    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.codec.language;
    018
    019import java.util.Locale;
    020
    021import org.apache.commons.codec.EncoderException;
    022import org.apache.commons.codec.StringEncoder;
    023
    024/**
    025 * Match Rating Approach Phonetic Algorithm Developed by <CITE>Western Airlines</CITE> in 1977.
    026 * <p>
    027 * This class is immutable and thread-safe.
    028 * </p>
    029 *
    030 * @see <a href="https://en.wikipedia.org/wiki/Match_rating_approach">Wikipedia - Match Rating Approach</a>
    031 * @since 1.8
    032 */
    033public class MatchRatingApproachEncoder implements StringEncoder {
    034
    035    private static final String SPACE = " ";
    036
    037    private static final String EMPTY = "";
    038
    039    /**
    040     * The plain letter equivalent of the accented letters.
    041     */
    042    private static final String PLAIN_ASCII = "AaEeIiOoUu" + // grave
    043            "AaEeIiOoUuYy" + // acute
    044            "AaEeIiOoUuYy" + // circumflex
    045            "AaOoNn" + // tilde
    046            "AaEeIiOoUuYy" + // umlaut
    047            "Aa" + // ring
    048            "Cc" + // cedilla
    049            "OoUu"; // double acute
    050
    051    /**
    052     * Unicode characters corresponding to various accented letters. For example: \u00DA is U acute etc...
    053     */
    054    private static final String UNICODE = "\u00C0\u00E0\u00C8\u00E8\u00CC\u00EC\u00D2\u00F2\u00D9\u00F9" +
    055            "\u00C1\u00E1\u00C9\u00E9\u00CD\u00ED\u00D3\u00F3\u00DA\u00FA\u00DD\u00FD" +
    056            "\u00C2\u00E2\u00CA\u00EA\u00CE\u00EE\u00D4\u00F4\u00DB\u00FB\u0176\u0177" +
    057            "\u00C3\u00E3\u00D5\u00F5\u00D1\u00F1" +
    058            "\u00C4\u00E4\u00CB\u00EB\u00CF\u00EF\u00D6\u00F6\u00DC\u00FC\u0178\u00FF" +
    059            "\u00C5\u00E5" + "\u00C7\u00E7" + "\u0150\u0151\u0170\u0171";
    060
    061    private static final String[] DOUBLE_CONSONANT =
    062            { "BB", "CC", "DD", "FF", "GG", "HH", "JJ", "KK", "LL", "MM", "NN", "PP", "QQ", "RR", "SS",
    063                   "TT", "VV", "WW", "XX", "YY", "ZZ" };
    064
    065    /**
    066     * Cleans up a name: 1. Upper-cases everything 2. Removes some common punctuation 3. Removes accents 4. Removes any
    067     * spaces.
    068     *
    069     * <h2>API Usage</h2>
    070     * <p>
    071     * Consider this method private, it is package protected for unit testing only.
    072     * </p>
    073     *
    074     * @param name
    075     *            The name to be cleaned
    076     * @return The cleaned name
    077     */
    078    String cleanName(final String name) {
    079        String upperName = name.toUpperCase(Locale.ENGLISH);
    080
    081        final String[] charsToTrim = { "\\-", "[&]", "\\'", "\\.", "[\\,]" };
    082        for (final String str : charsToTrim) {
    083            upperName = upperName.replaceAll(str, EMPTY);
    084        }
    085
    086        upperName = removeAccents(upperName);
    087        return upperName.replaceAll("\\s+", EMPTY);
    088    }
    089
    090    /**
    091     * Encodes an Object using the Match Rating Approach algorithm. Method is here to satisfy the requirements of the
    092     * Encoder interface Throws an EncoderException if input object is not of type {@link String}.
    093     *
    094     * @param pObject
    095     *            Object to encode
    096     * @return An object (or type {@link String}) containing the Match Rating Approach code which corresponds to the
    097     *         String supplied.
    098     * @throws EncoderException
    099     *             if the parameter supplied is not of type {@link String}
    100     */
    101    @Override
    102    public final Object encode(final Object pObject) throws EncoderException {
    103        if (!(pObject instanceof String)) {
    104            throw new EncoderException(
    105                    "Parameter supplied to Match Rating Approach encoder is not of type java.lang.String");
    106        }
    107        return encode((String) pObject);
    108    }
    109
    110    /**
    111     * Encodes a String using the Match Rating Approach (MRA) algorithm.
    112     *
    113     * @param name
    114     *            String object to encode
    115     * @return The MRA code corresponding to the String supplied
    116     */
    117    @Override
    118    public final String encode(String name) {
    119        // Bulletproof for trivial input - NINO
    120        if (name == null || EMPTY.equalsIgnoreCase(name) || SPACE.equalsIgnoreCase(name) || name.length() == 1) {
    121            return EMPTY;
    122        }
    123
    124        // Preprocessing
    125        name = cleanName(name);
    126
    127        // Bulletproof if name becomes empty after cleanName(name)
    128        if (SPACE.equals(name) || name.isEmpty()) {
    129            return EMPTY;
    130        }
    131
    132        // BEGIN: Actual encoding part of the algorithm...
    133        // 1. Delete all vowels unless the vowel begins the word
    134        name = removeVowels(name);
    135
    136        // Bulletproof if name becomes empty after removeVowels(name)
    137        if (SPACE.equals(name) || name.isEmpty()) {
    138            return EMPTY;
    139        }
    140
    141        // 2. Remove second consonant from any double consonant
    142        name = removeDoubleConsonants(name);
    143
    144        return getFirst3Last3(name);
    145    }
    146
    147    /**
    148     * Gets the first and last 3 letters of a name (if &gt; 6 characters) Else just returns the name.
    149     *
    150     * <h2>API Usage</h2>
    151     * <p>
    152     * Consider this method private, it is package protected for unit testing only.
    153     * </p>
    154     *
    155     * @param name
    156     *            The string to get the substrings from
    157     * @return Annexed first and last 3 letters of input word.
    158     */
    159    String getFirst3Last3(final String name) {
    160        final int nameLength = name.length();
    161
    162        if (nameLength > 6) {
    163            final String firstThree = name.substring(0, 3);
    164            final String lastThree = name.substring(nameLength - 3, nameLength);
    165            return firstThree + lastThree;
    166        }
    167        return name;
    168    }
    169
    170    /**
    171     * Obtains the min rating of the length sum of the 2 names. In essence the larger the sum length the smaller the
    172     * min rating. Values strictly from documentation.
    173     *
    174     * <h2>API Usage</h2>
    175     * <p>
    176     * Consider this method private, it is package protected for unit testing only.
    177     * </p>
    178     *
    179     * @param sumLength
    180     *            The length of 2 strings sent down
    181     * @return The min rating value
    182     */
    183    int getMinRating(final int sumLength) {
    184        int minRating = 0;
    185
    186        if (sumLength <= 4) {
    187            minRating = 5;
    188        } else if (sumLength <= 7) { // already know it is at least 5
    189            minRating = 4;
    190        } else if (sumLength <= 11) { // already know it is at least 8
    191            minRating = 3;
    192        } else if (sumLength == 12) {
    193            minRating = 2;
    194        } else {
    195            minRating = 1; // docs said little here.
    196        }
    197
    198        return minRating;
    199    }
    200
    201    /**
    202     * Determines if two names are homophonous via Match Rating Approach (MRA) algorithm. It should be noted that the
    203     * strings are cleaned in the same way as {@link #encode(String)}.
    204     *
    205     * @param name1
    206     *            First of the 2 strings (names) to compare
    207     * @param name2
    208     *            Second of the 2 names to compare
    209     * @return {@code true} if the encodings are identical {@code false} otherwise.
    210     */
    211    public boolean isEncodeEquals(String name1, String name2) {
    212        // Bulletproof for trivial input - NINO
    213        if (name1 == null || EMPTY.equalsIgnoreCase(name1) || SPACE.equalsIgnoreCase(name1)) {
    214            return false;
    215        }
    216        if (name2 == null || EMPTY.equalsIgnoreCase(name2) || SPACE.equalsIgnoreCase(name2)) {
    217            return false;
    218        }
    219        if (name1.length() == 1 || name2.length() == 1) {
    220            return false;
    221        }
    222        if (name1.equalsIgnoreCase(name2)) {
    223            return true;
    224        }
    225
    226        // Preprocessing
    227        name1 = cleanName(name1);
    228        name2 = cleanName(name2);
    229
    230        // Actual MRA Algorithm
    231
    232        // 1. Remove vowels
    233        name1 = removeVowels(name1);
    234        name2 = removeVowels(name2);
    235
    236        // 2. Remove double consonants
    237        name1 = removeDoubleConsonants(name1);
    238        name2 = removeDoubleConsonants(name2);
    239
    240        // 3. Reduce down to 3 letters
    241        name1 = getFirst3Last3(name1);
    242        name2 = getFirst3Last3(name2);
    243
    244        // 4. Check for length difference - if 3 or greater, then no similarity
    245        // comparison is done
    246        if (Math.abs(name1.length() - name2.length()) >= 3) {
    247            return false;
    248        }
    249
    250        // 5. Obtain the minimum rating value by calculating the length sum of the
    251        // encoded Strings and sending it down.
    252        final int sumLength = Math.abs(name1.length() + name2.length());
    253        final int minRating = getMinRating(sumLength);
    254
    255        // 6. Process the encoded Strings from left to right and remove any
    256        // identical characters found from both Strings respectively.
    257        final int count = leftToRightThenRightToLeftProcessing(name1, name2);
    258
    259        // 7. Each PNI item that has a similarity rating equal to or greater than
    260        // the min is considered to be a good candidate match
    261        return count >= minRating;
    262
    263    }
    264
    265    /**
    266     * Determines if a letter is a vowel.
    267     *
    268     * <h2>API Usage</h2>
    269     * <p>
    270     * Consider this method private, it is package protected for unit testing only.
    271     * </p>
    272     *
    273     * @param letter
    274     *            The letter under investigation
    275     * @return True if a vowel, else false
    276     */
    277    boolean isVowel(final String letter) {
    278        return letter.equalsIgnoreCase("E") || letter.equalsIgnoreCase("A") || letter.equalsIgnoreCase("O") ||
    279               letter.equalsIgnoreCase("I") || letter.equalsIgnoreCase("U");
    280    }
    281
    282    /**
    283     * Processes the names from left to right (first) then right to left removing identical letters in same positions.
    284     * Then subtracts the longer string that remains from 6 and returns this.
    285     *
    286     * <h2>API Usage</h2>
    287     * <p>
    288     * Consider this method private, it is package protected for unit testing only.
    289     * </p>
    290     *
    291     * @param name1
    292     *            name2
    293     * @return the length as above
    294     */
    295    int leftToRightThenRightToLeftProcessing(final String name1, final String name2) {
    296        final char[] name1Char = name1.toCharArray();
    297        final char[] name2Char = name2.toCharArray();
    298
    299        final int name1Size = name1.length() - 1;
    300        final int name2Size = name2.length() - 1;
    301
    302        String name1LtRStart = EMPTY;
    303        String name1LtREnd = EMPTY;
    304
    305        String name2RtLStart = EMPTY;
    306        String name2RtLEnd = EMPTY;
    307
    308        for (int i = 0; i < name1Char.length; i++) {
    309            if (i > name2Size) {
    310                break;
    311            }
    312
    313            name1LtRStart = name1.substring(i, i + 1);
    314            name1LtREnd = name1.substring(name1Size - i, name1Size - i + 1);
    315
    316            name2RtLStart = name2.substring(i, i + 1);
    317            name2RtLEnd = name2.substring(name2Size - i, name2Size - i + 1);
    318
    319            // Left to right...
    320            if (name1LtRStart.equals(name2RtLStart)) {
    321                name1Char[i] = ' ';
    322                name2Char[i] = ' ';
    323            }
    324
    325            // Right to left...
    326            if (name1LtREnd.equals(name2RtLEnd)) {
    327                name1Char[name1Size - i] = ' ';
    328                name2Char[name2Size - i] = ' ';
    329            }
    330        }
    331
    332        // Char arrays -> string & remove extraneous space
    333        final String strA = new String(name1Char).replaceAll("\\s+", EMPTY);
    334        final String strB = new String(name2Char).replaceAll("\\s+", EMPTY);
    335
    336        // Final bit - subtract the longest string from 6 and return this int value
    337        if (strA.length() > strB.length()) {
    338            return Math.abs(6 - strA.length());
    339        }
    340        return Math.abs(6 - strB.length());
    341    }
    342
    343    /**
    344     * Removes accented letters and replaces with non-accented ASCII equivalent Case is preserved.
    345     * http://www.codecodex.com/wiki/Remove_accent_from_letters_%28ex_.%C3%A9_to_e%29
    346     *
    347     * @param accentedWord
    348     *            The word that may have accents in it.
    349     * @return De-accented word
    350     */
    351    String removeAccents(final String accentedWord) {
    352        if (accentedWord == null) {
    353            return null;
    354        }
    355
    356        final StringBuilder sb = new StringBuilder();
    357        final int n = accentedWord.length();
    358
    359        for (int i = 0; i < n; i++) {
    360            final char c = accentedWord.charAt(i);
    361            final int pos = UNICODE.indexOf(c);
    362            if (pos > -1) {
    363                sb.append(PLAIN_ASCII.charAt(pos));
    364            } else {
    365                sb.append(c);
    366            }
    367        }
    368
    369        return sb.toString();
    370    }
    371
    372    /**
    373     * Replaces any double consonant pair with the single letter equivalent.
    374     *
    375     * <h2>API Usage</h2>
    376     * <p>
    377     * Consider this method private, it is package protected for unit testing only.
    378     * </p>
    379     *
    380     * @param name
    381     *            String to have double consonants removed
    382     * @return Single consonant word
    383     */
    384    String removeDoubleConsonants(final String name) {
    385        String replacedName = name.toUpperCase(Locale.ENGLISH);
    386        for (final String dc : DOUBLE_CONSONANT) {
    387            if (replacedName.contains(dc)) {
    388                final String singleLetter = dc.substring(0, 1);
    389                replacedName = replacedName.replace(dc, singleLetter);
    390            }
    391        }
    392        return replacedName;
    393    }
    394
    395    /**
    396     * Deletes all vowels unless the vowel begins the word.
    397     *
    398     * <h2>API Usage</h2>
    399     * <p>
    400     * Consider this method private, it is package protected for unit testing only.
    401     * </p>
    402     *
    403     * @param name
    404     *            The name to have vowels removed
    405     * @return De-voweled word
    406     */
    407    String removeVowels(String name) {
    408        // Extract first letter
    409        final String firstLetter = name.substring(0, 1);
    410
    411        name = name.replace("A", EMPTY);
    412        name = name.replace("E", EMPTY);
    413        name = name.replace("I", EMPTY);
    414        name = name.replace("O", EMPTY);
    415        name = name.replace("U", EMPTY);
    416
    417        name = name.replaceAll("\\s{2,}\\b", SPACE);
    418
    419        // return isVowel(firstLetter) ? (firstLetter + name) : name;
    420        if (isVowel(firstLetter)) {
    421            return firstLetter + name;
    422        }
    423        return name;
    424    }
    425}