[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/NamespaceListener.java b/utils/yangutils/plugin/src/main/java/org/onosproject/yangutils/parser/impl/listeners/NamespaceListener.java
new file mode 100644
index 0000000..f32a4ed
--- /dev/null
+++ b/utils/yangutils/plugin/src/main/java/org/onosproject/yangutils/parser/impl/listeners/NamespaceListener.java
@@ -0,0 +1,120 @@
+/*
+ * 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;
+
+import java.net.URI;
+
+import org.onosproject.yangutils.datamodel.YangModule;
+import org.onosproject.yangutils.datamodel.YangNameSpace;
+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.YangConstructType.NAMESPACE_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
+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_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
+
+/*
+ * Reference: RFC6020 and YANG ANTLR Grammar
+ *
+ * ABNF grammar as per RFC6020
+ * module-header-stmts = ;; these stmts can appear in any order
+ *                       [yang-version-stmt stmtsep]
+ *                        namespace-stmt stmtsep
+ *                        prefix-stmt stmtsep
+ *
+ * namespace-stmt      = namespace-keyword sep uri-str optsep stmtend
+ *
+ * ANTLR grammar rule
+ * module_header_statement : yang_version_stmt? namespace_stmt prefix_stmt
+ *                         | yang_version_stmt? prefix_stmt namespace_stmt
+ *                         | namespace_stmt yang_version_stmt? prefix_stmt
+ *                         | namespace_stmt prefix_stmt yang_version_stmt?
+ *                         | prefix_stmt namespace_stmt yang_version_stmt?
+ *                         | prefix_stmt yang_version_stmt? namespace_stmt
+ *                         ;
+ * namespace_stmt : NAMESPACE_KEYWORD string STMTEND;
+ */
+
+/**
+ * Represents listener based call back function corresponding to the "namespace"
+ * rule defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
+ */
+public final class NamespaceListener {
+
+    /**
+     * Creates a new namespace listener.
+     */
+    private NamespaceListener() {
+    }
+
+    /**
+     * It is called when parser receives an input matching the grammar rule
+     * (namespace), perform validations and update the data model tree.
+     *
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
+     */
+    public static void processNamespaceEntry(TreeWalkListener listener,
+            GeneratedYangParser.NamespaceStatementContext ctx) {
+
+        // Check for stack to be non empty.
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, NAMESPACE_DATA, ctx.string().getText(), ENTRY);
+
+        if (!validateUriValue(ctx.string().getText())) {
+            ParserException parserException = new ParserException("YANG file error: Invalid namespace URI");
+            parserException.setLine(ctx.string().STRING(0).getSymbol().getLine());
+            parserException.setCharPosition(ctx.string().STRING(0).getSymbol().getCharPositionInLine());
+            throw parserException;
+        }
+
+        // Obtain the node of the stack.
+        Parsable tmpNode = listener.getParsedDataStack().peek();
+        switch (tmpNode.getYangConstructType()) {
+            case MODULE_DATA: {
+                YangModule module = (YangModule) tmpNode;
+                YangNameSpace uri = new YangNameSpace();
+                uri.setUri(ctx.string().getText());
+                module.setNameSpace(uri);
+                break;
+            }
+            default:
+                throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, NAMESPACE_DATA,
+                        ctx.string().getText(), ENTRY));
+        }
+    }
+
+    /**
+     * Validate input URI.
+     *
+     * @param uri input namespace URI
+     * @return validation result
+     */
+    private static boolean validateUriValue(String uri) {
+        uri = uri.replace("\"", "");
+        try {
+            URI.create(uri);
+        } catch (Exception e1) {
+            return false;
+        }
+        return true;
+    }
+}