de.zib.gndms.stuff.misc.LanguageAlgebra.java Source code

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Here is the source code for de.zib.gndms.stuff.misc.LanguageAlgebra.java

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/*
 * Copyright 2008-2012 Zuse Institute Berlin (ZIB)
 * 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 de.zib.gndms.stuff.misc;

import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;

import java.util.Collection;
import java.util.Map;

/**
 * @date: 19.06.12
 * @time: 11:22
 * @author: Jrg Bachmann
 * @email: bachmann@zib.de
 */
public class LanguageAlgebra {
    /**
     * Get the largest prefix shared by a set of words.
     *
     * @param words The set of words to get the largest prefix from.
     * @return The greatest common prefix.
     */
    public static String getGreatestCommonPrefix(Collection<String> words) {
        if (null == words || 0 == words.size()) {
            throw new IllegalArgumentException(
                    "Cannot build the greatest common prefix out of an empty set of words!");
        }

        String commonprefix = words.iterator().next();

        for (String w : words) {
            commonprefix = getCommonPrefix(commonprefix, w);
        }

        return commonprefix;
    }

    /**
     * Get the greatest common prefix of two strings.
     *
     * @param a A string.
     * @param b A string.
     * @return The greatest common prefix of both strings.
     */
    public static String getCommonPrefix(String a, String b) {
        for (int i = 1; i < b.length(); ++i) {
            if (a.length() < i) {
                return a;
            }

            if (!a.substring(i - 1, i).equals(b.substring(i - 1, i))) {
                return a.substring(0, i - 1);
            }
        }

        return b;
    }

    public static MultiValueMap<String, String> getMultiValueMapFromMap(Map<String, String> map) {
        MultiValueMap<String, String> multiMap = new LinkedMultiValueMap<String, String>(map.size());

        for (String k : map.keySet()) {
            multiMap.add(k, map.get(k));
        }

        return multiMap;
    }
}