From 5ec89c0e9e90b1f25035d2451aa973359c728c34 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Tue, 27 Sep 2011 09:41:55 -0600
Subject: [PATCH] Fix reading metadata from filenames when the author regexp
 does not match anything

---
 src/calibre/ebooks/metadata/__init__.py |  2 ++
 src/calibre/ebooks/metadata/meta.py     | 27 +++++++++++++------------
 2 files changed, 16 insertions(+), 13 deletions(-)

diff --git a/src/calibre/ebooks/metadata/__init__.py b/src/calibre/ebooks/metadata/__init__.py
index dd90b4c2ec..decba3b780 100644
--- a/src/calibre/ebooks/metadata/__init__.py
+++ b/src/calibre/ebooks/metadata/__init__.py
@@ -22,6 +22,8 @@ except:
     _author_pat = re.compile(r'(?i),?\s+(and|with)\s+')
 
 def string_to_authors(raw):
+    if not raw:
+        return []
     raw = raw.replace('&&', u'\uffff')
     raw = _author_pat.sub('&', raw)
     authors = [a.strip().replace(u'\uffff', '&') for a in raw.split('&')]
diff --git a/src/calibre/ebooks/metadata/meta.py b/src/calibre/ebooks/metadata/meta.py
index d82a2268fa..7d8855de14 100644
--- a/src/calibre/ebooks/metadata/meta.py
+++ b/src/calibre/ebooks/metadata/meta.py
@@ -149,19 +149,20 @@ def metadata_from_filename(name, pat=None):
         try:
             au = match.group('author')
             aus = string_to_authors(au)
-            mi.authors = aus
-            if prefs['swap_author_names'] and mi.authors:
-                def swap(a):
-                    if ',' in a:
-                        parts = a.split(',', 1)
-                    else:
-                        parts = a.split(None, 1)
-                    if len(parts) > 1:
-                        t = parts[-1]
-                        parts = parts[:-1]
-                        parts.insert(0, t)
-                    return ' '.join(parts)
-                mi.authors = [swap(x) for x in mi.authors]
+            if aus:
+                mi.authors = aus
+                if prefs['swap_author_names'] and mi.authors:
+                    def swap(a):
+                        if ',' in a:
+                            parts = a.split(',', 1)
+                        else:
+                            parts = a.split(None, 1)
+                        if len(parts) > 1:
+                            t = parts[-1]
+                            parts = parts[:-1]
+                            parts.insert(0, t)
+                        return ' '.join(parts)
+                    mi.authors = [swap(x) for x in mi.authors]
         except (IndexError, ValueError):
             pass
         try: