guile/libguile/objects.h

/* classes: h_files */

#ifndef OBJECTSH
#define OBJECTSH

/*	Copyright (C) 1996, 1999, 2000 Free Software Foundation, Inc.
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this software; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307 USA
 *
 * As a special exception, the Free Software Foundation gives permission
 * for additional uses of the text contained in its release of GUILE.
 *
 * The exception is that, if you link the GUILE library with other files
 * to produce an executable, this does not by itself cause the
 * resulting executable to be covered by the GNU General Public License.
 * Your use of that executable is in no way restricted on account of
 * linking the GUILE library code into it.
 *
 * This exception does not however invalidate any other reasons why
 * the executable file might be covered by the GNU General Public License.
 *
 * This exception applies only to the code released by the
 * Free Software Foundation under the name GUILE.  If you copy
 * code from other Free Software Foundation releases into a copy of
 * GUILE, as the General Public License permits, the exception does
 * not apply to the code that you add in this way.  To avoid misleading
 * anyone as to the status of such modified files, you must delete
 * this exception notice from them.
 *
 * If you write modifications of your own for GUILE, it is your choice
 * whether to permit this exception to apply to your modifications.
 * If you do not wish that, delete this exception notice.  */


/* This file and objects.c contains those minimal pieces of the Guile
 * Object Oriented Programming System which need to be included in
 * libguile.
 *
 * {Objects and structs}
 *
 * Objects are currently based upon structs.  Although the struct
 * implementation will change thoroughly in the future, objects will
 * still be based upon structs.
 */

#include "libguile/__scm.h"
#include "libguile/struct.h"



/* {Class flags}
 *
 * These are used for efficient identification of instances of a
 * certain class or its subclasses when traversal of the inheritance
 * graph would be too costly.
 */
#define SCM_CLASS_FLAGS(class) (SCM_STRUCT_DATA (class) [scm_struct_i_flags])
#define SCM_OBJ_CLASS_FLAGS(obj) (SCM_STRUCT_VTABLE_DATA (obj) [scm_struct_i_flags])
#define SCM_SET_CLASS_FLAGS(c, f) (SCM_CLASS_FLAGS (c) |= (f))
#define SCM_CLEAR_CLASS_FLAGS(c, f) (SCM_CLASS_FLAGS (c) &= ~(f))
#define SCM_CLASSF_MASK SCM_STRUCTF_MASK

#define SCM_CLASSF_ENTITY	SCM_STRUCTF_ENTITY
/* Operator classes need to be identified in the evaluator.
   (Entities also have SCM_CLASSF_OPERATOR set in their vtable.) */
#define SCM_CLASSF_OPERATOR	(1L << 29)

#define SCM_I_OPERATORP(obj)\
	((SCM_OBJ_CLASS_FLAGS (obj) & SCM_CLASSF_OPERATOR) != 0)
#define SCM_OPERATOR_CLASS(obj)\
((struct scm_metaclass_operator *) SCM_STRUCT_DATA (obj))
#define SCM_OBJ_OPERATOR_CLASS(obj)\
((struct scm_metaclass_operator *) SCM_STRUCT_VTABLE_DATA (obj))
#define SCM_OPERATOR_PROCEDURE(obj) (SCM_OBJ_OPERATOR_CLASS (obj)->procedure)
#define SCM_OPERATOR_SETTER(obj) (SCM_OBJ_OPERATOR_CLASS (obj)->setter)

#define SCM_I_ENTITYP(obj)\
	((SCM_OBJ_CLASS_FLAGS (obj) & SCM_CLASSF_ENTITY) != 0)
#define SCM_ENTITY_PROCEDURE(obj) \
        (SCM_PACK (SCM_STRUCT_DATA (obj) [scm_struct_i_procedure]))
#define SCM_SET_ENTITY_PROCEDURE(obj,v) \
        (SCM_STRUCT_DATA (obj) [scm_struct_i_procedure] = SCM_UNPACK (v))
#define SCM_ENTITY_SETTER(obj) (SCM_PACK (SCM_STRUCT_DATA (obj)[scm_struct_i_setter]))
#define SCM_SET_ENTITY_SETTER(obj, v) \
        (SCM_STRUCT_DATA (obj) [scm_struct_i_setter] = SCM_UNPACK (v))

#define SCM_SET_CLASS_DESTRUCTOR(c, d) SCM_SET_VTABLE_DESTRUCTOR (c, d)
#define SCM_SET_CLASS_INSTANCE_SIZE(c, s) \
(SCM_STRUCT_DATA (c)[scm_struct_i_size] \
 = SCM_PACK ((SCM_UNPACK (SCM_STRUCT_DATA (c)[scm_struct_i_size])\
               & SCM_STRUCTF_MASK)\
              | s))

/* {Operator classes}
 *
 * Instances of operator classes can work as operators, i. e., they
 * can be applied to arguments just as if they were ordinary
 * procedures.
 *
 * For instances of operator classes, the procedures to be applied are
 * stored in four dedicated slots in the associated class object.
 * Which one is selected depends on the number of arguments in the
 * application.
 *
 * If zero arguments are passed, the first will be selected.
 * If one argument is passed, the second will be selected.
 * If two arguments are passed, the third will be selected.
 * If three or more arguments are passed, the fourth will be selected.
 *
 * This is complicated and may seem gratuitous but has to do with the
 * architecture of the evaluator.  Using only one procedure would
 * result in a great deal less efficient application, loss of
 * tail-recursion and would be difficult to reconcile with the
 * debugging evaluator.
 *
 * Also, using this "forked" application in low-level code has the
 * advantage of speeding up some code.  An example is method dispatch
 * for generic operators applied to few arguments.  On the user level,
 * the "forked" application will be hidden by mechanisms in the GOOPS
 * package.
 *
 * Operator classes have the metaclass <operator-metaclass>.
 *
 * An example of an operator class is the class <tk-command>.
 */
#define SCM_METACLASS_STANDARD_LAYOUT ""
struct scm_metaclass_standard {
  SCM layout;
  SCM vcell;
  SCM vtable;
  SCM print;
};

#define SCM_METACLASS_OPERATOR_LAYOUT "popo"
struct scm_metaclass_operator {
  SCM layout;
  SCM vcell;
  SCM vtable;
  SCM print;
  SCM procedure;
  SCM setter;
};

/* {Entity classes}
 *
 * For instances of entity classes (entities), the procedures to be
 * applied are stored in the instance itself rather than in the class
 * object as is the case for instances of operator classes (see above).
 *
 * An example of an entity class is the class of generic methods.
 */
#define SCM_ENTITY_LAYOUT ""

/* {Interface to Goops}
 *
 * The evaluator contains a multi-method dispatch mechanism.
 * This interface is used by that mechanism and during creation of
 * smob and struct classes. 
 */

/* Internal representation of Goops objects. */
#define SCM_CLASSF_PURE_GENERIC (0x010 << 20)
#define SCM_CLASSF_GOOPS_VALID  (0x080 << 20)
#define SCM_CLASSF_GOOPS        (0x100 << 20)
#define scm_si_redefined         6
#define scm_si_hashsets          7
#define SCM_CLASS_OF(x)         SCM_STRUCT_VTABLE (x)
#define SCM_OBJ_CLASS_REDEF(x)  (SCM_PACK (SCM_STRUCT_VTABLE_DATA (x) [scm_si_redefined]))

typedef struct scm_effective_slot_definition {
  SCM name;
  long location;
  SCM init_value;
  SCM (*get) (SCM obj, SCM slotdef);
  SCM (*set) (SCM obj, SCM slotdef, SCM value);
} scm_effective_slot_definition;

#define SCM_ESLOTDEF(x) ((scm_effective_slot_definition *) SCM_CDR (x))

#define SCM_CMETHOD_CODE(cmethod) SCM_CDR (cmethod)
#define SCM_CMETHOD_ENV(cmethod)  SCM_CAR (cmethod)

/* Port classes */
#define SCM_IN_PCLASS_INDEX    0x000
#define SCM_OUT_PCLASS_INDEX   0x100
#define SCM_INOUT_PCLASS_INDEX 0x200

/* Plugin proxy classes for basic types. */
extern SCM scm_metaclass_standard;
extern SCM scm_metaclass_operator;
extern SCM scm_class_boolean, scm_class_char, scm_class_pair;
extern SCM scm_class_procedure, scm_class_string, scm_class_symbol;
extern SCM scm_class_procedure_with_setter, scm_class_primitive_generic;
extern SCM scm_class_vector, scm_class_null;
extern SCM scm_class_real, scm_class_complex, scm_class_integer;
extern SCM scm_class_unknown;
extern SCM *scm_port_class;
extern SCM *scm_smob_class;

extern SCM scm_no_applicable_method;

/* Goops functions. */
extern SCM scm_make_extended_class (char *type_name);
extern void scm_make_port_classes (scm_bits_t ptobnum, char *type_name);
extern void scm_change_object_class (SCM, SCM, SCM);
extern SCM scm_memoize_method (SCM x, SCM args);

extern SCM scm_class_of (SCM obj);
extern SCM scm_mcache_lookup_cmethod (SCM cache, SCM args);
extern SCM scm_mcache_compute_cmethod (SCM cache, SCM args);
/* The following are declared in __scm.h
extern SCM scm_call_generic_0 (SCM gf);
extern SCM scm_call_generic_1 (SCM gf, SCM a1);
extern SCM scm_call_generic_2 (SCM gf, SCM a1, SCM a2);
extern SCM scm_apply_generic (SCM gf, SCM args);
*/
extern SCM scm_call_generic_3 (SCM gf, SCM a1, SCM a2, SCM a3);
extern SCM scm_entity_p (SCM obj);
extern SCM scm_operator_p (SCM obj);
extern SCM scm_valid_object_procedure_p (SCM proc);
extern SCM scm_set_object_procedure_x (SCM obj, SCM proc);
#ifdef GUILE_DEBUG
extern SCM scm_object_procedure (SCM obj);
#endif
extern SCM scm_make_class_object (SCM metaclass, SCM layout);
extern SCM scm_make_subclass_object (SCM c, SCM layout);

extern SCM scm_i_make_class_object (SCM metaclass, SCM layout_string,
				    scm_ubits_t flags);
extern void scm_init_objects (void);

#endif /* OBJECTSH */

/*
  Local Variables:
  c-file-style: "gnu"
  End:
*/