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from Tools.CList import CList
# down up
# Render Converter Converter Source
# a bidirectional connection
def cached(f):
name = f.__name__
def wrapper(self):
if self.cache is None:
return f(self)
if name not in self.cache:
self.cache[name] = (True, f(self))
return self.cache[name][1]
return wrapper
class Element(object):
CHANGED_DEFAULT = 0 # initial "pull" state
CHANGED_ALL = 1 # really everything changed
CHANGED_CLEAR = 2 # we're expecting a real update soon. don't bother polling NOW, but clear data.
CHANGED_SPECIFIC = 3 # second tuple will specify what exactly changed
CHANGED_POLL = 4 # a timer expired
def __init__(self):
self.downstream_elements = CList()
self.master = None
self.source = None
self.__suspended = True
self.cache = None
def connectDownstream(self, downstream):
self.downstream_elements.append(downstream)
if self.master is None:
self.master = downstream
def connectUpstream(self, upstream):
assert self.source is None
self.source = upstream
self.changed((self.CHANGED_DEFAULT,))
def connect(self, upstream):
self.connectUpstream(upstream)
upstream.connectDownstream(self)
# we disconnect from down to up
def disconnectAll(self):
# we should not disconnect from upstream if
# there are still elements depending on us.
assert len(self.downstream_elements) == 0, "there are still downstream elements left"
# Sources don't have a source themselves. don't do anything here.
if self.source is not None:
self.source.disconnectDownstream(self)
def disconnectDownstream(self, downstream):
self.downstream_elements.remove(downstream)
if self.master == downstream:
self.master = None
if len(self.downstream_elements) == 0:
self.disconnectAll()
# default action: push downstream
def changed(self, *args, **kwargs):
self.cache = { }
self.downstream_elements.changed(*args, **kwargs)
self.cache = None
def reconnectUpstream(self, new_upstream):
assert self.source is not None
self.source = new_upstream
def setSuspend(self, suspended):
changed = self.__suspended != suspended
if not self.__suspended and suspended:
self.doSuspend(1)
elif self.__suspended and not suspended:
self.doSuspend(0)
self.__suspended = suspended
if self.source is not None and changed:
self.source.checkSuspend()
suspended = property(lambda self: self.__suspended, setSuspend)
def checkSuspend(self):
self.suspended = reduce(lambda x, y: x and y.__suspended, self.downstream_elements, True)
def doSuspend(self, suspend):
pass
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