Initial set of improvementes merged into master, including a class hierarchy redesign and performance improvements

Merge commit 'origin/improvements'

* commit 'origin/improvements': (38 commits)
  test_performance: module containing benchmarks to get an idea of the achieved throughput
  Removed plenty of mocked tree tests as they cannot work anymore with persistent commands that require stdin AND binary data - not even an adapter would help here. These tests will have to be replaced.
  tree: now reads tress directly by parsing the binary data, allowing it to safe possibly hundreds of command calls
  Refs are now truly dynamic - this costs a little bit of (persistent command) work, but assures refs behave as expected
  persistent command signature changed to also return the hexsha from a possible input ref - the objects pointed to by refs are now baked on demand - perhaps it should change to always be re-retrieved using a property as it is relatively fast - this way refs can always be cached
  test_blob: removed many redundant tests that would fail now as the mock cannot handle the complexity of the command backend
  Implemented git command facility to keep persistent commands for fast object information retrieval
  test: Added time-consuming test which could also be a benchmark in fact - currently it cause hundreds of command invocations which is slow
  cmd: added option to return the process directly, allowing to read the output directly from the output stream
  added Iterable interface to Ref type
  renamed find_all to list_all, changed commit to use iterable interface in preparation for command changes
  Added base for all iteratable objects
  unified name of utils module, recently it was named util and utils in different packages
  tree: renamed content_from_string to _from_string to make it private. Removed tests that were testing that method
  tree: now behaves like a list with string indexing functionality - using a dict as cache is a problem as the tree is ordered, added blobs, trees and traverse method
  test_base: Improved basic object creation as well as set hash tests
  repo.active_branch now returns a Head object, not a string
  IndexObjects are now checking their slots to raise a proper error message in case someone tries to access an unset path or mode - this information cannot be retrieved afterwards as IndexObject information is kept in the object that pointed at them. To find this information, one would have to search all objects which is not feasible
  refs now take repo as first argument and derive from LazyMixin to allow them to dynamically retrieve their objects
  renamed from_string and list_from_string to _from_string and _list_from_string to indicate their new status as private method, adjusted all callers respectively
  ...

1 files changed, 70 insertions, 0 deletions

diff --git a/lib/git/objects/tag.py b/lib/git/objects/tag.py
new file mode 100644
index 00000000..ecf6349d
--- /dev/null
+++ b/lib/git/objects/tag.py
@@ -0,0 +1,70 @@
+# objects.py
+# Copyright (C) 2008, 2009 Michael Trier (mtrier@gmail.com) and contributors
+#
+# This module is part of GitPython and is released under
+# the BSD License: http://www.opensource.org/licenses/bsd-license.php
+"""
+Module containing all object based types.
+"""
+import base
+import commit
+from utils import get_object_type_by_name
+
+class TagObject(base.Object):
+	"""
+	Non-Lightweight tag carrying additional information about an object we are pointing 
+	to.
+	"""
+	type = "tag"
+	__slots__ = ( "object", "tag", "tagger", "tagged_date", "message" )
+		
+	def __init__(self, repo, id, object=None, tag=None, 
+				tagger=None, tagged_date=None, message=None):
+		"""
+		Initialize a tag object with additional data
+		
+		``repo``
+			repository this object is located in
+			
+		``id``
+			SHA1 or ref suitable for git-rev-parse
+			
+		 ``object``
+			Object instance of object we are pointing to
+		 
+		 ``tag``
+			name of this tag
+			
+		 ``tagger``
+			Actor identifying the tagger
+			
+		  ``tagged_date`` : (tm_year, tm_mon, tm_mday, tm_hour, tm_min, tm_sec, tm_wday, tm_yday, tm_isdst)
+			is the DateTime of the tag creation
+		"""
+		super(TagObject, self).__init__(repo, id )
+		self._set_self_from_args_(locals())
+		
+	def _set_cache_(self, attr):
+		"""
+		Cache all our attributes at once
+		"""
+		if attr in TagObject.__slots__:
+			lines = self.data.splitlines()
+			
+			obj, hexsha = lines[0].split(" ")		# object <hexsha>
+			type_token, type_name = lines[1].split(" ") # type <type_name>
+			self.object = get_object_type_by_name(type_name)(self.repo, hexsha)
+			
+			self.tag = lines[2][4:]  # tag <tag name>
+			
+			tagger_info = lines[3][7:]# tagger <actor> <date>
+			self.tagger, self.tagged_date = commit.Commit._actor(tagger_info)
+			
+			# line 4 empty - check git source to figure out purpose
+			self.message = "\n".join(lines[5:])
+		# END check our attributes
+		else:
+			super(TagObject, self)._set_cache_(attr)
+		
+		
+