lily/parse-scm.cc

   1 /*
   2   This file is part of LilyPond, the GNU music typesetter.
   3
   4   Copyright (C) 2004--2011 Han-Wen Nienhuys <hanwen@xs4all.nl>
   5
   6   LilyPond is free software: you can redistribute it and/or modify
   7   it under the terms of the GNU General Public License as published by
   8   the Free Software Foundation, either version 3 of the License, or
   9   (at your option) any later version.
  10
  11   LilyPond is distributed in the hope that it will be useful,
  12   but WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14   GNU General Public License for more details.
  15
  16   You should have received a copy of the GNU General Public License
  17   along with LilyPond.  If not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 #include "parse-scm.hh"
  21
  22 #include <cstdio>
  23 using namespace std;
  24
  25 #include "lily-parser.hh"
  26 #include "international.hh"
  27 #include "main.hh"
  28 #include "paper-book.hh"
  29 #include "source-file.hh"
  30
  31 /* Pass string to scm parser, evaluate one expression.
  32    Return result value and #chars read.
  33
  34    Thanks to Gary Houston <ghouston@freewire.co.uk>  */
  35 SCM
  36 internal_ly_parse_scm (Parse_start *ps)
  37 {
  38   Source_file *sf = ps->start_location_.get_source_file ();
  39   SCM port = sf->get_port ();
  40
  41   int off = ps->start_location_.start () - sf->c_str ();
  42
  43   scm_seek (port, scm_from_long (off), scm_from_long (SEEK_SET));
  44   SCM from = scm_ftell (port);
  45
  46   scm_set_port_line_x (port,  scm_from_int (ps->start_location_.line_number () -1));
  47   scm_set_port_column_x (port,  scm_from_int (ps->start_location_.column_number () -1));
  48
  49   SCM answer = SCM_UNSPECIFIED;
  50   SCM form = scm_read (port);
  51
  52   SCM to = scm_ftell (port);
  53   ps->nchars = scm_to_int (to) - scm_to_int (from);
  54
  55
  56   /* Read expression from port.  */
  57   if (!SCM_EOF_OBJECT_P (form))
  58     {
  59       if (ps->safe_)
  60         {
  61           static SCM module = SCM_BOOL_F;
  62           if (module == SCM_BOOL_F)
  63             {
  64               SCM function = ly_lily_module_constant ("make-safe-lilypond-module");
  65               module = scm_call_0 (function);
  66             }
  67
  68           // We define the parser so trusted Scheme functions can
  69           // access the real namespace underlying the parser.
  70           if (ps->parser_)
  71             scm_module_define (module, ly_symbol2scm ("parser"),
  72                                ps->parser_->self_scm());
  73           answer = scm_eval (form, module);
  74         }
  75       else
  76         answer = scm_primitive_eval (form);
  77     }
  78
  79   /* Don't close the port here; if we re-enter this function via a
  80      continuation, then the next time we enter it, we'll get an error.
  81      It's a string port anyway, so there's no advantage to closing it
  82      early. */
  83   // scm_close_port (port);
  84
  85   return answer;
  86 }
  87
  88 SCM
  89 catch_protected_parse_body (void *p)
  90 {
  91   Parse_start *ps = (Parse_start *) p;
  92
  93   return internal_ly_parse_scm (ps);
  94 }
  95
  96 SCM
  97 parse_handler (void *data, SCM tag, SCM args)
  98 {
  99   Parse_start *ps = (Parse_start *) data;
 100
 101   ps->start_location_.error (_ ("GUILE signaled an error for the expression beginning here"));
 102
 103   if (scm_ilength (args) > 2)
 104     scm_display_error_message (scm_cadr (args), scm_caddr (args), scm_current_error_port ());
 105
 106   if (tag == ly_symbol2scm ("read-error"))
 107     ps->nchars = 1;
 108
 109   return SCM_UNDEFINED;
 110 }
 111
 112 SCM
 113 protected_ly_parse_scm (Parse_start *ps)
 114 {
 115   /*
 116     Catch #t : catch all Scheme level errors.
 117    */
 118   return scm_internal_catch (SCM_BOOL_T,
 119                              &catch_protected_parse_body,
 120                              (void *) ps,
 121                              &parse_handler, (void *) ps);
 122 }
 123
 124 bool parse_protect_global = true;
 125 bool parsed_objects_should_be_dead = false;
 126
 127 /* Try parsing.  Upon failure return SCM_UNDEFINED.
 128    FIXME: shouldn't we return SCM_UNSCPECIFIED -- jcn  */
 129 SCM
 130 ly_parse_scm (char const *s, int *n, Input i, bool safe, Lily_parser *parser)
 131 {
 132   Parse_start ps;
 133   ps.str = s;
 134   ps.start_location_ = i;
 135   ps.safe_ = safe;
 136   ps.parser_ = parser;
 137
 138   SCM ans = parse_protect_global ? protected_ly_parse_scm (&ps)
 139     : internal_ly_parse_scm (&ps);
 140   *n = ps.nchars;
 141
 142   return ans;
 143 }
 144