2 music-head.cc -- implement Music_head
4 source file of the GNU LilyPond music typesetter
6 (c) 2004 Han-Wen Nienhuys <hanwen@xs4all.nl>
9 #include "music-head.hh"
13 C&P from example/box.c
16 static scm_t_bits music_head_tag;
18 /* Print a textual represenation of the smob to a given port. */
20 print_music_head (SCM b, SCM port, scm_print_state *)
22 SCM value = SCM_CELL_OBJECT_1 (b);
24 scm_puts ("#<packaged object ", port);
25 scm_write (value, port);
28 /* Non-zero means success. */
33 /* This defines the primitve `make-music_head', which returns a new smob of
34 type `music_head', initialized to `#f'. */
35 LY_DEFINE (ly_make_music_head, "ly:make-music-head", 2, 0, 0,
36 (SCM func, SCM signature),
37 "Make a function to process music, to be used for the "
38 "parser. @code{func} is the function, and @code{signature} describes "
39 "Its arguments. @code{signature} is a list containing either "
40 "@code{ly:music?} predicates or other type predicates.")
42 /* This macro creates the new objects, stores the value `#f' into it
43 and returns it to the caller. */
47 for (SCM s = signature; ly_c_pair_p (s); s = ly_cdr (s))
52 if (ly_car (s) == Music_type_p_proc)
54 else if (ly_procedure_p (ly_car (s)))
60 scm_set_object_property_x (func, ly_symbol2scm ("music-head-signature"),
63 scm_set_object_property_x (func, ly_symbol2scm ("music-head-signature-keyword"),
64 ly_symbol2scm (str.to_str0 ()));
66 SCM_RETURN_NEWSMOB (music_head_tag, func);
70 is_music_head (SCM music_head)
72 return (SCM_NIMP (music_head) && SCM_CELL_TYPE (music_head) == music_head_tag);
76 /* This is the primitive `music_head-ref' which returns the object stored in
79 get_music_head_transform (SCM music_head)
81 if (!is_music_head (music_head))
84 return SCM_CELL_OBJECT_1 (music_head);
88 init_music_head (void)
90 music_head_tag = scm_make_smob_type ("music-head", 0);
91 scm_set_smob_mark (music_head_tag, scm_markcdr);
92 scm_set_smob_print (music_head_tag, print_music_head);
94 ADD_SCM_INIT_FUNC (music_head_tag, init_music_head);