chore: import upstream snapshot with attribution

libnd4j/include/ops/declarable/helpers/cpu/invertPermutation.cpp

@@ -0,0 +1,52 @@
+/* ******************************************************************************
+ *
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Apache License, Version 2.0 which is available at
+ * https://www.apache.org/licenses/LICENSE-2.0.
+ *
+ *  See the NOTICE file distributed with this work for additional
+ *  information regarding copyright ownership.
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ ******************************************************************************/
+
+//
+// @author Yurii Shyrma (iuriish@yahoo.com), created on 20.04.2018
+//
+
+#include <helpers/Loops.h>
+#include <ops/declarable/helpers/transforms.h>
+#if NOT_EXCLUDED(OP_invert_permutation)
+namespace sd {
+namespace ops {
+namespace helpers {
+
+////////////////////////////////////////////////////////////////////////
+void invertPermutation(sd::LaunchContext* context, NDArray& input, NDArray& output) {
+  std::set<int> uniqueElems;
+  const int length = input.lengthOf();
+
+  for (int i = 0; i < length; ++i) {
+    int elem = input.e<int>(i);
+
+    if (!uniqueElems.insert(elem).second)  // this operation forbids us to use #pragma omp
+      THROW_EXCEPTION("helpers::invertPermutation function: input array contains duplicates !");
+
+    if (elem < 0 || elem > length - 1)
+      THROW_EXCEPTION(
+          "helpers::invertPermutation function: element of input array is out of range (0, length-1) !");
+
+    output.p<int>(elem, i);
+  }
+}
+
+}  // namespace helpers
+}  // namespace ops
+}  // namespace sd
+#endif