--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Framework/Loaders/BasicFetchingItemsSorter.cpp	Mon May 20 11:20:01 2019 +0200
@@ -0,0 +1,74 @@
+/**
+ * Stone of Orthanc
+ * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
+ * Department, University Hospital of Liege, Belgium
+ * Copyright (C) 2017-2019 Osimis S.A., Belgium
+ *
+ * This program is free software: you can redistribute it and/or
+ * modify it under the terms of the GNU Affero General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Affero General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ **/
+
+
+#include "BasicFetchingItemsSorter.h"
+
+#include <Core/OrthancException.h>
+
+namespace OrthancStone
+{
+  BasicFetchingItemsSorter::BasicFetchingItemsSorter(unsigned int itemsCount) :
+    itemsCount_(itemsCount)
+  {
+    if (itemsCount == 0)
+    {
+      throw Orthanc::OrthancException(Orthanc::ErrorCode_ParameterOutOfRange);
+    }
+  }
+
+
+  void BasicFetchingItemsSorter::Sort(std::vector<unsigned int>& target,
+                                      unsigned int current)
+  {
+    if (current >= itemsCount_)
+    {
+      throw Orthanc::OrthancException(Orthanc::ErrorCode_ParameterOutOfRange);
+    }
+
+    target.clear();
+    target.reserve(itemsCount_);
+    target.push_back(current);
+
+    const unsigned int countBelow = current;
+    const unsigned int countAbove = (itemsCount_ - 1) - current;
+    const unsigned int n = std::min(countBelow, countAbove);
+
+    for (unsigned int i = 1; i <= n; i++)
+    {
+      assert(current + i < itemsCount_ &&
+             current >= i);
+      target.push_back(current + i);
+      target.push_back(current - i);
+    }
+
+    for (unsigned int i = current - n; i > 0; i--)
+    {
+      target.push_back(i - 1);
+    }
+
+    for (unsigned int i = current + n + 1; i < itemsCount_; i++)
+    {
+      target.push_back(i);
+    }
+
+    assert(target.size() == itemsCount_);
+  }
+}