libguile/objects.h

   1 /* classes: h_files */
   2
   3 #ifndef SCM_OBJECTS_H
   4 #define SCM_OBJECTS_H
   5
   6 /* Copyright (C) 1996,1999,2000,2001, 2003, 2006, 2008, 2009 Free Software Foundation, Inc.
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * This library 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 GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 \f
  24
  25 /* This file and objects.c contains those minimal pieces of the Guile
  26  * Object Oriented Programming System which need to be included in
  27  * libguile.
  28  *
  29  * {Objects and structs}
  30  *
  31  * Objects are currently based upon structs.  Although the struct
  32  * implementation will change thoroughly in the future, objects will
  33  * still be based upon structs.
  34  */
  35
  36 #include "libguile/__scm.h"
  37 #include "libguile/struct.h"
  38
  39 \f
  40
  41 /* {Class flags}
  42  *
  43  * These are used for efficient identification of instances of a
  44  * certain class or its subclasses when traversal of the inheritance
  45  * graph would be too costly.
  46  */
  47 #define SCM_CLASS_FLAGS(class) (SCM_STRUCT_DATA (class) [scm_struct_i_flags])
  48 #define SCM_OBJ_CLASS_FLAGS(obj) (SCM_STRUCT_VTABLE_DATA (obj) [scm_struct_i_flags])
  49 #define SCM_SET_CLASS_FLAGS(c, f) (SCM_CLASS_FLAGS (c) |= (f))
  50 #define SCM_CLEAR_CLASS_FLAGS(c, f) (SCM_CLASS_FLAGS (c) &= ~(f))
  51 #define SCM_CLASSF_MASK SCM_STRUCTF_MASK
  52
  53 #define SCM_CLASSF_ENTITY       SCM_STRUCTF_ENTITY
  54 /* Operator classes need to be identified in the evaluator.
  55    (Entities also have SCM_CLASSF_OPERATOR set in their vtable.) */
  56 #define SCM_CLASSF_OPERATOR     (1L << 29)
  57
  58 #define SCM_I_OPERATORP(obj)\
  59         ((SCM_OBJ_CLASS_FLAGS (obj) & SCM_CLASSF_OPERATOR) != 0)
  60 #define SCM_OPERATOR_CLASS(obj)\
  61 ((struct scm_metaclass_operator *) SCM_STRUCT_DATA (obj))
  62 #define SCM_OBJ_OPERATOR_CLASS(obj)\
  63 ((struct scm_metaclass_operator *) SCM_STRUCT_VTABLE_DATA (obj))
  64 #define SCM_OPERATOR_PROCEDURE(obj) (SCM_OBJ_OPERATOR_CLASS (obj)->procedure)
  65 #define SCM_OPERATOR_SETTER(obj) (SCM_OBJ_OPERATOR_CLASS (obj)->setter)
  66
  67 #define SCM_I_ENTITYP(obj)\
  68         ((SCM_OBJ_CLASS_FLAGS (obj) & SCM_CLASSF_ENTITY) != 0)
  69 #define SCM_ENTITY_PROCEDURE(obj) \
  70         (SCM_PACK (SCM_STRUCT_DATA (obj) [scm_struct_i_procedure]))
  71 #define SCM_SET_ENTITY_PROCEDURE(obj, v) \
  72         (SCM_STRUCT_DATA (obj) [scm_struct_i_procedure] = SCM_UNPACK (v))
  73 #define SCM_ENTITY_SETTER(obj) (SCM_PACK (SCM_STRUCT_DATA (obj)[scm_struct_i_setter]))
  74 #define SCM_SET_ENTITY_SETTER(obj, v) \
  75         (SCM_STRUCT_DATA (obj) [scm_struct_i_setter] = SCM_UNPACK (v))
  76
  77 #define SCM_SET_CLASS_DESTRUCTOR(c, d) SCM_SET_VTABLE_DESTRUCTOR (c, d)
  78 #define SCM_SET_CLASS_INSTANCE_SIZE(c, s) \
  79   (SCM_STRUCT_DATA (c)[scm_struct_i_size] \
  80    = (SCM_STRUCT_DATA (c) [scm_struct_i_size] & SCM_STRUCTF_MASK) | s)
  81
  82 /* {Operator classes}
  83  *
  84  * Instances of operator classes can work as operators, i. e., they
  85  * can be applied to arguments just as if they were ordinary
  86  * procedures.
  87  *
  88  * For instances of operator classes, the procedures to be applied are
  89  * stored in four dedicated slots in the associated class object.
  90  * Which one is selected depends on the number of arguments in the
  91  * application.
  92  *
  93  * If zero arguments are passed, the first will be selected.
  94  * If one argument is passed, the second will be selected.
  95  * If two arguments are passed, the third will be selected.
  96  * If three or more arguments are passed, the fourth will be selected.
  97  *
  98  * This is complicated and may seem gratuitous but has to do with the
  99  * architecture of the evaluator.  Using only one procedure would
 100  * result in a great deal less efficient application, loss of
 101  * tail-recursion and would be difficult to reconcile with the
 102  * debugging evaluator.
 103  *
 104  * Also, using this "forked" application in low-level code has the
 105  * advantage of speeding up some code.  An example is method dispatch
 106  * for generic operators applied to few arguments.  On the user level,
 107  * the "forked" application will be hidden by mechanisms in the GOOPS
 108  * package.
 109  *
 110  * Operator classes have the metaclass <operator-metaclass>.
 111  *
 112  * An example of an operator class is the class <tk-command>.
 113  */
 114 #define SCM_METACLASS_STANDARD_LAYOUT ""
 115 struct scm_metaclass_standard {
 116   SCM layout;
 117   SCM vcell;
 118   SCM vtable;
 119   SCM print;
 120 };
 121
 122 #define SCM_METACLASS_OPERATOR_LAYOUT "popo"
 123 struct scm_metaclass_operator {
 124   SCM layout;
 125   SCM vcell;
 126   SCM vtable;
 127   SCM print;
 128   SCM procedure;
 129   SCM setter;
 130 };
 131
 132 /* {Entity classes}
 133  *
 134  * For instances of entity classes (entities), the procedures to be
 135  * applied are stored in the instance itself rather than in the class
 136  * object as is the case for instances of operator classes (see above).
 137  *
 138  * An example of an entity class is the class of generic methods.
 139  */
 140 #define SCM_ENTITY_LAYOUT ""
 141
 142 /* {Interface to Goops}
 143  *
 144  * The evaluator contains a multi-method dispatch mechanism.
 145  * This interface is used by that mechanism and during creation of
 146  * smob and struct classes.
 147  */
 148
 149 /* Internal representation of Goops objects. */
 150 #define SCM_CLASSF_PURE_GENERIC (0x010 << 20)
 151 #define SCM_CLASSF_GOOPS_VALID  (0x080 << 20)
 152 #define SCM_CLASSF_GOOPS        (0x100 << 20)
 153 #define scm_si_redefined         5
 154 #define scm_si_hashsets          6
 155 #define SCM_CLASS_OF(x)         SCM_STRUCT_VTABLE (x)
 156 #define SCM_OBJ_CLASS_REDEF(x)  (SCM_PACK (SCM_STRUCT_VTABLE_DATA (x) [scm_si_redefined]))
 157
 158 typedef struct scm_effective_slot_definition {
 159   SCM name;
 160   long location;
 161   SCM init_value;
 162   SCM (*get) (SCM obj, SCM slotdef);
 163   SCM (*set) (SCM obj, SCM slotdef, SCM value);
 164 } scm_effective_slot_definition;
 165
 166 #define SCM_ESLOTDEF(x) ((scm_effective_slot_definition *) SCM_CDR (x))
 167
 168 #define SCM_CMETHOD_CODE(cmethod) SCM_CDR (cmethod)
 169 #define SCM_CMETHOD_FORMALS(cmethod) SCM_CAR (SCM_CMETHOD_CODE (cmethod))
 170 #define SCM_CMETHOD_BODY(cmethod) SCM_CDR (SCM_CMETHOD_CODE (cmethod))
 171 #define SCM_CMETHOD_ENV(cmethod)  SCM_CAR (cmethod)
 172
 173 /* Port classes */
 174 #define SCM_IN_PCLASS_INDEX       0
 175 #define SCM_OUT_PCLASS_INDEX      SCM_I_MAX_PORT_TYPE_COUNT
 176 #define SCM_INOUT_PCLASS_INDEX    (2 * SCM_I_MAX_PORT_TYPE_COUNT)
 177
 178 /* Plugin proxy classes for basic types. */
 179 SCM_API SCM scm_metaclass_standard;
 180 SCM_API SCM scm_metaclass_operator;
 181
 182 /* Goops functions. */
 183 SCM_API SCM scm_make_extended_class (char const *type_name, int applicablep);
 184 SCM_INTERNAL void scm_i_inherit_applicable (SCM c);
 185 SCM_API void scm_make_port_classes (long ptobnum, char *type_name);
 186 SCM_API void scm_change_object_class (SCM, SCM, SCM);
 187 SCM_API SCM scm_memoize_method (SCM x, SCM args);
 188
 189 SCM_API SCM scm_mcache_lookup_cmethod (SCM cache, SCM args);
 190 SCM_API SCM scm_mcache_compute_cmethod (SCM cache, SCM args);
 191 /* The following are declared in __scm.h
 192 SCM_API SCM scm_call_generic_0 (SCM gf);
 193 SCM_API SCM scm_call_generic_1 (SCM gf, SCM a1);
 194 SCM_API SCM scm_call_generic_2 (SCM gf, SCM a1, SCM a2);
 195 SCM_API SCM scm_apply_generic (SCM gf, SCM args);
 196 */
 197 SCM_API SCM scm_call_generic_3 (SCM gf, SCM a1, SCM a2, SCM a3);
 198 SCM_API SCM scm_entity_p (SCM obj);
 199 SCM_API SCM scm_operator_p (SCM obj);
 200 SCM_API SCM scm_valid_object_procedure_p (SCM proc);
 201 SCM_API SCM scm_set_object_procedure_x (SCM obj, SCM proc);
 202 #ifdef GUILE_DEBUG
 203 SCM_API SCM scm_object_procedure (SCM obj);
 204 #endif
 205 SCM_API SCM scm_make_class_object (SCM metaclass, SCM layout);
 206 SCM_API SCM scm_make_subclass_object (SCM c, SCM layout);
 207
 208 SCM_INTERNAL SCM scm_i_make_class_object (SCM metaclass, SCM layout_string,
 209                                           unsigned long flags);
 210 SCM_INTERNAL void scm_init_objects (void);
 211
 212 #endif  /* SCM_OBJECTS_H */
 213
 214 /*
 215   Local Variables:
 216   c-file-style: "gnu"
 217   End:
 218 */