libguile/objects.c

   1 /* Copyright (C) 1995,1996,1999,2000,2001 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
  43 \f
  44
  45 /* This file and objects.h contains those minimal pieces of the Guile
  46  * Object Oriented Programming System which need to be included in
  47  * libguile.  See the comments in objects.h.
  48  */
  49
  50 #include "libguile/_scm.h"
  51
  52 #include "libguile/struct.h"
  53 #include "libguile/procprop.h"
  54 #include "libguile/chars.h"
  55 #include "libguile/keywords.h"
  56 #include "libguile/smob.h"
  57 #include "libguile/eval.h"
  58 #include "libguile/alist.h"
  59 #include "libguile/ports.h"
  60 #include "libguile/strings.h"
  61 #include "libguile/vectors.h"
  62
  63 #include "libguile/validate.h"
  64 #include "libguile/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 /* This function is used for efficient type dispatch.  */
  84 SCM_DEFINE (scm_class_of, "class-of", 1, 0, 0,
  85             (SCM x),
  86             "Return the class of @var{x}.")
  87 #define FUNC_NAME s_scm_class_of
  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             scm_t_bits 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_FALSEP (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_FALSEP (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 #undef FUNC_NAME
 217
 218 /* The cache argument for scm_mcache_lookup_cmethod has one of two possible
 219  * formats:
 220  *
 221  * Format #1:
 222  * (SCM_IM_DISPATCH ARGS N-SPECIALIZED
 223  *   #((TYPE1 ... ENV FORMALS FORM ...) ...)
 224  *   GF)
 225  *
 226  * Format #2:
 227  * (SCM_IM_HASH_DISPATCH ARGS N-SPECIALIZED HASHSET MASK
 228  *   #((TYPE1 ... ENV FORMALS FORM ...) ...)
 229  *   GF)
 230  *
 231  * ARGS is either a list of expressions, in which case they
 232  * are interpreted as the arguments of an application, or
 233  * a non-pair, which is interpreted as a single expression
 234  * yielding all arguments.
 235  *
 236  * SCM_IM_DISPATCH expressions in generic functions always
 237  * have ARGS = the symbol `args' or the iloc #@0-0.
 238  *
 239  * Need FORMALS in order to support varying arity.  This
 240  * also avoids the need for renaming of bindings.
 241  *
 242  * We should probably not complicate this mechanism by
 243  * introducing "optimizations" for getters and setters or
 244  * primitive methods.  Getters and setter will normally be
 245  * compiled into @slot-[ref|set!] or a procedure call.
 246  * They rely on the dispatch performed before executing
 247  * the code which contains them.
 248  *
 249  * We might want to use a more efficient representation of
 250  * this form in the future, perhaps after we have introduced
 251  * low-level support for syntax-case macros.
 252  */
 253
 254 SCM
 255 scm_mcache_lookup_cmethod (SCM cache, SCM args)
 256 {
 257   long i, n, end, mask;
 258   SCM ls, methods, z = SCM_CDDR (cache);
 259   n = SCM_INUM (SCM_CAR (z)); /* maximum number of specializers */
 260   methods = SCM_CADR (z);
 261
 262   if (SCM_INUMP (methods))
 263     {
 264       /* cache format #2: compute a hash value */
 265       long hashset = SCM_INUM (methods);
 266       long j = n;
 267       z = SCM_CDDR (z);
 268       mask = SCM_INUM (SCM_CAR (z));
 269       methods = SCM_CADR (z);
 270       i = 0;
 271       ls = args;
 272       if (!SCM_NULLP (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_NULLP (ls));
 280       i &= mask;
 281       end = i;
 282     }
 283   else /* SCM_VECTORP (methods) */
 284     {
 285       /* cache format #1: prepare for linear search */
 286       mask = -1;
 287       i = 0;
 288       end = SCM_VECTOR_LENGTH (methods);
 289     }
 290
 291   /* Search for match  */
 292   do
 293     {
 294       long j = n;
 295       z = SCM_VELTS (methods)[i];
 296       ls = args; /* list of arguments */
 297       if (!SCM_NULLP (ls))
 298         do
 299           {
 300             /* More arguments than specifiers => CLASS != ENV */
 301             if (! SCM_EQ_P (scm_class_of (SCM_CAR (ls)), SCM_CAR (z)))
 302               goto next_method;
 303             ls = SCM_CDR (ls);
 304             z = SCM_CDR (z);
 305           }
 306         while (j-- && !SCM_NULLP (ls));
 307       /* Fewer arguments than specifiers => CAR != ENV */
 308       if (SCM_NULLP (SCM_CAR (z)) || SCM_CONSP (SCM_CAR (z)))
 309         return z;
 310     next_method:
 311       i = (i + 1) & mask;
 312     } while (i != end);
 313   return SCM_BOOL_F;
 314 }
 315
 316 SCM
 317 scm_mcache_compute_cmethod (SCM cache, SCM args)
 318 {
 319   SCM cmethod = scm_mcache_lookup_cmethod (cache, args);
 320   if (SCM_FALSEP (cmethod))
 321     /* No match - memoize */
 322     return scm_memoize_method (cache, args);
 323   return cmethod;
 324 }
 325
 326 SCM
 327 scm_apply_generic (SCM gf, SCM args)
 328 {
 329   SCM cmethod = scm_mcache_compute_cmethod (SCM_ENTITY_PROCEDURE (gf), args);
 330   return scm_eval_body (SCM_CDR (SCM_CMETHOD_CODE (cmethod)),
 331                         SCM_EXTEND_ENV (SCM_CAR (SCM_CMETHOD_CODE (cmethod)),
 332                                         args,
 333                                         SCM_CMETHOD_ENV (cmethod)));
 334 }
 335
 336 SCM
 337 scm_call_generic_0 (SCM gf)
 338 {
 339   return scm_apply_generic (gf, SCM_EOL);
 340 }
 341
 342 SCM
 343 scm_call_generic_1 (SCM gf, SCM a1)
 344 {
 345   return scm_apply_generic (gf, scm_list_1 (a1));
 346 }
 347
 348 SCM
 349 scm_call_generic_2 (SCM gf, SCM a1, SCM a2)
 350 {
 351   return scm_apply_generic (gf, scm_list_2 (a1, a2));
 352 }
 353
 354 SCM
 355 scm_call_generic_3 (SCM gf, SCM a1, SCM a2, SCM a3)
 356 {
 357   return scm_apply_generic (gf, scm_list_3 (a1, a2, a3));
 358 }
 359
 360 SCM_DEFINE (scm_entity_p, "entity?", 1, 0, 0,
 361             (SCM obj),
 362             "Return @code{#t} if @var{obj} is an entity.")
 363 #define FUNC_NAME s_scm_entity_p
 364 {
 365   return SCM_BOOL(SCM_STRUCTP (obj) && SCM_I_ENTITYP (obj));
 366 }
 367 #undef FUNC_NAME
 368
 369 SCM_DEFINE (scm_operator_p, "operator?", 1, 0, 0,
 370             (SCM obj),
 371             "Return @code{#t} if @var{obj} is an operator.")
 372 #define FUNC_NAME s_scm_operator_p
 373 {
 374   return SCM_BOOL(SCM_STRUCTP (obj)
 375                   && SCM_I_OPERATORP (obj)
 376                   && !SCM_I_ENTITYP (obj));
 377 }
 378 #undef FUNC_NAME
 379
 380 /* XXX - What code requires the object procedure to be only of certain
 381          types? */
 382
 383 SCM_DEFINE (scm_valid_object_procedure_p, "valid-object-procedure?", 1, 0, 0,
 384             (SCM proc),
 385             "Return @code{#t} iff @var{proc} is a procedure that can be used "
 386             "with @code{set-object-procedure}.  It is always valid to use "
 387             "a closure constructed by @code{lambda}.")
 388 #define FUNC_NAME s_scm_valid_object_procedure_p
 389 {
 390   if (SCM_IMP (proc))
 391     return SCM_BOOL_F;
 392   switch (SCM_TYP7 (proc))
 393     {
 394     default:
 395       return SCM_BOOL_F;
 396     case scm_tcs_closures:
 397     case scm_tc7_subr_1:
 398     case scm_tc7_subr_2:
 399     case scm_tc7_subr_3:
 400     case scm_tc7_lsubr_2:
 401       return SCM_BOOL_T;
 402     }
 403 }
 404 #undef FUNC_NAME
 405
 406 SCM_DEFINE (scm_set_object_procedure_x, "set-object-procedure!", 2, 0, 0,
 407             (SCM obj, SCM proc),
 408             "Set the object procedure of @var{obj} to @var{proc}.\n"
 409             "@var{obj} must be either an entity or an operator.")
 410 #define FUNC_NAME s_scm_set_object_procedure_x
 411 {
 412   SCM_ASSERT (SCM_STRUCTP (obj)
 413               && ((SCM_CLASS_FLAGS (obj) & SCM_CLASSF_OPERATOR)
 414                   || (SCM_I_ENTITYP (obj)
 415                       && !(SCM_OBJ_CLASS_FLAGS (obj)
 416                            & SCM_CLASSF_PURE_GENERIC))),
 417               obj,
 418               SCM_ARG1,
 419               FUNC_NAME);
 420   SCM_ASSERT (scm_valid_object_procedure_p (proc), proc, SCM_ARG2, FUNC_NAME);
 421   if (SCM_I_ENTITYP (obj))
 422     SCM_SET_ENTITY_PROCEDURE (obj, proc);
 423   else
 424     SCM_OPERATOR_CLASS (obj)->procedure = proc;
 425   return SCM_UNSPECIFIED;
 426 }
 427 #undef FUNC_NAME
 428
 429 #ifdef GUILE_DEBUG
 430 SCM_DEFINE (scm_object_procedure, "object-procedure", 1, 0, 0,
 431             (SCM obj),
 432             "Return the object procedure of @var{obj}. @var{obj} must be\n"
 433             "an entity or an operator.")
 434 #define FUNC_NAME s_scm_object_procedure
 435 {
 436   SCM_ASSERT (SCM_STRUCTP (obj)
 437               && ((SCM_CLASS_FLAGS (obj) & SCM_CLASSF_OPERATOR)
 438                   || SCM_I_ENTITYP (obj)),
 439               obj, SCM_ARG1, FUNC_NAME);
 440   return (SCM_I_ENTITYP (obj)
 441           ? SCM_ENTITY_PROCEDURE (obj)
 442           : SCM_OPERATOR_CLASS (obj)->procedure);
 443 }
 444 #undef FUNC_NAME
 445 #endif /* GUILE_DEBUG */
 446
 447 /* The following procedures are not a part of Goops but a minimal
 448  * object system built upon structs.  They are here for those who
 449  * want to implement their own object system.
 450  */
 451
 452 SCM
 453 scm_i_make_class_object (SCM meta,
 454                          SCM layout_string,
 455                          unsigned long flags)
 456 {
 457   SCM c;
 458   SCM layout = scm_make_struct_layout (layout_string);
 459   c = scm_make_struct (meta,
 460                        SCM_INUM0,
 461                        scm_list_4 (layout, SCM_BOOL_F, SCM_EOL, SCM_EOL));
 462   SCM_SET_CLASS_FLAGS (c, flags);
 463   return c;
 464 }
 465
 466 SCM_DEFINE (scm_make_class_object, "make-class-object", 2, 0, 0,
 467             (SCM metaclass, SCM layout),
 468             "Create a new class object of class @var{metaclass}, with the\n"
 469             "slot layout specified by @var{layout}.")
 470 #define FUNC_NAME s_scm_make_class_object
 471 {
 472   unsigned long flags = 0;
 473   SCM_VALIDATE_STRUCT (1,metaclass);
 474   SCM_VALIDATE_STRING (2,layout);
 475   if (SCM_EQ_P (metaclass, scm_metaclass_operator))
 476     flags = SCM_CLASSF_OPERATOR;
 477   return scm_i_make_class_object (metaclass, layout, flags);
 478 }
 479 #undef FUNC_NAME
 480
 481 SCM_DEFINE (scm_make_subclass_object, "make-subclass-object", 2, 0, 0,
 482             (SCM class, SCM layout),
 483             "Create a subclass object of @var{class}, with the slot layout\n"
 484             "specified by @var{layout}.")
 485 #define FUNC_NAME s_scm_make_subclass_object
 486 {
 487   SCM pl;
 488   SCM_VALIDATE_STRUCT (1,class);
 489   SCM_VALIDATE_STRING (2,layout);
 490   pl = SCM_PACK (SCM_STRUCT_DATA (class) [scm_vtable_index_layout]);
 491   /* Convert symbol->string */
 492   pl = scm_mem2string (SCM_SYMBOL_CHARS (pl), SCM_SYMBOL_LENGTH (pl));
 493   return scm_i_make_class_object (SCM_STRUCT_VTABLE (class),
 494                                   scm_string_append (scm_list_2 (pl, layout)),
 495                                   SCM_CLASS_FLAGS (class));
 496 }
 497 #undef FUNC_NAME
 498
 499 void
 500 scm_init_objects ()
 501 {
 502   SCM ms = scm_makfrom0str (SCM_METACLASS_STANDARD_LAYOUT);
 503   SCM mt = scm_make_vtable_vtable (ms, SCM_INUM0,
 504                                    scm_list_3 (SCM_BOOL_F, SCM_EOL, SCM_EOL));
 505
 506   SCM os = scm_makfrom0str (SCM_METACLASS_OPERATOR_LAYOUT);
 507   SCM ot = scm_make_vtable_vtable (os, SCM_INUM0,
 508                                    scm_list_3 (SCM_BOOL_F, SCM_EOL, SCM_EOL));
 509
 510   SCM es = scm_makfrom0str (SCM_ENTITY_LAYOUT);
 511   SCM el = scm_make_struct_layout (es);
 512   SCM et = scm_make_struct (mt, SCM_INUM0,
 513                             scm_list_4 (el, SCM_BOOL_F, SCM_EOL, SCM_EOL));
 514
 515   scm_c_define ("<class>", mt);
 516   scm_metaclass_standard = mt;
 517   scm_c_define ("<operator-class>", ot);
 518   scm_metaclass_operator = ot;
 519   SCM_SET_CLASS_FLAGS (et, SCM_CLASSF_OPERATOR | SCM_CLASSF_ENTITY);
 520   SCM_SET_CLASS_DESTRUCTOR (et, scm_struct_free_entity);
 521   scm_c_define ("<entity>", et);
 522
 523 #ifndef SCM_MAGIC_SNARFER
 524 #include "libguile/objects.x"
 525 #endif
 526 }
 527
 528 /*
 529   Local Variables:
 530   c-file-style: "gnu"
 531   End:
 532 */