SRL_TABLE

#include <stdio.h>
#include <string.h>
#include <ctype.h>
int i2,j2,i,j,k,m2=0,n=0,o,p,ns=0,tn=0,rr=0,ch=0;
char read[15][10],gl[15],gr[15][10],temp,templ[15],tempr[15][10],*ptr,temp2[5],dfa[15][15];
char variables[15]={'\0'}, terminals[15]={'\0'};
char slr[15][15][10]={'\0'};
char foll[10];
int len_var, len_ter;
struct states//State for forming cannonical sets
{
    char lhs[15],rhs[15][10];
    int n;
}I[15];
void follow(char c);//calculate follow
void first(char c);//calculate first
int compstruct(struct states s1,struct states s2)//Compare states with GOTO states and merge
{
    int t;
    if(s1.n!=s2.n)
        return 0;
    if( strcmp(s1.lhs,s2.lhs)!=0 )
        return 0;
    for(t=0;t<s1.n;t++)
        if( strcmp(s1.rhs[t],s2.rhs[t])!=0 )
            return 0;
    return 1;
}
void moreprod()//For finding CLOSURE of a set
{
    int r,s,t,l1=0,rr1=0;
    char *ptr1,read1[15][10];
    for(r=0;r<I[ns].n;r++)
    {
        ptr1=strchr(I[ns].rhs[l1],'.');
        t=ptr1-I[ns].rhs[l1];
        if( t+1==strlen(I[ns].rhs[l1]) )
        {
            l1++;
            continue;
        }
        temp=I[ns].rhs[l1][t+1];
        l1++;
        for(s=0;s<rr1;s++)
            if( temp==read1[s][0] )
                break;
        if(s==rr1)
        {
            read1[rr1][0]=temp;
            rr1++;
        }
        else
            continue;

        for(s=0;s<n;s++)
        {
            if(gl[s]==temp)
            {
                I[ns].rhs[I[ns].n][0]='.';
                I[ns].rhs[I[ns].n][1]='\0';
                strcat(I[ns].rhs[I[ns].n],gr[s]);
                I[ns].lhs[I[ns].n]=gl[s];
                I[ns].lhs[I[ns].n+1]='\0';
                I[ns].n++;
            }
        }
    }
}
void canonical(int l)//To find the CANONICAL SET of items using GOTO and SHIFT
{
    int t1;
    char read1[15][10],rr1=0,*ptr1;
    for(i=0;i<I[l].n;i++)
    {
        temp2[0]='.';
        ptr1=strchr(I[l].rhs[i],'.');
        t1=ptr1-I[l].rhs[i];
        if( t1+1==strlen(I[l].rhs[i]) )
            continue;
        temp2[1]=I[l].rhs[i][t1+1];
        temp2[2]='\0';
        for(j=0;j<rr1;j++)
            if( strcmp(temp2,read1[j])==0 )
                break;
        if(j==rr1)
        {
            strcpy(read1[rr1],temp2);
            read1[rr1][2]='\0';
            rr1++;
        }
        else
            continue;
        for(j=0;j<I[0].n;j++)
        {
            ptr=strstr(I[l].rhs[j],temp2);
            if( ptr )
            {
                templ[tn]=I[l].lhs[j];
                templ[tn+1]='\0';
                strcpy(tempr[tn],I[l].rhs[j]);
                tn++;
            }
        }
        for(j=0;j<tn;j++)
        {
            ptr=strchr(tempr[j],'.');
            p=ptr-tempr[j];
            tempr[j][p]=tempr[j][p+1];
            tempr[j][p+1]='.';
            I[ns].lhs[I[ns].n]=templ[j];
            I[ns].lhs[I[ns].n+1]='\0';
            strcpy(I[ns].rhs[I[ns].n],tempr[j]);
            I[ns].n++;
        }
        moreprod();
        for(j=0;j<ns;j++)
        {
            //if ( memcmp(&I[ns],&I[j],sizeof(struct states))==1 )
            if( compstruct(I[ns],I[j])==1 )
            {
                I[ns].lhs[0]='\0';
                for(k=0;k<I[ns].n;k++)
                    I[ns].rhs[k][0]='\0';
                I[ns].n=0;
                dfa[l][j]=temp2[1];
                break;
            }
        }
        if(j<ns)
        {
            tn=0;
            for(j=0;j<15;j++)
            {
                templ[j]='\0';
                tempr[j][0]='\0';
            }
            continue;
        }
        dfa[l][j]=temp2[1];
        printf("\n\nI%d :",ns);
        for(j=0;j<I[ns].n;j++)
            printf("\n\t%c -> %s",I[ns].lhs[j],I[ns].rhs[j]);
        ns++;
        tn=0;
        for(j=0;j<15;j++)
        {
            templ[j]='\0';
            tempr[j][0]='\0';
        }
    }
}

void extract_var_char()//For determining TERMINAL and NOT-TERMINAL
{
    for (i=0;i<n;i++)
    {
        if (gl[i] >= 'A' && gl[i] <= 'Z')
            if (!strchr(variables,gl[i]))
                sprintf(variables,"%s%c",variables,gl[i]);
        for (j=0;j<strlen(gr[i]);j++)
            if (gr[i][j] < 'A' || gr[i][j] > 'Z')
                if (!strchr(terminals,gr[i][j]))
                    sprintf(terminals,"%s%c",terminals,gr[i][j]);
    }
    strcat(terminals,"$");
    printf ("Variables : %s\nTerminals : %s\n",variables,terminals);
}

void print_dfa(){
    printf("\n\tDFA Table...\n\n");
    for(i=0;i<ns;i++)
    {
        printf("I%d : ",i);
        for(j=0;j<ns;j++)
            if(dfa[i][j]!='\0')
                printf("'%c'->I%d | ",dfa[i][j],j);
        printf("\n\n");
    }
}
void change_slr()
{
    strcpy(slr[2][0],"r2");
    strcpy(slr[3][1],"r4");
    strcpy(slr[4][2],"s4");
    strcpy(slr[4][6],"8");
    strcpy(slr[4][7],"2");
    strcpy(slr[4][8],"3");
    strcpy(slr[5][1],"r6");
}
void display_slr()//IT displays the SLR TABLE
{
    printf("\n\t\tSLR(1) Table...\n\n\t");
    for (i=0;i<len_ter;i++)
        printf("%c\t",terminals[i]);
    for (i=0;i<len_var;i++)
        printf("%c\t",variables[i]);
    printf("\n");
    for (i=0;i<ns;i++){
        printf("I%d\t",i);
        for (j=0;j<len_var+len_ter;j++)
            printf("%s\t",slr[i][j]);
        printf("\n");
    }
}
void main()
{
    FILE *f;
    int l;
    for(i=0;i<15;i++)
    {
        I[i].n=0;
        I[i].lhs[0]='\0';
        I[i].rhs[0][0]='\0';
        dfa[i][0]='\0';
    }
    f=fopen("grammar.txt","r");//Reading Grammar from text file
    while(!feof(f))
    {
        fscanf(f,"%c",&gl[n]);
        fscanf(f,"%s\n",gr[n]);
        n++;
    }
    printf("\tGiven Grammar...\n");
    for(i=0;i<n;i++)
        printf("\t\t%c -> %s\n",gl[i],gr[i]);
    I[0].lhs[0]='Z';
    strcpy(I[0].rhs[0],".S");
    I[0].n++;
    l=0;
    for(i=0;i<n;i++)
    {
        temp=I[0].rhs[l][1];
        l++;
        for(j=0;j<rr;j++)
            if( temp==read[j][0] )
                break;
        if(j==rr)
        {
            read[rr][0]=temp;
            rr++;
        }
        else
            continue;
        for(j=0;j<n;j++)
        {
            if(gl[j]==temp)
            {
                I[0].rhs[I[0].n][0]='.';
                strcat(I[0].rhs[I[0].n],gr[j]);
                I[0].lhs[I[0].n]=gl[j];
                I[0].n++;
            }
        }
    }
    ns++;
    printf("\n\tCanonicals...\n");
    printf("\nI%d :\n",ns-1);
    for(i=0;i<I[0].n;i++)
        printf("\t%c -> %s\n",I[0].lhs[i],I[0].rhs[i]);

    for(l=0;l<ns;l++){
        canonical(l);
    }
    printf("\n\n");
    print_dfa();
     //~~~~~~~~~~~~~~~~~~~~~Construction of SLR(1) Table~~~~~~~~~~~~~~~~~~//
    int t,tempo;
    extract_var_char();
    len_var = strlen(variables);
    len_ter = strlen(terminals);
    int columns = len_var + len_ter;

    for (i=0;i<ns;i++)
    {
        for (j=0;j<ns;j++)
            if (dfa[i][j] != '\0')
                if (strchr(terminals,dfa[i][j]))
                    sprintf(slr[i][strchr(terminals,dfa[i][j])-terminals],"s%d",j);
                else if (strchr(variables,dfa[i][j]))
                    sprintf(slr[i][len_ter+strchr(variables,dfa[i][j])-variables],"%d",j);
        for (j=0;j<I[i].n;j++)
        {
            int temp_ind = strlen(I[i].rhs[j])-1; // to make the 1st state that end with "S." accept.
            if (I[i].rhs[j][temp_ind] == '.')
            {
                if (I[i].rhs[j][temp_ind-1] == 'S' && i==1)
                    sprintf(slr[i][strchr(terminals,'$')-terminals],"accept");
                else
                {
                    follow(I[i].lhs[j]);
                    int ha,prod_num,tempo_store;
                    for (ha=0;gl[ha]!='\0';ha++)
                    {
                        if (strncmp(gr[ha],I[i].rhs[j],temp_ind)==0)
                            prod_num = ha + 1;
                    }
                    for (ha=0; ha<m2 ; ha++)
                    {
                        tempo_store = strchr(terminals,foll[ha])-terminals;
                        if (strlen(slr[i][tempo_store]) > 0)
                        {
                            if (slr[i][tempo_store][0] == 's')
                                printf("\nSR-Conflict occurred....\n");
                            else
                                printf("\nRR-Conflict occurred....\n");
                        }
                        else
                            sprintf(slr[i][tempo_store],"r%d",prod_num);
                    }
                    m2=0;
                }
            }
        }
    }
    change_slr();
    display_slr();
    //~~~~~~~~~~~~~~~~~~~~~~~~~~~Check for the given string~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~//
    char input[100],stack[100]={'\0'};//Declaing Stack for PARSING process
    printf("\nGive the input string : ");
    scanf("%s",input);
    int temp32,temp36,len_rhs,state,top=0,input_len = strlen(input);
    if (input[input_len-1] != '$')
        input[input_len++] = '$';
    i=0;
    stack[0] = '0';
    printf("\n\nSTACK\t\tINPUT STRING\t\tACTION\n");
    printf("-----\t\t------------\t\t------\n");
    while(i<input_len)
    {
        printf("%s\t\t",stack);
        for (j=i;j<input_len;j++)
            printf("%c",input[j]);
            printf("\t\t\t");
        if (strchr(terminals,input[i]))
        {
            temp32 = strchr(terminals,input[i])-terminals; // only terminals are present in the input....
            state = stack[top] - 48;
        }
        else
        {
            printf("Unknown symbol encountered...\n");
            break;
        }
        if (stack[top]=='1' && input[i]=='$' && strcmp(slr[state][temp32],"accept") == 0 )
        {
            printf("String Accepted...\n");
            break;
        }
        else if(slr[state][temp32][0]=='s')
        {
            top++;
            stack[top++] = input[i];
            stack[top] = slr[state][temp32][1];
            i++;
            printf("Shift %c\n",terminals[temp32]);
        }
        else if(slr[state][temp32][0]=='r')
        {
            len_rhs = strlen(gr[slr[state][temp32][1]-49]);
            printf("Reduce-step : %c -> %s \n",gl[slr[state][temp32][1]-49],gr[slr[state][temp32][1]-49]);
            for (j=0;j<2*len_rhs;j++)
                stack[top--]='\0';
            temp36 = stack[top] - 48;
            stack[++top] = gl[slr[state][temp32][1]-49];
            stack[++top] = slr[temp36][len_ter + strchr(variables,stack[top-1])-variables][0];
        }
        else
        {
            printf("String rejected...\n");
            break;
        }
    }
}
void follow(char c)
{
    if(gl[0]==c)
    foll[m2++]='$';
    for(i2=0;i2<n;i2++)
        for(j2=0;j2<strlen(gr[i2]);j2++)
            if(gr[i2][j2]==c)
            {
                if(gr[i2][j2+1]!='\0')
                first(gr[i2][j2+1]);
                if(gr[i2][j2+1]=='\0'&&c!=gl[i2])
                follow(gl[i2]);
            }
}
void first(char c)
{
    int k;
    if(!(isupper(c)))
        foll[m2++]=c;
    for(k=0;k<n;k++)
        if(gl[k]==c)
            if(gr[k][0]=='$')
                follow(gl[i2]);
            else if(islower(gr[k][0]))
                foll[m2++]=gr[k][0];
            else
                first(gr[k][0]);
}

// S S+A
// S A
// A A*B
// A B
// B (S)
// B i