lily/music-function.cc

   1 /*
   2   music-function.cc --  implement music_function
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c) 2004 Han-Wen Nienhuys <hanwen@xs4all.nl>
   7
   8 */
   9 #include "music-function.hh"
  10 #include "string.hh"
  11 #include "music.hh"
  12
  13 static scm_t_bits music_function_tag;
  14
  15 /* Print a textual represenation of the smob to a given port.  */
  16 static int
  17 print_music_function (SCM b, SCM port, scm_print_state *)
  18 {
  19   SCM value = SCM_CELL_OBJECT_1 (b);
  20
  21   scm_puts ("#<Music function ", port);
  22   scm_write (value, port);
  23   scm_puts (">", port);
  24
  25   /* Non-zero means success.  */
  26   return 1;
  27 }
  28
  29
  30 LY_DEFINE (ly_make_music_function, "ly:make-music-function", 2, 0, 0,
  31            (SCM signature, SCM func),
  32           "Make a function to process music, to be used for the "
  33            "parser. @code{func} is the function, and @code{signature} describes "
  34            "Its arguments. @code{signature} is a list containing either "
  35            "@code{ly:music?} predicates or other type predicates.")
  36 {
  37   String str = "";
  38   for (SCM s = signature; ly_c_pair_p (s); s = ly_cdr (s))
  39     {
  40       if (str != "")
  41         str += "-";
  42
  43       if (ly_car (s) == Music_type_p_proc)
  44         str += "music";
  45       else if (ly_c_procedure_p (ly_car (s)))
  46         str += "scm";
  47     }
  48   if (str == "") str = "noarg";
  49   scm_set_object_property_x (func, ly_symbol2scm ("music-function-signature"),
  50                              signature);
  51
  52   scm_set_object_property_x (func, ly_symbol2scm ("music-function-signature-keyword"),
  53                              ly_symbol2scm (str.to_str0 ()));
  54
  55   SCM_RETURN_NEWSMOB (music_function_tag, func);
  56 }
  57
  58 bool
  59 is_music_function (SCM music_function)
  60 {
  61   return (SCM_NIMP (music_function) && SCM_CELL_TYPE (music_function) == music_function_tag);
  62 }
  63
  64
  65 SCM
  66 get_music_function_transform (SCM music_function)
  67 {
  68   if (!is_music_function (music_function))
  69     return SCM_UNDEFINED;
  70
  71   return SCM_CELL_OBJECT_1 (music_function);
  72 }
  73
  74 static void
  75 init_music_function (void)
  76 {
  77   music_function_tag = scm_make_smob_type ("music-function", 0);
  78   scm_set_smob_mark (music_function_tag, scm_markcdr);
  79   scm_set_smob_print (music_function_tag, print_music_function);
  80 }
  81
  82 ADD_SCM_INIT_FUNC (music_function_tag, init_music_function);