Add third_party/pexpect

third_party/pexpect/pexpect/async.py

Index: third_party/pexpect/pexpect/async.py
diff --git a/third_party/pexpect/pexpect/async.py b/third_party/pexpect/pexpect/async.py
new file mode 100644
index 0000000000000000000000000000000000000000..ad759947232c51b492b57d99fa974aeeb60b82c9
--- /dev/null
+++ b/third_party/pexpect/pexpect/async.py
@@ -0,0 +1,72 @@
+import asyncio
+import errno
+
+from pexpect import EOF
+
+@asyncio.coroutine
+def expect_async(expecter, timeout=None):
+    # First process data that was previously read - if it maches, we don't need
+    # async stuff.
+    previously_read = expecter.spawn.buffer
+    expecter.spawn.buffer = expecter.spawn.string_type()
+    idx = expecter.new_data(previously_read)
+    if idx is not None:
+        return idx
+
+    transport, pw = yield from asyncio.get_event_loop()\
+        .connect_read_pipe(lambda: PatternWaiter(expecter), expecter.spawn)
+
+    try:
+        return (yield from asyncio.wait_for(pw.fut, timeout))
+    except asyncio.TimeoutError as e:
+        transport.pause_reading()
+        return expecter.timeout(e)
+
+class PatternWaiter(asyncio.Protocol):
+    def __init__(self, expecter):
+        self.expecter = expecter
+        self.fut = asyncio.Future()
+    
+    def found(self, result):
+        if not self.fut.done():
+            self.fut.set_result(result)
+    
+    def error(self, exc):
+        if not self.fut.done():
+            self.fut.set_exception(exc)
+    
+    def data_received(self, data):
+        spawn = self.expecter.spawn
+        s = spawn._decoder.decode(data)
+        spawn._log(s, 'read')
+
+        if self.fut.done():
+            spawn.buffer += data
+            return
+
+        try:
+            index = self.expecter.new_data(data)
+            if index is not None:
+                # Found a match
+                self.found(index)
+        except Exception as e:
+            self.expecter.errored()
+            self.error(e)
+    
+    def eof_received(self):
+        # N.B. If this gets called, async will close the pipe (the spawn object)
+        # for us
+        try:
+            self.expecter.spawn.flag_eof = True
+            index = self.expecter.eof()
+        except EOF as e:
+            self.error(e)
+        else:
+            self.found(index)
+    
+    def connection_lost(self, exc):
+        if isinstance(exc, OSError) and exc.errno == errno.EIO:
+            # We may get here without eof_received being called, e.g on Linux
+            self.eof_received()
+        elif exc is not None:
+            self.error(exc)