CharSequenceComparator.java

/*
 * 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.
 */

package com.addthis.basis.chars;

import java.util.Comparator;

import com.google.common.annotations.Beta;

/**
 * Implements Comparator for CharSequence and returns lexicographic
 * ordering.
 */
@Beta
public class CharSequenceComparator implements Comparator<CharSequence> {

    public static final Comparator<CharSequence> INSTANCE = new CharSequenceComparator();

    @Override
    public int compare(CharSequence o1, CharSequence o2) {
        int o1Len = o1.length();
        int o2Len = o2.length();
        int minLength = Math.min(o1Len, o2Len);

        for (int i = 0; i< minLength; i++) {
            char o1Char = o1.charAt(i);
            char o2Char = o2.charAt(i);
            int charCompare = Character.compare(o1Char, o2Char);
            if (charCompare != 0) {
                return charCompare;
            }
        }

        // Cannot overflow because the lengths are bounded to the positive domain.
        //noinspection SubtractionInCompareTo
        return o1Len - o2Len;
    }
}