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Linux/lib/python2.7/site-packages/twisted/persisted/crefutil.py

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+# -*- test-case-name: twisted.test.test_persisted -*-
+
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+
+"""
+Utility classes for dealing with circular references.
+"""
+
+import types
+
+from twisted.python import log, reflect
+
+
+class NotKnown:
+    def __init__(self):
+        self.dependants = []
+        self.resolved = 0
+
+    def addDependant(self, mutableObject, key):
+        assert not self.resolved
+        self.dependants.append( (mutableObject, key) )
+
+    resolvedObject = None
+
+    def resolveDependants(self, newObject):
+        self.resolved = 1
+        self.resolvedObject = newObject
+        for mut, key in self.dependants:
+            mut[key] = newObject
+            if isinstance(newObject, NotKnown):
+                newObject.addDependant(mut, key)
+
+    def __hash__(self):
+        assert 0, "I am not to be used as a dictionary key."
+
+
+
+class _Container(NotKnown):
+    """
+    Helper class to resolve circular references on container objects.
+    """
+
+    def __init__(self, l, containerType):
+        """
+        @param l: The list of object which may contain some not yet referenced
+        objects.
+
+        @param containerType: A type of container objects (e.g., C{tuple} or
+            C{set}).
+        """
+        NotKnown.__init__(self)
+        self.containerType = containerType
+        self.l = l
+        self.locs = range(len(l))
+        for idx in xrange(len(l)):
+            if not isinstance(l[idx], NotKnown):
+                self.locs.remove(idx)
+            else:
+                l[idx].addDependant(self, idx)
+        if not self.locs:
+            self.resolveDependants(self.containerType(self.l))
+
+
+    def __setitem__(self, n, obj):
+        """
+        Change the value of one contained objects, and resolve references if
+        all objects have been referenced.
+        """
+        self.l[n] = obj
+        if not isinstance(obj, NotKnown):
+            self.locs.remove(n)
+            if not self.locs:
+                self.resolveDependants(self.containerType(self.l))
+
+
+
+class _Tuple(_Container):
+    """
+    Manage tuple containing circular references. Deprecated: use C{_Container}
+    instead.
+    """
+
+    def __init__(self, l):
+        """
+        @param l: The list of object which may contain some not yet referenced
+        objects.
+        """
+        _Container.__init__(self, l, tuple)
+
+
+
+class _InstanceMethod(NotKnown):
+    def __init__(self, im_name, im_self, im_class):
+        NotKnown.__init__(self)
+        self.my_class = im_class
+        self.name = im_name
+        # im_self _must_ be a
+        im_self.addDependant(self, 0)
+
+    def __call__(self, *args, **kw):
+        import traceback
+        log.msg('instance method %s.%s' % (reflect.qual(self.my_class), self.name))
+        log.msg('being called with %r %r' % (args, kw))
+        traceback.print_stack(file=log.logfile)
+        assert 0
+
+    def __setitem__(self, n, obj):
+        assert n == 0, "only zero index allowed"
+        if not isinstance(obj, NotKnown):
+            method = types.MethodType(self.my_class.__dict__[self.name],
+                                      obj, self.my_class)
+            self.resolveDependants(method)
+
+class _DictKeyAndValue:
+    def __init__(self, dict):
+        self.dict = dict
+    def __setitem__(self, n, obj):
+        if n not in (1, 0):
+            raise RuntimeError("DictKeyAndValue should only ever be called with 0 or 1")
+        if n: # value
+            self.value = obj
+        else:
+            self.key = obj
+        if hasattr(self, "key") and hasattr(self, "value"):
+            self.dict[self.key] = self.value
+
+
+class _Dereference(NotKnown):
+    def __init__(self, id):
+        NotKnown.__init__(self)
+        self.id = id
+
+
+from twisted.internet.defer import Deferred
+
+class _Catcher:
+    def catch(self, value):
+        self.value = value
+
+class _Defer(Deferred, NotKnown):
+    def __init__(self):
+        Deferred.__init__(self)
+        NotKnown.__init__(self)
+        self.pause()
+
+    wasset = 0
+
+    def __setitem__(self, n, obj):
+        if self.wasset:
+            raise RuntimeError('setitem should only be called once, setting %r to %r' % (n, obj))
+        else:
+            self.wasset = 1
+        self.callback(obj)
+
+    def addDependant(self, dep, key):
+        # by the time I'm adding a dependant, I'm *not* adding any more
+        # callbacks
+        NotKnown.addDependant(self,  dep, key)
+        self.unpause()
+        resovd = self.result
+        self.resolveDependants(resovd)