/*
* This library is part of OpenCms -
* the Open Source Content Management System
*
* Copyright (c) Alkacon Software GmbH (http://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: http://www.alkacon.com
*
* For further information about OpenCms, please see the
* project website: http://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 CmsCollectionUtil {
/**
* Hide default constructor.<p>
*/
private CmsCollectionUtil() {
// 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);
}
}
}
}