[ONOS-4798] Error Message implementation for YANG utils
Change-Id: Idb13e851258754773f8f447ace69a9393c7c1b3d
diff --git a/plugin/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ErrorMessageListener.java b/plugin/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ErrorMessageListener.java
new file mode 100644
index 0000000..b6722b5
--- /dev/null
+++ b/plugin/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ErrorMessageListener.java
@@ -0,0 +1,82 @@
+/*
+ * 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 org.onosproject.yangutils.datamodel.YangAppErrorHolder;
+import org.onosproject.yangutils.datamodel.YangAppErrorInfo;
+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.ERROR_MESSAGE_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.ListenerUtil.removeQuotesAndHandleConcat;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
+
+/*
+ * Reference: RFC6020 and YANG ANTLR Grammar
+ *
+ * ABNF grammar as per RFC6020
+ *
+ * error-message-stmt = error-message-keyword sep string stmtend
+ *
+ * ANTLR grammar rule
+ * errorMessageStatement : ERROR_MESSAGE_KEYWORD string STMTEND;
+ */
+
+/**
+ * Represents listener based call back function corresponding to the
+ * app error message defined in ANTLR grammar file for corresponding ABNF rule
+ * in RFC 6020.
+ */
+public final class ErrorMessageListener {
+
+ /**
+ * Creates a new must listener.
+ */
+ private ErrorMessageListener() {
+ }
+
+ /**
+ * Performs validations and updates the data model tree. It is called when parser
+ * receives an input matching the grammar rule (app error message).
+ *
+ * @param listener listener's object
+ * @param ctx context object of the grammar rule
+ */
+ public static void processErrorMessageEntry(TreeWalkListener listener,
+ GeneratedYangParser.ErrorMessageStatementContext ctx) {
+
+ // Check for stack to be non empty.
+ checkStackIsNotEmpty(listener, MISSING_HOLDER, ERROR_MESSAGE_DATA, ctx.string().getText(), ENTRY);
+ String errorMessage = removeQuotesAndHandleConcat(ctx.string().getText());
+
+ // Obtain the node of the stack.
+ Parsable tmpNode = listener.getParsedDataStack().peek();
+ if (tmpNode instanceof YangAppErrorHolder) {
+ YangAppErrorInfo yangAppErrorInfo = ((YangAppErrorHolder) tmpNode).getAppErrorInfo();
+ yangAppErrorInfo.setErrorMessage(errorMessage);
+ } else {
+ throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, ERROR_MESSAGE_DATA,
+ ctx.string().getText(), ENTRY));
+ }
+ }
+}
\ No newline at end of file