py: Implement support for generalized generator protocol.

Iterators and ducktype objects can now be arguments of yield from.

2 files changed, 52 insertions, 0 deletions

diff --git a/tests/basics/gen-yield-from-ducktype.py b/tests/basics/gen-yield-from-ducktype.py
new file mode 100644
index 0000000000..aa0109c914
--- /dev/null
+++ b/tests/basics/gen-yield-from-ducktype.py
@@ -0,0 +1,44 @@
+class MyGen:
+
+    def __init__(self):
+        self.v = 0
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        self.v += 1
+        if self.v > 5:
+            raise StopIteration
+        return self.v
+
+def gen():
+    yield from MyGen()
+
+def gen2():
+    yield from gen()
+
+print(list(gen()))
+print(list(gen2()))
+
+
+class Incrementer:
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        return self.send(None)
+
+    def send(self, val):
+        if val is None:
+            return "Incrementer initialized"
+        return val + 1
+
+def gen3():
+    yield from Incrementer()
+
+g = gen3()
+print(next(g))
+print(g.send(5))
+print(g.send(100))
diff --git a/tests/basics/gen-yield-from-iter.py b/tests/basics/gen-yield-from-iter.py
new file mode 100644
index 0000000000..2d06328fbb
--- /dev/null
+++ b/tests/basics/gen-yield-from-iter.py
@@ -0,0 +1,8 @@
+def gen():
+    yield from (1, 2, 3)
+
+def gen2():
+    yield from gen()
+
+print(list(gen()))
+print(list(gen2()))