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# Source Generated with Decompyle++
# File: in.pyc (Python 2.4)

'''Support for ZODB object serialization.

ZODB serializes objects using a custom format based on Python pickles.
When an object is unserialized, it can be loaded as either a ghost or
a real object.  A ghost is a persistent object of the appropriate type
but without any state.  The first time a ghost is accessed, the
persistence machinery traps access and loads the actual state.  A
ghost allows many persistent objects to be loaded while minimizing the
memory consumption of referenced but otherwise unused objects.

Pickle format
-------------

ZODB stores serialized objects using a custom format based on pickle.
Each serialized object has two parts: the class description and the
object state.  The class description must provide enough information
to call the class\'s ``__new__`` and create an empty object.  Once the
object exists as a ghost, its state is passed to ``__setstate__``.

The class description can be in a variety of formats, in part to
provide backwards compatibility with earlier versions of Zope.  The
four current formats for class description are:

    1. type(obj)
    2. type(obj), obj.__getnewargs__()
    3. (module name, class name), None
    7. (module name, class name), obj.__getnewargs__()

The second of these options is used if the object has a __getnewargs__()
method.  It is intended to support objects like persistent classes that have
custom C layouts that are determined by arguments to __new__().  The
third and fourth (#3 & #7) apply to instances of a persistent class (which
means the class itself is persistent, not that it\'s a subclass of
Persistent).

The type object is usually stored using the standard pickle mechanism, which
involves the pickle GLOBAL opcode (giving the type\'s module and name as
strings).  The type may itself be a persistent object, in which case a
persistent reference (see below) is used.

It\'s unclear what "usually" means in the last paragraph.  There are two
useful places to concentrate confusion about exactly which formats exist:

- ObjectReader.getClassName() below returns a dotted "module.class"
  string, via actually loading a pickle.  This requires that the
  implementation of application objects be available.

- ZODB/utils.py\'s get_pickle_metadata() tries to return the module and
  class names (as strings) without importing any application modules or
  classes, via analyzing the pickle.

Earlier versions of Zope supported several other kinds of class
descriptions.  The current serialization code reads these descriptions, but
does not write them.  The three earlier formats are:

    4. (module name, class name), __getinitargs__()
    5. class, None
    6. class, __getinitargs__()

Formats 4 and 6 are used only if the class defines a __getinitargs__()
method, but we really can\'t tell them apart from formats 7 and 2
(respectively).  Formats 5 and 6 are used if the class does not have a
__module__ attribute (I\'m not sure when this applies, but I think it occurs
for some but not all ZClasses).


Persistent references
---------------------

When one persistent object pickle refers to another persistent object,
the database uses a persistent reference.

ZODB persistent references are of the form::

oid
    A simple object reference.

(oid, class meta data)
    A persistent object reference

[reference_type, args]
    An extended reference

    Extension references come in a number of subforms, based on the
    reference types.

    The following reference types are defined:

    \'w\'
        Persistent weak reference.  The arguments consist of an oid.

    The following are planned for the future:

    \'n\'
        Multi-database simple object reference.  The arguments consist
        of a databaase name, and an object id.

    \'m\'
        Multi-database persistent object reference.  The arguments consist
        of a databaase name, an object id, and class meta data.

The following legacy format is also supported.

[oid]
    A persistent weak reference

Because the persistent object reference forms include class
information, it is not possible to change the class of a persistent
object for which this form is used.  If a transaction changed the
class of an object, a new record with new class metadata would be
written but all the old references would still use the old class.  (It
is possible that we could deal with this limitation in the future.)

An object id is used alone when a class requires arguments
to it\'s __new__ method, which is signalled by the class having a
__getnewargs__ attribute.

A number of legacyforms are defined:


'''
import cPickle
import cStringIO
import logging
from persistent import Persistent
from persistent.wref import WeakRefMarker, WeakRef
from ZODB import broken
from ZODB.broken import Broken
from ZODB.POSException import InvalidObjectReference
_oidtypes = (str, type(None))

def myhasattr(obj, name, _marker = object()):
    """Make sure we don't mask exceptions like hasattr().

    We don't want exceptions other than AttributeError to be masked,
    since that too often masks other programming errors.
    Three-argument getattr() doesn't mask those, so we use that to
    implement our own hasattr() replacement.
    """
    return getattr(obj, name, _marker) is not _marker


class ObjectWriter:
    '''Serializes objects for storage in the database.

    The ObjectWriter creates object pickles in the ZODB format.  It
    also detects new persistent objects reachable from the current
    object.
    '''
    _jar = None

    def __init__(self, obj = None):
        self._file = cStringIO.StringIO()
        self._p = cPickle.Pickler(self._file, 1)
        self._p.persistent_id = self.persistent_id
        self._stack = []
        if obj is not None:
            self._stack.append(obj)
            jar = obj._p_jar
            if not myhasattr(jar, 'new_oid'):
                raise AssertionError
            self._jar = jar



    def persistent_id(self, obj):
        """Return the persistent id for obj.

        >>> from ZODB.tests.util import P
        >>> class DummyJar:
        ...     def new_oid(self):
        ...         return 42
        ...     def db(self):
        ...         return self
        ...     databases = {}

        >>> jar = DummyJar()
        >>> class O:
        ...     _p_jar = jar
        >>> writer = ObjectWriter(O)

        Normally, object references include the oid and a cached named
        reference to the class.  Having the class information
        available allows fast creation of the ghost, avoiding
        requiring an additional database lookup.

        >>> bob = P('bob')
        >>> oid, cls = writer.persistent_id(bob)
        >>> oid
        42
        >>> cls is P
        True

        If a persistent object does not already have an oid and jar,
        these will be assigned by persistent_id():

        >>> bob._p_oid
        42
        >>> bob._p_jar is jar
        True

        If the object already has a persistent id, the id is not changed:

        >>> bob._p_oid = 24
        >>> oid, cls = writer.persistent_id(bob)
        >>> oid
        24
        >>> cls is P
        True

        If the jar doesn't match that of the writer, an error is raised:

        >>> bob._p_jar = DummyJar()
        >>> writer.persistent_id(bob)
        Traceback (most recent call last):
          ...
        InvalidObjectReference: Attempt to store an object from a foreign database connection

        Constructor arguments used by __new__(), as returned by
        __getnewargs__(), can affect memory allocation, but may also
        change over the life of the object.  This makes it useless to
        cache even the object's class.

        >>> class PNewArgs(P):
        ...     def __getnewargs__(self):
        ...         return ()

        >>> sam = PNewArgs('sam')
        >>> writer.persistent_id(sam)
        42
        >>> sam._p_oid
        42
        >>> sam._p_jar is jar
        True

        Check that simple objects don't get accused of persistence:

        >>> writer.persistent_id(42)
        >>> writer.persistent_id(object())

        Check that a classic class doesn't get identified improperly:

        >>> class ClassicClara:
        ...    pass
        >>> clara = ClassicClara()

        >>> writer.persistent_id(clara)
        """
        if not isinstance(obj, (Persistent, type, WeakRef)):
            return None


        try:
            oid = obj._p_oid
        except AttributeError:
            return None

        if not oid is None or isinstance(oid, str):
            if hasattr(oid, '__get__'):
                return None

            if oid is WeakRefMarker:
                oid = obj.oid
                if oid is None:
                    obj = obj()
                    oid = obj._p_oid
                    if oid is None:
                        oid = self._jar.new_oid()
                        obj._p_jar = self._jar
                        obj._p_oid = oid
                        self._stack.append(obj)


                return [
                    'w',
                    (oid,)]


        database_name = None
        if oid is None:
            oid = obj._p_oid = self._jar.new_oid()
            obj._p_jar = self._jar
            self._stack.append(obj)
        elif obj._p_jar is not self._jar:

            try:
                otherdb = obj._p_jar.db()
                database_name = otherdb.database_name
            except AttributeError:
                otherdb = self

            if self._jar.db().databases.get(database_name) is not otherdb:
                raise InvalidObjectReference('Attempt to store an object from a foreign database connection')

            if self._jar.get_connection(database_name) is not obj._p_jar:
                raise InvalidObjectReference('Attempt to store a reference to an object from a separate connection to the same database or multidatabase')

            if obj._p_jar._implicitlyAdding(oid):
                raise InvalidObjectReference("A new object is reachable from multiple databases. Won't try to guess which one was correct!")


        klass = type(obj)
        if hasattr(klass, '__getnewargs__'):
            if database_name:
                return [
                    'n',
                    (database_name, oid)]

            return oid

        if database_name:
            return [
                'm',
                (database_name, oid, klass)]

        return (oid, klass)


    def serialize(self, obj):
        klass = type(obj)
        newargs = getattr(obj, '__getnewargs__', None)
        if isinstance(getattr(klass, '_p_oid', 0), _oidtypes) and klass.__module__:
            klass = (klass.__module__, klass.__name__)
            if newargs is None:
                meta = (klass, None)
            else:
                meta = (klass, newargs())
        elif newargs is None:
            meta = klass
        else:
            meta = (klass, newargs())
        return self._dump(meta, obj.__getstate__())


    def _dump(self, classmeta, state):
        self._file.seek(0)
        self._p.clear_memo()
        self._p.dump(classmeta)
        self._p.dump(state)
        self._file.truncate()
        return self._file.getvalue()


    def __iter__(self):
        return NewObjectIterator(self._stack)



class NewObjectIterator:

    def __init__(self, stack):
        self._stack = stack


    def __iter__(self):
        return self


    def next(self):
        if self._stack:
            elt = self._stack.pop()
            return elt
        else:
            raise StopIteration



class ObjectReader:

    def __init__(self, conn = None, cache = None, factory = None):
        self._conn = conn
        self._cache = cache
        self._factory = factory


    def _get_class(self, module, name):
        return self._factory(self._conn, module, name)


    def _get_unpickler(self, pickle):
        file = cStringIO.StringIO(pickle)
        unpickler = cPickle.Unpickler(file)
        unpickler.persistent_load = self._persistent_load
        factory = self._factory
        conn = self._conn

        def find_global(modulename, name):
            return factory(conn, modulename, name)

        unpickler.find_global = find_global
        return unpickler

    loaders = { }

    def _persistent_load(self, reference):
        if isinstance(reference, tuple):
            return self.load_persistent(*reference)
        elif isinstance(reference, str):
            return self.load_oid(reference)
        else:

            try:
                (reference_type, args) = reference
            except ValueError:
                return self.loaders['w'](self, *reference)

            return self.loaders[reference_type](self, *args)


    def load_persistent(self, oid, klass):
        obj = self._cache.get(oid, None)
        if obj is not None:
            return obj

        if isinstance(klass, tuple):
            klass = self._get_class(*klass)

        if issubclass(klass, Broken):
            if not issubclass(klass, broken.PersistentBroken):
                klass = broken.persistentBroken(klass)



        try:
            obj = klass.__new__(klass)
        except TypeError:
            return self._conn.get(oid)

        obj._p_oid = oid
        obj._p_jar = self._conn
        obj._p_changed = None
        self._cache[oid] = obj
        return obj


    def load_multi_persistent(self, database_name, oid, klass):
        conn = self._conn.get_connection(database_name)
        reader = ObjectReader(conn, conn._cache, self._factory)
        return reader.load_persistent(oid, klass)

    loaders['m'] = load_multi_persistent

    def load_persistent_weakref(self, oid):
        obj = WeakRef.__new__(WeakRef)
        obj.oid = oid
        obj.dm = self._conn
        return obj

    loaders['w'] = load_persistent_weakref

    def load_oid(self, oid):
        obj = self._cache.get(oid, None)
        if obj is not None:
            return obj

        return self._conn.get(oid)


    def load_multi_oid(self, database_name, oid):
        conn = self._conn.get_connection(database_name)
        reader = ObjectReader(conn, conn._cache, self._factory)
        return reader.load_oid(oid)

    loaders['n'] = load_multi_oid

    def _new_object(self, klass, args):
        if not args and not myhasattr(klass, '__getnewargs__'):
            obj = klass.__new__(klass)
        else:
            obj = klass(*args)
            if not isinstance(klass, type):
                obj.__dict__.clear()

        return obj


    def getClassName(self, pickle):
        unpickler = self._get_unpickler(pickle)
        klass = unpickler.load()
        if isinstance(klass, tuple):
            (klass, args) = klass
            if isinstance(klass, tuple):
                return '%s.%s' % klass


        return '%s.%s' % (klass.__module__, klass.__name__)


    def getGhost(self, pickle):
        unpickler = self._get_unpickler(pickle)
        klass = unpickler.load()
        if isinstance(klass, tuple):
            (klass, args) = klass
            if isinstance(klass, tuple):
                klass = self._get_class(*klass)

            if args is None:
                args = ()

        else:
            args = ()
        if issubclass(klass, Broken):
            if not issubclass(klass, broken.PersistentBroken):
                klass = broken.persistentBroken(klass)


        return klass.__new__(klass, *args)


    def getState(self, pickle):
        unpickler = self._get_unpickler(pickle)

        try:
            unpickler.load()
            return unpickler.load()
        except EOFError:
            msg = None
            log = logging.getLogger('ZODB.serialize')
            log.exception('Unpickling error: %r', pickle)
            raise



    def setGhostState(self, obj, pickle):
        state = self.getState(pickle)
        obj.__setstate__(state)


oid_loaders = {
    'w': (lambda oid: pass) }

def referencesf(p, oids = None):
    '''Return a list of object ids found in a pickle

    A list may be passed in, in which case, information is
    appended to it.

    Weak references are not included.
    '''
    refs = []
    u = cPickle.Unpickler(cStringIO.StringIO(p))
    u.persistent_load = refs
    u.noload()
    u.noload()
    if oids is None:
        oids = []

    for reference in refs:
        if isinstance(reference, tuple):
            oid = reference[0]
        elif isinstance(reference, str):
            oid = reference
        else:

            try:
                (reference_type, args) = reference
            except ValueError:
                continue

            oid = oid_loaders[reference_type](*args)
        if oid:
            oids.append(oid)
            continue

    return oids

oid_klass_loaders = {
    'w': (lambda oid: pass) }

def get_refs(a_pickle):
    """Return oid and class information for references in a pickle

    The result of a list of oid and class information tuples.
    If the reference doesn't contain class information, then the
    klass information is None.
    """
    refs = []
    u = cPickle.Unpickler(cStringIO.StringIO(a_pickle))
    u.persistent_load = refs
    u.noload()
    u.noload()
    result = []
    for reference in refs:
        if isinstance(reference, tuple):
            data = reference
        elif isinstance(reference, str):
            data = (reference, None)
        else:

            try:
                (reference_type, args) = reference
            except ValueError:
                continue

            data = oid_klass_loaders[reference_type](*args)
        if data:
            result.append(data)
            continue

    return result