3 files changed, 119 insertions, 0 deletions
diff --git a/indra/llcommon/CMakeLists.txt b/indra/llcommon/CMakeLists.txt
index 4481d334b2..3c689930b8 100644
--- a/indra/llcommon/CMakeLists.txt
+++ b/indra/llcommon/CMakeLists.txt
@@ -35,6 +35,7 @@ set(llcommon_SOURCE_FILES
     llbase32.cpp
     llbase64.cpp
     llcommon.cpp
+    llcommonutils.cpp
     llcoros.cpp
     llcrc.cpp
     llcriticaldamp.cpp
@@ -124,6 +125,7 @@ set(llcommon_HEADER_FILES
     llchat.h
     llclickaction.h
     llcommon.h
+    llcommonutils.h
     llcoros.h
     llcrc.h
     llcriticaldamp.h
diff --git a/indra/llcommon/llcommonutils.cpp b/indra/llcommon/llcommonutils.cpp
new file mode 100644
index 0000000000..0022dc6915
--- /dev/null
+++ b/indra/llcommon/llcommonutils.cpp
@@ -0,0 +1,61 @@
+/**
+ * @file llcommonutils.h
+ * @brief Commin utils
+ *
+ * $LicenseInfo:firstyear=2010&license=viewergpl$
+ *
+ * Copyright (c) 2010, Linden Research, Inc.
+ *
+ * Second Life Viewer Source Code
+ * The source code in this file ("Source Code") is provided by Linden Lab
+ * to you under the terms of the GNU General Public License, version 2.0
+ * ("GPL"), unless you have obtained a separate licensing agreement
+ * ("Other License"), formally executed by you and Linden Lab.  Terms of
+ * the GPL can be found in doc/GPL-license.txt in this distribution, or
+ * online at http://secondlifegrid.net/programs/open_source/licensing/gplv2
+ *
+ * There are special exceptions to the terms and conditions of the GPL as
+ * it is applied to this Source Code. View the full text of the exception
+ * in the file doc/FLOSS-exception.txt in this software distribution, or
+ * online at http://secondlifegrid.net/programs/open_source/licensing/flossexception
+ *
+ * By copying, modifying or distributing this software, you acknowledge
+ * that you have read and understood your obligations described above,
+ * and agree to abide by those obligations.
+ *
+ * ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
+ * WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY,
+ * COMPLETENESS OR PERFORMANCE.
+ * $/LicenseInfo$
+ */
+
+#include "linden_common.h"
+#include "llcommonutils.h"
+
+void LLCommonUtils::computeDifference(
+	const uuid_vec_t& vnew,
+	const uuid_vec_t& vcur,
+	uuid_vec_t& vadded,
+	uuid_vec_t& vremoved)
+{
+	uuid_vec_t vnew_copy(vnew);
+	uuid_vec_t vcur_copy(vcur);
+
+	std::sort(vnew_copy.begin(), vnew_copy.end());
+	std::sort(vcur_copy.begin(), vcur_copy.end());
+
+	size_t maxsize = llmax(vnew_copy.size(), vcur_copy.size());
+	vadded.resize(maxsize);
+	vremoved.resize(maxsize);
+
+	uuid_vec_t::iterator it;
+	// what was removed
+	it = set_difference(vcur_copy.begin(), vcur_copy.end(), vnew_copy.begin(), vnew_copy.end(), vremoved.begin());
+	vremoved.erase(it, vremoved.end());
+
+	// what was added
+	it = set_difference(vnew_copy.begin(), vnew_copy.end(), vcur_copy.begin(), vcur_copy.end(), vadded.begin());
+	vadded.erase(it, vadded.end());
+}
+
+// EOF
diff --git a/indra/llcommon/llcommonutils.h b/indra/llcommon/llcommonutils.h
new file mode 100644
index 0000000000..ad0d884e37
--- /dev/null
+++ b/indra/llcommon/llcommonutils.h
@@ -0,0 +1,56 @@
+/**
+ * @file llcommonutils.h
+ * @brief Common utils
+ *
+ * $LicenseInfo:firstyear=2010&license=viewergpl$
+ *
+ * Copyright (c) 2010, Linden Research, Inc.
+ *
+ * Second Life Viewer Source Code
+ * The source code in this file ("Source Code") is provided by Linden Lab
+ * to you under the terms of the GNU General Public License, version 2.0
+ * ("GPL"), unless you have obtained a separate licensing agreement
+ * ("Other License"), formally executed by you and Linden Lab.  Terms of
+ * the GPL can be found in doc/GPL-license.txt in this distribution, or
+ * online at http://secondlifegrid.net/programs/open_source/licensing/gplv2
+ *
+ * There are special exceptions to the terms and conditions of the GPL as
+ * it is applied to this Source Code. View the full text of the exception
+ * in the file doc/FLOSS-exception.txt in this software distribution, or
+ * online at http://secondlifegrid.net/programs/open_source/licensing/flossexception
+ *
+ * By copying, modifying or distributing this software, you acknowledge
+ * that you have read and understood your obligations described above,
+ * and agree to abide by those obligations.
+ *
+ * ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
+ * WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY,
+ * COMPLETENESS OR PERFORMANCE.
+ * $/LicenseInfo$
+ */
+
+#ifndef LL_LLCOMMONUTILS_H
+#define LL_LLCOMMONUTILS_H
+
+namespace LLCommonUtils
+{
+	/**
+	 * Computes difference between 'vnew' and 'vcur' vectors.
+	 * Items present in 'vnew' and missing in 'vcur' are treated as added and are copied into 'vadded'
+	 * Items missing in 'vnew' and present in 'vcur' are treated as removed and are copied into 'vremoved'
+	 *
+	 * @param vnew[in] - incoming IDs
+	 * @param vcur[in] - current IDs
+	 * @param vadded[out] - difference between incoming and current IDS - added IDs
+	 * @param vremoved[out] - difference between incoming and current IDS - removed IDs
+	 */
+	LL_COMMON_API void computeDifference(
+		const uuid_vec_t& vnew,
+		const uuid_vec_t& vcur,
+		uuid_vec_t& vadded,
+		uuid_vec_t& vremoved);
+};
+
+#endif //LL_LLCOMMONUTILS_H
+
+// EOF