// LISP Interpreter Main Program
//
// File:	lisp.cc
// Author:	course
// Version:	1

#include "lisp.h"
#include "obtype.h"
#include "prims.h"
#include <fstream.h>

// The LISP local variable environment.
//
object * environment = NIL;

// Input and output streams.  All input and output must
// use these: e.g., as in *out << "Hello there!" <<
// endl;
//
estream * in;
ostream * out;

// Macros to write messages to screen.
//
static inline void welcome()
  { cout << "Welcome to lisp51, Lisp-in-C++." << endl; }
static inline void goodbye()
  { cout << endl << "Goodbye." << endl; }

// Function to initialize LISP interpreter data
// structures.
//
static void initialize_data();

//  main -- arranges for all the initializations and
//    then calls the read-eval-print loop
//
main()
{
    welcome();

    enable_out_of_memory_error (true);
    out	= &cout;
    initialize_data();
	// Setup LISP data structures.
    {
	// Load in lisp51.lsp if it exits.
	//
	ifstream * input =
	    new ifstream ( "lisp51.lsp" );
	if (*input)
	{
	    in = new estream (*input, *out);
	    in->echo (false);
	    toplevel (true, true);
		// Silent, stop on error.
	    delete in;
	}
	delete input;
    }

    in = &ein;

    toplevel (false, false);
	// Noisy, continue on error.

    goodbye();

    return 0;
}

//  initialize_data --- Init the Interpreter data
//    structures.
//
	void 
initialize_data ()
{
    // Initialize object management.

    preserve_stack::initialize();
    initialize_all_object_types();

    // Preserve all symbols that now exist.
    //
    preserve_all_existing_symbols();

    // Initialize primitive functions.
    //
    initialize_primitive_functions();

    // Initialize the environment and catch_area stack.
    //
    environment = NIL;
    catch_area::initialize();
}