[ONOS-3878] parse tree traversal using listener framework

Change-Id: I53c18593281399f83a2b9bf9df2f7261c69c00b2

+/*
+ * 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.
+ */
+
+/**
+ * Provide call back functions for listeners based tree walk.
+ */
+package org.onosproject.yangutils.parser.impl.listeners;
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+/*
+ * 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.parserutils;
+
+/**
+ * Error information while doing a listener's based walk is maintained in it.
+ */
+public class ListenerError {
+
+    // Maintains the state of Exception.
+    private boolean errorFlag = false;
+
+    // Maintains the reason of Exception.
+    private String errorMsg;
+
+    /**
+     * Returns error flag.
+     *
+     * @return error flag.
+     */
+    public boolean isErrorFlag() {
+        return errorFlag;
+    }
+
+    /**
+     * Returns error message.
+     *
+     * @return error msg.
+     */
+    public String getErrorMsg() {
+        return errorMsg;
+    }
+
+    /**
+     * Set error flag.
+     *
+     * @param errorFlag error existence flag
+     */
+    public void setErrorFlag(boolean errorFlag) {
+        this.errorFlag = errorFlag;
+    }
+
+    /**
+     * Set error message.
+     *
+      * @param errorMsg reason for error.
+     */
+    public void setErrorMsg(String errorMsg) {
+        this.errorMsg = errorMsg;
+    }
+}
\ 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.
+ */
+
+/**
+ * Provide common utils for parser implementation.
+ */
+package org.onosproject.yangutils.parser.impl.parserutils;
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