[ONOS-4350] Inter Jar dependency implementation and code restructuring.

Change-Id: Iacac75e4187aed93ce1754c170a9c19707e5b8c3
diff --git a/utils/yangutils/plugin/src/main/java/org/onosproject/yangutils/parser/impl/listeners/UnionListener.java b/utils/yangutils/plugin/src/main/java/org/onosproject/yangutils/parser/impl/listeners/UnionListener.java
new file mode 100644
index 0000000..32eb4d9
--- /dev/null
+++ b/utils/yangutils/plugin/src/main/java/org/onosproject/yangutils/parser/impl/listeners/UnionListener.java
@@ -0,0 +1,220 @@
+/*
+ * Copyright 2016-present 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.parser.impl.listeners;
+
+/*
+ * Reference: RFC6020 and YANG ANTLR Grammar
+ *
+ * ABNF grammar as per RFC6020
+ * type-body-stmts     = numerical-restrictions /
+ *                       decimal64-specification /
+ *                      string-restrictions /
+ *                       enum-specification /
+ *                       leafref-specification /
+ *                       identityref-specification /
+ *                       instance-identifier-specification /
+ *                       bits-specification /
+ *                       union-specification
+ *
+ * union-specification = 1*(type-stmt stmtsep)
+ *
+ * ANTLR grammar rule
+ * typeBodyStatements : numericalRestrictions | stringRestrictions | enumSpecification
+ *                 | leafrefSpecification | identityrefSpecification | instanceIdentifierSpecification
+ *                 | bitsSpecification | unionSpecification;
+ *
+ * unionSpecification : typeStatement+;
+ */
+
+import org.onosproject.yangutils.datamodel.YangLeaf;
+import org.onosproject.yangutils.datamodel.YangLeafList;
+import org.onosproject.yangutils.datamodel.YangNode;
+import org.onosproject.yangutils.datamodel.YangType;
+import org.onosproject.yangutils.datamodel.YangTypeDef;
+import org.onosproject.yangutils.datamodel.YangUnion;
+import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
+import org.onosproject.yangutils.datamodel.utils.Parsable;
+import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
+import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+
+import static org.onosproject.yangutils.datamodel.utils.GeneratedLanguage.JAVA_GENERATION;
+import static org.onosproject.yangutils.datamodel.utils.YangConstructType.TYPE_DATA;
+import static org.onosproject.yangutils.datamodel.utils.YangConstructType.UNION_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.EXIT;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructExtendedListenerErrorMessage;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_CURRENT_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.UNHANDLED_PARSED_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
+import static org.onosproject.yangutils.translator.tojava.YangDataModelFactory.getYangUnionNode;
+
+/**
+ * Represents listener based call back function corresponding to the "union" rule
+ * defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
+ */
+public final class UnionListener {
+
+    /**
+     * Suffix to be used while creating union class.
+     */
+    private static final String UNION_CLASS_SUFFIX = "_union";
+
+    /**
+     * Creates a new union listener.
+     */
+    private UnionListener() {
+    }
+
+    /**
+     * It is called when parser enters grammar rule (union), it perform
+     * validations and updates the data model tree.
+     *
+     * @param listener listener's object
+     * @param ctx      context object of the grammar rule
+     */
+    public static void processUnionEntry(TreeWalkListener listener,
+                                         GeneratedYangParser.UnionSpecificationContext ctx) {
+
+        // Check for stack to be non empty.
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, UNION_DATA, "", ENTRY);
+
+        if (listener.getParsedDataStack().peek() instanceof YangType) {
+            YangUnion unionNode = getYangUnionNode(JAVA_GENERATION);
+            Parsable typeData = listener.getParsedDataStack().pop();
+
+            // Check for stack to be non empty.
+            checkStackIsNotEmpty(listener, MISSING_HOLDER, UNION_DATA, "", ENTRY);
+
+            Parsable tmpData = listener.getParsedDataStack().peek();
+
+            switch (tmpData.getYangConstructType()) {
+                case LEAF_DATA:
+                    // Set the name of union same as leaf.
+                    unionNode.setName(((YangLeaf) tmpData).getName() + UNION_CLASS_SUFFIX);
+                    // Pop the stack entry to obtain the parent YANG node.
+                    Parsable leaf = listener.getParsedDataStack().pop();
+                    // Add the union node to the parent holder of leaf.
+                    addChildToParentNode(listener, unionNode);
+                    // Push the popped entry back to the stack.
+                    listener.getParsedDataStack().push(leaf);
+                    break;
+                case LEAF_LIST_DATA:
+                    // Set the name of union same as leaf list.
+                    unionNode.setName(((YangLeafList) tmpData).getName() + UNION_CLASS_SUFFIX);
+                    // Pop the stack entry to obtain the parent YANG node.
+                    Parsable leafList = listener.getParsedDataStack().pop();
+                    // Add the union node to the parent holder of leaf.
+                    addChildToParentNode(listener, unionNode);
+                    // Push the popped entry back to the stack.
+                    listener.getParsedDataStack().push(leafList);
+                    break;
+                case UNION_DATA:
+                    YangUnion parentUnion = (YangUnion) tmpData;
+                    /*
+                     * In case parent of union is again a union, name of the
+                     * child union is parent union name suffixed with running
+                     * integer number, this is done because under union there
+                     * could be multiple child union types.
+                     */
+                    unionNode.setName(parentUnion.getName() + UNION_CLASS_SUFFIX + parentUnion.getChildUnionNumber());
+                    // Increment the running number.
+                    parentUnion.setChildUnionNumber(parentUnion.getChildUnionNumber() + 1);
+                    // Add union as a child to parent union.
+                    addChildToParentNode(listener, unionNode);
+                    break;
+                case TYPEDEF_DATA:
+                    YangTypeDef typeDef = (YangTypeDef) tmpData;
+                    // Set the name of union same as typedef name.
+                    unionNode.setName(typeDef.getName() + UNION_CLASS_SUFFIX);
+                    // Add union as a child to parent type def.
+                    addChildToParentNode(listener, unionNode);
+                    break;
+                // TODO deviate.
+                default:
+                    throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, TYPE_DATA,
+                            ((YangType<?>) typeData).getDataTypeName(), ENTRY));
+            }
+            listener.getParsedDataStack().push(typeData);
+            listener.getParsedDataStack().push(unionNode);
+        } else {
+            throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, UNION_DATA, "", ENTRY));
+        }
+    }
+
+    /**
+     * It is called when parser exits from grammar rule (union), it perform
+     * validations and update the data model tree.
+     *
+     * @param listener Listener's object
+     * @param ctx      context object of the grammar rule
+     */
+    public static void processUnionExit(TreeWalkListener listener,
+                                       GeneratedYangParser.UnionSpecificationContext ctx) {
+
+        // Check for stack to be non empty.
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, UNION_DATA, "", EXIT);
+
+        Parsable tmpUnionNode = listener.getParsedDataStack().peek();
+        if (tmpUnionNode instanceof YangUnion) {
+            YangUnion unionNode = (YangUnion) tmpUnionNode;
+            listener.getParsedDataStack().pop();
+
+            // Check for stack to be non empty.
+            checkStackIsNotEmpty(listener, MISSING_HOLDER, UNION_DATA, "", EXIT);
+
+            Parsable tmpNode = listener.getParsedDataStack().peek();
+            switch (tmpNode.getYangConstructType()) {
+                case TYPE_DATA: {
+                    YangType<YangUnion> typeNode = (YangType<YangUnion>) tmpNode;
+                    typeNode.setDataTypeExtendedInfo(unionNode);
+                    break;
+                }
+                default:
+                    throw new ParserException(
+                            constructListenerErrorMessage(INVALID_HOLDER, UNION_DATA, "", EXIT));
+            }
+        } else {
+            throw new ParserException(
+                    constructListenerErrorMessage(MISSING_CURRENT_HOLDER, UNION_DATA, "", EXIT));
+        }
+    }
+
+    /**
+     * Adds the union node to the parent holder.
+     *
+     * @param listener listener's object
+     * @param unionNode union node which needs to be added to parent
+     */
+    private static void addChildToParentNode(TreeWalkListener listener, YangUnion unionNode) {
+        if (!(listener.getParsedDataStack().peek() instanceof YangNode)) {
+            throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, UNION_DATA,
+                    "", ENTRY));
+        } else {
+            YangNode curNode = (YangNode) listener.getParsedDataStack().peek();
+            try {
+                curNode.addChild(unionNode);
+            } catch (DataModelException e) {
+                throw new ParserException(constructExtendedListenerErrorMessage(UNHANDLED_PARSED_DATA,
+                        UNION_DATA, "", ENTRY, e.getMessage()));
+            }
+        }
+    }
+}