1 files changed, 129 insertions, 0 deletions
diff --git a/lib/git/odb/db.py b/lib/git/odb/db.py
new file mode 100644
index 00000000..fd1b640a
--- /dev/null
+++ b/lib/git/odb/db.py
@@ -0,0 +1,129 @@
+"""Contains implementations of database retrieveing objects"""
+import os
+from git.errors import InvalidDBRoot
+
+
+class iObjectDBR(object):
+	"""Defines an interface for object database lookup.
+	Objects are identified either by hex-sha (40 bytes) or 
+	by sha (20 bytes)"""
+	__slots__ = tuple()
+	
+	#{ Query Interface 
+	def has_obj_hex(self, hexsha):
+		""":return: True if the object identified by the given 40 byte hexsha is 
+		contained in the database"""
+		raise NotImplementedError("To be implemented in subclass")
+		
+	def has_obj_bin(self, sha):
+		""":return: as ``has_obj_hex``, but takes a 20 byte binary sha"""
+		raise NotImplementedError("To be implemented in subclass")
+		
+	def obj_hex(self, hexsha):
+		""":return: tuple(type_string, size_in_bytes, stream) a tuple with object
+		information including its type, its size as well as a stream from which its
+		contents can be read"""
+		raise NotImplementedError("To be implemented in subclass")
+		
+	def obj_bin(self, sha):
+		""":return: as in ``obj_hex``, but takes a binary sha"""
+		raise NotImplementedError("To be implemented in subclass")
+		
+	def obj_info_hex(self, hexsha):
+		""":return: tuple(type_string, size_in_bytes) tuple with the object's type 
+			string as well as its size in bytes"""
+		raise NotImplementedError("To be implemented in subclass")
+			
+	#} END query interface
+	
+class iObjectDBW(object):
+	"""Defines an interface to create objects in the database"""
+	__slots__ = tuple()
+	
+	#{ Edit Interface
+	
+	def to_obj(self, type, size, stream, dry_run=False, sha_as_hex=True):
+		"""Create a new object in the database
+		:return: the sha identifying the object in the database
+		:param type: type string identifying the object
+		:param size: size of the data to read from stream
+		:param stream: stream providing the data
+		:param dry_run: if True, the object database will not actually be changed
+		:param sha_as_hex: if True, the returned sha identifying the object will be 
+			hex encoded, not binary"""
+		raise NotImplementedError("To be implemented in subclass")
+	
+	def to_objs(self, iter_info, dry_run=False, sha_as_hex=True, max_threads=0):
+		"""Create multiple new objects in the database
+		:return: sequence of shas identifying the created objects in the order in which 
+			they where given.
+		:param iter_info: iterable yielding tuples containing the type_string
+			size_in_bytes and the steam with the content data.
+		:param dry_run: see ``to_obj``
+		:param sha_as_hex: see ``to_obj``
+		:param max_threads: if < 1, any number of threads may be started while processing
+			the request, otherwise the given number of threads will be started."""
+		# a trivial implementation, ignoring the threads for now
+		# TODO: add configuration to the class to determine whether we may 
+		# actually use multiple threads, default False of course. If the add
+		shas = list()
+		for args in iter_info:
+			shas.append(self.to_obj(*args, dry_run=dry_run, sha_as_hex=sha_as_hex))
+		return shas
+		
+	#} END edit interface
+	
+
+class FileDBBase(object):
+	"""Provides basic facilities to retrieve files of interest, including 
+	caching facilities to help mapping hexsha's to objects"""
+	__slots__ = ('_root_path', )
+	
+	def __init__(self, root_path):
+		"""Initialize this instance to look for its files at the given root path
+		All subsequent operations will be relative to this path
+		:raise InvalidDBRoot: 
+		:note: The base will perform basic checking for accessability, but the subclass
+			is required to verify that the root_path contains the database structure it needs"""
+		if not os.path.isdir(root_path):
+			raise InvalidDBRoot(root_path)
+		self._root_path = root_path
+		
+		
+	#{ Interface 
+	def root_path(self):
+		""":return: path at which this db operates"""
+		return self._root_path
+	
+	#} END interface
+		
+	#{ Utiltities
+	def _root_rela_path(self, rela_path):
+		""":return: the given relative path relative to our database root"""
+		return os.path.join(self._root_path, rela_path)
+		
+	#} END utilities
+	
+	
+class LooseObjectDB(FileDBBase, iObjectDBR, iObjectDBW):
+	"""A database which operates on loose object files"""
+	
+	
+class PackedDB(FileDBBase, iObjectDBR):
+	"""A database operating on a set of object packs"""
+	
+	
+class CompoundDB(iObjectDBR):
+	"""A database which delegates calls to sub-databases"""
+	
+
+class ReferenceDB(CompoundDB):
+	"""A database consisting of database referred to in a file"""
+	
+	
+class GitObjectDB(CompoundDB, iObjectDBW):
+	"""A database representing the default git object store, which includes loose 
+	objects, pack files and an alternates file
+	
+	It will create objects only in the loose object database."""
+