    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="http://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        upperName = upperName.replaceAll("\\s+", EMPTY);
    088
    089        return upperName;
    090    }
    091
    092    /**
    093     * Encodes an Object using the Match Rating Approach algorithm. Method is here to satisfy the requirements of the
    094     * Encoder interface Throws an EncoderException if input object is not of type java.lang.String.
    095     *
    096     * @param pObject
    097     *            Object to encode
    098     * @return An object (or type java.lang.String) containing the Match Rating Approach code which corresponds to the
    099     *         String supplied.
    100     * @throws EncoderException
    101     *             if the parameter supplied is not of type java.lang.String
    102     */
    103    @Override
    104    public final Object encode(final Object pObject) throws EncoderException {
    105        if (!(pObject instanceof String)) {
    106            throw new EncoderException(
    107                    "Parameter supplied to Match Rating Approach encoder is not of type java.lang.String");
    108        }
    109        return encode((String) pObject);
    110    }
    111
    112    /**
    113     * Encodes a String using the Match Rating Approach (MRA) algorithm.
    114     *
    115     * @param name
    116     *            String object to encode
    117     * @return The MRA code corresponding to the String supplied
    118     */
    119    @Override
    120    public final String encode(String name) {
    121        // Bulletproof for trivial input - NINO
    122        if (name == null || EMPTY.equalsIgnoreCase(name) || SPACE.equalsIgnoreCase(name) || name.length() == 1) {
    123            return EMPTY;
    124        }
    125
    126        // Preprocessing
    127        name = cleanName(name);
    128
    129        // BEGIN: Actual encoding part of the algorithm...
    130        // 1. Delete all vowels unless the vowel begins the word
    131        name = removeVowels(name);
    132
    133        // 2. Remove second consonant from any double consonant
    134        name = removeDoubleConsonants(name);
    135
    136        // 3. Reduce codex to 6 letters by joining the first 3 and last 3 letters
    137        name = getFirst3Last3(name);
    138
    139        return name;
    140    }
    141
    142    /**
    143     * Gets the first and last 3 letters of a name (if &gt; 6 characters) Else just returns the name.
    144     *
    145     * <h2>API Usage</h2>
    146     * <p>
    147     * Consider this method private, it is package protected for unit testing only.
    148     * </p>
    149     *
    150     * @param name
    151     *            The string to get the substrings from
    152     * @return Annexed first and last 3 letters of input word.
    153     */
    154    String getFirst3Last3(final String name) {
    155        final int nameLength = name.length();
    156
    157        if (nameLength > 6) {
    158            final String firstThree = name.substring(0, 3);
    159            final String lastThree = name.substring(nameLength - 3, nameLength);
    160            return firstThree + lastThree;
    161        }
    162        return name;
    163    }
    164
    165    /**
    166     * Obtains the min rating of the length sum of the 2 names. In essence the larger the sum length the smaller the
    167     * min rating. Values strictly from documentation.
    168     *
    169     * <h2>API Usage</h2>
    170     * <p>
    171     * Consider this method private, it is package protected for unit testing only.
    172     * </p>
    173     *
    174     * @param sumLength
    175     *            The length of 2 strings sent down
    176     * @return The min rating value
    177     */
    178    int getMinRating(final int sumLength) {
    179        int minRating = 0;
    180
    181        if (sumLength <= 4) {
    182            minRating = 5;
    183        } else if (sumLength <= 7) { // already know it is at least 5
    184            minRating = 4;
    185        } else if (sumLength <= 11) { // already know it is at least 8
    186            minRating = 3;
    187        } else if (sumLength == 12) {
    188            minRating = 2;
    189        } else {
    190            minRating = 1; // docs said little here.
    191        }
    192
    193        return minRating;
    194    }
    195
    196    /**
    197     * Determines if two names are homophonous via Match Rating Approach (MRA) algorithm. It should be noted that the
    198     * strings are cleaned in the same way as {@link #encode(String)}.
    199     *
    200     * @param name1
    201     *            First of the 2 strings (names) to compare
    202     * @param name2
    203     *            Second of the 2 names to compare
    204     * @return {@code true} if the encodings are identical {@code false} otherwise.
    205     */
    206    public boolean isEncodeEquals(String name1, String name2) {
    207        // Bulletproof for trivial input - NINO
    208        if (name1 == null || EMPTY.equalsIgnoreCase(name1) || SPACE.equalsIgnoreCase(name1)) {
    209            return false;
    210        }
    211        if (name2 == null || EMPTY.equalsIgnoreCase(name2) || SPACE.equalsIgnoreCase(name2)) {
    212            return false;
    213        }
    214        if (name1.length() == 1 || name2.length() == 1) {
    215            return false;
    216        }
    217        if (name1.equalsIgnoreCase(name2)) {
    218            return true;
    219        }
    220
    221        // Preprocessing
    222        name1 = cleanName(name1);
    223        name2 = cleanName(name2);
    224
    225        // Actual MRA Algorithm
    226
    227        // 1. Remove vowels
    228        name1 = removeVowels(name1);
    229        name2 = removeVowels(name2);
    230
    231        // 2. Remove double consonants
    232        name1 = removeDoubleConsonants(name1);
    233        name2 = removeDoubleConsonants(name2);
    234
    235        // 3. Reduce down to 3 letters
    236        name1 = getFirst3Last3(name1);
    237        name2 = getFirst3Last3(name2);
    238
    239        // 4. Check for length difference - if 3 or greater, then no similarity
    240        // comparison is done
    241        if (Math.abs(name1.length() - name2.length()) >= 3) {
    242            return false;
    243        }
    244
    245        // 5. Obtain the minimum rating value by calculating the length sum of the
    246        // encoded Strings and sending it down.
    247        final int sumLength = Math.abs(name1.length() + name2.length());
    248        final int minRating = getMinRating(sumLength);
    249
    250        // 6. Process the encoded Strings from left to right and remove any
    251        // identical characters found from both Strings respectively.
    252        final int count = leftToRightThenRightToLeftProcessing(name1, name2);
    253
    254        // 7. Each PNI item that has a similarity rating equal to or greater than
    255        // the min is considered to be a good candidate match
    256        return count >= minRating;
    257
    258    }
    259
    260    /**
    261     * Determines if a letter is a vowel.
    262     *
    263     * <h2>API Usage</h2>
    264     * <p>
    265     * Consider this method private, it is package protected for unit testing only.
    266     * </p>
    267     *
    268     * @param letter
    269     *            The letter under investigation
    270     * @return True if a vowel, else false
    271     */
    272    boolean isVowel(final String letter) {
    273        return letter.equalsIgnoreCase("E") || letter.equalsIgnoreCase("A") || letter.equalsIgnoreCase("O") ||
    274               letter.equalsIgnoreCase("I") || letter.equalsIgnoreCase("U");
    275    }
    276
    277    /**
    278     * Processes the names from left to right (first) then right to left removing identical letters in same positions.
    279     * Then subtracts the longer string that remains from 6 and returns this.
    280     *
    281     * <h2>API Usage</h2>
    282     * <p>
    283     * Consider this method private, it is package protected for unit testing only.
    284     * </p>
    285     *
    286     * @param name1
    287     *            name2
    288     * @return the length as above
    289     */
    290    int leftToRightThenRightToLeftProcessing(final String name1, final String name2) {
    291        final char[] name1Char = name1.toCharArray();
    292        final char[] name2Char = name2.toCharArray();
    293
    294        final int name1Size = name1.length() - 1;
    295        final int name2Size = name2.length() - 1;
    296
    297        String name1LtRStart = EMPTY;
    298        String name1LtREnd = EMPTY;
    299
    300        String name2RtLStart = EMPTY;
    301        String name2RtLEnd = EMPTY;
    302
    303        for (int i = 0; i < name1Char.length; i++) {
    304            if (i > name2Size) {
    305                break;
    306            }
    307
    308            name1LtRStart = name1.substring(i, i + 1);
    309            name1LtREnd = name1.substring(name1Size - i, name1Size - i + 1);
    310
    311            name2RtLStart = name2.substring(i, i + 1);
    312            name2RtLEnd = name2.substring(name2Size - i, name2Size - i + 1);
    313
    314            // Left to right...
    315            if (name1LtRStart.equals(name2RtLStart)) {
    316                name1Char[i] = ' ';
    317                name2Char[i] = ' ';
    318            }
    319
    320            // Right to left...
    321            if (name1LtREnd.equals(name2RtLEnd)) {
    322                name1Char[name1Size - i] = ' ';
    323                name2Char[name2Size - i] = ' ';
    324            }
    325        }
    326
    327        // Char arrays -> string & remove extraneous space
    328        final String strA = new String(name1Char).replaceAll("\\s+", EMPTY);
    329        final String strB = new String(name2Char).replaceAll("\\s+", EMPTY);
    330
    331        // Final bit - subtract the longest string from 6 and return this int value
    332        if (strA.length() > strB.length()) {
    333            return Math.abs(6 - strA.length());
    334        }
    335        return Math.abs(6 - strB.length());
    336    }
    337
    338    /**
    339     * Removes accented letters and replaces with non-accented ASCII equivalent Case is preserved.
    340     * http://www.codecodex.com/wiki/Remove_accent_from_letters_%28ex_.%C3%A9_to_e%29
    341     *
    342     * @param accentedWord
    343     *            The word that may have accents in it.
    344     * @return De-accented word
    345     */
    346    String removeAccents(final String accentedWord) {
    347        if (accentedWord == null) {
    348            return null;
    349        }
    350
    351        final StringBuilder sb = new StringBuilder();
    352        final int n = accentedWord.length();
    353
    354        for (int i = 0; i < n; i++) {
    355            final char c = accentedWord.charAt(i);
    356            final int pos = UNICODE.indexOf(c);
    357            if (pos > -1) {
    358                sb.append(PLAIN_ASCII.charAt(pos));
    359            } else {
    360                sb.append(c);
    361            }
    362        }
    363
    364        return sb.toString();
    365    }
    366
    367    /**
    368     * Replaces any double consonant pair with the single letter equivalent.
    369     *
    370     * <h2>API Usage</h2>
    371     * <p>
    372     * Consider this method private, it is package protected for unit testing only.
    373     * </p>
    374     *
    375     * @param name
    376     *            String to have double consonants removed
    377     * @return Single consonant word
    378     */
    379    String removeDoubleConsonants(final String name) {
    380        String replacedName = name.toUpperCase(Locale.ENGLISH);
    381        for (final String dc : DOUBLE_CONSONANT) {
    382            if (replacedName.contains(dc)) {
    383                final String singleLetter = dc.substring(0, 1);
    384                replacedName = replacedName.replace(dc, singleLetter);
    385            }
    386        }
    387        return replacedName;
    388    }
    389
    390    /**
    391     * Deletes all vowels unless the vowel begins the word.
    392     *
    393     * <h2>API Usage</h2>
    394     * <p>
    395     * Consider this method private, it is package protected for unit testing only.
    396     * </p>
    397     *
    398     * @param name
    399     *            The name to have vowels removed
    400     * @return De-voweled word
    401     */
    402    String removeVowels(String name) {
    403        // Extract first letter
    404        final String firstLetter = name.substring(0, 1);
    405
    406        name = name.replace("A", EMPTY);
    407        name = name.replace("E", EMPTY);
    408        name = name.replace("I", EMPTY);
    409        name = name.replace("O", EMPTY);
    410        name = name.replace("U", EMPTY);
    411
    412        name = name.replaceAll("\\s{2,}\\b", SPACE);
    413
    414        // return isVowel(firstLetter) ? (firstLetter + name) : name;
    415        if (isVowel(firstLetter)) {
    416            return firstLetter + name;
    417        }
    418        return name;
    419    }
    420}