;
}
printf("\t\t\t");
char her = input[i_ptr];
char him = stack[s_ptr];
s_ptr--;
if(!isupper(him)){
if(her == him){
i_ptr++;
printf("POP ACTION\n");
}
else{
printf("\nString Not Accepted by LL(1) Parser !!\n");
exit(0);
}
}
else{
for(i=0;i<sid;i++){
if(ter[i] == her)
break;
}
char produ[100];
for(j=0;j<land;j++){
if(him == table[j][0]){
if (table[j][i+1] == '#'){
printf("%c=#\n",table[j][0]);
produ[0] = '#';
produ[1] = '\0';
}
else if(table[j][i+1] != '!'){
int mum = (int)(table[j][i+1]);
mum -= 65;
strcpy(produ,production[mum]);
printf("%s\n",produ);
}
else{
printf("\nString Not Accepted by LL(1) Parser !!\n");
exit(0);
}
}
}
int le = strlen(produ);
le = le - 1;
if(le == 0){
continue;
}
for(j=le;j>=2;j--){
s_ptr++;
stack[s_ptr] = produ[j];
}
}
}
printf("\n\t\t\t=======================================================================================================================\n");
if (input[i_ptr] == '\0'){
printf("\t\t\t\t\t\t\t\tYOUR STRING HAS BEEN ACCEPTED !!\n");
}
else
printf("\n\t\t\t\t\t\t\t\tYOUR STRING HAS BEEN REJECTED !!\n");
printf("\t\t\t=======================================================================================================================\n");
}
void follow(char c)
{
int i ,j;
if(production[0][0]==c){
f[m++]='$';
}
for(i=0;i<10;i++)
{
for(j=2;j<10;j++)
{
if(production[i][j]==c)
{
if(production[i][j+1]!='\0'){
followfirst(production[i][j+1],i,(j+2));
}
if(production[i][j+1]=='\0'&&c!=production[i][0]){
follow(production[i][0]);
}
}
}
}
}
void findfirst(char c ,int q1 , int q2)
{
int j;
if(!(isupper(c))){
first[n++]=c;
}
for(j=0;j<count;j++)
{
if(production[j][0]==c)
{
if(production[j][2]=='#'){
if(production[q1][q2] == '\0')
first[n++]='#';
else if(production[q1][q2] != '\0' && (q1 != 0 || q2 != 0))
{
findfirst(production[q1][q2], q1, (q2+1));
}
else
first[n++]='#';
}
else if(!isupper(production[j][2])){
first[n++]=production[j][2];
}
else {
findfirst(production[j][2], j, 3);
}
}
}
}
void followfirst(char c, int c1 , int c2)
{
int k;
if(!(isupper(c)))
f[m++]=c;
else{
int i=0,j=1;
for(i=0;i<count;i++)
{
if(calc_first[i][0] == c)
break;
}
while(calc_first[i][j] != '!')
{
if(calc_first[i][j] != '#'){
f[m++] = calc_first[i][j];
}
else{
if(production[c1][c2] == '\0'){
follow(production[c1][0]);
}
else{
followfirst(production[c1][c2],c1,c2+1);
}
}
j++;
}
}
}
/**
sample input:
-------------------------------
10
S=ABCDE
A=a
A=#
B=b
B=#
C=c
D=d
D=#
E=e
E=#
abcde$
------------------------------
6
S=Bb
S=Cd
B=aB
B=#
C=cC
C=#
aaaaab$
*/
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