add a small set of default path functions (#231)

beets/library.py

@@ -817,7 +817,7 @@ class Library(BaseLibrary):
             mapping['albumartist'] = mapping['artist']
         
         # Perform substitution.
-        subpath = subpath_tmpl.substitute(mapping)
+        subpath = subpath_tmpl.substitute(mapping, TEMPLATE_FUNCTIONS)
         
         # Encode for the filesystem, dropping unencodable characters.
         if isinstance(subpath, unicode) and not fragment:
@@ -1260,3 +1260,48 @@ class Album(BaseAlbum):
             util.soft_remove(oldart)
         util.copy(path, artdest)
         self.artpath = artdest
+
+
+# Default path template resources.
+
+def _int_arg(s):
+    """Convert a string argument to an integer for use in a template
+    function.  May raise a ValueError.
+    """
+    return int(s.strip())
+def _tmpl_lower(s):
+    """Convert a string to lower case."""
+    return s.lower()
+def _tmpl_upper(s):
+    """Covert a string to upper case."""
+    return s.upper()
+def _tmpl_title(s):
+    """Convert a string to title case."""
+    return s.title()
+def _tmpl_left(s, chars):
+    """Get the leftmost characters of a string."""
+    return s[0:_int_arg(chars)]
+def _tmpl_right(s, chars):
+    """Get the rightmost characters of a string."""
+    return s[-_int_arg(chars):]
+def _tmpl_if(condition, trueval, falseval=u''):
+    """If ``condition`` is nonempty and nonzero, emit ``trueval``;
+    otherwise, emit ``falseval`` (if provided).
+    """
+    try:
+        condition = _int_arg(condition)
+    except ValueError:
+        condition = condition.strip()
+    if condition:
+        return trueval
+    else:
+        return falseval
+
+TEMPLATE_FUNCTIONS = {
+    'lower': _tmpl_lower,
+    'upper': _tmpl_upper,
+    'title': _tmpl_title,
+    'left': _tmpl_left,
+    'right': _tmpl_right,
+    'if': _tmpl_if,
+}

test/test_db.py

@@ -363,6 +363,60 @@ class DestinationTest(unittest.TestCase):
         p = util.sanitize_path('', posixpath)
         self.assertEqual(p, '')
 
+class DestinationFunctionTest(unittest.TestCase):
+    def setUp(self):
+        self.lib = beets.library.Library(':memory:')
+        self.lib.directory = '/base'
+        self.lib.path_formats = {'default': u'path'}
+        self.i = item()
+    def tearDown(self):
+        self.lib.conn.close()
+
+    def _setf(self, fmt):
+        self.lib.path_formats['default'] = fmt
+    def _assert_dest(self, dest):
+        self.assertEqual(self.lib.destination(self.i), dest)
+
+    def test_upper_case_literal(self):
+        self._setf(u'%upper{foo}')
+        self._assert_dest('/base/FOO')
+    
+    def test_upper_case_variable(self):
+        self._setf(u'%upper{$title}')
+        self._assert_dest('/base/THE TITLE')
+
+    def test_title_case_variable(self):
+        self._setf(u'%title{$title}')
+        self._assert_dest('/base/The Title')
+
+    def test_left_variable(self):
+        self._setf(u'%left{$title, 3}')
+        self._assert_dest('/base/the')
+    
+    def test_right_variable(self):
+        self._setf(u'%right{$title,3}')
+        self._assert_dest('/base/tle')
+
+    def test_if_false(self):
+        self._setf(u'%if{,foo}')
+        self._assert_dest('/base/')
+    
+    def test_if_true(self):
+        self._setf(u'%if{bar,foo}')
+        self._assert_dest('/base/foo')
+    
+    def test_if_else_false(self):
+        self._setf(u'%if{,foo,baz}')
+        self._assert_dest('/base/baz')
+
+    def test_if_int_value(self):
+        self._setf(u'%if{0,foo,baz}')
+        self._assert_dest('/base/baz')
+
+    def test_nonexistent_function(self):
+        self._setf(u'%foo{bar}')
+        self._assert_dest('/base/%foo{bar}')
+    
 class MigrationTest(unittest.TestCase):
     """Tests the ability to change the database schema between
     versions.