[ONOS-3882, 3883, 3892]Implement Yang container, list, leaf, leaf-list parsing

Change-Id: I39039c91385fe0d530d037350ef7833c2459514d

+/*
+ * 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.parser.impl.listeners;
+
+import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+
+/*
+ * Reference: RFC6020 and YANG ANTLR Grammar
+ *
+ * ABNF grammar as per RFC6020
+ * config-stmt         = config-keyword sep
+ *                       config-arg-str stmtend
+ * config-arg-str      = < a string that matches the rule
+ *                         config-arg >
+ * config-arg          = true-keyword / false-keyword
+ *
+ * ANTLR grammar rule
+ * configStatement : CONFIG_KEYWORD (TRUE_KEYWORD | FALSE_KEYWORD) STMTEND;
+ */
+
+/**
+ * Implements listener based call back function corresponding to the "config"
+ * rule defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
+ */
+public final class ConfigListener {
+
+    /**
+     * Creates a new config listener.
+     */
+    private ConfigListener() {
+    }
+
+    /**
+     * It is called when parser receives an input matching the grammar
+     * rule (config), performs validation and updates the data model
+     * tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processConfigEntry(TreeWalkListener listener,
+                                             GeneratedYangParser.ConfigStatementContext ctx) {
+        // TODO method implementation
+    }
+
+    /**
+     * It is called when parser exits from grammar rule (config), it performs
+     * validation and updates the data model tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processConfigExit(TreeWalkListener listener,
+                                            GeneratedYangParser.ConfigStatementContext ctx) {
+        // TODO method implementation
+    }
+}
\ No newline at end of file

+/*
+ * 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.parser.impl.listeners;
+
+import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+
+/*
+ * Reference: RFC6020 and YANG ANTLR Grammar
+ *
+ * ABNF grammar as per RFC6020
+ *  container-stmt      = container-keyword sep identifier-arg-str optsep
+ *                        (";" /
+ *                         "{" stmtsep
+ *                             ;; these stmts can appear in any order
+ *                             [when-stmt stmtsep]
+ *                             *(if-feature-stmt stmtsep)
+ *                             *(must-stmt stmtsep)
+ *                             [presence-stmt stmtsep]
+ *                             [config-stmt stmtsep]
+ *                             [status-stmt stmtsep]
+ *                             [description-stmt stmtsep]
+ *                             [reference-stmt stmtsep]
+ *                             *((typedef-stmt /
+ *                                grouping-stmt) stmtsep)
+ *                             *(data-def-stmt stmtsep)
+ *                         "}")
+ *
+ * ANTLR grammar rule
+ *  containerStatement : CONTAINER_KEYWORD IDENTIFIER
+ *                   (STMTEND | LEFT_CURLY_BRACE (whenStatement | ifFeatureStatement | mustStatement |
+ *                   presenceStatement | configStatement | statusStatement | descriptionStatement |
+ *                   referenceStatement | typedefStatement | groupingStatement
+ *                    | dataDefStatement)* RIGHT_CURLY_BRACE);
+ */
+
+/**
+ * Implements listener based call back function corresponding to the "container"
+ * rule defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
+ */
+public final class ContainerListener {
+
+    /**
+     * Creates a new container listener.
+     */
+    private ContainerListener() {
+    }
+
+    /**
+     * It is called when parser receives an input matching the grammar
+     * rule (container), performs validation and updates the data model
+     * tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processContainerEntry(TreeWalkListener listener,
+                                             GeneratedYangParser.ContainerStatementContext ctx) {
+        // TODO method implementation
+    }
+
+    /**
+     * It is called when parser exits from grammar rule (container), 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 processContainerExit(TreeWalkListener listener,
+                                            GeneratedYangParser.ContainerStatementContext ctx) {
+        //TODO method implementation
+    }
+}

+/*
+ * 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.parser.impl.listeners;
+
+import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+
+/*
+ * Reference: RFC6020 and YANG ANTLR Grammar
+ *
+ * ABNF grammar as per RFC6020
+ * description-stmt    = description-keyword sep string optsep stmtend
+ *
+ * ANTLR grammar rule
+ * descriptionStatement : DESCRIPTION_KEYWORD string STMTEND;
+ */
+
+/**
+ * Implements listener based call back function corresponding to the "description"
+ * rule defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
+ */
+public final class DescriptionListener {
+
+    /**
+     * Creates a new description listener.
+     */
+    private DescriptionListener() {
+    }
+
+    /**
+     * It is called when parser receives an input matching the grammar
+     * rule (description), perform validations and updates the data model
+     * tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processDescriptionEntry(TreeWalkListener listener,
+                                             GeneratedYangParser.DescriptionStatementContext ctx) {
+        // TODO method implementation
+    }
+
+    /**
+     * It is called when parser exits from grammar rule (description), 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 processDescriptionExit(TreeWalkListener listener,
+                                            GeneratedYangParser.DescriptionStatementContext ctx) {
+        // TODO method implementation
+    }
+}
\ No newline at end of file

+/*
+ * 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.parser.impl.listeners;
+
+import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+
+/*
+ * Reference: RFC6020 and YANG ANTLR Grammar
+ *
+ * ABNF grammar as per RFC6020
+ * key-stmt            = key-keyword sep key-arg-str stmtend
+ *
+ * ANTLR grammar rule
+ * keyStatement : KEY_KEYWORD string STMTEND;
+ */
+
+/**
+ * Implements listener based call back function corresponding to the "key"
+ * rule defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
+ */
+public final class KeyListener {
+
+    /**
+     * Creates a new key listener.
+     */
+    private KeyListener() {
+    }
+
+    /**
+     * It is called when parser receives an input matching the grammar
+     * rule (key), perform validations and updates the data model
+     * tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processKeyEntry(TreeWalkListener listener,
+                                         GeneratedYangParser.KeyStatementContext ctx) {
+        // TODO method implementation
+    }
+
+    /**
+     * It is called when parser exits from grammar rule (key), 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 processKeyExit(TreeWalkListener listener,
+                                        GeneratedYangParser.KeyStatementContext ctx) {
+        // TODO method implementation
+    }
+}
\ No newline at end of file

+/*
+ * 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.parser.impl.listeners;
+
+import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+
+/*
+ * Reference: RFC6020 and YANG ANTLR Grammar
+ *
+ * ABNF grammar as per RFC6020
+ *  leaf-list-stmt      = leaf-list-keyword sep identifier-arg-str optsep
+ *                        "{" stmtsep
+ *                            ;; these stmts can appear in any order
+ *                            [when-stmt stmtsep]
+ *                            *(if-feature-stmt stmtsep)
+ *                            type-stmt stmtsep
+ *                            [units-stmt stmtsep]
+ *                            *(must-stmt stmtsep)
+ *                            [config-stmt stmtsep]
+ *                            [min-elements-stmt stmtsep]
+ *                            [max-elements-stmt stmtsep]
+ *                            [ordered-by-stmt stmtsep]
+ *                            [status-stmt stmtsep]
+ *                            [description-stmt stmtsep]
+ *                            [reference-stmt stmtsep]
+ *                         "}"
+ *
+ * ANTLR grammar rule
+ *  leafListStatement : LEAF_LIST_KEYWORD IDENTIFIER LEFT_CURLY_BRACE (whenStatement | ifFeatureStatement |
+ *  typeStatement | unitsStatement | mustStatement | configStatement | minElementsStatement | maxElementsStatement |
+ *  orderedByStatement | statusStatement | descriptionStatement | referenceStatement)* RIGHT_CURLY_BRACE;
+ */
+
+/**
+ * Implements listener based call back function corresponding to the "leaf-list"
+ * rule defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
+ */
+public final class LeafListListener {
+
+    /**
+     * Creates a new leaf list listener.
+     */
+    private LeafListListener() {
+    }
+
+    /**
+     * It is called when parser receives an input matching the grammar
+     * rule (leaf-list), performs validation and updates the data model
+     * tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processLeafListEntry(TreeWalkListener listener,
+                                            GeneratedYangParser.LeafListStatementContext ctx) {
+        // TODO method implementation
+    }
+
+    /**
+     * It is called when parser exits from grammar rule (leaf-list), it performs
+     * validation and updates the data model tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processLeafListExit(TreeWalkListener listener,
+                                           GeneratedYangParser.LeafListStatementContext ctx) {
+        // TODO method implementation
+    }
+}
\ No newline at end of file

+/*
+ * 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.
+ */
+
+/**
+ * Implements listener based call back function corresponding to the "leaf"
+ * rule defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
+ */
+package org.onosproject.yangutils.parser.impl.listeners;
+
+import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+
+/*
+ * Reference: RFC6020 and YANG ANTLR Grammar
+ *
+ * ABNF grammar as per RFC6020
+ *  leaf-stmt           = leaf-keyword sep identifier-arg-str optsep
+ *                        "{" stmtsep
+ *                            ;; these stmts can appear in any order
+ *                            [when-stmt stmtsep]
+ *                            *(if-feature-stmt stmtsep)
+ *                            type-stmt stmtsep
+ *                            [units-stmt stmtsep]
+ *                            *(must-stmt stmtsep)
+ *                            [default-stmt stmtsep]
+ *                            [config-stmt stmtsep]
+ *                            [mandatory-stmt stmtsep]
+ *                            [status-stmt stmtsep]
+ *                            [description-stmt stmtsep]
+ *                            [reference-stmt stmtsep]
+ *                         "}"
+ *
+ * ANTLR grammar rule
+ *  leafStatement : LEAF_KEYWORD IDENTIFIER LEFT_CURLY_BRACE (whenStatement | ifFeatureStatement | typeStatement |
+ *  unitsStatement | mustStatement | defaultStatement | configStatement | mandatoryStatement | statusStatement  |
+ *  descriptionStatement | referenceStatement)* RIGHT_CURLY_BRACE;
+ */
+
+/**
+ * Implements listener based call back function corresponding to the "leaf"
+ * rule defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
+ */
+public final class LeafListener {
+
+    /**
+     * Creates a new leaf listener.
+     */
+    private LeafListener() {
+    }
+
+    /**
+     * It is called when parser receives an input matching the grammar
+     * rule (leaf), performs validation and updates the data model
+     * tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processLeafEntry(TreeWalkListener listener,
+                                        GeneratedYangParser.LeafStatementContext ctx) {
+        // TODO method implementation
+    }
+
+    /**
+     * It is called when parser exits from grammar rule (leaf), performs
+     * validation and updates the data model tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processLeafExit(TreeWalkListener listener,
+                                       GeneratedYangParser.LeafStatementContext ctx) {
+        // TODO method implementation
+    }
+}
\ No newline at end of file

+/*
+ * 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.parser.impl.listeners;
+
+import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+
+/*
+ * Reference: RFC6020 and YANG ANTLR Grammar
+ *
+ * ABNF grammar as per RFC6020
+ *  list-stmt           = list-keyword sep identifier-arg-str optsep
+ *                        "{" stmtsep
+ *                            ;; these stmts can appear in any order
+ *                            [when-stmt stmtsep]
+ *                            *(if-feature-stmt stmtsep)
+ *                            *(must-stmt stmtsep)
+ *                            [key-stmt stmtsep]
+ *                            *(unique-stmt stmtsep)
+ *                            [config-stmt stmtsep]
+ *                            [min-elements-stmt stmtsep]
+ *                            [max-elements-stmt stmtsep]
+ *                            [ordered-by-stmt stmtsep]
+ *                            [status-stmt stmtsep]
+ *                            [description-stmt stmtsep]
+ *                            [reference-stmt stmtsep]
+ *                            *((typedef-stmt /
+ *                               grouping-stmt) stmtsep)
+ *                            1*(data-def-stmt stmtsep)
+ *                         "}"
+ *
+ * ANTLR grammar rule
+ *  listStatement : LIST_KEYWORD IDENTIFIER LEFT_CURLY_BRACE (whenStatement | ifFeatureStatement | mustStatement |
+ *  keyStatement | uniqueStatement | configStatement | minElementsStatement | maxElementsStatement |
+ *  orderedByStatement | statusStatement | descriptionStatement | referenceStatement | typedefStatement |
+ *  groupingStatement| dataDefStatement)* RIGHT_CURLY_BRACE;
+ */
+
+/**
+ * Implements listener based call back function corresponding to the "list"
+ * rule defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
+ */
+public final class ListListener {
+
+    /**
+     * Creates a new list listener.
+     */
+    private ListListener() {
+    }
+
+    /**
+     * It is called when parser receives an input matching the grammar
+     * rule (list), performs validation and updates the data model
+     * tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processListEntry(TreeWalkListener listener,
+                                             GeneratedYangParser.ListStatementContext ctx) {
+        // TODO
+    }
+
+    /**
+     * It is called when parser exits from grammar rule (list), it performs
+     * validation and updates the data model tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processListExit(TreeWalkListener listener,
+                                            GeneratedYangParser.ListStatementContext ctx) {
+        // TODO
+    }
+}
\ No newline at end of file

+/*
+ * 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.parser.impl.listeners;
+
+import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+
+/*
+ * Reference: RFC6020 and YANG ANTLR Grammar
+ *
+ * ABNF grammar as per RFC6020
+ *  mandatory-stmt      = mandatory-keyword sep
+ *                        mandatory-arg-str stmtend
+ *
+ *  mandatory-arg-str   = < a string that matches the rule
+ *                          mandatory-arg >
+ *
+ *  mandatory-arg       = true-keyword / false-keyword
+ *
+ * ANTLR grammar rule
+ *  mandatoryStatement : MANDATORY_KEYWORD (TRUE_KEYWORD | FALSE_KEYWORD) STMTEND;
+ */
+
+/**
+ * Implements listener based call back function corresponding to the "mandatory"
+ * rule defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
+ */
+public final class MandatoryListener {
+
+    /**
+     * Creates a new mandatory listener.
+     */
+    private MandatoryListener() {
+    }
+
+    /**
+     * It is called when parser receives an input matching the grammar
+     * rule (mandatory), performs validation and updates the data model
+     * tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processMandatoryEntry(TreeWalkListener listener,
+                                          GeneratedYangParser.MandatoryStatementContext ctx) {
+        // TODO method implementation
+    }
+
+    /**
+     * It is called when parser exits from grammar rule (mandatory), it performs
+     * validation and updates the data model tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processMandatoryExit(TreeWalkListener listener,
+                                         GeneratedYangParser.MandatoryStatementContext ctx) {
+        // TODO method implementation
+    }
+}
\ No newline at end of file

+/*
+ * 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.parser.impl.listeners;
+
+import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+
+/*
+ * Reference: RFC6020 and YANG ANTLR Grammar
+ *
+ * ABNF grammar as per RFC6020
+ *  max-elements-stmt   = max-elements-keyword sep
+ *                        max-value-arg-str stmtend
+ *  max-value-arg-str   = < a string that matches the rule
+ *                          max-value-arg >
+ *
+ * ANTLR grammar rule
+ * maxElementsStatement :  MAX_ELEMENTS_KEYWORD maxValueArgument STMTEND;
+ */
+
+/**
+ * Implements listener based call back function corresponding to the "max-elements"
+ * rule defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
+ */
+public final class MaxElementsListener {
+
+    /**
+     * Creates a new max-elements listener.
+     */
+    private MaxElementsListener() {
+    }
+
+    /**
+     * It is called when parser receives an input matching the grammar
+     * rule (max-elements), performs validation and updates the data model
+     * tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processMaxElementsEntry(TreeWalkListener listener,
+                                             GeneratedYangParser.MaxElementsStatementContext ctx) {
+        // TODO method implementation
+    }
+
+    /**
+     * It is called when parser exits from grammar rule (max-elements), it performs
+     * validation and updates the data model tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processMaxElementsExit(TreeWalkListener listener,
+                                            GeneratedYangParser.MaxElementsStatementContext ctx) {
+        // TODO method implementation
+    }
+}
\ No newline at end of file

+/*
+ * 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.parser.impl.listeners;
+
+import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+
+/*
+ * Reference: RFC6020 and YANG ANTLR Grammar
+ *
+ * ABNF grammar as per RFC6020
+ *  min-elements-stmt   = min-elements-keyword sep
+ *                        min-value-arg-str stmtend
+ *  min-value-arg-str   = < a string that matches the rule
+ *                          min-value-arg >
+ *  min-value-arg       = non-negative-integer-value
+ *
+ * ANTLR grammar rule
+ * minElementsStatement : MIN_ELEMENTS_KEYWORD INTEGER STMTEND;
+ */
+
+/**
+ * Implements listener based call back function corresponding to the "min-elements"
+ * rule defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
+ */
+public final class MinElementsListener {
+
+    /**
+     * Creates a new min-elements listener.
+     */
+    private MinElementsListener() {
+    }
+
+    /**
+     * It is called when parser receives an input matching the grammar
+     * rule (min-elements), performs validation and updates the data model
+     * tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processMinElementsEntry(TreeWalkListener listener,
+                                               GeneratedYangParser.MinElementsStatementContext ctx) {
+        // TODO method implementation
+    }
+
+    /**
+     * It is called when parser exits from grammar rule (min-elements), it performs
+     * validation and updates the data model tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processMinElementsExit(TreeWalkListener listener,
+                                              GeneratedYangParser.MinElementsStatementContext ctx) {
+        // TODO method implementation
+    }
+}
\ No newline at end of file

+/*
+ * 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.parser.impl.listeners;
+
+import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+
+/*
+ * Reference: RFC6020 and YANG ANTLR Grammar
+ *
+ * ABNF grammar as per RFC6020
+ * presence-stmt       = presence-keyword sep string stmtend
+ *
+ * ANTLR grammar rule
+ * presenceStatement : PRESENCE_KEYWORD string STMTEND;
+ */
+
+/**
+ * Implements listener based call back function corresponding to the "presence"
+ * rule defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
+ */
+public final class PresenceListener {
+
+    /**
+     * Creates a new presence listener.
+     */
+    private PresenceListener() {
+    }
+
+    /**
+     * It is called when parser receives an input matching the grammar
+     * rule (presence), performs validation and updates the data model
+     * tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processPresenceEntry(TreeWalkListener listener,
+                                             GeneratedYangParser.PresenceStatementContext ctx) {
+        // TODO method implementation
+    }
+
+    /**
+     * It is called when parser exits from grammar rule (presence), it performs
+     * validation and updates the data model tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processPresenceExit(TreeWalkListener listener,
+                                            GeneratedYangParser.PresenceStatementContext ctx) {
+        // TODO method implementation
+    }
+}
\ No newline at end of file

+/*
+ * 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.parser.impl.listeners;
+
+import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+
+/*
+ * Reference: RFC6020 and YANG ANTLR Grammar
+ *
+ * ABNF grammar as per RFC6020
+ * reference-stmt      = reference-keyword sep string optsep stmtend
+ *
+ * ANTLR grammar rule
+ * referenceStatement : REFERENCE_KEYWORD string STMTEND;
+ */
+
+/**
+ * Implements listener based call back function corresponding to the "reference"
+ * rule defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
+ */
+public final class ReferenceListener {
+
+    /**
+     * Creates a new reference listener.
+     */
+    private ReferenceListener() {
+    }
+
+    /**
+     * It is called when parser receives an input matching the grammar
+     * rule (reference), performs validation and updates the data model
+     * tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processReferenceEntry(TreeWalkListener listener,
+                                             GeneratedYangParser.ReferenceStatementContext ctx) {
+        // TODO method implementation
+    }
+
+    /**
+     * It is called when parser exits from grammar rule (reference), it performs
+     * validation and updates the data model tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processReferenceExit(TreeWalkListener listener,
+                                            GeneratedYangParser.ReferenceStatementContext ctx) {
+        // TODO method implementation
+    }
+}
\ No newline at end of file

+/*
+ * 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.parser.impl.listeners;
+
+import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+
+/*
+ * Reference: RFC6020 and YANG ANTLR Grammar
+ *
+ * ABNF grammar as per RFC6020
+ *  status-stmt         = status-keyword sep status-arg-str stmtend
+ *  status-arg-str      = < a string that matches the rule
+ *                         status-arg >
+ *  status-arg          = current-keyword /
+ *                        obsolete-keyword /
+ *                        deprecated-keyword
+ *
+ * ANTLR grammar rule
+ * statusStatement : STATUS_KEYWORD (CURRENT_KEYWORD | OBSOLETE_KEYWORD | DEPRECATED_KEYWORD) STMTEND;
+ */
+
+/**
+ * Implements listener based call back function corresponding to the "status"
+ * rule defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
+ */
+public final class StatusListener {
+
+    /**
+     * Creates a new status listener.
+     */
+    private StatusListener() {
+    }
+
+    /**
+     * It is called when parser receives an input matching the grammar
+     * rule (status), performs validation and updates the data model
+     * tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processStatusEntry(TreeWalkListener listener,
+                                          GeneratedYangParser.StatusStatementContext ctx) {
+        // TODO method implementation
+    }
+
+    /**
+     * It is called when parser exits from grammar rule (status), it performs
+     * validation and updates the data model tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processStatusExit(TreeWalkListener listener,
+                                              GeneratedYangParser.StatusStatementContext ctx) {
+        // TODO method implementation
+    }
+}
\ No newline at end of file

+/*
+ * 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.parser.impl.listeners;
+
+import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+
+/*
+ * Reference: RFC6020 and YANG ANTLR Grammar
+ *
+ * ABNF grammar as per RFC6020
+ *  type-stmt           = type-keyword sep identifier-ref-arg-str optsep
+ *                        (";" /
+ *                         "{" stmtsep
+ *                            type-body-stmts
+ *                         "}")
+ *
+ * ANTLR grammar rule
+ * typeStatement : TYPE_KEYWORD string (STMTEND | LEFT_CURLY_BRACE typeBodyStatements RIGHT_CURLY_BRACE);
+ */
+
+/**
+ * Implements listener based call back function corresponding to the "type"
+ * rule defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
+ */
+public final class TypeListener {
+
+    /**
+     * Creates a new type listener.
+     */
+    private TypeListener() {
+    }
+
+    /**
+     * It is called when parser receives an input matching the grammar
+     * rule (type), performs validation and updates the data model
+     * tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processTypeEntry(TreeWalkListener listener,
+                                        GeneratedYangParser.TypeStatementContext ctx) {
+        // TODO method implementation
+    }
+
+    /**
+     * It is called when parser exits from grammar rule (type), it performs
+     * validation and updates the data model tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processTypeExit(TreeWalkListener listener,
+                                       GeneratedYangParser.TypeStatementContext ctx) {
+        // TODO method implementation
+    }
+}
\ No newline at end of file

+/*
+ * 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.parser.impl.listeners;
+
+import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+
+/*
+ * Reference: RFC6020 and YANG ANTLR Grammar
+ *
+ * ABNF grammar as per RFC6020
+ * units-stmt          = units-keyword sep string optsep stmtend
+ *
+ * ANTLR grammar rule
+ * unitsStatement : UNITS_KEYWORD string STMTEND;
+ */
+
+/**
+ * Implements listener based call back function corresponding to the "units"
+ * rule defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
+ */
+public final class UnitsListener {
+
+    /**
+     * Creates a new units listener.
+     */
+    private UnitsListener() {
+    }
+
+    /**
+     * It is called when parser receives an input matching the grammar
+     * rule (units), performs validation and updates the data model
+     * tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processUnitsEntry(TreeWalkListener listener,
+                                           GeneratedYangParser.UnitsStatementContext ctx) {
+        // TODO method implementation
+    }
+
+    /**
+     * It is called when parser exits from grammar rule (units), it performs
+     * validation and updates the data model tree.
+     *
+     * @param listener listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processUnitsExit(TreeWalkListener listener,
+                                          GeneratedYangParser.UnitsStatementContext ctx) {
+        // TODO method implementation
+    }
+}
\ No newline at end of file