Incorporated basic evaluation logic to play and test nodes

Author: Leandro Inocencio

NodeGraphQt/base/node.py

@@ -669,7 +669,7 @@ def output_ports(self):
             list[NodeGraphQt.Port]: node output ports.
         """
         return self._outputs
-    
+
     def input(self, index):
         """
         Return the input port with the matching index.
@@ -775,6 +775,36 @@ def on_input_disconnected(self, in_port, out_port):
         """
         return
 
+    def update_streams(self, *args):
+        """
+        Update all nodes joined by pipes to this.
+        """
+        nodes = []
+        trash = []
+
+        for port, nodeList in node.connected_output_nodes().items():
+            nodes.extend(nodeList)
+
+        while nodes:
+            node = nodes.pop()
+            if node not in trash:
+                trash.append(node)
+
+            for port, nodeList in node.connected_output_nodes().items():
+                nodes.extend(nodeList)
+
+            if not nodes:
+                try:
+                    node.run()
+                except Exception as error:
+                    print("Error Update Streams: %s" % str(error))
+
+    def run(self):
+        """
+        Node evaluation logics.
+        """
+        return
+
 
 class BackdropNode(NodeObject):
     """