nbt: code style fixes

We're ignoring E221 and E741 since I disagree with them; I think extra
whitespace around operators to align repeated operations can aid
readability and help spot bugs.

This was mostly whitespace issues, e.g. trailing whitespace and
a single space on blank lines.

overviewer_core/nbt.py

@@ -13,10 +13,12 @@
 #    You should have received a copy of the GNU General Public License along
 #    with the Overviewer.  If not, see <http://www.gnu.org/licenses/>.
 
-import gzip, zlib
-import struct
-import StringIO
 import functools
+import gzip
+import StringIO
+import struct
+import zlib
+
 
 # decorator that turns the first argument from a string into an open file
 # handle
@@ -29,6 +31,7 @@ def _file_loader(func):
         return func(fileobj, *args)
     return wrapper
 
+
 @_file_loader
 def load(fileobj):
     """Reads in the given file as NBT format, parses it, and returns the
@@ -36,6 +39,7 @@ def load(fileobj):
     """
     return NBTFileReader(fileobj).read_all()
 
+
 @_file_loader
 def load_region(fileobj):
     """Reads in the given file as a MCR region, and returns an object
@@ -45,23 +49,29 @@ def load_region(fileobj):
 
 class CorruptionError(Exception):
     pass
+
+
 class CorruptRegionError(CorruptionError):
     """An exception raised when the MCRFileReader class encounters an
     error during region file parsing.
     """
     pass
+
+
 class CorruptChunkError(CorruptionError):
     pass
+
+
 class CorruptNBTError(CorruptionError):
     """An exception raised when the NBTFileReader class encounters
     something unexpected in an NBT file."""
     pass
 
+
 class NBTFileReader(object):
     """Low level class that reads the Named Binary Tag format used by Minecraft
 
     """
-    
     # compile the unpacker's into a classes
     _byte   = struct.Struct("b")
     _short  = struct.Struct(">h")
@@ -96,9 +106,9 @@ class NBTFileReader(object):
             7: self._read_tag_byte_array,
             8: self._read_tag_string,
             9: self._read_tag_list,
-            10:self._read_tag_compound,
-            11:self._read_tag_int_array,
-            12:self._read_tag_long_array,
+            10: self._read_tag_compound,
+            11: self._read_tag_int_array,
+            12: self._read_tag_long_array,
         }
 
     # These private methods read the payload only of the following types
@@ -137,12 +147,12 @@ class NBTFileReader(object):
 
     def _read_tag_int_array(self):
         length = self._uint.unpack(self._file.read(4))[0]
-        int_bytes = self._file.read(length*4)
+        int_bytes = self._file.read(length * 4)
         return struct.unpack(">%ii" % length, int_bytes)
 
     def _read_tag_long_array(self):
         length = self._uint.unpack(self._file.read(4))[0]
-        long_bytes = self._file.read(length*8)
+        long_bytes = self._file.read(length * 8)
         return struct.unpack(">%iq" % length, long_bytes)
 
     def _read_tag_string(self):
@@ -189,15 +199,14 @@ class NBTFileReader(object):
             tagtype = ord(self._file.read(1))
             if tagtype != 10:
                 raise Exception("Expected a tag compound")
-            
             # Read the tag name
             name = self._read_tag_string()
             payload = self._read_tag_compound()
-            
             return (name, payload)
         except (struct.error, ValueError, TypeError), e:
             raise CorruptNBTError("could not parse nbt: %s" % (str(e),))
 
+
 # For reference, the MCR format is outlined at
 # <http://www.minecraftwiki.net/wiki/Beta_Level_Format>
 class MCRFileReader(object):
@@ -246,7 +255,7 @@ class MCRFileReader(object):
         for x in xrange(32):
             for z in xrange(32):
                 if self._locations[x + z * 32] >> 8 != 0:
-                    yield (x,z)
+                    yield (x, z)
 
     def get_chunk_timestamp(self, x, z):
         """Return the given chunk's modification time. If the given
@@ -273,8 +282,8 @@ class MCRFileReader(object):
         x = x % 32
         z = z % 32
         location = self._locations[x + z * 32]
-        offset = (location >> 8) * 4096;
-        sectors = location & 0xff;
+        offset = (location >> 8) * 4096
+        sectors = location & 0xff
 
         if offset == 0:
             return None
@@ -286,19 +295,21 @@ class MCRFileReader(object):
         header = self._file.read(5)
         if len(header) != 5:
             raise CorruptChunkError("chunk header is invalid")
-        data_length, compression =  self._chunk_header_format.unpack(header)
+        data_length, compression = self._chunk_header_format.unpack(header)
 
         # figure out the compression
         is_gzip = True
         if compression == 1:
-            # gzip -- not used by the official client, but trivial to support here so...
+            # gzip -- not used by the official client, but trivial to
+            # support here so...
             is_gzip = True
         elif compression == 2:
             # deflate -- pure zlib stream
             is_gzip = False
         else:
             # unsupported!
-            raise CorruptRegionError("unsupported chunk compression type: %i (should be 1 or 2)" % (compression,))
+            raise CorruptRegionError("unsupported chunk compression type: %i "
+                                     "(should be 1 or 2)" % (compression,))
 
         # turn the rest of the data into a StringIO object
         # (using data_length - 1, as we already read 1 byte for compression)