feat: autolabel flag in diagrams that modifies label (#482)

* autolabel flag in diagrams that modifies label

* update based on review

diagrams/__init__.py

@@ -83,6 +83,7 @@ class Diagram:
         direction: str = "LR",
         curvestyle: str = "ortho",
         outformat: str = "png",
+        autolabel: bool = False,
         show: bool = True,
         graph_attr: dict = {},
         node_attr: dict = {},
@@ -142,6 +143,7 @@ class Diagram:
         self.dot.edge_attr.update(edge_attr)
 
         self.show = show
+        self.autolabel = autolabel
 
     def __str__(self) -> str:
         return str(self.dot)
@@ -292,11 +294,23 @@ class Node:
         self._id = nodeid or self._rand_id()
         self.label = label
 
+        # Node must be belong to a diagrams.
+        self._diagram = getdiagram()
+        if self._diagram is None:
+            raise EnvironmentError("Global diagrams context not set up")
+        
+        if self._diagram.autolabel:
+            prefix = self.__class__.__name__
+            if self.label:
+                self.label = prefix + "\n" + self.label
+            else:
+                self.label = prefix
+
         # fmt: off
         # If a node has an icon, increase the height slightly to avoid
         # that label being spanned between icon image and white space.
         # Increase the height by the number of new lines included in the label.
-        padding = 0.4 * (label.count('\n'))
+        padding = 0.4 * (self.label.count('\n'))
         self._attrs = {
             "shape": "none",
             "height": str(self._height + padding),
@@ -306,10 +320,6 @@ class Node:
         # fmt: on
         self._attrs.update(attrs)
 
-        # Node must be belong to a diagrams.
-        self._diagram = getdiagram()
-        if self._diagram is None:
-            raise EnvironmentError("Global diagrams context not set up")
         self._cluster = getcluster()
 
         # If a node is in the cluster context, add it to cluster.

tests/test_diagram.py

@@ -107,6 +107,12 @@ class DiagramTest(unittest.TestCase):
         with Diagram(show=False):
             Node("node1")
         self.assertTrue(os.path.exists(f"{self.name}.png"))
+    
+    def test_autolabel(self):
+        with Diagram(name=os.path.join(self.name, "nodes_to_node"), show=False):
+            node1 = Node("node1")
+            self.assertTrue(node1.label,"Node\nnode1")
+
 
     def test_outformat_list(self):
         """Check that outformat render all the files from the list."""