lv2include/lv2include.py

   1 #!/usr/bin/python
   2 # -*- coding: utf-8 -*-
   3
   4 """A program (and Python module) to generate a tree of symlinks to LV2
   5 extension bundles, where the path of the symlink corresponds to the URI of
   6 the extension.  This allows including extension headers in code without using
   7 the bundle name.  Including extension headers in this way is much better,
   8 since there is no dependency on the (meaningless and non-persistent) bundle
   9 name in the code using the header.
  10
  11 For example, after running lv2includegen (and setting the compiler include
  12 path appropriately), LV2 headers could be included like so:
  13
  14 #include "lv2/lv2plug.in/ns/lv2core/lv2.h"
  15 #include "lv2/lv2plug.in/ns/ext/event/event.h"
  16 #include "lv2/example.org/foo/foo.h"
  17
  18 Where the initial "lv2" is arbitrary; in this case lv2includegen's output
  19 directory was "lv2", and that directory's parent was added to the compiler
  20 include search path.  It is a good idea to use such a prefix directory so
  21 domain names do not conflict with anything else in the include path.
  22 """
  23
  24 __authors__ = 'David Robillard'
  25 __license   = 'GNU GPL v3 or later <http://www.gnu.org/licenses/gpl.html>'
  26 __contact__ = 'devel@lists.lv2plug.in'
  27 __date__    = '2010-10-05'
  28
  29 import errno
  30 import glob
  31 import os
  32 import stat
  33 import sys
  34
  35 import RDF
  36
  37 def rdf_load(uri):
  38     model = RDF.Model()
  39     parser = RDF.Parser(name="guess")
  40     parser.parse_into_model(model, uri)
  41     return model
  42
  43 def rdf_find(model, s, p, o):
  44     return model.find_statements(RDF.Statement(s, p, o))
  45
  46 def rdf_namespace(uri):
  47     return RDF.NS(uri)
  48
  49 rdf = rdf_namespace('http://www.w3.org/1999/02/22-rdf-syntax-ns#')
  50 lv2 = rdf_namespace('http://lv2plug.in/ns/lv2core#')
  51
  52 def lv2_path():
  53     "Return the LV2 search path (LV2_PATH in the environment, or a default)."
  54     if 'LV2_PATH' in os.environ:
  55         return os.environ['LV2_PATH']
  56     else:
  57         ret = '/usr/lib/lv2' + os.pathsep + '/usr/local/lib/lv2'
  58         print 'LV2_PATH unset, using default ' + ret
  59         return ret
  60
  61 def __bundles(search_path):
  62     "Return a list of all LV2 bundles found in search_path."
  63     dirs = search_path.split(os.pathsep)
  64     bundles = []
  65     for dir in dirs:
  66         bundles += glob.glob(os.path.join(dir, '*.lv2'))
  67     return bundles
  68
  69 def __usage():
  70     script = os.path.basename(sys.argv[0])
  71     print """Usage:
  72     %s OUTDIR
  73
  74         OUTDIR : Directory to build include tree
  75
  76 Example:
  77     %s /usr/local/include/lv2
  78 """ % (script, script)
  79
  80 def __mkdir_p(path):
  81     "Equivalent of UNIX mkdir -p"
  82     try:
  83         os.makedirs(path)
  84     except OSError as e:
  85         if e.errno == errno.EEXIST:
  86             pass
  87         else:
  88             raise
  89
  90 def build_tree(search_path, outdir):
  91     """Build a directory tree under outdir containing symlinks to all LV2
  92     extensions found in search_path, such that the symlink paths correspond to
  93     the extension URIs."""
  94     for bundle in __bundles(search_path):
  95         # Load manifest into model
  96         manifest = rdf_load('file://' + os.path.join(bundle, 'manifest.ttl'))
  97
  98         # Query extension URI
  99         results = rdf_find(manifest, None, rdf.type, lv2.Specification)
 100         for r in results:
 101             ext_uri    = str(r.subject.uri)
 102             ext_scheme = ext_uri[0:ext_uri.find(':')]
 103             ext_path   = os.path.normpath(ext_uri[ext_uri.find(':') + 1:].lstrip('/'))
 104             ext_dir    = os.path.join(outdir, ext_scheme, ext_path)
 105
 106             # Make parent directories
 107             __mkdir_p(os.path.dirname(ext_dir))
 108
 109             # Remove existing symlink if necessary
 110             if os.access(ext_dir, os.F_OK):
 111                 mode = os.lstat(ext_dir)[stat.ST_MODE]
 112                 if stat.S_ISLNK(mode):
 113                     os.remove(ext_dir)
 114                 else:
 115                     raise Exception(ext_dir + " exists and is not a link")
 116
 117             # Make symlink to bundle directory
 118             os.symlink(bundle, ext_dir)
 119
 120 if __name__ == "__main__":
 121     args = sys.argv[1:]
 122     if len(args) != 1:
 123         __usage()
 124         sys.exit(1)
 125
 126     outdir = args[0]
 127     print "Building LV2 include tree at", outdir
 128
 129     build_tree(lv2_path(), outdir)