add simple virtual filesystem construction

--HG--
rename : test/test_art.py => test/test_vfs.py

beets/library.py

@@ -757,10 +757,12 @@ class Library(BaseLibrary):
         self.conn.executescript(setup_sql)
         self.conn.commit()
     
-    def destination(self, item, pathmod=None, in_album=False):
+    def destination(self, item, pathmod=None, in_album=False, noroot=False):
         """Returns the path in the library directory designated for item
         item (i.e., where the file ought to be). in_album forces the
-        item to be treated as part of an album.
+        item to be treated as part of an album. noroot makes this
+        method return just the path fragment underneath the root library
+        directory.
         """
         pathmod = pathmod or os.path
         
@@ -817,7 +819,10 @@ class Library(BaseLibrary):
         _, extension = pathmod.splitext(item.path)
         subpath += extension
         
-        return normpath(os.path.join(self.directory, subpath))   
+        if noroot:
+            return subpath
+        else:
+            return normpath(os.path.join(self.directory, subpath))   
 
     
     # Main interface.

beets/vfs.py

@@ -0,0 +1,48 @@
+# This file is part of beets.
+# Copyright 2011, Adrian Sampson.
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+# 
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+
+"""A simple utility for constructing filesystem-like trees from beets
+libraries.
+"""
+from collections import namedtuple
+from beets import util
+
+Node = namedtuple('Node', ['files', 'dirs'])
+
+def _insert(node, path, itemid):
+    """Insert an item into a virtual filesystem node."""
+    if len(path) == 1:
+        # Last component. Insert file.
+        node.files[path[0]] = itemid
+    else:
+        # In a directory.
+        dirname = path[0]
+        rest = path[1:]
+        if dirname not in node.dirs:
+            node.dirs[dirname] = Node({}, {})
+        _insert(node.dirs[dirname], rest, itemid)
+
+def libtree(lib):
+    """Generates a filesystem-like directory tree for the files
+    contained in `lib`. Filesystem nodes are (files, dirs) named
+    tuples in which both components are dictionaries. The first
+    maps filenames to Item ids. The second maps directory names to
+    child node tuples.
+    """
+    root = Node({}, {})
+    for item in lib.items():
+        dest = lib.destination(item, noroot=True)
+        parts = util.components(dest)
+        _insert(root, parts, item.id)
+    return root

test/test_vfs.py

@@ -0,0 +1,45 @@
+# This file is part of beets.
+# Copyright 2011, Adrian Sampson.
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+# 
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+
+"""Tests for the virtual filesystem builder.."""
+import unittest
+
+import _common
+from beets import library
+from beets import vfs
+
+class VFSTest(unittest.TestCase):
+    def setUp(self):
+        self.lib = library.Library(':memory:', path_formats={
+            'default': 'albums/$album/$title',
+            'singleton': 'tracks/$artist/$title',
+        })
+        self.lib.add(_common.item())
+        self.lib.add_album([_common.item()])
+        self.lib.save()
+        self.tree = vfs.libtree(self.lib)
+    
+    def test_singleton_item(self):
+        self.assertEqual(self.tree.dirs['tracks'].dirs['the artist'].
+                         files['the title'], 1)
+
+    def test_album_item(self):
+        self.assertEqual(self.tree.dirs['albums'].dirs['the album'].
+                         files['the title'], 2)
+
+def suite():
+    return unittest.TestLoader().loadTestsFromName(__name__)
+
+if __name__ == '__main__':
+    unittest.main(defaultTest='suite')