YANG construct collision detection framework added

Change-Id: I1458f9e3192641f3f90c444798c31a64536ffa5d
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/utils/DataModelUtils.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/utils/DataModelUtils.java
new file mode 100644
index 0000000..8d94dfe
--- /dev/null
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/utils/DataModelUtils.java
@@ -0,0 +1,73 @@
+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * 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.
+ */
+
+package org.onosproject.yangutils.datamodel.utils;
+
+import org.onosproject.yangutils.datamodel.CollisionDetector;
+import org.onosproject.yangutils.datamodel.YangLeaf;
+import org.onosproject.yangutils.datamodel.YangLeafList;
+import org.onosproject.yangutils.datamodel.YangLeavesHolder;
+import org.onosproject.yangutils.datamodel.YangNode;
+import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
+import org.onosproject.yangutils.utils.YangConstructType;
+
+/**
+ * Utilities for data model tree.
+ */
+public final class DataModelUtils {
+
+    /**
+     * Creates a new data model tree utility.
+     */
+    private DataModelUtils() {
+    }
+
+    /**
+     * Detects the colliding identifier name in a given YANG node and its child.
+     *
+     * @param identifierName name for which collision detection is to be
+     *            checked.
+     * @param dataType type of YANG node asking for detecting collision.
+     * @param node instance of calling node.
+     * @throws DataModelException a violation of data model rules.
+     */
+    public static void detectCollidingChildUtil(String identifierName, YangConstructType dataType, YangNode node)
+            throws DataModelException {
+        if (((YangLeavesHolder) node).getListOfLeaf() != null) {
+            for (YangLeaf leaf : ((YangLeavesHolder) node).getListOfLeaf()) {
+                if (leaf.getLeafName().equals(identifierName)) {
+                    throw new DataModelException("YANG file error: Duplicate input identifier detected, same as leaf \""
+                            + leaf.getLeafName() + "\"");
+                }
+            }
+        }
+        if (((YangLeavesHolder) node).getListOfLeafList() != null) {
+            for (YangLeafList leafList : ((YangLeavesHolder) node).getListOfLeafList()) {
+                if (leafList.getLeafName().equals(identifierName)) {
+                    throw new DataModelException("YANG file error: Duplicate input identifier detected, same as leaf " +
+                            "list \"" + leafList.getLeafName() + "\"");
+                }
+            }
+        }
+        node = node.getChild();
+        while ((node != null)) {
+            if (node instanceof CollisionDetector) {
+                ((CollisionDetector) node).detectSelfCollision(identifierName, dataType);
+            }
+            node = node.getNextSibling();
+        }
+    }
+}