libguile/objects.c

   1 /* Copyright (C) 1995,1996,1999,2000,2001, 2003 Free Software Foundation, Inc.
   2  *
   3  * This library is free software; you can redistribute it and/or
   4  * modify it under the terms of the GNU Lesser General Public
   5  * License as published by the Free Software Foundation; either
   6  * version 2.1 of the License, or (at your option) any later version.
   7  *
   8  * This library is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * Lesser General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public
  14  * License along with this library; if not, write to the Free Software
  15  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  16  */
  17
  18
  19 \f
  20
  21 /* This file and objects.h contains those minimal pieces of the Guile
  22  * Object Oriented Programming System which need to be included in
  23  * libguile.  See the comments in objects.h.
  24  */
  25
  26 #include "libguile/_scm.h"
  27
  28 #include "libguile/struct.h"
  29 #include "libguile/procprop.h"
  30 #include "libguile/chars.h"
  31 #include "libguile/keywords.h"
  32 #include "libguile/smob.h"
  33 #include "libguile/eval.h"
  34 #include "libguile/alist.h"
  35 #include "libguile/ports.h"
  36 #include "libguile/strings.h"
  37 #include "libguile/vectors.h"
  38
  39 #include "libguile/validate.h"
  40 #include "libguile/objects.h"
  41 \f
  42
  43 SCM scm_metaclass_standard;
  44 SCM scm_metaclass_operator;
  45
  46 /* These variables are filled in by the object system when loaded. */
  47 SCM scm_class_boolean, scm_class_char, scm_class_pair;
  48 SCM scm_class_procedure, scm_class_string, scm_class_symbol;
  49 SCM scm_class_procedure_with_setter, scm_class_primitive_generic;
  50 SCM scm_class_vector, scm_class_null;
  51 SCM scm_class_integer, scm_class_real, scm_class_complex;
  52 SCM scm_class_unknown;
  53
  54 SCM *scm_port_class = 0;
  55 SCM *scm_smob_class = 0;
  56
  57 SCM scm_no_applicable_method;
  58
  59 /* This function is used for efficient type dispatch.  */
  60 SCM_DEFINE (scm_class_of, "class-of", 1, 0, 0,
  61             (SCM x),
  62             "Return the class of @var{x}.")
  63 #define FUNC_NAME s_scm_class_of
  64 {
  65   switch (SCM_ITAG3 (x))
  66     {
  67     case scm_tc3_int_1:
  68     case scm_tc3_int_2:
  69       return scm_class_integer;
  70
  71     case scm_tc3_imm24:
  72       if (SCM_CHARP (x))
  73         return scm_class_char;
  74       else
  75         {
  76           switch (SCM_ISYMNUM (x))
  77             {
  78             case SCM_ISYMNUM (SCM_BOOL_F):
  79             case SCM_ISYMNUM (SCM_BOOL_T):
  80               return scm_class_boolean;
  81             case SCM_ISYMNUM (SCM_EOL):
  82               return scm_class_null;
  83             default:
  84               return scm_class_unknown;
  85             }
  86         }
  87
  88     case scm_tc3_cons:
  89       switch (SCM_TYP7 (x))
  90         {
  91         case scm_tcs_cons_nimcar:
  92           return scm_class_pair;
  93         case scm_tcs_closures:
  94           return scm_class_procedure;
  95         case scm_tc7_symbol:
  96           return scm_class_symbol;
  97         case scm_tc7_vector:
  98         case scm_tc7_wvect:
  99 #if SCM_HAVE_ARRAYS
 100         case scm_tc7_bvect:
 101         case scm_tc7_byvect:
 102         case scm_tc7_svect:
 103         case scm_tc7_ivect:
 104         case scm_tc7_uvect:
 105         case scm_tc7_fvect:
 106         case scm_tc7_dvect:
 107         case scm_tc7_cvect:
 108 #endif
 109           return scm_class_vector;
 110         case scm_tc7_string:
 111           return scm_class_string;
 112         case scm_tc7_asubr:
 113         case scm_tc7_subr_0:
 114         case scm_tc7_subr_1:
 115         case scm_tc7_cxr:
 116         case scm_tc7_subr_3:
 117         case scm_tc7_subr_2:
 118         case scm_tc7_rpsubr:
 119         case scm_tc7_subr_1o:
 120         case scm_tc7_subr_2o:
 121         case scm_tc7_lsubr_2:
 122         case scm_tc7_lsubr:
 123           if (SCM_SUBR_GENERIC (x) && *SCM_SUBR_GENERIC (x))
 124             return scm_class_primitive_generic;
 125           else
 126             return scm_class_procedure;
 127         case scm_tc7_cclo:
 128           return scm_class_procedure;
 129         case scm_tc7_pws:
 130           return scm_class_procedure_with_setter;
 131
 132         case scm_tc7_smob:
 133           {
 134             scm_t_bits type = SCM_TYP16 (x);
 135             if (type != scm_tc16_port_with_ps)
 136               return scm_smob_class[SCM_TC2SMOBNUM (type)];
 137             x = SCM_PORT_WITH_PS_PORT (x);
 138             /* fall through to ports */
 139           }
 140         case scm_tc7_port:
 141           return scm_port_class[(SCM_WRTNG & SCM_CELL_WORD_0 (x)
 142                                  ? (SCM_RDNG & SCM_CELL_WORD_0 (x)
 143                                     ? SCM_INOUT_PCLASS_INDEX | SCM_PTOBNUM (x)
 144                                     : SCM_OUT_PCLASS_INDEX | SCM_PTOBNUM (x))
 145                                  : SCM_IN_PCLASS_INDEX | SCM_PTOBNUM (x))];
 146         case scm_tcs_struct:
 147           if (SCM_OBJ_CLASS_FLAGS (x) & SCM_CLASSF_GOOPS_VALID)
 148             return SCM_CLASS_OF (x);
 149           else if (SCM_OBJ_CLASS_FLAGS (x) & SCM_CLASSF_GOOPS)
 150             {
 151               /* Goops object */
 152               if (! SCM_FALSEP (SCM_OBJ_CLASS_REDEF (x)))
 153                 scm_change_object_class (x,
 154                                          SCM_CLASS_OF (x),         /* old */
 155                                          SCM_OBJ_CLASS_REDEF (x)); /* new */
 156               return SCM_CLASS_OF (x);
 157             }
 158           else
 159             {
 160               /* ordinary struct */
 161               SCM handle = scm_struct_create_handle (SCM_STRUCT_VTABLE (x));
 162               if (!SCM_FALSEP (SCM_STRUCT_TABLE_CLASS (SCM_CDR (handle))))
 163                 return SCM_STRUCT_TABLE_CLASS (SCM_CDR (handle));
 164               else
 165                 {
 166                   SCM name = SCM_STRUCT_TABLE_NAME (SCM_CDR (handle));
 167                   SCM class = scm_make_extended_class (!SCM_FALSEP (name)
 168                                                        ? SCM_SYMBOL_CHARS (name)
 169                                                        : 0,
 170                                                        SCM_I_OPERATORP (x));
 171                   SCM_SET_STRUCT_TABLE_CLASS (SCM_CDR (handle), class);
 172                   return class;
 173                 }
 174             }
 175         default:
 176           if (SCM_CONSP (x))
 177             return scm_class_pair;
 178           else
 179             return scm_class_unknown;
 180         }
 181
 182     case scm_tc3_struct:
 183     case scm_tc3_tc7_1:
 184     case scm_tc3_tc7_2:
 185     case scm_tc3_closure:
 186       /* Never reached */
 187       break;
 188     }
 189   return scm_class_unknown;
 190 }
 191 #undef FUNC_NAME
 192
 193 /* The cache argument for scm_mcache_lookup_cmethod has one of two possible
 194  * formats:
 195  *
 196  * Format #1:
 197  * (SCM_IM_DISPATCH ARGS N-SPECIALIZED
 198  *   #((TYPE1 ... ENV FORMALS FORM ...) ...)
 199  *   GF)
 200  *
 201  * Format #2:
 202  * (SCM_IM_HASH_DISPATCH ARGS N-SPECIALIZED HASHSET MASK
 203  *   #((TYPE1 ... ENV FORMALS FORM ...) ...)
 204  *   GF)
 205  *
 206  * ARGS is either a list of expressions, in which case they
 207  * are interpreted as the arguments of an application, or
 208  * a non-pair, which is interpreted as a single expression
 209  * yielding all arguments.
 210  *
 211  * SCM_IM_DISPATCH expressions in generic functions always
 212  * have ARGS = the symbol `args' or the iloc #@0-0.
 213  *
 214  * Need FORMALS in order to support varying arity.  This
 215  * also avoids the need for renaming of bindings.
 216  *
 217  * We should probably not complicate this mechanism by
 218  * introducing "optimizations" for getters and setters or
 219  * primitive methods.  Getters and setter will normally be
 220  * compiled into @slot-[ref|set!] or a procedure call.
 221  * They rely on the dispatch performed before executing
 222  * the code which contains them.
 223  *
 224  * We might want to use a more efficient representation of
 225  * this form in the future, perhaps after we have introduced
 226  * low-level support for syntax-case macros.
 227  */
 228
 229 SCM
 230 scm_mcache_lookup_cmethod (SCM cache, SCM args)
 231 {
 232   long i, n, end, mask;
 233   SCM ls, methods, z = SCM_CDDR (cache);
 234   n = SCM_INUM (SCM_CAR (z)); /* maximum number of specializers */
 235   methods = SCM_CADR (z);
 236
 237   if (SCM_INUMP (methods))
 238     {
 239       /* cache format #2: compute a hash value */
 240       long hashset = SCM_INUM (methods);
 241       long j = n;
 242       z = SCM_CDDR (z);
 243       mask = SCM_INUM (SCM_CAR (z));
 244       methods = SCM_CADR (z);
 245       i = 0;
 246       ls = args;
 247       if (!SCM_NULLP (ls))
 248         do
 249           {
 250             i += SCM_STRUCT_DATA (scm_class_of (SCM_CAR (ls)))
 251                  [scm_si_hashsets + hashset];
 252             ls = SCM_CDR (ls);
 253           }
 254         while (j-- && !SCM_NULLP (ls));
 255       i &= mask;
 256       end = i;
 257     }
 258   else /* SCM_VECTORP (methods) */
 259     {
 260       /* cache format #1: prepare for linear search */
 261       mask = -1;
 262       i = 0;
 263       end = SCM_VECTOR_LENGTH (methods);
 264     }
 265
 266   /* Search for match  */
 267   do
 268     {
 269       long j = n;
 270       z = SCM_VELTS (methods)[i];
 271       ls = args; /* list of arguments */
 272       if (!SCM_NULLP (ls))
 273         do
 274           {
 275             /* More arguments than specifiers => CLASS != ENV */
 276             if (! SCM_EQ_P (scm_class_of (SCM_CAR (ls)), SCM_CAR (z)))
 277               goto next_method;
 278             ls = SCM_CDR (ls);
 279             z = SCM_CDR (z);
 280           }
 281         while (j-- && !SCM_NULLP (ls));
 282       /* Fewer arguments than specifiers => CAR != ENV */
 283       if (SCM_NULLP (SCM_CAR (z)) || SCM_CONSP (SCM_CAR (z)))
 284         return z;
 285     next_method:
 286       i = (i + 1) & mask;
 287     } while (i != end);
 288   return SCM_BOOL_F;
 289 }
 290
 291 SCM
 292 scm_mcache_compute_cmethod (SCM cache, SCM args)
 293 {
 294   SCM cmethod = scm_mcache_lookup_cmethod (cache, args);
 295   if (SCM_FALSEP (cmethod))
 296     /* No match - memoize */
 297     return scm_memoize_method (cache, args);
 298   return cmethod;
 299 }
 300
 301 SCM
 302 scm_apply_generic (SCM gf, SCM args)
 303 {
 304   SCM cmethod = scm_mcache_compute_cmethod (SCM_ENTITY_PROCEDURE (gf), args);
 305   return scm_eval_body (SCM_CDR (SCM_CMETHOD_CODE (cmethod)),
 306                         SCM_EXTEND_ENV (SCM_CAR (SCM_CMETHOD_CODE (cmethod)),
 307                                         args,
 308                                         SCM_CMETHOD_ENV (cmethod)));
 309 }
 310
 311 SCM
 312 scm_call_generic_0 (SCM gf)
 313 {
 314   return scm_apply_generic (gf, SCM_EOL);
 315 }
 316
 317 SCM
 318 scm_call_generic_1 (SCM gf, SCM a1)
 319 {
 320   return scm_apply_generic (gf, scm_list_1 (a1));
 321 }
 322
 323 SCM
 324 scm_call_generic_2 (SCM gf, SCM a1, SCM a2)
 325 {
 326   return scm_apply_generic (gf, scm_list_2 (a1, a2));
 327 }
 328
 329 SCM
 330 scm_call_generic_3 (SCM gf, SCM a1, SCM a2, SCM a3)
 331 {
 332   return scm_apply_generic (gf, scm_list_3 (a1, a2, a3));
 333 }
 334
 335 SCM_DEFINE (scm_entity_p, "entity?", 1, 0, 0,
 336             (SCM obj),
 337             "Return @code{#t} if @var{obj} is an entity.")
 338 #define FUNC_NAME s_scm_entity_p
 339 {
 340   return SCM_BOOL(SCM_STRUCTP (obj) && SCM_I_ENTITYP (obj));
 341 }
 342 #undef FUNC_NAME
 343
 344 SCM_DEFINE (scm_operator_p, "operator?", 1, 0, 0,
 345             (SCM obj),
 346             "Return @code{#t} if @var{obj} is an operator.")
 347 #define FUNC_NAME s_scm_operator_p
 348 {
 349   return SCM_BOOL(SCM_STRUCTP (obj)
 350                   && SCM_I_OPERATORP (obj)
 351                   && !SCM_I_ENTITYP (obj));
 352 }
 353 #undef FUNC_NAME
 354
 355 /* XXX - What code requires the object procedure to be only of certain
 356          types? */
 357
 358 SCM_DEFINE (scm_valid_object_procedure_p, "valid-object-procedure?", 1, 0, 0,
 359             (SCM proc),
 360             "Return @code{#t} iff @var{proc} is a procedure that can be used "
 361             "with @code{set-object-procedure}.  It is always valid to use "
 362             "a closure constructed by @code{lambda}.")
 363 #define FUNC_NAME s_scm_valid_object_procedure_p
 364 {
 365   if (SCM_IMP (proc))
 366     return SCM_BOOL_F;
 367   switch (SCM_TYP7 (proc))
 368     {
 369     default:
 370       return SCM_BOOL_F;
 371     case scm_tcs_closures:
 372     case scm_tc7_subr_1:
 373     case scm_tc7_subr_2:
 374     case scm_tc7_subr_3:
 375     case scm_tc7_lsubr_2:
 376       return SCM_BOOL_T;
 377     }
 378 }
 379 #undef FUNC_NAME
 380
 381 SCM_DEFINE (scm_set_object_procedure_x, "set-object-procedure!", 2, 0, 0,
 382             (SCM obj, SCM proc),
 383             "Set the object procedure of @var{obj} to @var{proc}.\n"
 384             "@var{obj} must be either an entity or an operator.")
 385 #define FUNC_NAME s_scm_set_object_procedure_x
 386 {
 387   SCM_ASSERT (SCM_STRUCTP (obj)
 388               && ((SCM_CLASS_FLAGS (obj) & SCM_CLASSF_OPERATOR)
 389                   || (SCM_I_ENTITYP (obj)
 390                       && !(SCM_OBJ_CLASS_FLAGS (obj)
 391                            & SCM_CLASSF_PURE_GENERIC))),
 392               obj,
 393               SCM_ARG1,
 394               FUNC_NAME);
 395   SCM_ASSERT (scm_valid_object_procedure_p (proc), proc, SCM_ARG2, FUNC_NAME);
 396   if (SCM_I_ENTITYP (obj))
 397     SCM_SET_ENTITY_PROCEDURE (obj, proc);
 398   else
 399     SCM_OPERATOR_CLASS (obj)->procedure = proc;
 400   return SCM_UNSPECIFIED;
 401 }
 402 #undef FUNC_NAME
 403
 404 #ifdef GUILE_DEBUG
 405 SCM_DEFINE (scm_object_procedure, "object-procedure", 1, 0, 0,
 406             (SCM obj),
 407             "Return the object procedure of @var{obj}. @var{obj} must be\n"
 408             "an entity or an operator.")
 409 #define FUNC_NAME s_scm_object_procedure
 410 {
 411   SCM_ASSERT (SCM_STRUCTP (obj)
 412               && ((SCM_CLASS_FLAGS (obj) & SCM_CLASSF_OPERATOR)
 413                   || SCM_I_ENTITYP (obj)),
 414               obj, SCM_ARG1, FUNC_NAME);
 415   return (SCM_I_ENTITYP (obj)
 416           ? SCM_ENTITY_PROCEDURE (obj)
 417           : SCM_OPERATOR_CLASS (obj)->procedure);
 418 }
 419 #undef FUNC_NAME
 420 #endif /* GUILE_DEBUG */
 421
 422 /* The following procedures are not a part of Goops but a minimal
 423  * object system built upon structs.  They are here for those who
 424  * want to implement their own object system.
 425  */
 426
 427 SCM
 428 scm_i_make_class_object (SCM meta,
 429                          SCM layout_string,
 430                          unsigned long flags)
 431 {
 432   SCM c;
 433   SCM layout = scm_make_struct_layout (layout_string);
 434   c = scm_make_struct (meta,
 435                        SCM_INUM0,
 436                        scm_list_4 (layout, SCM_BOOL_F, SCM_EOL, SCM_EOL));
 437   SCM_SET_CLASS_FLAGS (c, flags);
 438   return c;
 439 }
 440
 441 SCM_DEFINE (scm_make_class_object, "make-class-object", 2, 0, 0,
 442             (SCM metaclass, SCM layout),
 443             "Create a new class object of class @var{metaclass}, with the\n"
 444             "slot layout specified by @var{layout}.")
 445 #define FUNC_NAME s_scm_make_class_object
 446 {
 447   unsigned long flags = 0;
 448   SCM_VALIDATE_STRUCT (1, metaclass);
 449   SCM_VALIDATE_STRING (2, layout);
 450   if (SCM_EQ_P (metaclass, scm_metaclass_operator))
 451     flags = SCM_CLASSF_OPERATOR;
 452   return scm_i_make_class_object (metaclass, layout, flags);
 453 }
 454 #undef FUNC_NAME
 455
 456 SCM_DEFINE (scm_make_subclass_object, "make-subclass-object", 2, 0, 0,
 457             (SCM class, SCM layout),
 458             "Create a subclass object of @var{class}, with the slot layout\n"
 459             "specified by @var{layout}.")
 460 #define FUNC_NAME s_scm_make_subclass_object
 461 {
 462   SCM pl;
 463   SCM_VALIDATE_STRUCT (1, class);
 464   SCM_VALIDATE_STRING (2, layout);
 465   pl = SCM_PACK (SCM_STRUCT_DATA (class) [scm_vtable_index_layout]);
 466   /* Convert symbol->string */
 467   pl = scm_mem2string (SCM_SYMBOL_CHARS (pl), SCM_SYMBOL_LENGTH (pl));
 468   return scm_i_make_class_object (SCM_STRUCT_VTABLE (class),
 469                                   scm_string_append (scm_list_2 (pl, layout)),
 470                                   SCM_CLASS_FLAGS (class));
 471 }
 472 #undef FUNC_NAME
 473
 474 void
 475 scm_init_objects ()
 476 {
 477   SCM ms = scm_makfrom0str (SCM_METACLASS_STANDARD_LAYOUT);
 478   SCM mt = scm_make_vtable_vtable (ms, SCM_INUM0,
 479                                    scm_list_3 (SCM_BOOL_F, SCM_EOL, SCM_EOL));
 480
 481   SCM os = scm_makfrom0str (SCM_METACLASS_OPERATOR_LAYOUT);
 482   SCM ot = scm_make_vtable_vtable (os, SCM_INUM0,
 483                                    scm_list_3 (SCM_BOOL_F, SCM_EOL, SCM_EOL));
 484
 485   SCM es = scm_makfrom0str (SCM_ENTITY_LAYOUT);
 486   SCM el = scm_make_struct_layout (es);
 487   SCM et = scm_make_struct (mt, SCM_INUM0,
 488                             scm_list_4 (el, SCM_BOOL_F, SCM_EOL, SCM_EOL));
 489
 490   scm_c_define ("<class>", mt);
 491   scm_metaclass_standard = mt;
 492   scm_c_define ("<operator-class>", ot);
 493   scm_metaclass_operator = ot;
 494   SCM_SET_CLASS_FLAGS (et, SCM_CLASSF_OPERATOR | SCM_CLASSF_ENTITY);
 495   SCM_SET_CLASS_DESTRUCTOR (et, scm_struct_free_entity);
 496   scm_c_define ("<entity>", et);
 497
 498 #include "libguile/objects.x"
 499 }
 500
 501 /*
 502   Local Variables:
 503   c-file-style: "gnu"
 504   End:
 505 */