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