2 parse-scm -- Parse a single SCM expression exactly.
4 source file of the GNU LilyPond music typesetter
6 (c) 2004--2005 Han-Wen Nienhuys <hanwen@cs.uu.nl>
9 #include "parse-scm.hh"
15 #include "paper-book.hh"
16 #include "source-file.hh"
18 /* Pass string to scm parser, evaluate one expression.
19 Return result value and #chars read.
21 Thanks to Gary Houston <ghouston@freewire.co.uk> */
23 internal_ly_parse_scm (Parse_start *ps)
25 Source_file *sf = ps->start_location_.get_source_file ();
26 SCM port = sf->get_port ();
28 int off = ps->start_location_.start () - sf->to_str0 ();
30 scm_seek (port, scm_long2num (off), scm_long2num (SEEK_SET));
31 SCM from = scm_ftell (port);
33 SCM answer = SCM_UNSPECIFIED;
34 SCM form = scm_read (port);
36 /* Read expression from port. */
37 if (!SCM_EOF_OBJECT_P (form))
41 static SCM module = SCM_BOOL_F;
42 if (module == SCM_BOOL_F)
44 SCM function = ly_lily_module_constant ("make-safe-lilypond-module");
45 module = scm_call_0 (function);
47 answer = scm_eval (form, module);
50 answer = scm_primitive_eval (form);
53 /* Reset read_buf for scm_ftell.
54 Shouldn't scm_read () do this for us? */
55 scm_fill_input (port);
56 SCM to = scm_ftell (port);
57 ps->nchars = scm_to_int (to) - scm_to_int (from);
59 /* Don't close the port here; if we re-enter this function via a
60 continuation, then the next time we enter it, we'll get an error.
61 It's a string port anyway, so there's no advantage to closing it
63 // scm_close_port (port);
69 catch_protected_parse_body (void *p)
71 Parse_start *ps = (Parse_start *) p;
73 return internal_ly_parse_scm (ps);
77 parse_handler (void *data, SCM tag, SCM args)
79 Parse_start *ps = (Parse_start *) data;
82 ps->start_location_.error (_ ("GUILE signaled an error for the expression beginning here"));
84 if (scm_ilength (args) > 2)
85 scm_display_error_message (scm_cadr (args), scm_caddr (args), scm_current_error_port ());
88 The following is a kludge; we should probably search for
89 [a-z][0-9] (a note), and start before that.
97 Do some magical incantations: if not, lily will exit on the first
98 GUILE error, leaving no location trace.
101 #if GUILE_MINOR_VERSION < 7
102 #define READ_ERROR "misc-error"
104 #define READ_ERROR "read-error"
108 protected_ly_parse_scm (Parse_start *ps)
110 return scm_internal_catch (ly_symbol2scm (READ_ERROR),
111 &catch_protected_parse_body,
113 &parse_handler, (void *) ps);
116 bool parse_protect_global = true;
118 /* Try parsing. Upon failure return SCM_UNDEFINED.
119 FIXME: shouldn't we return SCM_UNSCPECIFIED -- jcn */
121 ly_parse_scm (char const *s, int *n, Input i, bool safe)
125 ps.start_location_ = i;
128 SCM ans = parse_protect_global ? protected_ly_parse_scm (&ps)
129 : internal_ly_parse_scm (&ps);