Basic infrastructure for Undo/Redo

gramps/gen/db/undoredo.py

@@ -0,0 +1,136 @@
+import time
+from collections import deque
+
+class DbUndo(object):
+    """
+    Base class for the Gramps undo/redo manager.  Needs to be subclassed
+    for use with a real backend.
+    """
+
+    __slots__ = ('undodb', 'db', 'mapbase', 'undo_history_timestamp',
+                 'txn', 'undoq', 'redoq')
+
+    def __init__(self, grampsdb):
+        """
+        Class constructor. Set up main instance variables
+        """
+        self.db = grampsdb
+        self.undoq = deque()
+        self.redoq = deque()
+        self.undo_history_timestamp = time.time()
+        self.txn = None
+
+    def clear(self):
+        """
+        Clear the undo/redo list (but not the backing storage)
+        """
+        self.undoq.clear()
+        self.redoq.clear()
+        self.undo_history_timestamp = time.time()
+        self.txn = None
+
+    def __enter__(self, value):
+        """
+        Context manager method to establish the context
+        """
+        self.open(value)
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        """
+        Context manager method to finish the context
+        """
+        if exc_type is None:
+            self.close()
+        return exc_type is None
+
+    def open(self, value):
+        """
+        Open the backing storage.  Needs to be overridden in the derived
+        class.
+        """
+        raise NotImplementedError
+
+    def close(self):
+        """
+        Close the backing storage.  Needs to be overridden in the derived
+        class.
+        """        
+        raise NotImplementedError
+
+    def append(self, value):
+        """
+        Add a new entry on the end.  Needs to be overridden in the derived
+        class.
+        """        
+        raise NotImplementedError
+
+    def __getitem__(self, index):
+        """
+        Returns an entry by index number.  Needs to be overridden in the
+        derived class.
+        """        
+        raise NotImplementedError
+
+    def __setitem__(self, index, value):
+        """
+        Set an entry to a value.  Needs to be overridden in the derived class.
+        """           
+        raise NotImplementedError
+
+    def __len__(self):
+        """
+        Returns the number of entries.  Needs to be overridden in the derived
+        class.
+        """         
+        raise NotImplementedError
+
+    def commit(self, txn, msg):
+        """
+        Commit the transaction to the undo/redo database.  "txn" should be
+        an instance of Gramps transaction class
+        """
+        txn.set_description(msg)
+        txn.timestamp = time.time()
+        self.undoq.append(txn)
+
+    def undo(self, update_history=True):
+        """
+        Undo a previously committed transaction
+        """
+        if self.db.readonly or self.undo_count == 0:
+            return False
+        return self.__undo(update_history)
+
+    def redo(self, update_history=True):
+        """
+        Redo a previously committed, then undone, transaction
+        """
+        if self.db.readonly or self.redo_count == 0:
+            return False
+        return self.__redo(update_history)
+
+    def undoredo(func):
+        """
+        Decorator function to wrap undo and redo operations within a bsddb
+        transaction.  It also catches bsddb errors and raises an exception
+        as appropriate
+        """
+        pass
+
+    def __redo(self, update_history=True):
+        """
+        Access the last undone transaction, and revert the data to the state 
+        before the transaction was undone.
+        """
+        pass
+
+    def __undo(self, db=None, update_history=True):
+        """
+        Access the last committed transaction, and revert the data to the 
+        state before the transaction was committed.
+        """
+        pass
+
+    undo_count = property(lambda self:len(self.undoq))
+    redo_count = property(lambda self:len(self.redoq))

gramps/plugins/database/dictionarydb.py

@@ -37,6 +37,7 @@ import logging
 #
 #------------------------------------------------------------------------
 from gramps.gen.db import DbReadBase, DbWriteBase, DbTxn, KEY_TO_NAME_MAP
+from gramps.gen.db.undoredo import DbUndo
 from gramps.gen.db.dbconst import *
 from gramps.gen.utils.callback import Callback
 from gramps.gen.updatecallback import UpdateCallback
@@ -390,6 +391,8 @@ class DictionaryDb(DbWriteBase, DbReadBase, UpdateCallback, Callback):
         self.modified   = 0
         self.txn = DictionaryTxn("DbDictionary Transaction", self)
         self.transaction = None
+        self.undodb = DbUndo(self)
+        self.abort_possible = False
         self._directory = directory
         if directory:
             self.load(directory)
@@ -1212,7 +1215,7 @@ class DictionaryDb(DbWriteBase, DbReadBase, UpdateCallback, Callback):
         if emit:
             self.emit(emit, ([tag.handle],))
 
-    def commit_media_object(self, media, transaction, change_time=None):
+    def commit_media_object(self, media, trans, change_time=None):
         emit = None
         if not trans.batch:
             if media.handle in self.media_map:

gramps/plugins/database/djangodb.py

@@ -44,6 +44,7 @@ from gramps.gen.lib import (Person, Family, Event, Place, Repository,
                             Citation, Source, Note, MediaObject, Tag, 
                             Researcher)
 from gramps.gen.db import DbReadBase, DbWriteBase, DbTxn
+from gramps.gen.db.undoredo import DbUndo
 from gramps.gen.utils.callback import Callback
 from gramps.gen.updatecallback import UpdateCallback
 from gramps.gen.db import (PERSON_KEY,
@@ -335,6 +336,8 @@ class DbDjango(DbWriteBase, DbReadBase, UpdateCallback, Callback):
         self.import_cache = {}
         self.use_import_cache = False
         self.use_db_cache = True
+        self.undodb = DbUndo(self)
+        self.abort_possible = False
         self._directory = directory
         if directory:
             self.load(directory)