X-Git-Url: https://git.cweiske.de/enigma2.git/blobdiff_plain/732961ea798182d334d26e2fa2ce8d91672a932f..aa63e716977d5f341495cf0694b327116b978f89:/lib/python/Components/Element.py

diff --git a/lib/python/Components/Element.py b/lib/python/Components/Element.py
index 5b8bed86..3297a4ad 100644
--- a/lib/python/Components/Element.py
+++ b/lib/python/Components/Element.py
@@ -4,12 +4,41 @@ from Tools.CList import CList
 # Render Converter Converter Source
 
 # a bidirectional connection
-class Element:
+
+def cached(f):
+	name = f.__name__
+	def wrapper(self):
+		cache = self.cache
+		if cache is None:
+			return f(self)
+		if name not in cache:
+			cache[name] = (True, f(self))
+		return cache[name][1]
+	return wrapper
+
+class ElementError(Exception):
+    def __init__(self, message):
+        self.msg = message
+
+    def __str__(self):
+        return self.msg
+
+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
+
+	SINGLE_SOURCE = True
+
 	def __init__(self):
 		self.downstream_elements = CList()
-		self.upstream_elements = CList()
 		self.master = None
+		self.sources = [ ]
 		self.source = None
+		self.__suspended = True
+		self.cache = None
 
 	def connectDownstream(self, downstream):
 		self.downstream_elements.append(downstream)
@@ -17,9 +46,11 @@ class Element:
 			self.master = downstream
 	
 	def connectUpstream(self, upstream):
-		self.upstream_elements.append(upstream)
-		self.source = upstream # for single-source elements (i.e., most of them.)
-		self.changed()
+		assert not self.SINGLE_SOURCE or self.source is None
+		self.sources.append(upstream)
+		# self.source always refers to the last recent source added.
+		self.source = upstream
+		self.changed((self.CHANGED_DEFAULT,))
 	
 	def connect(self, upstream):
 		self.connectUpstream(upstream)
@@ -30,11 +61,17 @@ 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"
-		
-		# disconnect all upstream elements from us
-		for upstream in self.upstream_elements:
-			upstream.disconnectDownstream(self)
-	
+
+		# Sources don't have a source themselves. don't do anything here.
+		for s in self.sources:
+			s.disconnectDownstream(self)
+
+		if self.source:
+			# sources are owned by the Screen, so don't destroy them here.
+			self.destroy()
+		self.source = None
+		self.sources = [ ]
+
 	def disconnectDownstream(self, downstream):
 		self.downstream_elements.remove(downstream)
 		if self.master == downstream:
@@ -45,4 +82,29 @@ class Element:
 
 	# default action: push downstream
 	def changed(self, *args, **kwargs):
+		self.cache = { }
 		self.downstream_elements.changed(*args, **kwargs)
+		self.cache = None
+
+	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 changed:
+			for s in self.sources:
+				s.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
+
+	def destroy(self):
+		pass