addons.View: better order reversal

Deal with some subtleties in order reversal, add a toggle method that emits
refresh.

mitmproxy/addons/view.py

@@ -34,7 +34,7 @@ class View(collections.Sequence):
         self._store = {}
         self.filter = matchall
         self.order_key = key_request_start
-        self.order_reverse = False
+        self.order_reversed = False
         self._view = sortedcontainers.SortedListWithKey(key = self.order_key)
 
         # These signals broadcast events that affect the view. That is, an
@@ -46,13 +46,42 @@ class View(collections.Sequence):
         # Signals that the view should be refreshed completely
         self.sig_refresh = blinker.Signal()
 
+    def _rev(self, idx: int) -> int:
+        """
+            Reverses an index, if needed
+        """
+        if self.order_reversed:
+            if idx < 0:
+                idx = -idx - 1
+            else:
+                idx = len(self._view) - idx - 1
+                if idx < 0:
+                    raise IndexError
+        return idx
+
     def __len__(self):
         return len(self._view)
 
     def __getitem__(self, offset) -> flow.Flow:
-        if self.order_reverse:
+        return self._view[self._rev(offset)]
-            offset = -offset - 1
+
-        return self._view[offset]
+    # Reflect some methods to the efficient underlying implementation
+
+    def bisect(self, f: flow.Flow) -> int:
+        v = self._view.bisect(f)
+        # Bisect returns an item to the RIGHT of the existing entries.
+        if v == 0:
+            return v
+        return self._rev(v - 1) + 1
+
+    def index(self, f: flow.Flow) -> int:
+        return self._rev(self._view.index(f))
+
+    # API
+
+    def toggle_reversed(self):
+        self.order_reversed = not self.order_reversed
+        self.sig_refresh.send(self)
 
     def set_order(self, order_key: typing.Callable):
         """
@@ -122,14 +151,8 @@ class View(collections.Sequence):
                     # The value was not in the view
                     pass
 
-    # Reflect some methods to the efficient underlying implementation
-    def bisect(self, f: flow.Flow) -> int:
-        return self._view.bisect(f)
-
-    def index(self, f: flow.Flow) -> int:
-        return self._view.index(f)
-
     # Event handlers
+
     def request(self, f):
         self.add(f)
 
@@ -186,8 +209,7 @@ class Focus:
     def _sig_refresh(self, view):
         if len(view) == 0:
             self.focusflow = None
-        else:
+        elif self.focusflow not in view:
-            if self.focusflow not in view:
             self.focusflow = view[0]
 
     def _sig_add(self, view, flow):

test/mitmproxy/addons/test_view.py

@@ -62,16 +62,33 @@ def test_order():
 
     v.set_order(view.key_request_method)
     assert [i.request.method for i in v] == ["GET", "GET", "PUT", "PUT"]
-    v.order_reverse = True
+    v.toggle_reversed()
     assert [i.request.method for i in v] == ["PUT", "PUT", "GET", "GET"]
 
     v.set_order(view.key_request_start)
     assert [i.request.timestamp_start for i in v] == [4, 3, 2, 1]
 
-    v.order_reverse = False
+    v.toggle_reversed()
     assert [i.request.timestamp_start for i in v] == [1, 2, 3, 4]
 
 
+def test_reversed():
+    v = view.View()
+    v.request(tft(start=1))
+    v.request(tft(start=2))
+    v.request(tft(start=3))
+    v.toggle_reversed()
+
+    assert v[0].request.timestamp_start == 3
+    assert v[-1].request.timestamp_start == 1
+    assert v[2].request.timestamp_start == 1
+    tutils.raises(IndexError, v.__getitem__, 5)
+    tutils.raises(IndexError, v.__getitem__, -5)
+
+    assert v.bisect(v[0]) == 1
+    assert v.bisect(v[2]) == 3
+
+
 def test_update():
     v = view.View()
     flt = flowfilter.parse("~m get")