refs bug #429

[enigma2.git] / lib / python / Components / Element.py

diff --git a/lib/python/Components/Element.py b/lib/python/Components/Element.py
index 5b8bed866cf1368c88fbb8574b7e46121fc87726..3297a4adf80a4af6dce071f9d629920aa9e8003f 100644 (file)
--- 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