lily/grob.cc

   1 /*
   2   score-elem.cc -- implement Grob
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c)  1997--2001 Han-Wen Nienhuys <hanwen@cs.uu.nl>
   7 */
   8
   9
  10 #include <string.h>
  11 #include <math.h>
  12
  13 #include "input-smob.hh"
  14 #include "libc-extension.hh"
  15 #include "group-interface.hh"
  16 #include "misc.hh"
  17 #include "paper-score.hh"
  18 #include "paper-def.hh"
  19 #include "molecule.hh"
  20 #include "grob.hh"
  21 #include "debug.hh"
  22 #include "spanner.hh"
  23 #include "line-of-score.hh"
  24 #include "item.hh"
  25 #include "paper-column.hh"
  26 #include "molecule.hh"
  27 #include "misc.hh"
  28 #include "paper-outputter.hh"
  29 #include "dimension-cache.hh"
  30 #include "side-position-interface.hh"
  31 #include "item.hh"
  32
  33 #include "ly-smobs.icc"
  34
  35 /*
  36 TODO:
  37
  38 remove dynamic_cast<Spanner,Item> and put this code into respective
  39   subclass.
  40 */
  41
  42
  43 #define INFINITY_MSG "Infinity or NaN encountered"
  44
  45 Grob::Grob (SCM basicprops)
  46 {
  47   /*
  48     fixme: default should be no callback.
  49    */
  50
  51   pscore_l_=0;
  52   status_c_ = 0;
  53   original_l_ = 0;
  54   immutable_property_alist_ =  basicprops;
  55   mutable_property_alist_ = SCM_EOL;
  56
  57   smobify_self ();
  58
  59   /*
  60     TODO:
  61
  62     destill this into a function, so we can re-init the immutable
  63     properties with a new BASICPROPS value after creation. Convenient
  64     eg. when using \override with StaffSymbol.  */
  65
  66   char const*onames[] = {"X-offset-callbacks", "Y-offset-callbacks"};
  67   char const*enames[] = {"X-extent-callback", "Y-extent-callback"};
  68
  69   for (int a = X_AXIS; a <= Y_AXIS; a++)
  70     {
  71       SCM l = get_grob_property (onames[a]);
  72
  73       if (scm_ilength (l) >=0)
  74         {
  75           dim_cache_[a].offset_callbacks_ = l;
  76           dim_cache_[a].offsets_left_ = scm_ilength (l);
  77         }
  78       else
  79         {
  80           programming_error ("[XY]-offset-callbacks must be a list");
  81         }
  82
  83       SCM cb = get_grob_property (enames[a]);
  84
  85       /*
  86         Should change default to be empty?
  87       */
  88       if (cb != SCM_BOOL_F && !gh_procedure_p (cb) && !gh_pair_p (cb))
  89         cb = molecule_extent_proc;
  90
  91       dim_cache_[a].dimension_ = cb;
  92     }
  93
  94   SCM meta = get_grob_property ("meta");
  95   SCM ifs = scm_assoc (ly_symbol2scm ("interfaces"), meta);
  96
  97   set_grob_property ("interfaces",gh_cdr (ifs));
  98 }
  99
 100
 101 Grob::Grob (Grob const&s)
 102    : dim_cache_ (s.dim_cache_)
 103 {
 104   original_l_ = (Grob*) &s;
 105   immutable_property_alist_ = s.immutable_property_alist_;
 106   mutable_property_alist_ = SCM_EOL;
 107
 108   status_c_ = s.status_c_;
 109   pscore_l_ = s.pscore_l_;
 110
 111   smobify_self ();
 112 }
 113
 114 Grob::~Grob ()
 115 {
 116   /*
 117     do nothing scm-ish and no unprotecting here.
 118    */
 119 }
 120
 121
 122 SCM
 123 Grob::get_grob_property (const char *nm) const
 124 {
 125   SCM sym = ly_symbol2scm (nm);
 126   return get_grob_property (sym);
 127 }
 128
 129 SCM
 130 Grob::get_grob_property (SCM sym) const
 131 {
 132   SCM s = scm_sloppy_assq (sym, mutable_property_alist_);
 133   if (s != SCM_BOOL_F)
 134     return gh_cdr (s);
 135
 136   s = scm_sloppy_assq (sym, immutable_property_alist_);
 137   return (s == SCM_BOOL_F) ? SCM_EOL : gh_cdr (s);
 138 }
 139
 140 /*
 141   Remove the value associated with KEY, and return it. The result is
 142   that a next call will yield SCM_UNDEFINED (and not the underlying
 143   `basic' property.
 144 */
 145 SCM
 146 Grob::remove_grob_property (const char* key)
 147 {
 148   SCM val = get_grob_property (key);
 149   if (val != SCM_EOL)
 150     set_grob_property (key, SCM_EOL);
 151   return val;
 152 }
 153
 154 void
 155 Grob::set_grob_property (const char* k, SCM v)
 156 {
 157   SCM s = ly_symbol2scm (k);
 158   set_grob_property (s, v);
 159 }
 160
 161 /*
 162   Puts the k, v in the immutable_property_alist_, which is convenient for
 163   storing variables that are needed during the breaking process. (eg.
 164   Line_of_score::rank : int)
 165  */
 166 void
 167 Grob::set_immutable_grob_property (const char*k, SCM v)
 168 {
 169   SCM s = ly_symbol2scm (k);
 170   set_immutable_grob_property (s, v);
 171 }
 172
 173 void
 174 Grob::set_immutable_grob_property (SCM s, SCM v)
 175 {
 176   immutable_property_alist_ = gh_cons (gh_cons (s,v), mutable_property_alist_);
 177   mutable_property_alist_ = scm_assq_remove_x (mutable_property_alist_, s);
 178 }
 179 void
 180 Grob::set_grob_property (SCM s, SCM v)
 181 {
 182   mutable_property_alist_ = scm_assq_set_x (mutable_property_alist_, s, v);
 183 }
 184
 185
 186 MAKE_SCHEME_CALLBACK (Grob,molecule_extent,2);
 187 SCM
 188 Grob::molecule_extent (SCM element_smob, SCM scm_axis)
 189 {
 190   Grob *s = unsmob_grob (element_smob);
 191   Axis a = (Axis) gh_scm2int (scm_axis);
 192
 193   Molecule *m = s->get_molecule ();
 194   Interval e ;
 195   if (m)
 196     e = m->extent (a);
 197   return ly_interval2scm (e);
 198 }
 199
 200 MAKE_SCHEME_CALLBACK (Grob,preset_extent,2);
 201
 202 SCM
 203 Grob::preset_extent (SCM element_smob, SCM scm_axis)
 204 {
 205   Grob *s = unsmob_grob (element_smob);
 206   Axis a = (Axis) gh_scm2int (scm_axis);
 207
 208   SCM ext = s->get_grob_property ((a == X_AXIS)
 209                                  ? "extent-X"
 210                                  : "extent-Y");
 211
 212   if (gh_pair_p (ext))
 213     {
 214       Real l = gh_scm2double (gh_car (ext));
 215       Real r = gh_scm2double (gh_cdr (ext));
 216       return ly_interval2scm (Interval (l, r));
 217     }
 218
 219   return ly_interval2scm (Interval ());
 220 }
 221
 222
 223
 224 Paper_def*
 225 Grob::paper_l ()  const
 226 {
 227  return pscore_l_ ? pscore_l_->paper_l_ : 0;
 228 }
 229
 230 void
 231 Grob::calculate_dependencies (int final, int busy, SCM funcname)
 232 {
 233   if (status_c_ >= final)
 234     return;
 235
 236   if (status_c_== busy)
 237     {
 238       programming_error ("Element is busy, come back later");
 239       return;
 240     }
 241
 242   status_c_= busy;
 243
 244   for (SCM d=  get_grob_property ("dependencies"); gh_pair_p (d); d = gh_cdr (d))
 245     {
 246       unsmob_grob (gh_car (d))
 247         ->calculate_dependencies (final, busy, funcname);
 248     }
 249
 250   // ughugh.
 251   String s = ly_symbol2string (funcname);
 252   SCM proc = get_grob_property (s.ch_C ());
 253   if (gh_procedure_p (proc))
 254     gh_call1 (proc, this->self_scm ());
 255
 256   status_c_= final;
 257
 258 }
 259
 260 Molecule *
 261 Grob::get_molecule ()  const
 262 {
 263   SCM mol = get_grob_property ("molecule");
 264   if (unsmob_molecule (mol))
 265     return unsmob_molecule (mol);
 266
 267   mol =  get_uncached_molecule ();
 268
 269   Grob *me = (Grob*)this;
 270   me->set_grob_property ("molecule", mol);
 271
 272   return unsmob_molecule (mol);
 273 }
 274 SCM
 275 Grob::get_uncached_molecule ()const
 276 {
 277   SCM proc = get_grob_property ("molecule-callback");
 278
 279   SCM  mol = SCM_EOL;
 280   if (gh_procedure_p (proc))
 281     mol = gh_apply (proc, gh_list (this->self_scm (), SCM_UNDEFINED));
 282
 283
 284   Molecule *m = unsmob_molecule (mol);
 285
 286   if (unsmob_molecule (mol))
 287     {
 288       /*
 289         TODO: add option for not copying origin info.
 290       */
 291       SCM origin =get_grob_property ("origin");
 292       if (!unsmob_input (origin))
 293         origin =ly_symbol2scm ("no-origin");
 294
 295
 296       // ugr.
 297
 298       mol = Molecule (m->extent_box (),
 299                       gh_list (origin, m->get_expr (), SCM_UNDEFINED)
 300                       ). smobbed_copy ();
 301
 302       m = unsmob_molecule (mol);
 303     }
 304
 305   /*
 306     transparent retains dimensions of element.
 307    */
 308   if (m && to_boolean (get_grob_property ("transparent")))
 309     mol = Molecule (m->extent_box (), SCM_EOL).smobbed_copy ();
 310
 311   return mol;
 312 }
 313
 314 /*
 315
 316   VIRTUAL STUBS
 317
 318  */
 319 void
 320 Grob::do_break_processing ()
 321 {
 322 }
 323
 324
 325
 326
 327
 328
 329 Line_of_score *
 330 Grob::line_l () const
 331 {
 332   return 0;
 333 }
 334
 335 void
 336 Grob::add_dependency (Grob*e)
 337 {
 338   if (e)
 339     {
 340       Pointer_group_interface ::add_element (this, "dependencies",e);
 341
 342     }
 343   else
 344     programming_error ("Null dependency added");
 345 }
 346
 347
 348
 349
 350 /**
 351       Do break substitution in S, using CRITERION. Return new value.
 352       CRITERION is either a SMOB pointer to the desired line, or a number
 353       representing the break direction. Do not modify SRC.
 354 */
 355 SCM
 356 Grob::handle_broken_grobs (SCM src, SCM criterion)
 357 {
 358  again:
 359   Grob *sc = unsmob_grob (src);
 360   if (sc)
 361     {
 362       if (gh_number_p (criterion))
 363         {
 364           Item * i = dynamic_cast<Item*> (sc);
 365           Direction d = to_dir (criterion);
 366           if (i && i->break_status_dir () != d)
 367             {
 368               Item *br = i->find_prebroken_piece (d);
 369               return (br) ? br->self_scm () : SCM_UNDEFINED;
 370             }
 371         }
 372       else
 373         {
 374           Line_of_score * line
 375             = dynamic_cast<Line_of_score*> (unsmob_grob (criterion));
 376           if (sc->line_l () != line)
 377             {
 378               sc = sc->find_broken_piece (line);
 379
 380             }
 381
 382           /* now: !sc || (sc && sc->line_l () == line) */
 383           if (!sc)
 384             return SCM_UNDEFINED;
 385
 386           /* now: sc && sc->line_l () == line */
 387           if (!line
 388               || (sc->common_refpoint (line, X_AXIS)
 389                   && sc->common_refpoint (line, Y_AXIS)))
 390             {
 391               return sc->self_scm ();
 392             }
 393           return SCM_UNDEFINED;
 394         }
 395     }
 396   else if (gh_pair_p (src))
 397     {
 398       SCM oldcar =gh_car (src);
 399       /*
 400         UGH! breaks on circular lists.
 401       */
 402       SCM newcar = handle_broken_grobs (oldcar, criterion);
 403       SCM oldcdr = gh_cdr (src);
 404
 405       if (newcar == SCM_UNDEFINED
 406           && (gh_pair_p (oldcdr) || oldcdr == SCM_EOL))
 407         {
 408           /*
 409             This is tail-recursion, ie.
 410
 411             return handle_broken_grobs (cdr, criterion);
 412
 413             We don't want to rely on the compiler to do this.  Without
 414             tail-recursion, this easily crashes with a stack overflow.  */
 415           src =  oldcdr;
 416           goto again;
 417         }
 418
 419       SCM newcdr = handle_broken_grobs (oldcdr, criterion);
 420       return gh_cons (newcar, newcdr);
 421     }
 422   else
 423     return src;
 424
 425   return src;
 426 }
 427
 428 void
 429 Grob::handle_broken_dependencies ()
 430 {
 431   Spanner * s= dynamic_cast<Spanner*> (this);
 432   if (original_l_ && s)
 433     return;
 434
 435   if (s)
 436     {
 437       for (int i = 0;  i< s->broken_into_l_arr_ .size (); i++)
 438         {
 439           Grob * sc = s->broken_into_l_arr_[i];
 440           Line_of_score * l = sc->line_l ();
 441           sc->mutable_property_alist_ =
 442             handle_broken_grobs (mutable_property_alist_,
 443                                  l ? l->self_scm () : SCM_UNDEFINED);
 444         }
 445     }
 446
 447
 448   Line_of_score *line = line_l ();
 449
 450   if (line && common_refpoint (line, X_AXIS) && common_refpoint (line, Y_AXIS))
 451     {
 452       mutable_property_alist_
 453         = handle_broken_grobs (mutable_property_alist_,
 454                                line ? line->self_scm () : SCM_UNDEFINED);
 455     }
 456   else if (dynamic_cast <Line_of_score*> (this))
 457     {
 458       mutable_property_alist_ = handle_broken_grobs (mutable_property_alist_,
 459                                             SCM_UNDEFINED);
 460     }
 461   else
 462     {
 463       /*
 464         This element is `invalid'; it has been removed from all
 465         dependencies, so let's junk the element itself.
 466
 467         do not do this for Line_of_score, since that would remove
 468         references to the originals of score-elts, which get then GC'd
 469  (a bad thing.)
 470       */
 471       suicide ();
 472     }
 473 }
 474
 475 /*
 476  Note that we still want references to this element to be
 477  rearranged, and not silently thrown away, so we keep pointers
 478  like {broken_into_{drul,array}, original}
 479 */
 480 void
 481 Grob::suicide ()
 482 {
 483   mutable_property_alist_ = SCM_EOL;
 484   immutable_property_alist_ = SCM_EOL;
 485
 486   set_extent_callback (SCM_EOL, Y_AXIS);
 487   set_extent_callback (SCM_EOL, X_AXIS);
 488
 489   for (int a= X_AXIS; a <= Y_AXIS; a++)
 490     {
 491       dim_cache_[a].offset_callbacks_ = SCM_EOL;
 492       dim_cache_[a].offsets_left_ = 0;
 493     }
 494 }
 495
 496 void
 497 Grob::handle_prebroken_dependencies ()
 498 {
 499 }
 500
 501 Grob*
 502 Grob::find_broken_piece (Line_of_score*) const
 503 {
 504   return 0;
 505 }
 506
 507 void
 508 Grob::translate_axis (Real y, Axis a)
 509 {
 510   if (isinf (y) || isnan (y))
 511     programming_error (_ (INFINITY_MSG));
 512   else
 513     {
 514       dim_cache_[a].offset_ += y;
 515     }
 516 }
 517
 518 Real
 519 Grob::relative_coordinate (Grob const*refp, Axis a) const
 520 {
 521   if (refp == this)
 522     return 0.0;
 523
 524   /*
 525     We catch PARENT_L_ == nil case with this, but we crash if we did
 526     not ask for the absolute coordinate (ie. REFP == nil.)
 527
 528    */
 529   if (refp == dim_cache_[a].parent_l_)
 530     return get_offset (a);
 531   else
 532     return get_offset (a) + dim_cache_[a].parent_l_->relative_coordinate (refp, a);
 533 }
 534
 535 Real
 536 Grob::get_offset (Axis a) const
 537 {
 538   Grob *me = (Grob*) this;
 539   while (dim_cache_[a].offsets_left_)
 540     {
 541       int l = --me->dim_cache_[a].offsets_left_;
 542       SCM cb = scm_list_ref (dim_cache_[a].offset_callbacks_,  gh_int2scm (l));
 543       SCM retval = gh_call2 (cb, self_scm (), gh_int2scm (a));
 544
 545       Real r =  gh_scm2double (retval);
 546       if (isinf (r) || isnan (r))
 547         {
 548           programming_error (INFINITY_MSG);
 549           r = 0.0;
 550         }
 551       me->dim_cache_[a].offset_ +=r;
 552     }
 553   return dim_cache_[a].offset_;
 554 }
 555
 556
 557 MAKE_SCHEME_CALLBACK (Grob,point_dimension_callback,2);
 558 SCM
 559 Grob::point_dimension_callback (SCM , SCM)
 560 {
 561   return ly_interval2scm (Interval (0,0));
 562 }
 563
 564 bool
 565 Grob::empty_b (Axis a)const
 566 {
 567   return ! (gh_pair_p (dim_cache_[a].dimension_) ||
 568             gh_procedure_p (dim_cache_[a].dimension_));
 569 }
 570
 571 /*
 572   TODO: add
 573
 574     Grob *refpoint
 575
 576   to arguments?
 577  */
 578 Interval
 579 Grob::extent (Grob * refp, Axis a) const
 580 {
 581   Real x = relative_coordinate (refp, a);
 582
 583
 584   Dimension_cache * d = (Dimension_cache *)&dim_cache_[a];
 585   Interval ext ;
 586   if (gh_pair_p (d->dimension_))
 587     ;
 588   else if (gh_procedure_p (d->dimension_))
 589     {
 590       /*
 591         FIXME: add doco on types, and should typecheck maybe?
 592        */
 593       d->dimension_= gh_call2 (d->dimension_, self_scm (), gh_int2scm (a));
 594     }
 595   else
 596     return ext;
 597
 598   if (!gh_pair_p (d->dimension_))
 599     return ext;
 600
 601   ext = ly_scm2interval (d->dimension_);
 602
 603   SCM extra = get_grob_property (a == X_AXIS
 604                                 ? "extra-extent-X"
 605                                 : "extra-extent-Y");
 606
 607   /*
 608     signs ?
 609    */
 610   if (gh_pair_p (extra))
 611     {
 612       ext[BIGGER] +=  gh_scm2double (gh_cdr (extra));
 613       ext[SMALLER] +=   gh_scm2double (gh_car (extra));
 614     }
 615
 616   extra = get_grob_property (a == X_AXIS
 617                                 ? "minimum-extent-X"
 618                                 : "minimum-extent-Y");
 619   if (gh_pair_p (extra))
 620     {
 621       ext.unite (Interval (gh_scm2double (gh_car (extra)),
 622                            gh_scm2double (gh_cdr (extra))));
 623     }
 624
 625   ext.translate (x);
 626
 627   return ext;
 628 }
 629
 630
 631 Grob*
 632 Grob::parent_l (Axis a) const
 633 {
 634   return  dim_cache_[a].parent_l_;
 635 }
 636
 637 Grob *
 638 Grob::common_refpoint (Grob const* s, Axis a) const
 639 {
 640   /*
 641     I don't like the quadratic aspect of this code, but I see no other
 642     way. The largest chain of parents might be 10 high or so, so
 643     it shouldn't be a real issue. */
 644   for (Grob const *c = this; c; c = c->dim_cache_[a].parent_l_)
 645     for (Grob const * d = s; d; d = d->dim_cache_[a].parent_l_)
 646       if (d == c)
 647         return (Grob*)d;
 648
 649   return 0;
 650 }
 651
 652
 653 Grob *
 654 Grob::common_refpoint (SCM elist, Axis a) const
 655 {
 656   Grob * common = (Grob*) this;
 657   for (; gh_pair_p (elist); elist = gh_cdr (elist))
 658     {
 659       Grob * s = unsmob_grob (gh_car (elist));
 660       if (s)
 661         common = common->common_refpoint (s, a);
 662     }
 663
 664   return common;
 665 }
 666
 667 String
 668 Grob::name () const
 669 {
 670   SCM meta = get_grob_property ("meta");
 671   SCM nm = scm_assoc (ly_symbol2scm ("name"), meta);
 672   nm = (gh_pair_p (nm)) ? gh_cdr (nm) : SCM_EOL;
 673   return  gh_string_p (nm) ?ly_scm2string (nm) :  classname (this);
 674 }
 675
 676 void
 677 Grob::add_offset_callback (SCM cb, Axis a)
 678 {
 679   if (!has_offset_callback_b (cb, a))
 680   {
 681     dim_cache_[a].offset_callbacks_ = gh_cons (cb, dim_cache_[a].offset_callbacks_);
 682     dim_cache_[a].offsets_left_ ++;
 683   }
 684 }
 685
 686 bool
 687 Grob::has_extent_callback_b (SCM cb, Axis a)const
 688 {
 689   return scm_equal_p (cb, dim_cache_[a].dimension_) == SCM_BOOL_T;
 690 }
 691
 692
 693 bool
 694 Grob::has_extent_callback_b (Axis a) const
 695 {
 696   return gh_procedure_p (dim_cache_[a].dimension_);
 697 }
 698
 699 bool
 700 Grob::has_offset_callback_b (SCM cb, Axis a)const
 701 {
 702   return scm_memq (cb, dim_cache_[a].offset_callbacks_) != SCM_BOOL_F;
 703 }
 704
 705 void
 706 Grob::set_extent_callback (SCM dc, Axis a)
 707 {
 708   dim_cache_[a].dimension_ =dc;
 709 }
 710
 711 void
 712 Grob::set_parent (Grob *g, Axis a)
 713 {
 714   dim_cache_[a].parent_l_ = g;
 715 }
 716
 717 MAKE_SCHEME_CALLBACK (Grob,fixup_refpoint,1);
 718 SCM
 719 Grob::fixup_refpoint (SCM smob)
 720 {
 721   Grob *me = unsmob_grob (smob);
 722   for (int a = X_AXIS; a < NO_AXES; a ++)
 723     {
 724       Axis ax = (Axis)a;
 725       Grob * parent = me->parent_l (ax);
 726
 727       if (!parent)
 728         continue;
 729
 730       if (parent->line_l () != me->line_l () && me->line_l ())
 731         {
 732           Grob * newparent = parent->find_broken_piece (me->line_l ());
 733           me->set_parent (newparent, ax);
 734         }
 735
 736       if (Item * i  = dynamic_cast<Item*> (me))
 737         {
 738           Item *parenti = dynamic_cast<Item*> (parent);
 739
 740           if (parenti && i)
 741             {
 742               Direction  my_dir = i->break_status_dir () ;
 743               if (my_dir!= parenti->break_status_dir ())
 744                 {
 745                   Item *newparent =  parenti->find_prebroken_piece (my_dir);
 746                   me->set_parent (newparent, ax);
 747                 }
 748             }
 749         }
 750     }
 751   return smob;
 752 }
 753
 754
 755
 756 /****************************************************
 757   SMOB funcs
 758  ****************************************************/
 759
 760
 761 IMPLEMENT_UNSMOB (Grob, grob);
 762 IMPLEMENT_SMOBS (Grob);
 763 IMPLEMENT_DEFAULT_EQUAL_P (Grob);
 764
 765 SCM
 766 Grob::mark_smob (SCM ses)
 767 {
 768   Grob * s = (Grob*) SCM_CELL_WORD_1 (ses);
 769   scm_gc_mark (s->immutable_property_alist_);
 770   scm_gc_mark (s->mutable_property_alist_);
 771
 772   for (int a =0 ; a < 2; a++)
 773     {
 774       scm_gc_mark (s->dim_cache_[a].offset_callbacks_);
 775       scm_gc_mark (s->dim_cache_[a].dimension_);
 776     }
 777
 778   if (s->parent_l (Y_AXIS))
 779     scm_gc_mark (s->parent_l (Y_AXIS)->self_scm ());
 780   if (s->parent_l (X_AXIS))
 781     scm_gc_mark (s->parent_l (X_AXIS)->self_scm ());
 782
 783   if (s->original_l_)
 784     scm_gc_mark (s->original_l_->self_scm ());
 785   return s->do_derived_mark ();
 786 }
 787
 788 int
 789 Grob::print_smob (SCM s, SCM port, scm_print_state *)
 790 {
 791   Grob *sc = (Grob *) gh_cdr (s);
 792
 793   scm_puts ("#<Grob ", port);
 794   scm_puts ((char *)sc->name ().ch_C (), port);
 795
 796   /*
 797     don't try to print properties, that is too much hassle.
 798    */
 799   scm_puts (" >", port);
 800   return 1;
 801 }
 802
 803 SCM
 804 Grob::do_derived_mark ()
 805 {
 806   return SCM_EOL;
 807 }
 808
 809
 810 SCM
 811 ly_set_grob_property (SCM elt, SCM sym, SCM val)
 812 {
 813   Grob * sc = unsmob_grob (elt);
 814
 815   if (!gh_symbol_p (sym))
 816     {
 817       error ("Not a symbol");
 818       ly_display_scm (sym);
 819       return SCM_UNSPECIFIED;
 820     }
 821
 822   if (sc)
 823     {
 824       sc->set_grob_property (sym, val);
 825     }
 826   else
 827     {
 828       error ("Not a score element");
 829       ly_display_scm (elt);
 830     }
 831
 832   return SCM_UNSPECIFIED;
 833 }
 834
 835
 836 SCM
 837 ly_get_grob_property (SCM elt, SCM sym)
 838 {
 839   Grob * sc = unsmob_grob (elt);
 840
 841   if (sc)
 842     {
 843       return sc->get_grob_property (sym);
 844     }
 845   else
 846     {
 847       error ("Not a score element");
 848       ly_display_scm (elt);
 849     }
 850   return SCM_UNSPECIFIED;
 851 }
 852
 853
 854 void
 855 Grob::discretionary_processing ()
 856 {
 857 }
 858
 859
 860
 861 SCM
 862 spanner_get_bound (SCM slur, SCM dir)
 863 {
 864   return dynamic_cast<Spanner*> (unsmob_grob (slur))->get_bound (to_dir (dir))->self_scm ();
 865 }
 866
 867
 868
 869 static SCM interfaces_sym;
 870 static void
 871 init_functions ()
 872 {
 873   interfaces_sym = scm_permanent_object (ly_symbol2scm ("interfaces"));
 874
 875   scm_c_define_gsubr ("ly-get-grob-property", 2, 0, 0,
 876                       (Scheme_function_unknown)ly_get_grob_property);
 877   scm_c_define_gsubr ("ly-set-grob-property", 3, 0, 0,
 878                       (Scheme_function_unknown)ly_set_grob_property);
 879   scm_c_define_gsubr ("ly-get-spanner-bound", 2 , 0, 0,
 880                       (Scheme_function_unknown) spanner_get_bound);
 881 }
 882
 883 bool
 884 Grob::has_interface (SCM k)
 885 {
 886   SCM ifs = get_grob_property (interfaces_sym);
 887
 888   return scm_memq (k, ifs) != SCM_BOOL_F;
 889 }
 890
 891 void
 892 Grob::set_interface (SCM k)
 893 {
 894   if (has_interface (k))
 895     return ;
 896   else
 897     {
 898       set_grob_property (interfaces_sym,
 899                         gh_cons (k, get_grob_property (interfaces_sym)));
 900     }
 901 }
 902
 903
 904 ADD_SCM_INIT_FUNC (scoreelt, init_functions);
 905 IMPLEMENT_TYPE_P (Grob, "ly-grob?");