// Object Type Class Code
//
// File:        obtype.cc
// Author:      {your name} <{your e-mail address}>
// Assignment:  9

#include "lisp.h"
#include "obtype.h"
#include <strstream.h>

// List of object types.
//
object_type * object_type::list = NULL;

// Initialize all object types.  First initializes NIL,
// and then calls the object type initializers that
// allocate other symbols, etc.
//
void initialize_all_object_types ()
{
    // Because NIL is use to initialize other things,
    // it must be initialized first as a special case.
    //
    NIL = make_symbol ("NIL");
    set_symbol_value ((symbol *)NIL, NIL);
    set_symbol_plist ((symbol *)NIL, NIL);

    // Now call oll object_type initialize members.
    //
    for ( object_type * obty = object_type::list;
	  obty != NULL;
	  obty = obty->link
	)
	obty->initialize();
}

// Call error indicating object is not of this type.
//
void type_error (object * ob, object_type * ty)
{
    char buffer [100];
    ostrstream s (buffer, 100);
    s << "Object is not a " << ty->name << ": "
      << ends;
    if (ob)	error (s.str(), ob);
    else	error (s.str(), "NULL");
}

// Construct object type with simple free and used lists
// and the given name.  Put the object type on the
// object_type::list.
//
object_type::object_type (char * name)
{
    this->name		= name;
    free_list		= NULL;
    used_list		= NULL;
    link		= object_type::list;
    object_type::list	= this;
}

// Return object from free list, or NULL if none.  Does
// no initialization.
//
object * object_type::get_free()
{
    object * ob;
    if (ob = free_list)
    {
	free_list = ob->link;
	return ob;
    }
    else return NULL;
}

// Put object on used list.
//
void object_type::put_used (object * ob)
{
    ob->link = used_list;
    used_list = ob;
}

// Go through used lists clearing marked bits.
//
void object_type::clear_marked()
{
    // ***** Put gc code here for assignment 9 ***** 
}

// Go through used lists calling gc_mark in special
// cases, as for symbols with bound value or function or
// non-NIL plist.
//
void object_type::mark() {}	// Do nothing normally.

// Sweep used lists to free list.
//
void object_type::sweep()
{
    // ***** Put gc code here for assignment 9 ***** 
}

// Print memory statistics for this type.
//
void object_type::gc_print()
{
    unsigned free = 0;
    unsigned used = 0;
    object * p; 

    for (p = free_list; p; p = p->link) ++ free;
    for (p = used_list; p; p = p->link) ++ used;

    *out << "    " << name << ": free " << free
         << ", used " << used << endl;
}