Merge branch 'iteration_and_retrieval' into improvements

* iteration_and_retrieval:
  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

1 files changed, 67 insertions, 70 deletions

diff --git a/lib/git/refs.py b/lib/git/refs.py
index 820150d3..3c9eb817 100644
--- a/lib/git/refs.py
+++ b/lib/git/refs.py
@@ -7,17 +7,20 @@
 Module containing all ref based objects
 """
 from objects.base import Object
-from objects.util import get_object_type_by_name
+from objects.utils import get_object_type_by_name
+from utils import LazyMixin, Iterable
 
-class Ref(object):
+class Ref(LazyMixin, Iterable):
 	"""
 	Represents a named reference to any object
 	"""
-	__slots__ = ("path", "object")
+	__slots__ = ("repo", "path")
 	
-	def __init__(self, path, object = None):
+	def __init__(self, repo, path, object = None):
 		"""
 		Initialize this instance
+		``repo``
+			Our parent repository
 		
 		``path``
 			Path relative to the .git/ directory pointing to the ref in question, i.e.
@@ -26,8 +29,10 @@ class Ref(object):
 		``object``
 			Object instance, will be retrieved on demand if None
 		"""
+		self.repo = repo
 		self.path = path
-		self.object = object
+		if object is not None:
+			self.object = object
 		
 	def __str__(self):
 		return self.name
@@ -57,9 +62,20 @@ class Ref(object):
 			return self.path	# could be refs/HEAD
 		
 		return '/'.join(tokens[2:])
-		
+	
+	@property
+	def object(self):
+		"""
+		Returns
+			The object our ref currently refers to. Refs can be cached, they will 
+			always point to the actual object as it gets re-created on each query
+		"""
+		# have to be dynamic here as we may be a tag which can point to anything
+		hexsha, typename, size = self.repo.git.get_object_header(self.path)
+		return get_object_type_by_name(typename)(self.repo, hexsha)
+	
 	@classmethod
-	def find_all(cls, repo, common_path = "refs", **kwargs):
+	def iter_items(cls, repo, common_path = "refs", **kwargs):
 		"""
 		Find all refs in the repository
 
@@ -88,54 +104,38 @@ class Ref(object):
 		options.update(kwargs)
 
 		output = repo.git.for_each_ref(common_path, **options)
-		return cls._list_from_string(repo, output)
+		return cls._iter_from_stream(repo, iter(output.splitlines()))
 
 	@classmethod
-	def _list_from_string(cls, repo, text):
-		"""
-		Parse out ref information into a list of Ref compatible objects
-
-		``repo``
-			is the Repo
-		``text``
-			is the text output from the git-for-each-ref command
-
-		Returns
-			git.Ref[]
-			
-			list of Ref objects
-		"""
+	def _iter_from_stream(cls, repo, stream):
+		""" Parse out ref information into a list of Ref compatible objects
+		Returns git.Ref[] list of Ref objects """
 		heads = []
 
-		for line in text.splitlines():
+		for line in stream:
 			heads.append(cls._from_string(repo, line))
 
 		return heads
 
 	@classmethod
 	def _from_string(cls, repo, line):
-		"""
-		Create a new Ref instance from the given string.
-
-		``repo``
-			is the Repo
-
-		``line``
-			is the formatted ref information
-
-		Format::
-		
+		""" Create a new Ref instance from the given string.
+		Format
 			name: [a-zA-Z_/]+
 			<null byte>
 			id: [0-9A-Fa-f]{40}
-
-		Returns
-			git.Head
-		"""
+		Returns git.Head """
 		full_path, hexsha, type_name, object_size = line.split("\x00")
-		obj = get_object_type_by_name(type_name)(repo, hexsha)
-		obj.size = object_size
-		return cls(full_path, obj)
+		
+		# No, we keep the object dynamic by allowing it to be retrieved by
+		# our path on demand - due to perstent commands it is fast.
+		# This reduces the risk that the object does not match 
+		# the changed ref anymore in case it changes in the meanwhile
+		return cls(repo, full_path)
+		
+		# obj = get_object_type_by_name(type_name)(repo, hexsha)
+		# obj.size = object_size
+		# return cls(repo, full_path, obj)
 		
 
 class Head(Ref):
@@ -167,14 +167,14 @@ class Head(Ref):
 		return self.object
 		
 	@classmethod
-	def find_all(cls, repo, common_path = "refs/heads", **kwargs):
+	def iter_items(cls, repo, common_path = "refs/heads", **kwargs):
 		"""
 		Returns
-			git.Head[]
+			Iterator yielding Head items
 			
-		For more documentation, please refer to git.base.Ref.find_all
+		For more documentation, please refer to git.base.Ref.list_items
 		"""
-		return super(Head,cls).find_all(repo, common_path, **kwargs)
+		return super(Head,cls).iter_items(repo, common_path, **kwargs)
 
 	def __repr__(self):
 		return '<git.Head "%s">' % self.name
@@ -190,30 +190,13 @@ class TagRef(Ref):
 	This tag object will always point to a commit object, but may carray additional
 	information in a tag object::
 	
-	 tagref = TagRef.find_all(repo)[0]
+	 tagref = TagRef.list_items(repo)[0]
 	 print tagref.commit.message
 	 if tagref.tag is not None:
 		print tagref.tag.message
 	"""
 	
-	__slots__ = "tag"
-	
-	def __init__(self, path, commit_or_tag):
-		"""
-		Initialize a newly instantiated Tag
-
-		``path``
-			is the full path to the tag
-
-		``commit_or_tag``
-			is the Commit or TagObject that this tag ref points to
-		"""
-		super(TagRef, self).__init__(path, commit_or_tag)
-		self.tag = None
-		
-		if commit_or_tag.type == "tag":
-			self.tag = commit_or_tag
-		# END tag object handling 
+	__slots__ = tuple()
 	
 	@property
 	def commit(self):
@@ -223,18 +206,32 @@ class TagRef(Ref):
 		"""
 		if self.object.type == "commit":
 			return self.object
-		# it is a tag object
-		return self.object.object
+		elif self.object.type == "tag":
+			# it is a tag object which carries the commit as an object - we can point to anything
+			return self.object.object
+		else:
+			raise ValueError( "Tag %s points to a Blob or Tree - have never seen that before" % self )  
+
+	@property
+	def tag(self):
+		"""
+		Returns
+			Tag object this tag ref points to or None in case 
+			we are a light weight tag
+		"""
+		if self.object.type == "tag":
+			return self.object
+		return None
 
 	@classmethod
-	def find_all(cls, repo, common_path = "refs/tags", **kwargs):
+	def iter_items(cls, repo, common_path = "refs/tags", **kwargs):
 		"""
 		Returns
-			git.Tag[]
+			Iterator yielding commit items
 			
-		For more documentation, please refer to git.base.Ref.find_all
+		For more documentation, please refer to git.base.Ref.list_items
 		"""
-		return super(TagRef,cls).find_all(repo, common_path, **kwargs)
+		return super(TagRef,cls).iter_items(repo, common_path, **kwargs)
 		
 		
 # provide an alias