From 9e24b56099612b2be36964e56441a77aa2d59572 Mon Sep 17 00:00:00 2001
From: Sebastien Bourdeauducq <sb@m-labs.hk>
Date: Sat, 1 Aug 2015 16:48:27 +0800
Subject: [PATCH] gui: add state manager

---
 artiq/gui/state.py | 63 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)
 create mode 100644 artiq/gui/state.py

diff --git a/artiq/gui/state.py b/artiq/gui/state.py
new file mode 100644
index 000000000..9c5e7b8bb
--- /dev/null
+++ b/artiq/gui/state.py
@@ -0,0 +1,63 @@
+import asyncio
+from collections import OrderedDict
+
+from artiq.tools import TaskObject
+from artiq.protocols import pyon
+
+
+# support Qt CamelCase naming scheme for save/restore state
+def _save_state(obj):
+    method = getattr(obj, "save_state", None)
+    if method is None:
+        method = obj.saveState
+    return method()
+
+
+def _restore_state(obj, state):
+    method = getattr(obj, "restore_state", None)
+    if method is None:
+        method = obj.restoreState
+    method(state)
+
+
+class StateManager(TaskObject):
+    def __init__(self, filename, autosave_period=30):
+        self.filename = filename
+        self.autosave_period = autosave_period
+        self.stateful_objects = OrderedDict()
+
+    def register(self, obj, name=None):
+        if name is None:
+            name = obj.__class__.__name__
+        if name in self.stateful_objects:
+            raise RuntimeError("Name '{}' already exists in state"
+                               .format(name))
+        self.stateful_objects[name] = obj
+
+    def load(self):
+        try:
+            data = pyon.load_file(self.filename)
+        except FileNotFoundError:
+            return
+        # The state of one object may depend on the state of another,
+        # e.g. the display state may create docks that are referenced in
+        # the area state.
+        # To help address this problem, state is restored in the opposite
+        # order as the stateful objects are registered.
+        for name, obj in reversed(list(self.stateful_objects.items())):
+            state = data.get(name, None)
+            if state is not None:
+                _restore_state(obj, state)
+
+    def save(self):
+        data = {k: _save_state(v) for k, v in self.stateful_objects.items()}
+        pyon.store_file(self.filename, data)
+
+    @asyncio.coroutine
+    def _do(self):
+        try:
+            while True:
+                yield from asyncio.sleep(self.autosave_period)
+                self.save()
+        finally:
+            self.save()