LexicalComparatorImpl.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.lang.MathLib;
import javolution.util.function.Equality;
 
public class LexicalComparatorImpl implements Equality<CharSequence>,
        Serializable {
 
    private static final long serialVersionUID = 7904852144917623728L;
 
    @Override
    public int hashCodeOf(CharSequence csq) {
        if (csq == null)
            return 0;
        if (csq instanceof String) // Optimization.
            return csq.hashCode();
        int h = 0;
        for (int i = 0, n = csq.length(); i < n;) {
            h = 31 * h + 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) { // Optimization.
            if (csq2 instanceof String)
                return csq1.equals(csq2);
            return ((String) csq1).contentEquals(csq2);
        } else if (csq2 instanceof String) { return ((String) csq2)
                .contentEquals(csq1); }
 
        // None of the CharSequence is a String. 
        int n = csq1.length();
        if (csq2.length() != n)
            return false;
        for (int i = 0; i < n;) {
            if (csq1.charAt(i) != 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).compareTo((String) right);
        int i = 0;
        int n = MathLib.min(left.length(), right.length());
        while (n-- != 0) {
            char c1 = left.charAt(i);
            char c2 = right.charAt(i++);
            if (c1 != c2)
                return c1 - c2;
        }
        return left.length() - right.length();
    }
}