Bug 841061 - Handle comments properly in Preferences.read_prefs, r=jh…

…ammel

mozprofile/mozprofile/prefs.py

@@ -8,7 +8,9 @@
 
 import os
 import re
+import tokenize
 from ConfigParser import SafeConfigParser as ConfigParser
+from StringIO import StringIO
 
 try:
     import json
@@ -156,18 +158,27 @@ def read_prefs(cls, path, pref_setter='user_pref'):
 
         comment = re.compile('/\*([^*]|[\r\n]|(\*+([^*/]|[\r\n])))*\*+/', re.MULTILINE)
 
-        token = '##//' # magical token
+        marker = '##//' # magical marker
         lines = [i.strip() for i in file(path).readlines() if i.strip()]
         _lines = []
         for line in lines:
-            if line.startswith('#'):
+            if line.startswith(('#', '//')):
                 continue
             if '//' in line:
-                line = line.replace('//', token)
+                line = line.replace('//', marker)
             _lines.append(line)
         string = '\n'.join(_lines)
         string = re.sub(comment, '', string)
 
+        # skip trailing comments
+        processed_tokens = []
+        f_obj = StringIO(string)
+        for token in tokenize.generate_tokens(f_obj.readline):
+            if token[0] == tokenize.COMMENT:
+                continue
+            processed_tokens.append(token[:2]) # [:2] gets around http://bugs.python.org/issue9974
+        string = tokenize.untokenize(processed_tokens)
+
         retval = []
         def pref(a, b):
             retval.append((a, b))
@@ -182,10 +193,10 @@ def pref(a, b):
                 print line
                 raise
 
-        # de-magic the token
+        # de-magic the marker
         for index, (key, value) in enumerate(retval):
-            if isinstance(value, basestring) and token in value:
-                retval[index] = (key, value.replace(token, '//'))
+            if isinstance(value, basestring) and marker in value:
+                retval[index] = (key, value.replace(marker, '//'))
 
         return retval
 

mozprofile/tests/files/prefs_with_comments.js

@@ -0,0 +1,6 @@
+# A leading comment
+user_pref("browser.startup.homepage", "http://planet.mozilla.org"); # A trailing comment
+user_pref("zoom.minPercent", 30);
+// Another leading comment
+user_pref("zoom.maxPercent", 300); // Another trailing comment
+user_pref("webgl.verbose", "false");

mozprofile/tests/test_preferences.py

@@ -12,6 +12,8 @@
 from mozprofile.prefs import Preferences
 from mozprofile.profile import Profile
 
+here = os.path.dirname(os.path.abspath(__file__))
+
 class PreferencesTest(unittest.TestCase):
     """test mozprofile preference handling"""
 
@@ -241,6 +243,16 @@ def test_prefs_write(self):
             # cleanup
             os.remove(path)
 
+    def test_read_prefs_with_comments(self):
+        """test reading preferences from a prefs.js file that contains comments"""
+
+        _prefs = {'browser.startup.homepage': 'http://planet.mozilla.org',
+                  'zoom.minPercent': 30,
+                  'zoom.maxPercent': 300,
+                  'webgl.verbose': 'false'}
+        path = os.path.join(here, 'files', 'prefs_with_comments.js')
+        self.assertEqual(dict(Preferences.read_prefs(path)), _prefs)
+
 
 if __name__ == '__main__':
     unittest.main()