lily/identifier-smob.cc

   1 /*
   2 identifier-smob.cc -- implement glue to pass Scheme expressions off as
   3 identifiers.
   4
   5 source file of the GNU LilyPond music typesetter
   6
   7 (c) 2002--2004 Han-Wen Nienhuys <hanwen@cs.uu.nl>
   8
   9 */
  10 #include "identifier-smob.hh"
  11
  12
  13 scm_t_bits package_tag;
  14
  15 static int
  16 print_box (SCM b, SCM port, scm_print_state *)
  17 {
  18   SCM value = SCM_CELL_OBJECT_1 (b);
  19
  20   scm_puts ("#<packaged object ", port);
  21   scm_write (value, port);
  22   scm_puts (">", port);
  23
  24   /* Non-zero means success.  */
  25   return 1;
  26 }
  27
  28
  29 /* This defines the primitve `make-box', which returns a new smob of
  30    type `box', initialized to `#f'.  */
  31 LY_DEFINE (package_identifier, "ly:export", 1,0,0, (SCM arg),
  32           "Export a Scheme object to the parser, so it is treated as an identifier.")
  33 {
  34   SCM_RETURN_NEWSMOB (package_tag, arg);
  35 }
  36
  37
  38 SCM
  39 unpack_identifier (SCM box)
  40 {
  41   if (SCM_IMP (box) || SCM_CELL_TYPE (box) != package_tag)
  42     return SCM_UNDEFINED;
  43
  44   return SCM_CELL_OBJECT_1 (box);
  45 }
  46
  47 static void
  48 init_box_type (void)
  49 {
  50   package_tag = scm_make_smob_type ("box", 0);
  51   scm_set_smob_mark (package_tag, scm_markcdr);
  52   scm_set_smob_print (package_tag, print_box);
  53 }
  54 ADD_SCM_INIT_FUNC (package, init_box_type);