libguile/objects.h

   1 /* classes: h_files */
   2
   3 #ifndef OBJECTSH
   4 #define OBJECTSH
   5
   6 /*      Copyright (C) 1996, 1999, 2000 Free Software Foundation, Inc.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2, or (at your option)
  11  * any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this software; see the file COPYING.  If not, write to
  20  * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  21  * Boston, MA 02111-1307 USA
  22  *
  23  * As a special exception, the Free Software Foundation gives permission
  24  * for additional uses of the text contained in its release of GUILE.
  25  *
  26  * The exception is that, if you link the GUILE library with other files
  27  * to produce an executable, this does not by itself cause the
  28  * resulting executable to be covered by the GNU General Public License.
  29  * Your use of that executable is in no way restricted on account of
  30  * linking the GUILE library code into it.
  31  *
  32  * This exception does not however invalidate any other reasons why
  33  * the executable file might be covered by the GNU General Public License.
  34  *
  35  * This exception applies only to the code released by the
  36  * Free Software Foundation under the name GUILE.  If you copy
  37  * code from other Free Software Foundation releases into a copy of
  38  * GUILE, as the General Public License permits, the exception does
  39  * not apply to the code that you add in this way.  To avoid misleading
  40  * anyone as to the status of such modified files, you must delete
  41  * this exception notice from them.
  42  *
  43  * If you write modifications of your own for GUILE, it is your choice
  44  * whether to permit this exception to apply to your modifications.
  45  * If you do not wish that, delete this exception notice.  */
  46 \f
  47
  48 /* This file and objects.c contains those minimal pieces of the Guile
  49  * Object Oriented Programming System which need to be included in
  50  * libguile.
  51  *
  52  * {Objects and structs}
  53  *
  54  * Objects are currently based upon structs.  Although the struct
  55  * implementation will change thoroughly in the future, objects will
  56  * still be based upon structs.
  57  */
  58
  59 #include "libguile/__scm.h"
  60 #include "libguile/struct.h"
  61
  62 \f
  63
  64 /* {Class flags}
  65  *
  66  * These are used for efficient identification of instances of a
  67  * certain class or its subclasses when traversal of the inheritance
  68  * graph would be too costly.
  69  */
  70 #define SCM_CLASS_FLAGS(class)\
  71         SCM_ASWORD (SCM_STRUCT_DATA (class)[scm_struct_i_flags])
  72 #define SCM_OBJ_CLASS_FLAGS(obj)\
  73         SCM_ASWORD (SCM_STRUCT_VTABLE_DATA (obj)[scm_struct_i_flags])
  74 #define SCM_SET_CLASS_FLAGS(c, f) (SCM_CLASS_FLAGS (c) |= (f))
  75 #define SCM_CLEAR_CLASS_FLAGS(c, f) (SCM_CLASS_FLAGS (c) &= ~(f))
  76 #define SCM_CLASSF_MASK SCM_STRUCTF_MASK
  77
  78 #define SCM_CLASSF_ENTITY       SCM_STRUCTF_ENTITY
  79 /* Operator classes need to be identified in the evaluator.
  80    (Entities also have SCM_CLASSF_OPERATOR set in their vtable.) */
  81 #define SCM_CLASSF_OPERATOR     (1L << 29)
  82
  83 #define SCM_I_OPERATORP(obj)\
  84         ((SCM_OBJ_CLASS_FLAGS (obj) & SCM_CLASSF_OPERATOR) != 0)
  85 #define SCM_OPERATOR_CLASS(obj)\
  86 ((struct scm_metaclass_operator *) SCM_STRUCT_DATA (obj))
  87 #define SCM_OBJ_OPERATOR_CLASS(obj)\
  88 ((struct scm_metaclass_operator *) SCM_STRUCT_VTABLE_DATA (obj))
  89 #define SCM_OPERATOR_PROCEDURE(obj) (SCM_OBJ_OPERATOR_CLASS (obj)->procedure)
  90 #define SCM_OPERATOR_SETTER(obj) (SCM_OBJ_OPERATOR_CLASS (obj)->setter)
  91
  92 #define SCM_I_ENTITYP(obj)\
  93         ((SCM_OBJ_CLASS_FLAGS (obj) & SCM_CLASSF_ENTITY) != 0)
  94 #define SCM_ENTITY_PROCEDURE(obj) \
  95         (SCM_STRUCT_DATA (obj)[scm_struct_i_procedure])
  96 #define SCM_ENTITY_SETTER(obj) (SCM_STRUCT_DATA (obj)[scm_struct_i_setter])
  97
  98 #define SCM_SET_CLASS_DESTRUCTOR(c, d) SCM_SET_VTABLE_DESTRUCTOR (c, d)
  99 #define SCM_SET_CLASS_INSTANCE_SIZE(c, s) \
 100 (SCM_STRUCT_DATA (c)[scm_struct_i_size] \
 101  = SCM_ASSCM ((SCM_ASWORD (SCM_STRUCT_DATA (c)[scm_struct_i_size])\
 102                & SCM_STRUCTF_MASK)\
 103               | s))
 104
 105 /* {Operator classes}
 106  *
 107  * Instances of operator classes can work as operators, i. e., they
 108  * can be applied to arguments just as if they were ordinary
 109  * procedures.
 110  *
 111  * For instances of operator classes, the procedures to be applied are
 112  * stored in four dedicated slots in the associated class object.
 113  * Which one is selected depends on the number of arguments in the
 114  * application.
 115  *
 116  * If zero arguments are passed, the first will be selected.
 117  * If one argument is passed, the second will be selected.
 118  * If two arguments are passed, the third will be selected.
 119  * If three or more arguments are passed, the fourth will be selected.
 120  *
 121  * This is complicated and may seem gratuitous but has to do with the
 122  * architecture of the evaluator.  Using only one procedure would
 123  * result in a great deal less efficient application, loss of
 124  * tail-recursion and would be difficult to reconcile with the
 125  * debugging evaluator.
 126  *
 127  * Also, using this "forked" application in low-level code has the
 128  * advantage of speeding up some code.  An example is method dispatch
 129  * for generic operators applied to few arguments.  On the user level,
 130  * the "forked" application will be hidden by mechanisms in the GOOPS
 131  * package.
 132  *
 133  * Operator classes have the metaclass <operator-metaclass>.
 134  *
 135  * An example of an operator class is the class <tk-command>.
 136  */
 137 #define SCM_METACLASS_STANDARD_LAYOUT ""
 138 struct scm_metaclass_standard {
 139   SCM layout;
 140   SCM vcell;
 141   SCM vtable;
 142   SCM print;
 143 };
 144
 145 #define SCM_METACLASS_OPERATOR_LAYOUT "popo"
 146 struct scm_metaclass_operator {
 147   SCM layout;
 148   SCM vcell;
 149   SCM vtable;
 150   SCM print;
 151   SCM procedure;
 152   SCM setter;
 153 };
 154
 155 /* {Entity classes}
 156  *
 157  * For instances of entity classes (entities), the procedures to be
 158  * applied are stored in the instance itself rather than in the class
 159  * object as is the case for instances of operator classes (see above).
 160  *
 161  * An example of an entity class is the class of generic methods.
 162  */
 163 #define SCM_ENTITY_LAYOUT ""
 164
 165 /* {Interface to Goops}
 166  *
 167  * The evaluator contains a multi-method dispatch mechanism.
 168  * This interface is used by that mechanism and during creation of
 169  * smob and struct classes.
 170  */
 171
 172 /* Internal representation of Goops objects. */
 173 #define SCM_CLASSF_PURE_GENERIC (0x010 << 20)
 174 #define SCM_CLASSF_GOOPS_VALID  (0x080 << 20)
 175 #define SCM_CLASSF_GOOPS        (0x100 << 20)
 176 #define scm_si_redefined         6
 177 #define scm_si_hashsets          7
 178 #define SCM_CLASS_OF(x)         SCM_STRUCT_VTABLE (x)
 179 #define SCM_OBJ_CLASS_REDEF(x)  (SCM_STRUCT_VTABLE_DATA(x)[scm_si_redefined])
 180
 181 typedef struct scm_effective_slot_definition {
 182   SCM name;
 183   long location;
 184   SCM init_value;
 185   SCM (*get) (SCM obj, SCM slotdef);
 186   SCM (*set) (SCM obj, SCM slotdef, SCM value);
 187 } scm_effective_slot_definition;
 188
 189 #define SCM_ESLOTDEF(x) ((scm_effective_slot_definition *) SCM_CDR (x))
 190
 191 #define SCM_CMETHOD_CODE(cmethod) SCM_CDR (cmethod)
 192 #define SCM_CMETHOD_ENV(cmethod)  SCM_CAR (cmethod)
 193
 194 /* Port classes */
 195 #define SCM_IN_PCLASS_INDEX    0x000
 196 #define SCM_OUT_PCLASS_INDEX   0x100
 197 #define SCM_INOUT_PCLASS_INDEX 0x200
 198
 199 /* Plugin proxy classes for basic types. */
 200 extern SCM scm_metaclass_standard;
 201 extern SCM scm_metaclass_operator;
 202 extern SCM scm_class_boolean, scm_class_char, scm_class_pair;
 203 extern SCM scm_class_procedure, scm_class_string, scm_class_symbol;
 204 extern SCM scm_class_procedure_with_setter, scm_class_primitive_generic;
 205 extern SCM scm_class_vector, scm_class_null;
 206 extern SCM scm_class_real, scm_class_complex, scm_class_integer;
 207 extern SCM scm_class_unknown;
 208 extern SCM *scm_port_class;
 209 extern SCM *scm_smob_class;
 210
 211 extern SCM scm_no_applicable_method;
 212
 213 /* Plugin Goops functions. */
 214 extern SCM (*scm_make_extended_class) (char *type_name);
 215 extern void (*scm_make_port_classes) (int ptobnum, char *type_name);
 216 extern void (*scm_change_object_class) (SCM, SCM, SCM);
 217 extern SCM (*scm_memoize_method) (SCM x, SCM args);
 218
 219 extern SCM scm_class_of (SCM obj);
 220 extern SCM scm_mcache_lookup_cmethod (SCM cache, SCM args);
 221 extern SCM scm_mcache_compute_cmethod (SCM cache, SCM args);
 222 extern SCM scm_call_generic_0 (SCM gf);
 223 /* The following are declared in __scm.h
 224 extern SCM scm_call_generic_1 (SCM gf, SCM a1);
 225 extern SCM scm_call_generic_2 (SCM gf, SCM a1, SCM a2);
 226 */
 227 extern SCM scm_call_generic_3 (SCM gf, SCM a1, SCM a2, SCM a3);
 228 extern SCM scm_apply_generic (SCM gf, SCM args);
 229 extern SCM scm_entity_p (SCM obj);
 230 extern SCM scm_operator_p (SCM obj);
 231 extern SCM scm_set_object_procedure_x (SCM obj, SCM procs);
 232 #ifdef GUILE_DEBUG
 233 extern SCM scm_object_procedure (SCM obj);
 234 #endif
 235 extern SCM scm_make_class_object (SCM metaclass, SCM layout);
 236 extern SCM scm_make_subclass_object (SCM c, SCM layout);
 237
 238 extern SCM scm_i_make_class_object (SCM metaclass, SCM layout_string,
 239                                     unsigned long flags);
 240 extern void scm_init_objects (void);
 241
 242 #endif /* OBJECTSH */