Xorn
backend.py
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1 # xorn.geda.netlist - gEDA Netlist Extraction and Generation
2 # Copyright (C) 1998-2010 Ales Hvezda
3 # Copyright (C) 1998-2010 gEDA Contributors (see ChangeLog for details)
4 # Copyright (C) 2013-2016 Roland Lutz
5 #
6 # This program is free software; you can redistribute it and/or modify
8 # the Free Software Foundation; either version 2 of the License, or
9 # (at your option) any later version.
10 #
11 # This program 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 this program; if not, write to the Free Software Foundation,
18 # Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
19
20 ## \namespace xorn.geda.netlist.backend
21 ## Handling netlist backends.
22 #
23 # After the netlist has been constructed, it is passed to a \a backend
24 # which creates some kind of output based on the information in the
25 # netlist. The backend is selected by the user via the command-line
26 # option <tt>-g \a BACKEND</tt>; a list of available options can be
27 # displayed using the command-line option --list-backends.
28 #
29 # A backend is a Python file in the special backend load path whose
30 # name starts with the prefix \c "gnet_". It should contain a special
31 # function \c run(f, netlist) as the main entry point.
32
33 import imp, os, sys
34 from gettext import gettext as _
35
36 ## Module name prefix for netlister backends.
37 #
38 # Only Python modules whose name starts with this prefix are
39 # considered netlister backends.
40
41 BACKEND_PREFIX = 'gnet_'
42
44 #
45 # A list of directory names in which to search for netlister backends.
46
48
49 ## Get a sorted list of available backends.
50 #
51 # Returns a list of available netlister backends by searching for
52 # files in each of the directories given in \ref load_path. A module
53 # is considered to be a netlister backend if its name begins with
54 # \ref BACKEND_PREFIX ("gnet_").
55
57  backend_names = set()
58
60  try:
61  d_names = os.listdir(dir_name)
62  except OSError as e:
63  sys.stderr.write(_("Can't open directory %s: %s\n")
64  % (dir_name, e.strerror))
65  continue
66
67  for d_name in d_names:
68  # Check that filename has the right format to be a backend
69  if not d_name.startswith(BACKEND_PREFIX):
70  continue
71
72  for suffix, mode, type in imp.get_suffixes():
73  if d_name.endswith(suffix, len(BACKEND_PREFIX)):
74  # Remove prefix & suffix. Add to list of backend names.
76  break
77
78  return sorted(backend_names)
79
80 ## Load a specific netlister backend.
81 #
82 # Searches in the backend load path for a module called \c
83 # gnet_<em>backend_name</em>, loads it, and returns the module object.
84 #
85 # The backend module's path is added to the system load path.
86 #
87 # \throws ImportError if the module could not be loaded
88
90  # Search for backend module in load path
91  f, pathname, description = imp.find_module(
93  if f is None:
94  # module is a package
95  raise ImportError
96