SlugBuilder.java

//
// Copyright 2009 Robin Komiwes, Bruno Verachten, Christophe Cordenier
//
// 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.wooki.services.utils;

import java.util.Locale;
import java.util.regex.Pattern;

/**
 * Contains utility method for string manipulation.
 * 
 * @author ccordenier
 */
public class SlugBuilder
{

    private static final String PLAIN_ASCII = "AaEeIiOoUu" // grave
            + "AaEeIiOoUuYy" // acute
            + "AaEeIiOoUuYy" // circumflex
            + "AaOoNn" // tilde
            + "AaEeIiOoUuYy" // umlaut
            + "Aa" // ring
            + "Cc" // cedilla
            + "OoUu" // double acute
    ;

    private static final String UNICODE = "\u00C0\u00E0\u00C8\u00E8\u00CC\u00EC\u00D2\u00F2\u00D9\u00F9"
            + "\u00C1\u00E1\u00C9\u00E9\u00CD\u00ED\u00D3\u00F3\u00DA\u00FA\u00DD\u00FD"
            + "\u00C2\u00E2\u00CA\u00EA\u00CE\u00EE\u00D4\u00F4\u00DB\u00FB\u0176\u0177"
            + "\u00C3\u00E3\u00D5\u00F5\u00D1\u00F1"
            + "\u00C4\u00E4\u00CB\u00EB\u00CF\u00EF\u00D6\u00F6\u00DC\u00FC\u0178\u00FF"
            + "\u00C5\u00E5" + "\u00C7\u00E7" + "\u0150\u0151\u0170\u0171";

    private static final Pattern NONLATIN = Pattern.compile("[^\\w-]");

    private static final Pattern WHITESPACE = Pattern.compile("[\\s]");

    /**
     * Remove whitespace and normalize title string and lower case the result.
     * 
     * @param title
     * @return
     */
    public static String buildSlug(String title)
    {
        if (title == null) { throw new IllegalArgumentException(
                "Title cannot be null to get a slug."); }
        String nowhitespace = WHITESPACE.matcher(title).replaceAll("-");
        String normalized = convertNonAscii(nowhitespace);
        String slug = NONLATIN.matcher(normalized).replaceAll("");
        return slug.toLowerCase(Locale.ENGLISH);
    }

    /**
     * Normalize string.
     * 
     * @param s
     * @return
     */
    public static String convertNonAscii(String s)
    {
        if (s == null) return null;
        StringBuilder sb = new StringBuilder();
        int n = s.length();
        for (int i = 0; i < n; i++)
        {
            char c = s.charAt(i);
            int pos = UNICODE.indexOf(c);
            if (pos > -1)
            {
                sb.append(PLAIN_ASCII.charAt(pos));
            }
            else
            {
                sb.append(c);
            }
        }
        return sb.toString();
    }

}