content: /*
   * This library is part of OpenCms -
   * the Open Source Content Management System
   *
   * Copyright (c) Alkacon Software GmbH & Co. KG (https://www.alkacon.com)
   *
   * This library is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
   * Lesser General Public License for more details.
   *
   * For further information about Alkacon Software, please see the
   * company website: https://www.alkacon.com
   *
   * For further information about OpenCms, please see the
   * project website: https://www.opencms.org
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   */
  
  package org.opencms.gwt.client.util;
  
  import java.util.Collection;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Map;
  import java.util.Set;
  
  /**
   * A utility class with functions for dealing with maps.<p>
   *
   * @since 8.0.0
   */
  public final class CmsClientCollectionUtil {
  
      /**
       * Hide default constructor.<p>
       */
      private CmsClientCollectionUtil() {
  
          // do nothing
      }
  
      /**
       * Returns the intersection of two sets without modifying the original sets.<p>
       *
       * @param <A> the type of objects contained in the sets
       *
       * @param first the first set
       * @param second the second set
       *
       * @return the intersection of both sets
       */
      public static <A> Set<A> intersection(Set<A> first, Set<A> second) {
  
          HashSet<A> result = new HashSet<A>(first);
          result.retainAll(second);
          return result;
      }
  
      /**
       * Checks whether a collection is empty or null.<p>
       *
       * @param collection a collection
       * @return true if <code>collection</code> is <code>null</code> or empty.
       */
      public static boolean isEmptyOrNull(Collection<?> collection) {
  
          return (collection == null) || collection.isEmpty();
      }
  
      /**
       * Parses properties from a string and returns them in a map.<p>
       *
       * @param text the text containing the properties
       * @return the map with the parsed properties
       */
      public static Map<String, String> parseProperties(String text) {
  
          String[] lines = text.split("\n");
          Map<String, String> result = new HashMap<String, String>();
          for (String line : lines) {
              line = line.replaceFirst("^ +", "");
              line = line.replaceAll("\r", "");
              if (line.startsWith("#")) {
                  continue;
              }
              int eqPos = line.indexOf('=');
              if (eqPos > 0) {
                  String key = line.substring(0, eqPos);
                  String value = line.substring(eqPos + 1);
                  result.put(key, value);
              }
          }
          return result;
      }
  
      /**
       * Returns a new map with all entries of the input map except those which have a value of null.<p>
       *
       * @param <A> the key type of the map
       * @param <B> the value type of the map
       * @param map the input map
       *
       * @return a map with all null entries removed
       */
      public static <A, B> Map<A, B> removeNullEntries(Map<A, B> map) {
  
          HashMap<A, B> result = new HashMap<A, B>();
  
          for (Map.Entry<A, B> entry : map.entrySet()) {
              if (entry.getValue() != null) {
                  result.put(entry.getKey(), entry.getValue());
              }
          }
          return result;
      }
  
      /**
       * Copies entries from one map to another and deletes those entries in the target map for which
       * the value in the source map is null.<p>
       *
       * @param <A> the key type of the map
       * @param <B> the value type of the map
       * @param source the source map
       * @param target the target map
       */
      public static <A, B> void updateMapAndRemoveNulls(Map<A, B> source, Map<A, B> target) {
  
          assert source != target;
          for (Map.Entry<A, B> entry : source.entrySet()) {
              A key = entry.getKey();
              B value = entry.getValue();
              if (value != null) {
                  target.put(key, value);
              } else {
                  target.remove(key);
              }
          }
      }
  }
  