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