libguile/objects.c

   1 /*      Copyright (C) 1995, 1996, 1999, 2000 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
  42 /* Software engineering face-lift by Greg J. Badros, 11-Dec-1999,
  43    gjb@cs.washington.edu, http://www.cs.washington.edu/homes/gjb */
  44
  45 \f
  46
  47 /* This file and objects.h contains those minimal pieces of the Guile
  48  * Object Oriented Programming System which need to be included in
  49  * libguile.  See the comments in objects.h.
  50  */
  51
  52 #include "_scm.h"
  53
  54 #include "struct.h"
  55 #include "procprop.h"
  56 #include "chars.h"
  57 #include "keywords.h"
  58 #include "smob.h"
  59 #include "eval.h"
  60 #include "alist.h"
  61 #include "vectors.h"
  62
  63 #include "validate.h"
  64 #include "objects.h"
  65 \f
  66
  67 SCM scm_metaclass_standard;
  68 SCM scm_metaclass_operator;
  69
  70 /* These variables are filled in by the object system when loaded. */
  71 SCM scm_class_boolean, scm_class_char, scm_class_pair;
  72 SCM scm_class_procedure, scm_class_string, scm_class_symbol;
  73 SCM scm_class_procedure_with_setter, scm_class_primitive_generic;
  74 SCM scm_class_vector, scm_class_null;
  75 SCM scm_class_integer, scm_class_real, scm_class_complex;
  76 SCM scm_class_unknown;
  77
  78 SCM *scm_port_class = 0;
  79 SCM *scm_smob_class = 0;
  80
  81 SCM scm_no_applicable_method;
  82
  83 SCM (*scm_make_extended_class) (char *type_name);
  84 void (*scm_make_port_classes) (int ptobnum, char *type_name);
  85 void (*scm_change_object_class) (SCM, SCM, SCM);
  86
  87 /* This function is used for efficient type dispatch.  */
  88 SCM
  89 scm_class_of (SCM x)
  90 {
  91   switch (SCM_ITAG3 (x))
  92     {
  93     case scm_tc3_int_1:
  94     case scm_tc3_int_2:
  95       return scm_class_integer;
  96
  97     case scm_tc3_imm24:
  98       if (SCM_CHARP (x))
  99         return scm_class_char;
 100       else
 101         {
 102           switch (SCM_ISYMNUM (x))
 103             {
 104             case SCM_ISYMNUM (SCM_BOOL_F):
 105             case SCM_ISYMNUM (SCM_BOOL_T):
 106               return scm_class_boolean;
 107             case SCM_ISYMNUM (SCM_EOL):
 108               return scm_class_null;
 109             default:
 110               return scm_class_unknown;
 111             }
 112         }
 113
 114     case scm_tc3_cons:
 115       switch (SCM_TYP7 (x))
 116         {
 117         case scm_tcs_cons_nimcar:
 118           return scm_class_pair;
 119         case scm_tcs_closures:
 120           return scm_class_procedure;
 121         case scm_tcs_symbols:
 122           return scm_class_symbol;
 123         case scm_tc7_vector:
 124         case scm_tc7_wvect:
 125 #ifdef HAVE_ARRAYS
 126         case scm_tc7_bvect:
 127         case scm_tc7_byvect:
 128         case scm_tc7_svect:
 129         case scm_tc7_ivect:
 130         case scm_tc7_uvect:
 131         case scm_tc7_fvect:
 132         case scm_tc7_dvect:
 133         case scm_tc7_cvect:
 134 #endif
 135           return scm_class_vector;
 136         case scm_tc7_string:
 137         case scm_tc7_substring:
 138           return scm_class_string;
 139         case scm_tc7_asubr:
 140         case scm_tc7_subr_0:
 141         case scm_tc7_subr_1:
 142         case scm_tc7_cxr:
 143         case scm_tc7_subr_3:
 144         case scm_tc7_subr_2:
 145         case scm_tc7_rpsubr:
 146         case scm_tc7_subr_1o:
 147         case scm_tc7_subr_2o:
 148         case scm_tc7_lsubr_2:
 149         case scm_tc7_lsubr:
 150           if (SCM_SUBR_GENERIC (x) && *SCM_SUBR_GENERIC (x))
 151             return scm_class_primitive_generic;
 152           else
 153             return scm_class_procedure;
 154         case scm_tc7_cclo:
 155           return scm_class_procedure;
 156         case scm_tc7_pws:
 157           return scm_class_procedure_with_setter;
 158
 159         case scm_tc7_smob:
 160           {
 161             long type = SCM_TYP16 (x);
 162             if (type != scm_tc16_port_with_ps)
 163               return scm_smob_class[SCM_TC2SMOBNUM (type)];
 164             x = SCM_PORT_WITH_PS_PORT (x);
 165             /* fall through to ports */
 166           }
 167         case scm_tc7_port:
 168           return scm_port_class[(SCM_WRTNG & SCM_UNPACK_CAR (x)
 169                                  ? (SCM_RDNG & SCM_UNPACK_CAR (x)
 170                                     ? SCM_INOUT_PCLASS_INDEX | SCM_PTOBNUM (x)
 171                                     : SCM_OUT_PCLASS_INDEX | SCM_PTOBNUM (x))
 172                                  : SCM_IN_PCLASS_INDEX | SCM_PTOBNUM (x))];
 173         case scm_tcs_cons_gloc:
 174           /* must be a struct */
 175           if (SCM_OBJ_CLASS_FLAGS (x) & SCM_CLASSF_GOOPS_VALID)
 176             return SCM_CLASS_OF (x);
 177           else if (SCM_OBJ_CLASS_FLAGS (x) & SCM_CLASSF_GOOPS)
 178             {
 179               /* Goops object */
 180               if (SCM_OBJ_CLASS_REDEF (x) != SCM_BOOL_F)
 181                 scm_change_object_class (x,
 182                                          SCM_CLASS_OF (x),         /* old */
 183                                          SCM_OBJ_CLASS_REDEF (x)); /* new */
 184               return SCM_CLASS_OF (x);
 185             }
 186           else
 187             {
 188               /* ordinary struct */
 189               SCM handle = scm_struct_create_handle (SCM_STRUCT_VTABLE (x));
 190               if (SCM_NFALSEP (SCM_STRUCT_TABLE_CLASS (SCM_CDR (handle))))
 191                 return SCM_STRUCT_TABLE_CLASS (SCM_CDR (handle));
 192               else
 193                 {
 194                   SCM name = SCM_STRUCT_TABLE_NAME (SCM_CDR (handle));
 195                   SCM class = scm_make_extended_class (SCM_NFALSEP (name)
 196                                                        ? SCM_ROCHARS (name)
 197                                                        : 0);
 198                   SCM_SET_STRUCT_TABLE_CLASS (SCM_CDR (handle), class);
 199                   return class;
 200                 }
 201             }
 202         default:
 203           if (SCM_CONSP (x))
 204             return scm_class_pair;
 205           else
 206             return scm_class_unknown;
 207         }
 208
 209     case scm_tc3_cons_gloc:
 210     case scm_tc3_tc7_1:
 211     case scm_tc3_tc7_2:
 212     case scm_tc3_closure:
 213       /* Never reached */
 214       break;
 215     }
 216   return scm_class_unknown;
 217 }
 218
 219 /* (SCM_IM_DISPATCH ARGS N-SPECIALIZED
 220  *   #((TYPE1 ... ENV FORMALS FORM ...) ...)
 221  *   GF)
 222  *
 223  * (SCM_IM_HASH_DISPATCH ARGS N-SPECIALIZED HASHSET MASK
 224  *   #((TYPE1 ... ENV FORMALS FORM ...) ...)
 225  *   GF)
 226  *
 227  * ARGS is either a list of expressions, in which case they
 228  * are interpreted as the arguments of an application, or
 229  * a non-pair, which is interpreted as a single expression
 230  * yielding all arguments.
 231  *
 232  * SCM_IM_DISPATCH expressions in generic functions always
 233  * have ARGS = the symbol `args' or the iloc #@0-0.
 234  *
 235  * Need FORMALS in order to support varying arity.  This
 236  * also avoids the need for renaming of bindings.
 237  *
 238  * We should probably not complicate this mechanism by
 239  * introducing "optimizations" for getters and setters or
 240  * primitive methods.  Getters and setter will normally be
 241  * compiled into @slot-[ref|set!] or a procedure call.
 242  * They rely on the dispatch performed before executing
 243  * the code which contains them.
 244  *
 245  * We might want to use a more efficient representation of
 246  * this form in the future, perhaps after we have introduced
 247  * low-level support for syntax-case macros.
 248  */
 249
 250 SCM
 251 scm_mcache_lookup_cmethod (SCM cache, SCM args)
 252 {
 253   int i, n, end, mask;
 254   SCM ls, methods, z = SCM_CDDR (cache);
 255   n = SCM_INUM (SCM_CAR (z)); /* maximum number of specializers */
 256   methods = SCM_CADR (z);
 257
 258   if (SCM_NIMP (methods))
 259     {
 260       /* Prepare for linear search */
 261       mask = -1;
 262       i = 0;
 263       end = SCM_LENGTH (methods);
 264     }
 265   else
 266     {
 267       /* Compute a hash value */
 268       int hashset = SCM_INUM (methods);
 269       int j = n;
 270       mask = SCM_INUM (SCM_CAR (z = SCM_CDDR (z)));
 271       methods = SCM_CADR (z);
 272       i = 0;
 273       ls = args;
 274       if (SCM_NIMP (ls))
 275         do
 276           {
 277             i += SCM_UNPACK (SCM_STRUCT_DATA (scm_class_of (SCM_CAR (ls)))
 278                   [scm_si_hashsets + hashset]);
 279             ls = SCM_CDR (ls);
 280           }
 281         while (--j && SCM_NIMP (ls));
 282       i &= mask;
 283       end = i;
 284     }
 285
 286   /* Search for match  */
 287   do
 288     {
 289       int j = n;
 290       z = SCM_VELTS (methods)[i];
 291       ls = args; /* list of arguments */
 292       if (SCM_NIMP (ls))
 293         do
 294           {
 295             /* More arguments than specifiers => CLASS != ENV */
 296             if (scm_class_of (SCM_CAR (ls)) != SCM_CAR (z))
 297               goto next_method;
 298             ls = SCM_CDR (ls);
 299             z = SCM_CDR (z);
 300           }
 301         while (--j && SCM_NIMP (ls));
 302       /* Fewer arguments than specifiers => CAR != ENV */
 303       if (!(SCM_IMP (SCM_CAR (z)) || SCM_CONSP (SCM_CAR (z))))
 304         goto next_method;
 305       return z;
 306     next_method:
 307       i = (i + 1) & mask;
 308     } while (i != end);
 309   return SCM_BOOL_F;
 310 }
 311
 312 SCM
 313 scm_mcache_compute_cmethod (SCM cache, SCM args)
 314 {
 315   SCM cmethod = scm_mcache_lookup_cmethod (cache, args);
 316   if (SCM_IMP (cmethod))
 317     /* No match - memoize */
 318     return scm_memoize_method (cache, args);
 319   return cmethod;
 320 }
 321
 322 SCM
 323 scm_apply_generic (SCM gf, SCM args)
 324 {
 325   SCM cmethod = scm_mcache_compute_cmethod (SCM_ENTITY_PROCEDURE (gf), args);
 326   return scm_eval_body (SCM_CDR (SCM_CMETHOD_CODE (cmethod)),
 327                         SCM_EXTEND_ENV (SCM_CAR (SCM_CMETHOD_CODE (cmethod)),
 328                                         args,
 329                                         SCM_CMETHOD_ENV (cmethod)));
 330 }
 331
 332 SCM
 333 scm_call_generic_0 (SCM gf)
 334 {
 335   return scm_apply_generic (gf, SCM_EOL);
 336 }
 337
 338 SCM
 339 scm_call_generic_1 (SCM gf, SCM a1)
 340 {
 341   return scm_apply_generic (gf, SCM_LIST1 (a1));
 342 }
 343
 344 SCM
 345 scm_call_generic_2 (SCM gf, SCM a1, SCM a2)
 346 {
 347   return scm_apply_generic (gf, SCM_LIST2 (a1, a2));
 348 }
 349
 350 SCM
 351 scm_call_generic_3 (SCM gf, SCM a1, SCM a2, SCM a3)
 352 {
 353   return scm_apply_generic (gf, SCM_LIST3 (a1, a2, a3));
 354 }
 355
 356 SCM_DEFINE (scm_entity_p, "entity?", 1, 0, 0,
 357             (SCM obj),
 358 "")
 359 #define FUNC_NAME s_scm_entity_p
 360 {
 361   return SCM_BOOL(SCM_STRUCTP (obj) && SCM_I_ENTITYP (obj));
 362 }
 363 #undef FUNC_NAME
 364
 365 SCM_DEFINE (scm_operator_p, "operator?", 1, 0, 0,
 366             (SCM obj),
 367 "")
 368 #define FUNC_NAME s_scm_operator_p
 369 {
 370   return SCM_BOOL(SCM_STRUCTP (obj)
 371                   && SCM_I_OPERATORP (obj)
 372                   && !SCM_I_ENTITYP (obj));
 373 }
 374 #undef FUNC_NAME
 375
 376 SCM_DEFINE (scm_set_object_procedure_x, "set-object-procedure!", 2, 0, 0,
 377             (SCM obj, SCM proc),
 378 "")
 379 #define FUNC_NAME s_scm_set_object_procedure_x
 380 {
 381   SCM_ASSERT (SCM_STRUCTP (obj)
 382               && ((SCM_CLASS_FLAGS (obj) & SCM_CLASSF_OPERATOR)
 383                   || (SCM_I_ENTITYP (obj)
 384                       && !(SCM_OBJ_CLASS_FLAGS (obj)
 385                            & SCM_CLASSF_PURE_GENERIC))),
 386               obj,
 387               SCM_ARG1,
 388               FUNC_NAME);
 389   SCM_VALIDATE_PROC (2,proc);
 390   if (SCM_I_ENTITYP (obj))
 391     SCM_ENTITY_PROCEDURE (obj) = proc;
 392   else
 393     SCM_OPERATOR_CLASS (obj)->procedure = proc;
 394   return SCM_UNSPECIFIED;
 395 }
 396 #undef FUNC_NAME
 397
 398 #ifdef GUILE_DEBUG
 399 SCM_DEFINE (scm_object_procedure, "object-procedure", 1, 0, 0,
 400             (SCM obj),
 401 "")
 402 #define FUNC_NAME s_scm_object_procedure
 403 {
 404   SCM_ASSERT (SCM_STRUCTP (obj)
 405               && ((SCM_CLASS_FLAGS (obj) & SCM_CLASSF_OPERATOR)
 406                   || SCM_I_ENTITYP (obj)),
 407               obj, SCM_ARG1, FUNC_NAME);
 408   return (SCM_I_ENTITYP (obj)
 409           ? SCM_ENTITY_PROCEDURE (obj)
 410           : SCM_OPERATOR_CLASS (obj)->procedure);
 411 }
 412 #undef FUNC_NAME
 413 #endif /* GUILE_DEBUG */
 414
 415 /* The following procedures are not a part of Goops but a minimal
 416  * object system built upon structs.  They are here for those who
 417  * want to implement their own object system.
 418  */
 419
 420 SCM
 421 scm_i_make_class_object (SCM meta,
 422                          SCM layout_string,
 423                          unsigned long flags)
 424 {
 425   SCM c;
 426   SCM layout = scm_make_struct_layout (layout_string);
 427   c = scm_make_struct (meta,
 428                        SCM_INUM0,
 429                        SCM_LIST4 (layout, SCM_BOOL_F, SCM_EOL, SCM_EOL));
 430   SCM_SET_CLASS_FLAGS (c, flags);
 431   return c;
 432 }
 433
 434 SCM_DEFINE (scm_make_class_object, "make-class-object", 2, 0, 0,
 435             (SCM metaclass, SCM layout),
 436 "")
 437 #define FUNC_NAME s_scm_make_class_object
 438 {
 439   unsigned long flags = 0;
 440   SCM_VALIDATE_STRUCT (1,metaclass);
 441   SCM_VALIDATE_STRING (2,layout);
 442   if (metaclass == scm_metaclass_operator)
 443     flags = SCM_CLASSF_OPERATOR;
 444   return scm_i_make_class_object (metaclass, layout, flags);
 445 }
 446 #undef FUNC_NAME
 447
 448 SCM_DEFINE (scm_make_subclass_object, "make-subclass-object", 2, 0, 0,
 449             (SCM class, SCM layout),
 450 "")
 451 #define FUNC_NAME s_scm_make_subclass_object
 452 {
 453   SCM pl;
 454   SCM_VALIDATE_STRUCT (1,class);
 455   SCM_VALIDATE_STRING (2,layout);
 456   pl = SCM_STRUCT_DATA (class)[scm_vtable_index_layout];
 457   /* Convert symbol->string */
 458   pl = scm_makfromstr (SCM_CHARS (pl), (scm_sizet) SCM_LENGTH (pl), 0);
 459   return scm_i_make_class_object (SCM_STRUCT_VTABLE (class),
 460                                   scm_string_append (SCM_LIST2 (pl, layout)),
 461                                   SCM_CLASS_FLAGS (class));
 462 }
 463 #undef FUNC_NAME
 464
 465 void
 466 scm_init_objects ()
 467 {
 468   SCM ms = scm_makfrom0str (SCM_METACLASS_STANDARD_LAYOUT);
 469   SCM ml = scm_make_struct_layout (ms);
 470   SCM mt = scm_make_vtable_vtable (ml, SCM_INUM0,
 471                                    SCM_LIST3 (SCM_BOOL_F, SCM_EOL, SCM_EOL));
 472
 473   SCM os = scm_makfrom0str (SCM_METACLASS_OPERATOR_LAYOUT);
 474   SCM ol = scm_make_struct_layout (os);
 475   SCM ot = scm_make_vtable_vtable (ol, SCM_INUM0,
 476                                    SCM_LIST3 (SCM_BOOL_F, SCM_EOL, SCM_EOL));
 477
 478   SCM es = scm_makfrom0str (SCM_ENTITY_LAYOUT);
 479   SCM el = scm_make_struct_layout (es);
 480   SCM et = scm_make_struct (mt, SCM_INUM0,
 481                             SCM_LIST4 (el, SCM_BOOL_F, SCM_EOL, SCM_EOL));
 482
 483   scm_sysintern ("<class>", mt);
 484   scm_metaclass_standard = mt;
 485   scm_sysintern ("<operator-class>", ot);
 486   scm_metaclass_operator = ot;
 487   SCM_SET_CLASS_FLAGS (et, SCM_CLASSF_OPERATOR | SCM_CLASSF_ENTITY);
 488   SCM_SET_CLASS_DESTRUCTOR (et, scm_struct_free_entity);
 489   scm_sysintern ("<entity>", et);
 490
 491 #include "objects.x"
 492 }