| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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.apache.drill.exec.store.xml; |
| |
| import org.apache.drill.shaded.guava.com.google.common.base.Strings; |
| import javax.xml.stream.XMLStreamConstants; |
| import javax.xml.stream.events.XMLEvent; |
| |
| public class XMLUtils { |
| |
| /** |
| * Empty events are not helpful so this method checks to see if the event consists solely of whitespace |
| * or newline characters. Unfortunately, newlines and other extraneous characters are treated as new elements, so |
| * this function wraps a lot of those checks in one function. |
| * @param event The input XMLEvent |
| * @return True if the XMLEvent is only whitespace, false if not. |
| */ |
| public static boolean isEmptyWhiteSpace(XMLEvent event) { |
| if (event.getEventType() == XMLStreamConstants.COMMENT) { |
| return true; |
| } else if (event.getEventType() != XMLStreamConstants.CHARACTERS) { |
| return false; |
| } |
| |
| String value = event.asCharacters().getData(); |
| if (Strings.isNullOrEmpty(value.trim())) { |
| return true; |
| } else { |
| return event.asCharacters().isIgnorableWhiteSpace(); |
| } |
| } |
| |
| /** |
| * Identifies XML events that may be populated but are not useful for extracting data. |
| * @param event The XMLEvent in question |
| * @return True if the event is useful, false if not |
| */ |
| public static boolean isNotCruft(XMLEvent event) { |
| int eventType = event.getEventType(); |
| return eventType == XMLStreamConstants.CHARACTERS || |
| eventType == XMLStreamConstants.START_ELEMENT || |
| eventType == XMLStreamConstants.END_ELEMENT; |
| } |
| |
| /** |
| * Generates a nested field name by combining a field prefix to the current field name. |
| * @param prefix The prefix to be added to the field name. |
| * @param field The field name |
| * @return the prefix, followed by an underscore and the fieldname. |
| */ |
| public static String addField(String prefix, String field) { |
| if (Strings.isNullOrEmpty(prefix)) { |
| return field; |
| } |
| return prefix + "_" + field; |
| } |
| |
| /** |
| * Returns the field name from nested field names. |
| * @param fieldName The nested field name |
| * @return The field name |
| */ |
| public static String removeField(String prefix, String fieldName) { |
| if (fieldName == null) { |
| return ""; |
| } |
| |
| int index = prefix.lastIndexOf(fieldName); |
| if (index <= 0) { |
| return ""; |
| } else { |
| return prefix.substring(0, index - 1); |
| } |
| } |
| |
| /** |
| * Returns true if a given XMLEvent has attributes, false if not. Since only |
| * start elements can by definition have attributes, returns false if the event |
| * is not a start element. |
| * @param event The XMLEvent in question |
| * @return True if the XMLEvent has attributes, false if not. |
| */ |
| public static boolean hasAttributes(XMLEvent event) { |
| if (! event.isStartElement()) { |
| return false; |
| } else { |
| return event.asStartElement().getAttributes().hasNext(); |
| } |
| } |
| } |