LexicalCaseInsensitiveComparatorImpl.java

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/*
 * Javolution - Java(TM) Solution for Real-Time and Embedded Systems
 * Copyright (C) 2012 - Javolution (http://javolution.org/)
 * All rights reserved.
 * 
 * Permission to use, copy, modify, and distribute this software is
 * freely granted, provided that this notice is preserved.
 */
package javolution.util.internal.comparator;
 
import java.io.Serializable;
 
import javolution.util.function.Equality;
 
public class LexicalCaseInsensitiveComparatorImpl implements
        Equality<CharSequence>, Serializable {
 
    private static final long serialVersionUID = -1046672327934410697L;
 
    @Override
    public int hashCodeOf(CharSequence csq) {
        if (csq == null)
            return 0;
        int h = 0;
        for (int i = 0, n = csq.length(); i < n;) {
            h = 31 * h + up(csq.charAt(i++));
        }
        return h;
    }
 
    @Override
    public boolean areEqual(CharSequence csq1, CharSequence csq2) {
        if (csq1 == csq2)
            return true;
        if ((csq1 == null) || (csq2 == null))
            return false;
        if ((csq1 instanceof String) && (csq2 instanceof String)) // Optimization.
            return ((String) csq1).equalsIgnoreCase((String) csq2);
        int n = csq1.length();
        if (csq2.length() != n)
            return false;
        for (int i = 0; i < n;) {
            if (up(csq1.charAt(i)) != up(csq2.charAt(i++)))
                return false;
        }
        return true;
    }
 
    @Override
    public int compare(CharSequence left, CharSequence right) {
        if (left == null)
            return -1;
        if (right == null)
            return 1;
        if ((left instanceof String) && (right instanceof String)) // Optimization.
            return ((String) left).compareToIgnoreCase((String) right);
        int i = 0;
        int n = Math.min(left.length(), right.length());
        while (n-- != 0) {
            char c1 = up(left.charAt(i));
            char c2 = up(right.charAt(i++));
            if (c1 != c2)
                return c1 - c2;
        }
        return left.length() - right.length();
    }
 
    // Converts to upper case.
    private static char up(char c) {
        return Character.toUpperCase(c);
    }
}