| /** |
| * 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.sentry.core.common.utils; |
| |
| import static org.apache.sentry.core.common.utils.SentryConstants.NULL_COL; |
| |
| import com.google.common.base.Strings; |
| import java.util.ArrayList; |
| import java.util.List; |
| |
| /** |
| * Classes to hold general utility functions that could be used across Sentry |
| */ |
| public final class SentryUtils { |
| |
| /** |
| * Given a list of sorted numbers, return the string that prints in the collapsed format. |
| * <p> |
| * e.g: |
| * <li> Input: [1, 2, 3, 5, 7] </li> |
| * <li> Output: "[1-3, 5, 7]" </li> |
| * </p> |
| * @param nums List of sorted numbers |
| * @return Collapsed string representation of the numbers |
| */ |
| public static String collapseNumsToString(List<Long> nums) { |
| List<String> collapsedStrings = new ArrayList<>(); |
| |
| // Using startIndex, movingIndex we maintain a variable size moving window across the Array where at any |
| // point in time, startIndex points to the beginning of a continuous sequence, movingIndex points to the last known |
| // sequential number of that particular subsequence and currentGroupSize captures the size of the subsequence. |
| int startIndex = 0; |
| int movingIndex = 0; |
| int currentGroupSize = 0; |
| int listSize = nums.size(); |
| |
| // Using the startIndex as terminating condition to capture the last sequence(before the list terminates) |
| // within the loop itself to avoid code duplication. |
| while (startIndex < listSize) { |
| if (movingIndex == listSize || |
| nums.get(startIndex) + currentGroupSize != nums.get(movingIndex)) { |
| long startID = nums.get(startIndex); |
| long endID = nums.get(movingIndex - 1); |
| if (startID == endID) { |
| collapsedStrings.add(String.format("%d", startID)); |
| } else if (endID - startID == 1) { |
| collapsedStrings.add(String.format("%d", startID)); |
| collapsedStrings.add(String.format("%d", endID)); |
| } else { |
| collapsedStrings.add(String.format("%d-%d", startID, endID)); |
| } |
| |
| startIndex = movingIndex; |
| currentGroupSize = 0; |
| continue; |
| } |
| |
| movingIndex++; |
| currentGroupSize++; |
| } |
| |
| return collapsedStrings.toString(); |
| } |
| |
| /** |
| * Function to check if a string is null, empty or @NULL_COLL specifier |
| * @param s string input, and can be null. |
| * @return True if the input string represents a NULL string - when it is null, empty or equals @NULL_COL |
| */ |
| public static boolean isNULL(String s) { |
| return Strings.isNullOrEmpty(s) || s.equals(NULL_COL); |
| } |
| } |