kdb: add elektraDiffUndo function

src/bindings/cpp/include/elektradiff.hpp

@@ -37,6 +37,8 @@ class ElektraDiff
 	inline static ElektraDiff calculateDiff (const KeySet & newKeys, const KeySet & oldKeys, const std::string & parentKeyName);
 	inline static ElektraDiff calculateDiff (const KeySet & newKeys, const KeySet & oldKeys, const Key & parentKey);
 
+	inline void undo (KeySet & ks);
+
 	// reference handling
 
 	inline void operator++ (int) const;
@@ -168,6 +170,15 @@ inline ElektraDiff ElektraDiff::calculateDiff (const KeySet & newKeys, const Key
 	return ElektraDiff (diff);
 }
 
+/**
+ * Undo the changes represented in this diff
+ * @param ks the keyset where the changs should be undone
+ */
+inline void ElektraDiff::undo (KeySet & ks)
+{
+	ckdb::elektraDiffUndo (diff, ks.getKeySet());
+}
+
 /**
  * @copydoc elektraDiffIncRef
  */

src/include/kdbdiff.h

@@ -21,6 +21,8 @@ void elektraDiffRemoveKey (ElektraDiff * ksd, Key * toRemove);
 ElektraDiff * elektraDiffCut (ElektraDiff * original, const Key * cutpoint);
 ElektraDiff * elektraDiffDup (const ElektraDiff * original);
 
+void elektraDiffUndo (ElektraDiff * ksd, KeySet * ks);
+
 uint16_t elektraDiffIncRef (ElektraDiff * ksd);
 uint16_t elektraDiffDecRef (ElektraDiff * ksd);
 uint16_t elektraDiffGetRef (ElektraDiff * ksd);

src/libs/elektra/diff.c

@@ -907,6 +907,28 @@ KeySet * elektraDiffGetModifiedMetaKeys (const ElektraDiff * ksd, Key * key)
 	return modifiedKeys;
 }
 
+/**
+ * Undos the changes that are presented in the diff.
+ *  - Added keys get removed from @p ks
+ *  - Removed keys get added back to @p ks,
+ *  - Modified keys will get their old values and meta data in @p ks
+ *
+ * @param ksd the diff
+ * @param ks the keyset that shall be undone
+ */
+void elektraDiffUndo (ElektraDiff * ksd, KeySet * ks)
+{
+	for (elektraCursor i = 0; i < ksGetSize (ksd->addedKeys); i++)
+	{
+		Key * toRemove = ksAtCursor (ksd->addedKeys, i);
+		Key * key = ksLookup (ks, toRemove, KDB_O_POP);
+		keyDel (key);
+	}
+
+	ksAppend (ks, ksd->modifiedKeys);
+	ksAppend (ks, ksd->removedKeys);
+}
+
 /**
  * @brief Increment the reference counter of a ElektraDiff object
  *

src/libs/elektra/symbols.map

@@ -171,6 +171,7 @@ libelektra_1.0 {
 	elektraDiffRemoveKey;
 	elektraDiffCut;
 	elektraDiffAppend;
+	elektraDiffUndo;
 };
 
 libelektraprivate_1.0 {

src/libs/record/record.c

@@ -507,19 +507,7 @@ bool elektraRecordUndo (KDB * handle, KDB * sessionStorageHandle, Key * parentKe
 			goto cleanup;
 		}
 
-		KeySet * keysToRemove = elektraDiffGetAddedKeys (undoDiff);
-		KeySet * keysToModify = elektraDiffGetModifiedKeys (undoDiff);
-		KeySet * keysToAdd = elektraDiffGetRemovedKeys (undoDiff);
-
-		for (elektraCursor i = 0; i < ksGetSize (keysToRemove); i++)
-		{
-			Key * toRemove = ksAtCursor (keysToRemove, i);
-			Key * key = ksLookup (ks, toRemove, KDB_O_POP);
-			keyDel (key);
-		}
-
-		ksAppend (ks, keysToModify);
-		ksAppend (ks, keysToAdd);
+		elektraDiffUndo (undoDiff, ks);
 
 		// Disable session recording for now
 		Key * activeKey = ksLookupByName (handle->global, ELEKTRA_RECORD_CONFIG_ACTIVE_KEY, KDB_O_POP);
@@ -546,9 +534,6 @@ bool elektraRecordUndo (KDB * handle, KDB * sessionStorageHandle, Key * parentKe
 			ksAppendKey (handle->global, activeKey);
 		}
 
-		ksDel (keysToRemove);
-		ksDel (keysToModify);
-		ksDel (keysToAdd);
 		ksDel (ks);
 
 		if (!successful)

tests/ctest/test_diff.c

@@ -856,6 +856,40 @@ static void test_elektraDiffDup_shouldDuplicate (void)
 	keyDel (parentKey);
 }
 
+static void test_elektraDiffUndo (void)
+{
+	printf ("Test %s\n", __func__);
+
+	// Arrange
+	KeySet * keyset = ksNew (1,
+			     keyNew ("user:/added", KEY_VALUE, "1234", KEY_END),
+			     keyNew ("user:/modified", KEY_VALUE, "modified value", KEY_END),
+			     KS_END);
+
+	Key * parentKey = keyNew ("/", KEY_END);
+
+	ElektraDiff * diff = elektraDiffNew (
+			ksNew (1, keyNew ("user:/added", KEY_VALUE, "1234", KEY_END), KS_END),
+			ksNew (1, keyNew ("user:/removed", KEY_VALUE, "removed key", KEY_END), KS_END),
+			ksNew (1, keyNew ("user:/modified", KEY_VALUE, "old value", KEY_END), KS_END),
+			ksNew (1, keyNew ("user:/modified", KEY_VALUE, "new value", KEY_END), KS_END),
+			parentKey
+		);
+
+	// Act
+	elektraDiffUndo (diff, keyset);
+
+
+	// Assert
+	succeed_if_fmt (ksGetSize (keyset) == 2, "expected 2 keys, got %zu", ksGetSize (keyset));
+	succeed_if_keyset_contains_key_with_string (keyset, "user:/removed", "removed key");
+	succeed_if_keyset_contains_key_with_string (keyset, "user:/modified", "old value");
+
+	ksDel (keyset);
+	keyDel (parentKey);
+	elektraDiffDel (diff);
+}
+
 int main (int argc, char ** argv)
 {
 	printf ("DIFF                 TESTS\n");
@@ -919,6 +953,8 @@ int main (int argc, char ** argv)
 
 	test_elektraDiffDup_shouldDuplicate ();
 
+	test_elektraDiffUndo ();
+
 	elektraDiffDel (demoDiff);
 
 	printf ("\ntest_diff RESULTS: %d test(s) done. %d error(s).\n", nbTest, nbError);