Top down parser source code in c plus plus?

Answer 1

#include<iostream.h>

#include<conio.h>

#include<string.h>

class parse

{

int nt,t,m[20][20],i,s,n,p1,q,k,j;

char p[30][30],n1[20],t1[20],ch,b,c,f[30][30],fl[30][30];

public:

int scant(char);

int scannt(char);

void process();

void input();

};

int parse::scannt(char a)

{

int c=-1,i;

for(i=0;i<nt;i++)

{

if(n1[i]==a)

{

return i;

}

}

return c;

}

int parse::scant(char b)

{

int c1=-1,j;

for(j=0;j<t;j++)

{

if(t1[j]==b)

{

return j;

}

}

return c1;

}

void parse::input()

{

cout<<"Enter the number of productions:";

cin>>n;

cout<<"Enter the productions one by one"<<endl;

for(i=0;i<n;i++)

cin>>p[i];

nt=0;

t=0;

}

void parse::process()

{

for(i=0;i<n;i++)

{

if(scannt(p[i][0])==-1)

n1[nt++]=p[i][0];

}

for(i=0;i<n;i++)

{

for(j=3;j<strlen(p[i]);j++)

{

if(p[i][j]!='e')

{

if(scannt(p[i][j])==-1)

{

if((scant(p[i][j]))==-1)

t1[t++]=p[i][j];

}

}

}

}

t1[t++]='$';

for(i=0;i<nt;i++)

{

for(j=0;j<t;j++)

m[i][j]=-1;

}

for(i=0;i<nt;i++)

{

cout<<"Enter first["<<n1[i]<<"]:";

cin>>f[i];

}

for(i=0;i<nt;i++)

{

cout<<"Enter follow["<<n1[i]<<"]:";

cin>>fl[i];

}

for(i=0;i<n;i++)

{

p1=scannt(p[i][0]);

if((q=scant(p[i][3]))!=-1)

m[p1][q]=i;

if((q=scannt(p[i][3]))!=-1)

{

for(j=0;j<strlen(f[q]);j++)

m[p1][scant(f[q][j])]=i;

}

if(p[i][3]=='e')

{

for(j=0;j<strlen(fl[p1]);j++)

m[p1][scant(fl[p1][j])]=i;

}

}

for(i=0;i<t;i++)

cout<<"\t"<<t1[i];

cout<<endl;

for(j=0;j<nt;j++)

{

cout<<n1[j];

for(i=0;i<t;i++)

{

cout<<"\t"<<" ";

if(m[j][i]!=-1)

cout<<p[m[j][i]];

}

cout<<endl;

}

}

void main()

{

clrscr();

parse p;

p.input();

p.process();

getch();

}