Comparator similar to String.CASE_INSENSITIVE_ORDER, but handles only ASCII characters
/*
* Copyright 2006-2007 The Scriptella Project Team.
*
* 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.
*/
import java.util.Comparator;
import java.util.Map;
import java.util.Properties;
import java.util.TreeMap;
/**
* Collections utility methods.
*
* @author Fyodor Kupolov
* @version 1.0
*/
public final class CollectionUtils {
private CollectionUtils() {//Singleton
}
/**
* Comparator similar to {@link String#CASE_INSENSITIVE_ORDER}, but
* handles only ASCII characters
*/
private static final Comparator<String> ASCII_CASE_INSENSITIVE_ORDER = new Comparator<String>() {
public int compare(String s1, String s2) {
int n1 = s1.length(), n2 = s2.length();
int n = n1 < n2 ? n1 : n2;
for (int i = 0; i < n; i++) {
char c1 = s1.charAt(i);
char c2 = s2.charAt(i);
if (c1 != c2) {
if (c1 >= 'A' && c1 <= 'Z') { //Fast lower case
c1 = (char) (c1 | 0x20);
}
if (c2 >= 'A' && c2 <= 'Z') {
c2 = (char) (c2 | 0x20);
}
if (c1 != c2) {
return c1 - c2;
}
}
}
return n1 - n2;
}
};
/**
* Create a map optimized for case insensitive search for keys.
* The case insensitive rules are simplified to ASCII chars for performance reasons.
*
* @return case insensitive map.
*/
public static <V> Map<String, V> newCaseInsensitiveAsciiMap() {
return new TreeMap<String, V>(ASCII_CASE_INSENSITIVE_ORDER);
}
/**
* Returns parameterized version of {@link Properties} the instance
* remains the same.
*
* @param properties properties to represent as a map.
*/
@SuppressWarnings("unchecked")
public static Map<String, String> asMap(Properties properties) {
return (Map) properties;
}
/**
* Converts specified map to {@link java.util.Properties}. The keys and String values
* are migrated unchnaged, other types of values are {@link Object#toString() converted to String}.
* @param map map to convert.
* @return converted map as Properties.
*/
public static Properties asProperties(Map<String, ?> map) {
Properties props = new Properties();
for (Map.Entry<String, ?> entry : map.entrySet()) {
Object v = entry.getValue();
if (v != null) {
props.put(entry.getKey(), v.toString());
}
}
return props;
}
}
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