Iteration over links in flow interface

In addition to iteration over its children (atoms or subflows) each
pattern now provides iter_links() method that iterates over
dependency links. This allows engines to treat all patterns
in the same way instead knowing what structure each pattern expresses.

Change-Id: I52cb5b0b501eefc8eb56a9ef5303aeb318013e11

1 files changed, 9 insertions, 0 deletions

diff --git a/taskflow/patterns/linear_flow.py b/taskflow/patterns/linear_flow.py
index 5ffd211..89fab08 100644
--- a/taskflow/patterns/linear_flow.py
+++ b/taskflow/patterns/linear_flow.py
@@ -18,6 +18,10 @@ from taskflow import exceptions
 from taskflow import flow
 
 
+# TODO(imelnikov): add metadata describing link here
+_LINK_METADATA = dict()
+
+
 class Flow(flow.Flow):
     """Linear Flow pattern.
 
@@ -71,6 +75,11 @@ class Flow(flow.Flow):
         for child in self._children:
             yield child
 
+    def iter_links(self):
+        for src, dst in zip(self._children[:-1],
+                            self._children[1:]):
+            yield (src, dst, _LINK_METADATA.copy())
+
     def __getitem__(self, index):
         return self._children[index]