X-Git-Url: https://git.cweiske.de/enigma2.git/blobdiff_plain/7c1b7fe307737d330493694f0735b380b718576c..9d3112aad388b4369a339b851aa2507a02bb2d4f:/lib/python/Components/Element.py

diff --git a/lib/python/Components/Element.py b/lib/python/Components/Element.py
index 54a1cc25..baab4cfb 100644
--- a/lib/python/Components/Element.py
+++ b/lib/python/Components/Element.py
@@ -4,11 +4,30 @@ from Tools.CList import CList
 # Render Converter Converter Source
 
 # a bidirectional connection
-class Element:
+
+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)
@@ -18,7 +37,7 @@ class Element:
 	def connectUpstream(self, upstream):
 		assert self.source is None
 		self.source = upstream
-		self.changed()
+		self.changed((self.CHANGED_DEFAULT,))
 	
 	def connect(self, upstream):
 		self.connectUpstream(upstream)
@@ -29,7 +48,9 @@ class Element:
 		# 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"
-		if self.source:
+		
+		# 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):
@@ -42,8 +63,29 @@ class Element:
 
 	# 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