allow multiple sources for elements. last added source will be in .source, a list...

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

diff --git a/lib/python/Components/Element.py b/lib/python/Components/Element.py
index 019155c6490482abfbb8cb7933a809edb87afc75..3297a4adf80a4af6dce071f9d629920aa9e8003f 100644 (file)
--- a/lib/python/Components/Element.py
+++ b/lib/python/Components/Element.py
@@ -4,6 +4,25 @@ from Tools.CList import CList
 # Render Converter Converter Source
 
 # a bidirectional connection
+
+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
@@ -11,12 +30,15 @@ class Element(object):
        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.master = None
+               self.sources = [ ]
                self.source = None
                self.__suspended = True
-               self.clearCache()
+               self.cache = None
 
        def connectDownstream(self, downstream):
                self.downstream_elements.append(downstream)
@@ -24,7 +46,9 @@ class Element(object):
                        self.master = downstream
        
        def connectUpstream(self, upstream):
-               assert self.source is None
+               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,))
        
@@ -37,11 +61,17 @@ class Element(object):
                # 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)
-       
+               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:
@@ -52,15 +82,8 @@ class Element(object):
 
        # default action: push downstream
        def changed(self, *args, **kwargs):
-               self.clearCache()
+               self.cache = { }
                self.downstream_elements.changed(*args, **kwargs)
-               self.clearCache()
-
-       def reconnectUpstream(self, new_upstream):
-               assert self.source is not None
-               self.source = new_upstream
-
-       def clearCache(self):
                self.cache = None
 
        def setSuspend(self, suspended):
@@ -71,8 +94,9 @@ class Element(object):
                        self.doSuspend(0)
                        
                self.__suspended = suspended
-               if self.source is not None and changed:
-                       self.source.checkSuspend()
+               if changed:
+                       for s in self.sources:
+                               s.checkSuspend()
        
        suspended = property(lambda self: self.__suspended, setSuspend)
        
@@ -81,3 +105,6 @@ class Element(object):
 
        def doSuspend(self, suspend):
                pass
+
+       def destroy(self):
+               pass