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--2009 Han-Wen Nienhuys <hanwen@xs4all.nl>
   8 */
   9
  10 #include "identifier-smob.hh"
  11
  12 scm_t_bits package_tag;
  13
  14 static int
  15 print_box (SCM b, SCM port, scm_print_state *)
  16 {
  17   SCM value = SCM_CELL_OBJECT_1 (b);
  18
  19   scm_puts ("#<packaged object ", port);
  20   scm_write (value, port);
  21   scm_puts (">", port);
  22
  23   /* Non-zero means success.  */
  24   return 1;
  25 }
  26
  27 /* This defines the primitve `make-box', which returns a new smob of
  28    type `box', initialized to `#f'.  */
  29 LY_DEFINE (ly_export, "ly:export",
  30            1, 0, 0, (SCM arg),
  31            "Export a Scheme object to the parser"
  32            " so it is treated as an identifier.")
  33 {
  34   SCM_RETURN_NEWSMOB (package_tag, arg);
  35 }
  36
  37 SCM
  38 unpack_identifier (SCM box)
  39 {
  40   if (SCM_IMP (box) || SCM_CELL_TYPE (box) != package_tag)
  41     return SCM_UNDEFINED;
  42
  43   return SCM_CELL_OBJECT_1 (box);
  44 }
  45
  46 static void
  47 init_box_type (void)
  48 {
  49   package_tag = scm_make_smob_type ("box", 0);
  50   scm_set_smob_mark (package_tag, scm_markcdr);
  51   scm_set_smob_print (package_tag, print_box);
  52 }
  53
  54 ADD_SCM_INIT_FUNC (package, init_box_type);