libguile/objects.c

   1 /*      Copyright (C) 1995,1996 Free Software Foundation, Inc.
   2  *
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License as published by
   5  * the Free Software Foundation; either version 2, or (at your option)
   6  * any later version.
   7  *
   8  * This program 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
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * along with this software; see the file COPYING.  If not, write to
  15  * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  16  * Boston, MA 02111-1307 USA
  17  *
  18  * As a special exception, the Free Software Foundation gives permission
  19  * for additional uses of the text contained in its release of GUILE.
  20  *
  21  * The exception is that, if you link the GUILE library with other files
  22  * to produce an executable, this does not by itself cause the
  23  * resulting executable to be covered by the GNU General Public License.
  24  * Your use of that executable is in no way restricted on account of
  25  * linking the GUILE library code into it.
  26  *
  27  * This exception does not however invalidate any other reasons why
  28  * the executable file might be covered by the GNU General Public License.
  29  *
  30  * This exception applies only to the code released by the
  31  * Free Software Foundation under the name GUILE.  If you copy
  32  * code from other Free Software Foundation releases into a copy of
  33  * GUILE, as the General Public License permits, the exception does
  34  * not apply to the code that you add in this way.  To avoid misleading
  35  * anyone as to the status of such modified files, you must delete
  36  * this exception notice from them.
  37  *
  38  * If you write modifications of your own for GUILE, it is your choice
  39  * whether to permit this exception to apply to your modifications.
  40  * If you do not wish that, delete this exception notice.  */
  41 \f
  42
  43 /* This file and objects.h contains those minimal pieces of the Guile
  44  * Object Oriented Programming System which need to be included in
  45  * libguile.  See the comments in objects.h.
  46  */
  47
  48 #include "_scm.h"
  49
  50 #include "struct.h"
  51 #include "procprop.h"
  52 #include "chars.h"
  53 #include "keywords.h"
  54 #include "smob.h"
  55 #include "eval.h"
  56 #include "alist.h"
  57
  58 #include "objects.h"
  59 \f
  60
  61 SCM scm_metaclass_standard;
  62 SCM scm_metaclass_operator;
  63
  64 /* These variables are filled in by the object system when loaded. */
  65 SCM scm_class_boolean, scm_class_char, scm_class_pair;
  66 SCM scm_class_procedure, scm_class_string, scm_class_symbol;
  67 SCM scm_class_procedure_with_setter, scm_class_primitive_generic;
  68 SCM scm_class_vector, scm_class_null;
  69 SCM scm_class_integer, scm_class_real, scm_class_complex;
  70 SCM scm_class_unknown;
  71
  72 SCM *scm_port_class = 0;
  73 SCM *scm_smob_class = 0;
  74
  75 SCM scm_no_applicable_method;
  76
  77 SCM (*scm_make_extended_class) (char *type_name);
  78 void (*scm_make_port_classes) (int ptobnum, char *type_name);
  79 void (*scm_change_object_class) (SCM, SCM, SCM);
  80
  81 /* This function is used for efficient type dispatch.  */
  82 SCM
  83 scm_class_of (SCM x)
  84 {
  85   switch (SCM_ITAG3 (x))
  86     {
  87     case scm_tc3_int_1:
  88     case scm_tc3_int_2:
  89       return scm_class_integer;
  90
  91     case scm_tc3_imm24:
  92       if (SCM_ICHRP (x))
  93         return scm_class_char;
  94       else
  95         {
  96           switch (SCM_ISYMNUM (x))
  97             {
  98             case SCM_ISYMNUM (SCM_BOOL_F):
  99             case SCM_ISYMNUM (SCM_BOOL_T):
 100               return scm_class_boolean;
 101             case SCM_ISYMNUM (SCM_EOL):
 102               return scm_class_null;
 103             default:
 104               return scm_class_unknown;
 105             }
 106         }
 107
 108     case scm_tc3_cons:
 109       switch (SCM_TYP7 (x))
 110         {
 111         case scm_tcs_cons_nimcar:
 112           return scm_class_pair;
 113         case scm_tcs_closures:
 114           return scm_class_procedure;
 115         case scm_tcs_symbols:
 116           return scm_class_symbol;
 117         case scm_tc7_vector:
 118         case scm_tc7_wvect:
 119         case scm_tc7_bvect:
 120         case scm_tc7_byvect:
 121         case scm_tc7_svect:
 122         case scm_tc7_ivect:
 123         case scm_tc7_uvect:
 124         case scm_tc7_fvect:
 125         case scm_tc7_dvect:
 126         case scm_tc7_cvect:
 127           return scm_class_vector;
 128         case scm_tc7_string:
 129         case scm_tc7_substring:
 130           return scm_class_string;
 131         case scm_tc7_asubr:
 132         case scm_tc7_subr_0:
 133         case scm_tc7_subr_1:
 134         case scm_tc7_cxr:
 135         case scm_tc7_subr_3:
 136         case scm_tc7_subr_2:
 137         case scm_tc7_rpsubr:
 138         case scm_tc7_subr_1o:
 139         case scm_tc7_subr_2o:
 140         case scm_tc7_lsubr_2:
 141         case scm_tc7_lsubr:
 142           if (SCM_SUBR_GENERIC (x) && *SCM_SUBR_GENERIC (x))
 143             return scm_class_primitive_generic;
 144           else
 145             return scm_class_procedure;
 146         case scm_tc7_cclo:
 147           return scm_class_procedure;
 148         case scm_tc7_pws:
 149           return scm_class_procedure_with_setter;
 150
 151         case scm_tc7_smob:
 152           {
 153             SCM type = SCM_TYP16 (x);
 154             if (type == scm_tc16_flo)
 155               {
 156                 if (SCM_CAR (x) & SCM_IMAG_PART)
 157                   return scm_class_complex;
 158                 else
 159                   return scm_class_real;
 160               }
 161             else if (type != scm_tc16_port_with_ps)
 162               return scm_smob_class[SCM_TC2SMOBNUM (type)];
 163             x = SCM_PORT_WITH_PS_PORT (x);
 164             /* fall through to ports */
 165           }
 166         case scm_tc7_port:
 167           return scm_port_class[(SCM_WRTNG & SCM_CAR (x)
 168                                  ? (SCM_RDNG & SCM_CAR (x)
 169                                     ? SCM_INOUT_PCLASS_INDEX | SCM_PTOBNUM (x)
 170                                     : SCM_OUT_PCLASS_INDEX | SCM_PTOBNUM (x))
 171                                  : SCM_IN_PCLASS_INDEX | SCM_PTOBNUM (x))];
 172         case scm_tcs_cons_gloc:
 173           /* must be a struct */
 174           if (SCM_OBJ_CLASS_FLAGS (x) & SCM_CLASSF_GOOPS_VALID)
 175             return SCM_CLASS_OF (x);
 176           else if (SCM_OBJ_CLASS_FLAGS (x) & SCM_CLASSF_GOOPS)
 177             {
 178               /* Goops object */
 179               if (SCM_OBJ_CLASS_REDEF (x) != SCM_BOOL_F)
 180                 scm_change_object_class (x,
 181                                          SCM_CLASS_OF (x),         /* old */
 182                                          SCM_OBJ_CLASS_REDEF (x)); /* new */
 183               return SCM_CLASS_OF (x);
 184             }
 185           else
 186             {
 187               /* ordinary struct */
 188               SCM handle = scm_struct_create_handle (SCM_STRUCT_VTABLE (x));
 189               if (SCM_NFALSEP (SCM_STRUCT_TABLE_CLASS (SCM_CDR (handle))))
 190                 return SCM_STRUCT_TABLE_CLASS (SCM_CDR (handle));
 191               else
 192                 {
 193                   SCM name = SCM_STRUCT_TABLE_NAME (SCM_CDR (handle));
 194                   SCM class = scm_make_extended_class (SCM_NFALSEP (name)
 195                                                        ? SCM_ROCHARS (name)
 196                                                        : 0);
 197                   SCM_SET_STRUCT_TABLE_CLASS (handle, class);
 198                   return class;
 199                 }
 200             }
 201         default:
 202           if (SCM_CONSP (x))
 203             return scm_class_pair;
 204           else
 205             return scm_class_unknown;
 206         }
 207
 208     case scm_tc3_cons_gloc:
 209     case scm_tc3_tc7_1:
 210     case scm_tc3_tc7_2:
 211     case scm_tc3_closure:
 212       /* Never reached */
 213       break;
 214     }
 215   return scm_class_unknown;
 216 }
 217
 218 /* (SCM_IM_DISPATCH ARGS N-SPECIALIZED
 219  *   #((TYPE1 ... ENV FORMALS FORM ...) ...)
 220  *   GF)
 221  *
 222  * (SCM_IM_HASH_DISPATCH ARGS N-SPECIALIZED HASHSET MASK
 223  *   #((TYPE1 ... ENV FORMALS FORM ...) ...)
 224  *   GF)
 225  *
 226  * ARGS is either a list of expressions, in which case they
 227  * are interpreted as the arguments of an application, or
 228  * a non-pair, which is interpreted as a single expression
 229  * yielding all arguments.
 230  *
 231  * SCM_IM_DISPATCH expressions in generic functions always
 232  * have ARGS = the symbol `args' or the iloc #@0-0.
 233  *
 234  * Need FORMALS in order to support varying arity.  This
 235  * also avoids the need for renaming of bindings.
 236  *
 237  * We should probably not complicate this mechanism by
 238  * introducing "optimizations" for getters and setters or
 239  * primitive methods.  Getters and setter will normally be
 240  * compiled into @slot-[ref|set!] or a procedure call.
 241  * They rely on the dispatch performed before executing
 242  * the code which contains them.
 243  *
 244  * We might want to use a more efficient representation of
 245  * this form in the future, perhaps after we have introduced
 246  * low-level support for syntax-case macros.
 247  */
 248
 249 SCM
 250 scm_mcache_lookup_cmethod (SCM cache, SCM args)
 251 {
 252   int i, n, end, mask;
 253   SCM ls, methods, z = SCM_CDDR (cache);
 254   n = SCM_INUM (SCM_CAR (z)); /* maximum number of specializers */
 255   methods = SCM_CADR (z);
 256
 257   if (SCM_NIMP (methods))
 258     {
 259       /* Prepare for linear search */
 260       mask = -1;
 261       i = 0;
 262       end = SCM_LENGTH (methods);
 263     }
 264   else
 265     {
 266       /* Compute a hash value */
 267       int hashset = SCM_INUM (methods);
 268       int j = n;
 269       mask = SCM_INUM (SCM_CAR (z = SCM_CDDR (z)));
 270       methods = SCM_CADR (z);
 271       i = 0;
 272       ls = args;
 273       if (SCM_NIMP (ls))
 274         do
 275           {
 276             i += (SCM_STRUCT_DATA (scm_class_of (SCM_CAR (ls)))
 277                   [scm_si_hashsets + hashset]);
 278             ls = SCM_CDR (ls);
 279           }
 280         while (--j && SCM_NIMP (ls));
 281       i &= mask;
 282       end = i;
 283     }
 284
 285   /* Search for match  */
 286   do
 287     {
 288       int j = n;
 289       z = SCM_VELTS (methods)[i];
 290       ls = args; /* list of arguments */
 291       if (SCM_NIMP (ls))
 292         do
 293           {
 294             /* More arguments than specifiers => CLASS != ENV */
 295             if (scm_class_of (SCM_CAR (ls)) != SCM_CAR (z))
 296               goto next_method;
 297             ls = SCM_CDR (ls);
 298             z = SCM_CDR (z);
 299           }
 300         while (--j && SCM_NIMP (ls));
 301       /* Fewer arguments than specifiers => CAR != ENV */
 302       if (!SCM_CONSP (SCM_CAR (z)))
 303         goto next_method;
 304       return z;
 305     next_method:
 306       i = (i + 1) & mask;
 307     } while (i != end);
 308   return SCM_BOOL_F;
 309 }
 310
 311 SCM (*scm_memoize_method) (SCM, SCM);
 312
 313 SCM
 314 scm_mcache_compute_cmethod (SCM cache, SCM args)
 315 {
 316   SCM cmethod = scm_mcache_lookup_cmethod (cache, args);
 317   if (SCM_IMP (cmethod))
 318     /* No match - memoize */
 319     return scm_memoize_method (cache, args);
 320   return cmethod;
 321 }
 322
 323 SCM
 324 scm_apply_generic (SCM gf, SCM args)
 325 {
 326   SCM cmethod = scm_mcache_compute_cmethod (SCM_ENTITY_PROCEDURE (gf), args);
 327   return scm_eval_body (SCM_CDR (SCM_CMETHOD_CODE (cmethod)),
 328                         SCM_EXTEND_ENV (SCM_CAR (SCM_CMETHOD_CODE (cmethod)),
 329                                         args,
 330                                         SCM_CMETHOD_ENV (cmethod)));
 331 }
 332
 333 SCM
 334 scm_call_generic_0 (SCM gf)
 335 {
 336   return scm_apply_generic (gf, SCM_EOL);
 337 }
 338
 339 SCM
 340 scm_call_generic_1 (SCM gf, SCM a1)
 341 {
 342   return scm_apply_generic (gf, SCM_LIST1 (a1));
 343 }
 344
 345 SCM
 346 scm_call_generic_2 (SCM gf, SCM a1, SCM a2)
 347 {
 348   return scm_apply_generic (gf, SCM_LIST2 (a1, a2));
 349 }
 350
 351 SCM
 352 scm_call_generic_3 (SCM gf, SCM a1, SCM a2, SCM a3)
 353 {
 354   return scm_apply_generic (gf, SCM_LIST3 (a1, a2, a3));
 355 }
 356
 357 SCM_PROC (s_entity_p, "entity?", 1, 0, 0, scm_entity_p);
 358
 359 SCM
 360 scm_entity_p (SCM obj)
 361 {
 362   return (SCM_NIMP (obj) && SCM_STRUCTP (obj) && SCM_I_ENTITYP (obj)
 363           ? SCM_BOOL_T
 364           : SCM_BOOL_F);
 365 }
 366
 367 SCM_PROC (s_operator_p, "operator?", 1, 0, 0, scm_operator_p);
 368
 369 SCM
 370 scm_operator_p (SCM obj)
 371 {
 372   return (SCM_NIMP (obj)
 373           && SCM_STRUCTP (obj)
 374           && SCM_I_OPERATORP (obj)
 375           && !SCM_I_ENTITYP (obj)
 376           ? SCM_BOOL_T
 377           : SCM_BOOL_F);
 378 }
 379
 380 SCM_PROC (s_set_object_procedure_x, "set-object-procedure!", 2, 0, 0, scm_set_object_procedure_x);
 381
 382 SCM
 383 scm_set_object_procedure_x (SCM obj, SCM proc)
 384 {
 385   SCM_ASSERT (SCM_NIMP (obj) && SCM_STRUCTP (obj)
 386               && ((SCM_CLASS_FLAGS (obj) & SCM_CLASSF_OPERATOR)
 387                   || (SCM_I_ENTITYP (obj)
 388                       && !(SCM_OBJ_CLASS_FLAGS (obj)
 389                            & SCM_CLASSF_PURE_GENERIC))),
 390               obj,
 391               SCM_ARG1,
 392               s_set_object_procedure_x);
 393   SCM_ASSERT (SCM_NFALSEP (scm_procedure_p (proc)),
 394               proc, SCM_ARG2, s_set_object_procedure_x);
 395   if (SCM_I_ENTITYP (obj))
 396     SCM_ENTITY_PROCEDURE (obj) = proc;
 397   else
 398     SCM_OPERATOR_CLASS (obj)->procedure = proc;
 399   return SCM_UNSPECIFIED;
 400 }
 401
 402 #ifdef GUILE_DEBUG
 403 SCM_PROC (s_object_procedure, "object-procedure", 1, 0, 0, scm_object_procedure);
 404
 405 SCM
 406 scm_object_procedure (SCM obj)
 407 {
 408   SCM_ASSERT (SCM_NIMP (obj) && SCM_STRUCTP (obj)
 409               && ((SCM_CLASS_FLAGS (obj) & SCM_CLASSF_OPERATOR)
 410                   || SCM_I_ENTITYP (obj)),
 411               obj, SCM_ARG1, s_object_procedure);
 412   return (SCM_I_ENTITYP (obj)
 413           ? SCM_ENTITY_PROCEDURE (obj)
 414           : SCM_OPERATOR_CLASS (obj)->procedure);
 415 }
 416 #endif /* GUILE_DEBUG */
 417
 418 /* The following procedures are not a part of Goops but a minimal
 419  * object system built upon structs.  They are here for those who
 420  * want to implement their own object system.
 421  */
 422
 423 SCM
 424 scm_i_make_class_object (SCM meta,
 425                          SCM layout_string,
 426                          unsigned long flags)
 427 {
 428   SCM c;
 429   SCM layout = scm_make_struct_layout (layout_string);
 430   c = scm_make_struct (meta,
 431                        SCM_INUM0,
 432                        SCM_LIST4 (layout, SCM_BOOL_F, SCM_EOL, SCM_EOL));
 433   SCM_SET_CLASS_FLAGS (c, flags);
 434   return c;
 435 }
 436
 437 SCM_PROC (s_make_class_object, "make-class-object", 2, 0, 0, scm_make_class_object);
 438
 439 SCM
 440 scm_make_class_object (SCM metaclass, SCM layout)
 441 {
 442   unsigned long flags = 0;
 443   SCM_ASSERT (SCM_NIMP (metaclass) && SCM_STRUCTP (metaclass),
 444               metaclass, SCM_ARG1, s_make_class_object);
 445   SCM_ASSERT (SCM_NIMP (layout) && SCM_STRINGP (layout),
 446               layout, SCM_ARG2, s_make_class_object);
 447   if (metaclass == scm_metaclass_operator)
 448     flags = SCM_CLASSF_OPERATOR;
 449   return scm_i_make_class_object (metaclass, layout, flags);
 450 }
 451
 452 SCM_PROC (s_make_subclass_object, "make-subclass-object", 2, 0, 0, scm_make_subclass_object);
 453
 454 SCM
 455 scm_make_subclass_object (SCM class, SCM layout)
 456 {
 457   SCM pl;
 458   SCM_ASSERT (SCM_NIMP (class) && SCM_STRUCTP (class),
 459               class,
 460               SCM_ARG1,
 461               s_make_subclass_object);
 462   SCM_ASSERT (SCM_NIMP (layout) && SCM_STRINGP (layout),
 463               layout,
 464               SCM_ARG2,
 465               s_make_subclass_object);
 466   pl = SCM_STRUCT_DATA (class)[scm_vtable_index_layout];
 467   /* Convert symbol->string */
 468   pl = scm_makfromstr (SCM_CHARS (pl), (scm_sizet) SCM_LENGTH (pl), 0);
 469   return scm_i_make_class_object (SCM_STRUCT_VTABLE (class),
 470                                   scm_string_append (SCM_LIST2 (pl, layout)),
 471                                   SCM_CLASS_FLAGS (class));
 472 }
 473
 474 void
 475 scm_init_objects ()
 476 {
 477   SCM ms = scm_makfrom0str (SCM_METACLASS_STANDARD_LAYOUT);
 478   SCM ml = scm_make_struct_layout (ms);
 479   SCM mt = scm_make_vtable_vtable (ml, SCM_INUM0,
 480                                    SCM_LIST3 (SCM_BOOL_F, SCM_EOL, SCM_EOL));
 481
 482   SCM os = scm_makfrom0str (SCM_METACLASS_OPERATOR_LAYOUT);
 483   SCM ol = scm_make_struct_layout (os);
 484   SCM ot = scm_make_vtable_vtable (ol, SCM_INUM0,
 485                                    SCM_LIST3 (SCM_BOOL_F, SCM_EOL, SCM_EOL));
 486
 487   SCM es = scm_makfrom0str (SCM_ENTITY_LAYOUT);
 488   SCM el = scm_make_struct_layout (es);
 489   SCM et = scm_make_struct (mt, SCM_INUM0,
 490                             SCM_LIST4 (el, SCM_BOOL_F, SCM_EOL, SCM_EOL));
 491
 492   scm_sysintern ("<class>", mt);
 493   scm_metaclass_standard = mt;
 494   scm_sysintern ("<operator-class>", ot);
 495   scm_metaclass_operator = ot;
 496   SCM_SET_CLASS_FLAGS (et, SCM_CLASSF_OPERATOR | SCM_CLASSF_ENTITY);
 497   SCM_SET_CLASS_DESTRUCTOR (et, scm_struct_free_entity);
 498   scm_sysintern ("<entity>", et);
 499
 500 #include "objects.x"
 501 }