A spot of refactoring

src/calibre/db/cache.py

@@ -7,7 +7,7 @@ __license__   = 'GPL v3'
 __copyright__ = '2011, Kovid Goyal <kovid@kovidgoyal.net>'
 __docformat__ = 'restructuredtext en'
 
-import os, traceback, random, shutil, re, operator
+import os, traceback, random, shutil, operator
 from io import BytesIO
 from collections import defaultdict
 from functools import wraps, partial
@@ -26,7 +26,7 @@ from calibre.db.tables import VirtualTable
 from calibre.db.write import get_series_values, uniq
 from calibre.db.lazy import FormatMetadata, FormatsList, ProxyMetadata
 from calibre.ebooks import check_ebook_format
-from calibre.ebooks.metadata import string_to_authors, author_to_author_sort, get_title_sort_pat
+from calibre.ebooks.metadata import string_to_authors, author_to_author_sort
 from calibre.ebooks.metadata.book.base import Metadata
 from calibre.ebooks.metadata.opf2 import metadata_to_opf
 from calibre.ptempfile import (base_dir, PersistentTemporaryFile,
@@ -1778,22 +1778,7 @@ class Cache(object):
     def find_identical_books(self, mi, search_restriction='', book_ids=None):
         ''' Finds books that have a superset of the authors in mi and the same
         title (title is fuzzy matched) '''
-        fuzzy_title_patterns = [(re.compile(pat, re.IGNORECASE) if
-            isinstance(pat, basestring) else pat, repl) for pat, repl in
-                [
-                    (r'[\[\](){}<>\'";,:#]', ''),
-                    (get_title_sort_pat(), ''),
-                    (r'[-._]', ' '),
-                    (r'\s+', ' ')
-                ]
-        ]
-
-        def fuzzy_title(title):
-            title = icu_lower(title.strip())
-            for pat, repl in fuzzy_title_patterns:
-                title = pat.sub(repl, title)
-            return title
-
+        from calibre.db.utils import fuzzy_title
         identical_book_ids = set()
         if mi.authors:
             try:

src/calibre/db/utils.py

@@ -6,7 +6,7 @@ from __future__ import (unicode_literals, division, absolute_import,
 __license__ = 'GPL v3'
 __copyright__ = '2013, Kovid Goyal <kovid at kovidgoyal.net>'
 
-import os, errno, cPickle, sys
+import os, errno, cPickle, sys, re
 from collections import OrderedDict, namedtuple
 from future_builtins import map
 from threading import Lock
@@ -30,6 +30,29 @@ def force_to_bool(val):
             val = None
     return val
 
+_fuzzy_title_patterns = None
+
+def fuzzy_title_patterns():
+    global _fuzzy_title_patterns
+    if _fuzzy_title_patterns is None:
+        from calibre.ebooks.metadata import get_title_sort_pat
+        _fuzzy_title_patterns = tuple((re.compile(pat, re.IGNORECASE) if
+            isinstance(pat, basestring) else pat, repl) for pat, repl in
+                [
+                    (r'[\[\](){}<>\'";,:#]', ''),
+                    (get_title_sort_pat(), ''),
+                    (r'[-._]', ' '),
+                    (r'\s+', ' ')
+                ]
+        )
+    return _fuzzy_title_patterns
+
+def fuzzy_title(title):
+    title = icu_lower(title.strip())
+    for pat, repl in fuzzy_title_patterns():
+        title = pat.sub(repl, title)
+    return title
+
 Entry = namedtuple('Entry', 'path size timestamp thumbnail_size')
 class CacheError(Exception):
     pass