Thread: Help getting started with a Command Line Interpreter:

Hi Everyone,

I am in desperate need of help here. I would appreciate if anyone can give me some input or some example to get me started with this problem.

I have been working on creating operator overloading functions to work on Sets. I have created the Class for the Set by using a linked list (Doubly Linked) of integers. The program is functional and works by presenting a menu and predefined operations. Now the assignment is to make it work as a command line interpreter. In few words, instead of having a menu of options, I have to prompt the user for the expression to work on:

Some Examples:

Valid commands:
Invalid Commands
Command
Result
Command
Result
A
A = { 1 2 3 4 5 }
! A
B = A * { 1 3 5 }
C = A – { 2 4 6 } << 7
{ 3 6 9 12 } << 3 << 8
3 <= A
A == B
A != C
A == 5

{ }
{ 1 2 3 4 5 }
5
{ 1 3 5 }
{1 3 5 7 }
{ 3 6 9 12 8 }
True
False
True
True



The good thing is that the professor already gave out the code to parse the command line expression and check for any errors or invalid expression, but that is all it does. What I need help with is to integrate one with the other and I am having a hell of time trying to understand the professor's code. I don't know which way to go without running into a corner. I just need to see maybe an example of an operation such as insert an element into a set for example, and then I can continue to work on the others.

I have attached 2 files:

1. Program 4 Final.zip which is the Set and Node Class with operator overloading functions and the User Menu in the main.
2. Program 5.zip, which is the SetInterpreter Class with command line parsing and just checks for valid expressions and number of tokens.

But I can't attach these 2 files here. If anyone is willing to help I can send them via email maybe?

Please let me know if anyone can take a look at the code and hopefully give me a kick-start on how to begin because I have absolute no idea.

Thanks in Advance for your precious help!

Vince

{EDIT}

I managed to upload the files individually with the exception of one and here is the code which is the main function that goes with the SetInterp.h and setinterp.h

Code:

#include <cstdlib>
#include <iostream>
#include "SetInterp.h"

using namespace std;

int main()
{
    SetInterpreter si;
    ReadFlag result;
    
    result = si.readLine();
    while (result != ENDF)
    {
//          cout << result << endl;
          if (result == FAIL) {
//             cout << "Bad Commandline\n";
             result = si.readLine();
             continue;
          }
          cout << "Number of tokens on command line were " << si.length() << endl;
          while (si.more())
          {

                TokenNode * t = si.getNext();
                switch(t->getToken()) {
                    default:      cout << "? ";
                    case OPERATOR:
                    case SETNAME: cout << t->getName() << " "; break;
                    case ELEMENT:
                    case VALUE:   cout << t->getValue() << " "; break;
                    case SET:     const int * list = t->getElements();
                                  cout << "{ ";
                                  for (int i=0; i<t->getSize(); i++) cout << list[i] << " ";
                                  cout << "} ";
                                  break;
                }
          }

          cout << endl;
          result = si.readLine();
    }
    
    system("PAUSE");
    return EXIT_SUCCESS;
}