[meld] undo: Extend the undo API to return the actions that were undone/redone

[Kai Willadsen <kaiw src gnome org>]

commit 036df602fbd50607a193c7f7b33193e55b15ec8c
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Sun Apr 3 07:25:39 2016 +1000

    undo: Extend the undo API to return the actions that were undone/redone
    
    Having the actions carried out as part of the API lets other parts of
    the stack use action features to add extra front-end behaviours.

 meld/meldbuffer.py |    2 ++
 meld/undo.py       |   14 ++++++++++----
 2 files changed, 12 insertions(+), 4 deletions(-)
---
diff --git a/meld/meldbuffer.py b/meld/meldbuffer.py
index 3c6d38e..f70eaff 100644
--- a/meld/meldbuffer.py
+++ b/meld/meldbuffer.py
@@ -308,10 +308,12 @@ class BufferAction(object):
         start = self.buffer.get_iter_at_offset(self.offset)
         end = self.buffer.get_iter_at_offset(self.offset + len(self.text))
         self.buffer.delete(start, end)
+        return [self]
 
     def insert(self):
         start = self.buffer.get_iter_at_offset(self.offset)
         self.buffer.insert(start, self.text)
+        return [self]
 
 
 class BufferInsertionAction(BufferAction):
diff --git a/meld/undo.py b/meld/undo.py
index 777c511..308b81e 100644
--- a/meld/undo.py
+++ b/meld/undo.py
@@ -44,12 +44,16 @@ class GroupAction(object):
         self.buffer = seq.actions[0].buffer
 
     def undo(self):
+        actions = []
         while self.seq.can_undo():
-            self.seq.undo()
+            actions.extend(self.seq.undo())
+        return actions
 
     def redo(self):
+        actions = []
         while self.seq.can_redo():
-            self.seq.redo()
+            actions.extend(self.seq.redo())
+        return actions
 
 
 class UndoSequence(GObject.GObject):
@@ -144,7 +148,7 @@ class UndoSequence(GObject.GObject):
             self.emit('checkpointed', buf, False)
         could_redo = self.can_redo()
         self.next_redo -= 1
-        self.actions[self.next_redo].undo()
+        actions = self.actions[self.next_redo].undo()
         self.busy = False
         if not self.can_undo():
             self.emit('can-undo', 0)
@@ -152,6 +156,7 @@ class UndoSequence(GObject.GObject):
             self.emit('can-redo', 1)
         if self.checkpointed(buf):
             self.emit('checkpointed', buf, True)
+        return actions
 
     def redo(self):
         """Redo an action.
@@ -166,7 +171,7 @@ class UndoSequence(GObject.GObject):
         could_undo = self.can_undo()
         a = self.actions[self.next_redo]
         self.next_redo += 1
-        a.redo()
+        actions = a.redo()
         self.busy = False
         if not could_undo:
             self.emit('can-undo', 1)
@@ -174,6 +179,7 @@ class UndoSequence(GObject.GObject):
             self.emit('can-redo', 0)
         if self.checkpointed(buf):
             self.emit('checkpointed', buf, True)
+        return actions
 
     def checkpoint(self, buf):
         start = self.next_redo