add experimental fuzzy matching plugin

fuzzy is a command which tries to be like the list command but using
fuzzy matching.

beetsplug/fuzzy_list.py

@@ -0,0 +1,84 @@
+# This file is part of beets.
+# Copyright 2011, Philippe Mongeau.
+#
+# 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.
+
+"""Get a random song or album from the library.
+"""
+from beets.plugins import BeetsPlugin
+from beets.ui import Subcommand, decargs, print_
+from beets.util.functemplate import Template
+import random
+import difflib
+
+def fuzzy_score(query, item):
+    return difflib.SequenceMatcher(a=query, b=item).quick_ratio()
+
+def is_match(query, item, verbose=False):
+    query = ' '.join(query)
+    s =  max(fuzzy_score(query, i) for i in (item.artist,
+                                           item.album,
+                                           item.title))
+    if s > 0.7: return (True, s) if verbose else True
+    else: return (False, s) if verbose else False
+
+def fuzzy_list(lib, config, opts, args):
+    query = decargs(args)
+    path = opts.path
+    fmt = opts.format
+    verbose = opts.verbose
+
+    if fmt is None:
+        # If no specific template is supplied, use a default
+        if opts.album:
+            fmt = u'$albumartist - $album'
+        else:
+            fmt = u'$artist - $album - $title'
+    template = Template(fmt)
+
+    if opts.album:
+        objs = list(lib.albums())
+    else:
+        objs = list(lib.items())
+
+    # matches = [i for i in objs if is_match(query, i)]
+
+    if opts.album:
+        for album in objs:
+            if path:
+                print_(album.item_dir())
+            else:
+                print_(album.evaluate_template(template))
+    else:
+        for item in objs:
+            if is_match(query, item):
+                if path:
+                    print_(item.path)
+                else:
+                    print_(item.evaluate_template(template, lib))
+                if verbose: print is_match(query,item, True)[1]
+
+fuzzy_cmd = Subcommand('fuzzy',
+                        help='list items using fuzzy matching')
+fuzzy_cmd.parser.add_option('-a', '--album', action='store_true',
+        help='choose an album instead of track')
+fuzzy_cmd.parser.add_option('-p', '--path', action='store_true',
+        help='print the path of the matched item')
+fuzzy_cmd.parser.add_option('-f', '--format', action='store',
+        help='print with custom format', default=None)
+fuzzy_cmd.parser.add_option('-v', '--verbose', action='store_true',
+        help='output scores for matches')
+fuzzy_cmd.func = fuzzy_list
+
+class Random(BeetsPlugin):
+    def commands(self):
+        return [fuzzy_cmd]