lily/parse-scm.cc

   1 /*
   2   parse-scm -- Parse a single SCM expression exactly.
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c) 2004--2007 Han-Wen Nienhuys <hanwen@xs4all.nl>
   7 */
   8
   9 #include "parse-scm.hh"
  10
  11 #include <cstdio>
  12 using namespace std;
  13
  14 #include "lily-parser.hh"
  15 #include "international.hh"
  16 #include "main.hh"
  17 #include "paper-book.hh"
  18 #include "source-file.hh"
  19
  20 /* Pass string to scm parser, evaluate one expression.
  21    Return result value and #chars read.
  22
  23    Thanks to Gary Houston <ghouston@freewire.co.uk>  */
  24 SCM
  25 internal_ly_parse_scm (Parse_start *ps)
  26 {
  27   Source_file *sf = ps->start_location_.get_source_file ();
  28   SCM port = sf->get_port ();
  29
  30   int off = ps->start_location_.start () - sf->c_str ();
  31
  32   scm_seek (port, scm_long2num (off), scm_long2num (SEEK_SET));
  33   SCM from = scm_ftell (port);
  34
  35   scm_set_port_line_x (port,  scm_from_int (ps->start_location_.line_number () -1));
  36   scm_set_port_column_x (port,  scm_from_int (ps->start_location_.column_number () -1));
  37
  38   SCM answer = SCM_UNSPECIFIED;
  39   SCM form = scm_read (port);
  40
  41   /* Reset read_buf for scm_ftell.
  42      Shouldn't scm_read () do this for us?  */
  43   scm_fill_input (port);
  44   SCM to = scm_ftell (port);
  45   ps->nchars = scm_to_int (to) - scm_to_int (from);
  46
  47
  48   /* Read expression from port.  */
  49   if (!SCM_EOF_OBJECT_P (form))
  50     {
  51       if (ps->safe_)
  52         {
  53           static SCM module = SCM_BOOL_F;
  54           if (module == SCM_BOOL_F)
  55             {
  56               SCM function = ly_lily_module_constant ("make-safe-lilypond-module");
  57               module = scm_call_0 (function);
  58             }
  59
  60           // We define the parser so trusted Scheme functions can
  61           // access the real namespace underlying the parser.
  62           if (ps->parser_)
  63             scm_module_define (module, ly_symbol2scm ("parser"),
  64                                ps->parser_->self_scm());
  65           answer = scm_eval (form, module);
  66         }
  67       else
  68         answer = scm_primitive_eval (form);
  69     }
  70
  71   /* Don't close the port here; if we re-enter this function via a
  72      continuation, then the next time we enter it, we'll get an error.
  73      It's a string port anyway, so there's no advantage to closing it
  74      early. */
  75   // scm_close_port (port);
  76
  77   return answer;
  78 }
  79
  80 SCM
  81 catch_protected_parse_body (void *p)
  82 {
  83   Parse_start *ps = (Parse_start *) p;
  84
  85   return internal_ly_parse_scm (ps);
  86 }
  87
  88 SCM
  89 parse_handler (void *data, SCM tag, SCM args)
  90 {
  91   Parse_start *ps = (Parse_start *) data;
  92
  93   ps->start_location_.error (_ ("GUILE signaled an error for the expression beginning here"));
  94
  95   if (scm_ilength (args) > 2)
  96     scm_display_error_message (scm_cadr (args), scm_caddr (args), scm_current_error_port ());
  97
  98   if (tag == ly_symbol2scm ("read-error"))
  99     ps->nchars = 1;
 100
 101   return SCM_UNDEFINED;
 102 }
 103
 104 SCM
 105 protected_ly_parse_scm (Parse_start *ps)
 106 {
 107   /*
 108     Catch #t : catch all Scheme level errors.
 109    */
 110   return scm_internal_catch (SCM_BOOL_T,
 111                              &catch_protected_parse_body,
 112                              (void *) ps,
 113                              &parse_handler, (void *) ps);
 114 }
 115
 116 bool parse_protect_global = true;
 117 bool parsed_objects_should_be_dead = false;
 118
 119 /* Try parsing.  Upon failure return SCM_UNDEFINED.
 120    FIXME: shouldn't we return SCM_UNSCPECIFIED -- jcn  */
 121 SCM
 122 ly_parse_scm (char const *s, int *n, Input i, bool safe, Lily_parser *parser)
 123 {
 124   Parse_start ps;
 125   ps.str = s;
 126   ps.start_location_ = i;
 127   ps.safe_ = safe;
 128   ps.parser_ = parser;
 129
 130   SCM ans = parse_protect_global ? protected_ly_parse_scm (&ps)
 131     : internal_ly_parse_scm (&ps);
 132   *n = ps.nchars;
 133
 134   return ans;
 135 }
 136