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 /* This function is used for efficient type dispatch.  */
  86 SCM
  87 scm_class_of (SCM x)
  88 {
  89   switch (SCM_ITAG3 (x))
  90     {
  91     case scm_tc3_int_1:
  92     case scm_tc3_int_2:
  93       return scm_class_integer;
  94
  95     case scm_tc3_imm24:
  96       if (SCM_CHARP (x))
  97         return scm_class_char;
  98       else
  99         {
 100           switch (SCM_ISYMNUM (x))
 101             {
 102             case SCM_ISYMNUM (SCM_BOOL_F):
 103             case SCM_ISYMNUM (SCM_BOOL_T):
 104               return scm_class_boolean;
 105             case SCM_ISYMNUM (SCM_EOL):
 106               return scm_class_null;
 107             default:
 108               return scm_class_unknown;
 109             }
 110         }
 111
 112     case scm_tc3_cons:
 113       switch (SCM_TYP7 (x))
 114         {
 115         case scm_tcs_cons_nimcar:
 116           return scm_class_pair;
 117         case scm_tcs_closures:
 118           return scm_class_procedure;
 119         case scm_tc7_symbol:
 120           return scm_class_symbol;
 121         case scm_tc7_vector:
 122         case scm_tc7_wvect:
 123 #ifdef HAVE_ARRAYS
 124         case scm_tc7_bvect:
 125         case scm_tc7_byvect:
 126         case scm_tc7_svect:
 127         case scm_tc7_ivect:
 128         case scm_tc7_uvect:
 129         case scm_tc7_fvect:
 130         case scm_tc7_dvect:
 131         case scm_tc7_cvect:
 132 #endif
 133           return scm_class_vector;
 134         case scm_tc7_string:
 135         case scm_tc7_substring:
 136           return scm_class_string;
 137         case scm_tc7_asubr:
 138         case scm_tc7_subr_0:
 139         case scm_tc7_subr_1:
 140         case scm_tc7_cxr:
 141         case scm_tc7_subr_3:
 142         case scm_tc7_subr_2:
 143         case scm_tc7_rpsubr:
 144         case scm_tc7_subr_1o:
 145         case scm_tc7_subr_2o:
 146         case scm_tc7_lsubr_2:
 147         case scm_tc7_lsubr:
 148           if (SCM_SUBR_GENERIC (x) && *SCM_SUBR_GENERIC (x))
 149             return scm_class_primitive_generic;
 150           else
 151             return scm_class_procedure;
 152         case scm_tc7_cclo:
 153           return scm_class_procedure;
 154         case scm_tc7_pws:
 155           return scm_class_procedure_with_setter;
 156
 157         case scm_tc7_smob:
 158           {
 159             long type = SCM_TYP16 (x);
 160             if (type != scm_tc16_port_with_ps)
 161               return scm_smob_class[SCM_TC2SMOBNUM (type)];
 162             x = SCM_PORT_WITH_PS_PORT (x);
 163             /* fall through to ports */
 164           }
 165         case scm_tc7_port:
 166           return scm_port_class[(SCM_WRTNG & SCM_CELL_WORD_0 (x)
 167                                  ? (SCM_RDNG & SCM_CELL_WORD_0 (x)
 168                                     ? SCM_INOUT_PCLASS_INDEX | SCM_PTOBNUM (x)
 169                                     : SCM_OUT_PCLASS_INDEX | SCM_PTOBNUM (x))
 170                                  : SCM_IN_PCLASS_INDEX | SCM_PTOBNUM (x))];
 171         case scm_tcs_cons_gloc:
 172           /* must be a struct */
 173           if (SCM_OBJ_CLASS_FLAGS (x) & SCM_CLASSF_GOOPS_VALID)
 174             return SCM_CLASS_OF (x);
 175           else if (SCM_OBJ_CLASS_FLAGS (x) & SCM_CLASSF_GOOPS)
 176             {
 177               /* Goops object */
 178               if (! SCM_FALSEP (SCM_OBJ_CLASS_REDEF (x)))
 179                 scm_change_object_class (x,
 180                                          SCM_CLASS_OF (x),         /* old */
 181                                          SCM_OBJ_CLASS_REDEF (x)); /* new */
 182               return SCM_CLASS_OF (x);
 183             }
 184           else
 185             {
 186               /* ordinary struct */
 187               SCM handle = scm_struct_create_handle (SCM_STRUCT_VTABLE (x));
 188               if (SCM_NFALSEP (SCM_STRUCT_TABLE_CLASS (SCM_CDR (handle))))
 189                 return SCM_STRUCT_TABLE_CLASS (SCM_CDR (handle));
 190               else
 191                 {
 192                   SCM name = SCM_STRUCT_TABLE_NAME (SCM_CDR (handle));
 193                   SCM class = scm_make_extended_class (SCM_NFALSEP (name)
 194                                                        ? SCM_SYMBOL_CHARS (name)
 195                                                        : 0);
 196                   SCM_SET_STRUCT_TABLE_CLASS (SCM_CDR (handle), class);
 197                   return class;
 198                 }
 199             }
 200         default:
 201           if (SCM_CONSP (x))
 202             return scm_class_pair;
 203           else
 204             return scm_class_unknown;
 205         }
 206
 207     case scm_tc3_cons_gloc:
 208     case scm_tc3_tc7_1:
 209     case scm_tc3_tc7_2:
 210     case scm_tc3_closure:
 211       /* Never reached */
 212       break;
 213     }
 214   return scm_class_unknown;
 215 }
 216
 217 /* (SCM_IM_DISPATCH ARGS N-SPECIALIZED
 218  *   #((TYPE1 ... ENV FORMALS FORM ...) ...)
 219  *   GF)
 220  *
 221  * (SCM_IM_HASH_DISPATCH ARGS N-SPECIALIZED HASHSET MASK
 222  *   #((TYPE1 ... ENV FORMALS FORM ...) ...)
 223  *   GF)
 224  *
 225  * ARGS is either a list of expressions, in which case they
 226  * are interpreted as the arguments of an application, or
 227  * a non-pair, which is interpreted as a single expression
 228  * yielding all arguments.
 229  *
 230  * SCM_IM_DISPATCH expressions in generic functions always
 231  * have ARGS = the symbol `args' or the iloc #@0-0.
 232  *
 233  * Need FORMALS in order to support varying arity.  This
 234  * also avoids the need for renaming of bindings.
 235  *
 236  * We should probably not complicate this mechanism by
 237  * introducing "optimizations" for getters and setters or
 238  * primitive methods.  Getters and setter will normally be
 239  * compiled into @slot-[ref|set!] or a procedure call.
 240  * They rely on the dispatch performed before executing
 241  * the code which contains them.
 242  *
 243  * We might want to use a more efficient representation of
 244  * this form in the future, perhaps after we have introduced
 245  * low-level support for syntax-case macros.
 246  */
 247
 248 SCM
 249 scm_mcache_lookup_cmethod (SCM cache, SCM args)
 250 {
 251   int i, n, end, mask;
 252   SCM ls, methods, z = SCM_CDDR (cache);
 253   n = SCM_INUM (SCM_CAR (z)); /* maximum number of specializers */
 254   methods = SCM_CADR (z);
 255
 256   if (SCM_NIMP (methods))
 257     {
 258       /* Prepare for linear search */
 259       mask = -1;
 260       i = 0;
 261       end = SCM_VECTOR_LENGTH (methods);
 262     }
 263   else
 264     {
 265       /* Compute a hash value */
 266       int hashset = SCM_INUM (methods);
 267       int j = n;
 268       mask = SCM_INUM (SCM_CAR (z = SCM_CDDR (z)));
 269       methods = SCM_CADR (z);
 270       i = 0;
 271       ls = args;
 272       if (SCM_NIMP (ls))
 273         do
 274           {
 275             i += SCM_STRUCT_DATA (scm_class_of (SCM_CAR (ls)))
 276                  [scm_si_hashsets + hashset];
 277             ls = SCM_CDR (ls);
 278           }
 279         while (j-- && SCM_NIMP (ls));
 280       i &= mask;
 281       end = i;
 282     }
 283
 284   /* Search for match  */
 285   do
 286     {
 287       int j = n;
 288       z = SCM_VELTS (methods)[i];
 289       ls = args; /* list of arguments */
 290       if (SCM_NIMP (ls))
 291         do
 292           {
 293             /* More arguments than specifiers => CLASS != ENV */
 294             if (! SCM_EQ_P (scm_class_of (SCM_CAR (ls)), SCM_CAR (z)))
 295               goto next_method;
 296             ls = SCM_CDR (ls);
 297             z = SCM_CDR (z);
 298           }
 299         while (j-- && SCM_NIMP (ls));
 300       /* Fewer arguments than specifiers => CAR != ENV */
 301       if (!(SCM_IMP (SCM_CAR (z)) || SCM_CONSP (SCM_CAR (z))))
 302         goto next_method;
 303       return z;
 304     next_method:
 305       i = (i + 1) & mask;
 306     } while (i != end);
 307   return SCM_BOOL_F;
 308 }
 309
 310 SCM
 311 scm_mcache_compute_cmethod (SCM cache, SCM args)
 312 {
 313   SCM cmethod = scm_mcache_lookup_cmethod (cache, args);
 314   if (SCM_IMP (cmethod))
 315     /* No match - memoize */
 316     return scm_memoize_method (cache, args);
 317   return cmethod;
 318 }
 319
 320 SCM
 321 scm_apply_generic (SCM gf, SCM args)
 322 {
 323   SCM cmethod = scm_mcache_compute_cmethod (SCM_ENTITY_PROCEDURE (gf), args);
 324   return scm_eval_body (SCM_CDR (SCM_CMETHOD_CODE (cmethod)),
 325                         SCM_EXTEND_ENV (SCM_CAR (SCM_CMETHOD_CODE (cmethod)),
 326                                         args,
 327                                         SCM_CMETHOD_ENV (cmethod)));
 328 }
 329
 330 SCM
 331 scm_call_generic_0 (SCM gf)
 332 {
 333   return scm_apply_generic (gf, SCM_EOL);
 334 }
 335
 336 SCM
 337 scm_call_generic_1 (SCM gf, SCM a1)
 338 {
 339   return scm_apply_generic (gf, SCM_LIST1 (a1));
 340 }
 341
 342 SCM
 343 scm_call_generic_2 (SCM gf, SCM a1, SCM a2)
 344 {
 345   return scm_apply_generic (gf, SCM_LIST2 (a1, a2));
 346 }
 347
 348 SCM
 349 scm_call_generic_3 (SCM gf, SCM a1, SCM a2, SCM a3)
 350 {
 351   return scm_apply_generic (gf, SCM_LIST3 (a1, a2, a3));
 352 }
 353
 354 SCM_DEFINE (scm_entity_p, "entity?", 1, 0, 0,
 355             (SCM obj),
 356 "")
 357 #define FUNC_NAME s_scm_entity_p
 358 {
 359   return SCM_BOOL(SCM_STRUCTP (obj) && SCM_I_ENTITYP (obj));
 360 }
 361 #undef FUNC_NAME
 362
 363 SCM_DEFINE (scm_operator_p, "operator?", 1, 0, 0,
 364             (SCM obj),
 365 "")
 366 #define FUNC_NAME s_scm_operator_p
 367 {
 368   return SCM_BOOL(SCM_STRUCTP (obj)
 369                   && SCM_I_OPERATORP (obj)
 370                   && !SCM_I_ENTITYP (obj));
 371 }
 372 #undef FUNC_NAME
 373
 374 SCM_DEFINE (scm_set_object_procedure_x, "set-object-procedure!", 2, 0, 0,
 375             (SCM obj, SCM proc),
 376 "")
 377 #define FUNC_NAME s_scm_set_object_procedure_x
 378 {
 379   SCM_ASSERT (SCM_STRUCTP (obj)
 380               && ((SCM_CLASS_FLAGS (obj) & SCM_CLASSF_OPERATOR)
 381                   || (SCM_I_ENTITYP (obj)
 382                       && !(SCM_OBJ_CLASS_FLAGS (obj)
 383                            & SCM_CLASSF_PURE_GENERIC))),
 384               obj,
 385               SCM_ARG1,
 386               FUNC_NAME);
 387   SCM_VALIDATE_PROC (2,proc);
 388   if (SCM_I_ENTITYP (obj))
 389     SCM_SET_ENTITY_PROCEDURE (obj, proc);
 390   else
 391     SCM_OPERATOR_CLASS (obj)->procedure = proc;
 392   return SCM_UNSPECIFIED;
 393 }
 394 #undef FUNC_NAME
 395
 396 #ifdef GUILE_DEBUG
 397 SCM_DEFINE (scm_object_procedure, "object-procedure", 1, 0, 0,
 398             (SCM obj),
 399 "")
 400 #define FUNC_NAME s_scm_object_procedure
 401 {
 402   SCM_ASSERT (SCM_STRUCTP (obj)
 403               && ((SCM_CLASS_FLAGS (obj) & SCM_CLASSF_OPERATOR)
 404                   || SCM_I_ENTITYP (obj)),
 405               obj, SCM_ARG1, FUNC_NAME);
 406   return (SCM_I_ENTITYP (obj)
 407           ? SCM_ENTITY_PROCEDURE (obj)
 408           : SCM_OPERATOR_CLASS (obj)->procedure);
 409 }
 410 #undef FUNC_NAME
 411 #endif /* GUILE_DEBUG */
 412
 413 /* The following procedures are not a part of Goops but a minimal
 414  * object system built upon structs.  They are here for those who
 415  * want to implement their own object system.
 416  */
 417
 418 SCM
 419 scm_i_make_class_object (SCM meta,
 420                          SCM layout_string,
 421                          unsigned long flags)
 422 {
 423   SCM c;
 424   SCM layout = scm_make_struct_layout (layout_string);
 425   c = scm_make_struct (meta,
 426                        SCM_INUM0,
 427                        SCM_LIST4 (layout, SCM_BOOL_F, SCM_EOL, SCM_EOL));
 428   SCM_SET_CLASS_FLAGS (c, flags);
 429   return c;
 430 }
 431
 432 SCM_DEFINE (scm_make_class_object, "make-class-object", 2, 0, 0,
 433             (SCM metaclass, SCM layout),
 434 "")
 435 #define FUNC_NAME s_scm_make_class_object
 436 {
 437   unsigned long flags = 0;
 438   SCM_VALIDATE_STRUCT (1,metaclass);
 439   SCM_VALIDATE_STRING (2,layout);
 440   if (SCM_EQ_P (metaclass, scm_metaclass_operator))
 441     flags = SCM_CLASSF_OPERATOR;
 442   return scm_i_make_class_object (metaclass, layout, flags);
 443 }
 444 #undef FUNC_NAME
 445
 446 SCM_DEFINE (scm_make_subclass_object, "make-subclass-object", 2, 0, 0,
 447             (SCM class, SCM layout),
 448 "")
 449 #define FUNC_NAME s_scm_make_subclass_object
 450 {
 451   SCM pl;
 452   SCM_VALIDATE_STRUCT (1,class);
 453   SCM_VALIDATE_STRING (2,layout);
 454   pl = SCM_PACK (SCM_STRUCT_DATA (class) [scm_vtable_index_layout]);
 455   /* Convert symbol->string */
 456   pl = scm_makfromstr (SCM_SYMBOL_CHARS (pl), SCM_SYMBOL_LENGTH (pl), 0);
 457   return scm_i_make_class_object (SCM_STRUCT_VTABLE (class),
 458                                   scm_string_append (SCM_LIST2 (pl, layout)),
 459                                   SCM_CLASS_FLAGS (class));
 460 }
 461 #undef FUNC_NAME
 462
 463 void
 464 scm_init_objects ()
 465 {
 466   SCM ms = scm_makfrom0str (SCM_METACLASS_STANDARD_LAYOUT);
 467   SCM mt = scm_make_vtable_vtable (ms, SCM_INUM0,
 468                                    SCM_LIST3 (SCM_BOOL_F, SCM_EOL, SCM_EOL));
 469
 470   SCM os = scm_makfrom0str (SCM_METACLASS_OPERATOR_LAYOUT);
 471   SCM ot = scm_make_vtable_vtable (os, SCM_INUM0,
 472                                    SCM_LIST3 (SCM_BOOL_F, SCM_EOL, SCM_EOL));
 473
 474   SCM es = scm_makfrom0str (SCM_ENTITY_LAYOUT);
 475   SCM el = scm_make_struct_layout (es);
 476   SCM et = scm_make_struct (mt, SCM_INUM0,
 477                             SCM_LIST4 (el, SCM_BOOL_F, SCM_EOL, SCM_EOL));
 478
 479   scm_sysintern ("<class>", mt);
 480   scm_metaclass_standard = mt;
 481   scm_sysintern ("<operator-class>", ot);
 482   scm_metaclass_operator = ot;
 483   SCM_SET_CLASS_FLAGS (et, SCM_CLASSF_OPERATOR | SCM_CLASSF_ENTITY);
 484   SCM_SET_CLASS_DESTRUCTOR (et, scm_struct_free_entity);
 485   scm_sysintern ("<entity>", et);
 486
 487 #ifndef SCM_MAGIC_SNARFER
 488 #include "libguile/objects.x"
 489 #endif
 490 }
 491
 492 /*
 493   Local Variables:
 494   c-file-style: "gnu"
 495   End:
 496 */