intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 74 insertions, 0 deletions

diff --git a/contrib/python/prompt-toolkit/py3/prompt_toolkit/eventloop/async_generator.py b/contrib/python/prompt-toolkit/py3/prompt_toolkit/eventloop/async_generator.py
new file mode 100644
index 0000000000..7ab3c28673
--- /dev/null
+++ b/contrib/python/prompt-toolkit/py3/prompt_toolkit/eventloop/async_generator.py
@@ -0,0 +1,74 @@
+"""
+Implementation for async generators.
+"""
+from asyncio import Queue
+from typing import AsyncGenerator, Callable, Iterable, TypeVar, Union
+
+from .utils import get_event_loop, run_in_executor_with_context
+
+__all__ = [
+    "generator_to_async_generator",
+]
+
+
+_T = TypeVar("_T")
+
+
+class _Done:
+    pass
+
+
+async def generator_to_async_generator(
+    get_iterable: Callable[[], Iterable[_T]]
+) -> AsyncGenerator[_T, None]:
+    """
+    Turn a generator or iterable into an async generator.
+
+    This works by running the generator in a background thread.
+
+    :param get_iterable: Function that returns a generator or iterable when
+        called.
+    """
+    quitting = False
+    _done = _Done()
+    q: Queue[Union[_T, _Done]] = Queue()
+    loop = get_event_loop()
+
+    def runner() -> None:
+        """
+        Consume the generator in background thread.
+        When items are received, they'll be pushed to the queue.
+        """
+        try:
+            for item in get_iterable():
+                # When this async generator was cancelled (closed), stop this
+                # thread.
+                if quitting:
+                    break
+
+                loop.call_soon_threadsafe(q.put_nowait, item)
+
+        finally:
+            loop.call_soon_threadsafe(q.put_nowait, _done)
+
+    # Start background thread.
+    runner_f = run_in_executor_with_context(runner)
+
+    try:
+        while True:
+            item = await q.get()
+            if isinstance(item, _Done):
+                break
+            else:
+                yield item
+    finally:
+        # When this async generator is closed (GeneratorExit exception, stop
+        # the background thread as well. - we don't need that anymore.)
+        quitting = True
+
+        # Wait for the background thread to finish. (should happen right after
+        # the next item is yielded). If we don't do this, and the event loop
+        # gets closed before the runner is done, then we'll get a
+        # `RuntimeError: Event loop is closed` exception printed to stdout that
+        # we can't handle.
+        await runner_f