// Fixnum integer definition.
//
// File:        fixnum.h
// Author:      course
// Version:     3

#ifndef FIXNUM_H
#define FIXNUM_H

#include "object.h"

class fixnum : public object
{

public:

    // Create a fixnum with a given value.
    //
    friend fixnum * make_fixnum (long value);

    // Get the value of a fixnum.  The unchecked version
    // may be used when you know you have a fixnum and
    // do not need to do type checking.
    //
    friend long value (fixnum * fx);
    friend long unchecked_value (object * ob);

private:

    long		value;

   // Virtuals to be implemented by subclasses.

    virtual ostream& print (ostream& s);
	// Print object.
    virtual void scavenge();
	// Scavenge object during garbage collection.

};


// Other fixnum functions:

// Return true iff object is a fixnum.
// 
bool fixnump (object * ob);

// Convert a pointer to an object to a pointer to a
// fixnum (which is the same as the object) if the
// object is a fixnum, or return NULL if the object
// is not a fixnum.
//
fixnum * may_be_fixnum (object * ob);

// Convert a pointer to an object to a pointer to a
// fixnum (which is the same as the object) if the
// object is a fixnum, or call error if the object is
// not a fixnum.
//
fixnum * must_be_fixnum (object * ob);

// Convert a pointer to an object to a pointer to a
// fixnum (which is the same as the object) if the
// object is a fixnum.  Produces undefined results if
// object is not a fixnum, but is the most efficient
// conversion because it does no checking.
//
fixnum * unchecked_must_be_fixnum (object * ob);

// Object type for fixnum.
//
extern object_type * FIXNUM_TYPE;



// Inline implementations of above.  See above for
// documentation.
//
inline long value (fixnum * fx)
    { return fx->value; }
inline long unchecked_value (object * ob)
    { return ((fixnum *) ob)->value; }

inline bool fixnump (object * ob)
    { return type_of (ob) == FIXNUM_TYPE; }
inline fixnum * may_be_fixnum (object * ob)
    { return fixnump(ob) ? (fixnum *) ob
			 : (fixnum *) NULL; }
inline fixnum * must_be_fixnum (object * ob)
{
    if ( ob == NULL || ! fixnump (ob) )
    	type_error (ob, FIXNUM_TYPE);

    return (fixnum *) ob;
}
inline fixnum * unchecked_must_be_fixnum (object * ob)
    { return (fixnum *) ob; }

#endif // FIXNUM_H