    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 */
    017
    018package org.apache.commons.codec.language.bm;
    019
    020import java.util.ArrayList;
    021import java.util.Arrays;
    022import java.util.Collections;
    023import java.util.EnumMap;
    024import java.util.HashSet;
    025import java.util.Iterator;
    026import java.util.LinkedHashSet;
    027import java.util.List;
    028import java.util.Locale;
    029import java.util.Map;
    030import java.util.Set;
    031import java.util.TreeMap;
    032
    033import org.apache.commons.codec.language.bm.Languages.LanguageSet;
    034import org.apache.commons.codec.language.bm.Rule.Phoneme;
    035
    036/**
    037 * Converts words into potential phonetic representations.
    038 * <p>
    039 * This is a two-stage process. Firstly, the word is converted into a phonetic representation that takes
    040 * into account the likely source language. Next, this phonetic representation is converted into a
    041 * pan-European 'average' representation, allowing comparison between different versions of essentially
    042 * the same word from different languages.
    043 * <p>
    044 * This class is intentionally immutable and thread-safe.
    045 * If you wish to alter the settings for a PhoneticEngine, you
    046 * must make a new one with the updated settings.
    047 * <p>
    048 * Ported from phoneticengine.php
    049 *
    050 * @since 1.6
    051 * @version $Id$
    052 */
    053public class PhoneticEngine {
    054
    055    /**
    056     * Utility for manipulating a set of phonemes as they are being built up. Not intended for use outside
    057     * this package, and probably not outside the {@link PhoneticEngine} class.
    058     *
    059     * @since 1.6
    060     */
    061    static final class PhonemeBuilder {
    062
    063        /**
    064         * An empty builder where all phonemes must come from some set of languages. This will contain a single
    065         * phoneme of zero characters. This can then be appended to. This should be the only way to create a new
    066         * phoneme from scratch.
    067         *
    068         * @param languages the set of languages
    069         * @return  a new, empty phoneme builder
    070         */
    071        public static PhonemeBuilder empty(final Languages.LanguageSet languages) {
    072            return new PhonemeBuilder(new Rule.Phoneme("", languages));
    073        }
    074
    075        private final Set<Rule.Phoneme> phonemes;
    076
    077        private PhonemeBuilder(final Rule.Phoneme phoneme) {
    078            this.phonemes = new LinkedHashSet<>();
    079            this.phonemes.add(phoneme);
    080        }
    081
    082        private PhonemeBuilder(final Set<Rule.Phoneme> phonemes) {
    083            this.phonemes = phonemes;
    084        }
    085
    086        /**
    087         * Creates a new phoneme builder containing all phonemes in this one extended by <code>str</code>.
    088         *
    089         * @param str   the characters to append to the phonemes
    090         */
    091        public void append(final CharSequence str) {
    092            for (final Rule.Phoneme ph : this.phonemes) {
    093                ph.append(str);
    094            }
    095        }
    096
    097        /**
    098         * Applies the given phoneme expression to all phonemes in this phoneme builder.
    099         * <p>
    100         * This will lengthen phonemes that have compatible language sets to the expression, and drop those that are
    101         * incompatible.
    102         *
    103         * @param phonemeExpr   the expression to apply
    104         * @param maxPhonemes   the maximum number of phonemes to build up
    105         */
    106        public void apply(final Rule.PhonemeExpr phonemeExpr, final int maxPhonemes) {
    107            final Set<Rule.Phoneme> newPhonemes = new LinkedHashSet<>(maxPhonemes);
    108
    109            EXPR: for (final Rule.Phoneme left : this.phonemes) {
    110                for (final Rule.Phoneme right : phonemeExpr.getPhonemes()) {
    111                    final LanguageSet languages = left.getLanguages().restrictTo(right.getLanguages());
    112                    if (!languages.isEmpty()) {
    113                        final Rule.Phoneme join = new Phoneme(left, right, languages);
    114                        if (newPhonemes.size() < maxPhonemes) {
    115                            newPhonemes.add(join);
    116                            if (newPhonemes.size() >= maxPhonemes) {
    117                                break EXPR;
    118                            }
    119                        }
    120                    }
    121                }
    122            }
    123
    124            this.phonemes.clear();
    125            this.phonemes.addAll(newPhonemes);
    126        }
    127
    128        /**
    129         * Gets underlying phoneme set. Please don't mutate.
    130         *
    131         * @return  the phoneme set
    132         */
    133        public Set<Rule.Phoneme> getPhonemes() {
    134            return this.phonemes;
    135        }
    136
    137        /**
    138         * Stringifies the phoneme set. This produces a single string of the strings of each phoneme,
    139         * joined with a pipe. This is explicitly provided in place of toString as it is a potentially
    140         * expensive operation, which should be avoided when debugging.
    141         *
    142         * @return  the stringified phoneme set
    143         */
    144        public String makeString() {
    145            final StringBuilder sb = new StringBuilder();
    146
    147            for (final Rule.Phoneme ph : this.phonemes) {
    148                if (sb.length() > 0) {
    149                    sb.append("|");
    150                }
    151                sb.append(ph.getPhonemeText());
    152            }
    153
    154            return sb.toString();
    155        }
    156    }
    157
    158    /**
    159     * A function closure capturing the application of a list of rules to an input sequence at a particular offset.
    160     * After invocation, the values <code>i</code> and <code>found</code> are updated. <code>i</code> points to the
    161     * index of the next char in <code>input</code> that must be processed next (the input up to that index having been
    162     * processed already), and <code>found</code> indicates if a matching rule was found or not. In the case where a
    163     * matching rule was found, <code>phonemeBuilder</code> is replaced with a new builder containing the phonemes
    164     * updated by the matching rule.
    165     *
    166     * Although this class is not thread-safe (it has mutable unprotected fields), it is not shared between threads
    167     * as it is constructed as needed by the calling methods.
    168     * @since 1.6
    169     */
    170    private static final class RulesApplication {
    171        private final Map<String, List<Rule>> finalRules;
    172        private final CharSequence input;
    173
    174        private final PhonemeBuilder phonemeBuilder;
    175        private int i;
    176        private final int maxPhonemes;
    177        private boolean found;
    178
    179        public RulesApplication(final Map<String, List<Rule>> finalRules, final CharSequence input,
    180                                final PhonemeBuilder phonemeBuilder, final int i, final int maxPhonemes) {
    181            if (finalRules == null) {
    182                throw new NullPointerException("The finalRules argument must not be null");
    183            }
    184            this.finalRules = finalRules;
    185            this.phonemeBuilder = phonemeBuilder;
    186            this.input = input;
    187            this.i = i;
    188            this.maxPhonemes = maxPhonemes;
    189        }
    190
    191        public int getI() {
    192            return this.i;
    193        }
    194
    195        public PhonemeBuilder getPhonemeBuilder() {
    196            return this.phonemeBuilder;
    197        }
    198
    199        /**
    200         * Invokes the rules. Loops over the rules list, stopping at the first one that has a matching context
    201         * and pattern. Then applies this rule to the phoneme builder to produce updated phonemes. If there was no
    202         * match, <code>i</code> is advanced one and the character is silently dropped from the phonetic spelling.
    203         *
    204         * @return <code>this</code>
    205         */
    206        public RulesApplication invoke() {
    207            this.found = false;
    208            int patternLength = 1;
    209            final List<Rule> rules = this.finalRules.get(input.subSequence(i, i+patternLength));
    210            if (rules != null) {
    211                for (final Rule rule : rules) {
    212                    final String pattern = rule.getPattern();
    213                    patternLength = pattern.length();
    214                    if (rule.patternAndContextMatches(this.input, this.i)) {
    215                        this.phonemeBuilder.apply(rule.getPhoneme(), maxPhonemes);
    216                        this.found = true;
    217                        break;
    218                    }
    219                }
    220            }
    221
    222            if (!this.found) {
    223                patternLength = 1;
    224            }
    225
    226            this.i += patternLength;
    227            return this;
    228        }
    229
    230        public boolean isFound() {
    231            return this.found;
    232        }
    233    }
    234
    235    private static final Map<NameType, Set<String>> NAME_PREFIXES = new EnumMap<>(NameType.class);
    236
    237    static {
    238        NAME_PREFIXES.put(NameType.ASHKENAZI,
    239                Collections.unmodifiableSet(
    240                        new HashSet<>(Arrays.asList("bar", "ben", "da", "de", "van", "von"))));
    241        NAME_PREFIXES.put(NameType.SEPHARDIC,
    242                Collections.unmodifiableSet(
    243                        new HashSet<>(Arrays.asList("al", "el", "da", "dal", "de", "del", "dela", "de la",
    244                                                          "della", "des", "di", "do", "dos", "du", "van", "von"))));
    245        NAME_PREFIXES.put(NameType.GENERIC,
    246                Collections.unmodifiableSet(
    247                        new HashSet<>(Arrays.asList("da", "dal", "de", "del", "dela", "de la", "della",
    248                                                          "des", "di", "do", "dos", "du", "van", "von"))));
    249    }
    250
    251    /**
    252     * Joins some strings with an internal separator.
    253     * @param strings   Strings to join
    254     * @param sep       String to separate them with
    255     * @return a single String consisting of each element of <code>strings</code> interleaved by <code>sep</code>
    256     */
    257    private static String join(final Iterable<String> strings, final String sep) {
    258        final StringBuilder sb = new StringBuilder();
    259        final Iterator<String> si = strings.iterator();
    260        if (si.hasNext()) {
    261            sb.append(si.next());
    262        }
    263        while (si.hasNext()) {
    264            sb.append(sep).append(si.next());
    265        }
    266
    267        return sb.toString();
    268    }
    269
    270    private static final int DEFAULT_MAX_PHONEMES = 20;
    271
    272    private final Lang lang;
    273
    274    private final NameType nameType;
    275
    276    private final RuleType ruleType;
    277
    278    private final boolean concat;
    279
    280    private final int maxPhonemes;
    281
    282    /**
    283     * Generates a new, fully-configured phonetic engine.
    284     *
    285     * @param nameType
    286     *            the type of names it will use
    287     * @param ruleType
    288     *            the type of rules it will apply
    289     * @param concat
    290     *            if it will concatenate multiple encodings
    291     */
    292    public PhoneticEngine(final NameType nameType, final RuleType ruleType, final boolean concat) {
    293        this(nameType, ruleType, concat, DEFAULT_MAX_PHONEMES);
    294    }
    295
    296    /**
    297     * Generates a new, fully-configured phonetic engine.
    298     *
    299     * @param nameType
    300     *            the type of names it will use
    301     * @param ruleType
    302     *            the type of rules it will apply
    303     * @param concat
    304     *            if it will concatenate multiple encodings
    305     * @param maxPhonemes
    306     *            the maximum number of phonemes that will be handled
    307     * @since 1.7
    308     */
    309    public PhoneticEngine(final NameType nameType, final RuleType ruleType, final boolean concat,
    310                          final int maxPhonemes) {
    311        if (ruleType == RuleType.RULES) {
    312            throw new IllegalArgumentException("ruleType must not be " + RuleType.RULES);
    313        }
    314        this.nameType = nameType;
    315        this.ruleType = ruleType;
    316        this.concat = concat;
    317        this.lang = Lang.instance(nameType);
    318        this.maxPhonemes = maxPhonemes;
    319    }
    320
    321    /**
    322     * Applies the final rules to convert from a language-specific phonetic representation to a
    323     * language-independent representation.
    324     *
    325     * @param phonemeBuilder the current phonemes
    326     * @param finalRules the final rules to apply
    327     * @return the resulting phonemes
    328     */
    329    private PhonemeBuilder applyFinalRules(final PhonemeBuilder phonemeBuilder,
    330                                           final Map<String, List<Rule>> finalRules) {
    331        if (finalRules == null) {
    332            throw new NullPointerException("finalRules can not be null");
    333        }
    334        if (finalRules.isEmpty()) {
    335            return phonemeBuilder;
    336        }
    337
    338        final Map<Rule.Phoneme, Rule.Phoneme> phonemes =
    339            new TreeMap<>(Rule.Phoneme.COMPARATOR);
    340
    341        for (final Rule.Phoneme phoneme : phonemeBuilder.getPhonemes()) {
    342            PhonemeBuilder subBuilder = PhonemeBuilder.empty(phoneme.getLanguages());
    343            final String phonemeText = phoneme.getPhonemeText().toString();
    344
    345            for (int i = 0; i < phonemeText.length();) {
    346                final RulesApplication rulesApplication =
    347                        new RulesApplication(finalRules, phonemeText, subBuilder, i, maxPhonemes).invoke();
    348                final boolean found = rulesApplication.isFound();
    349                subBuilder = rulesApplication.getPhonemeBuilder();
    350
    351                if (!found) {
    352                    // not found, appending as-is
    353                    subBuilder.append(phonemeText.subSequence(i, i + 1));
    354                }
    355
    356                i = rulesApplication.getI();
    357            }
    358
    359            // the phonemes map orders the phonemes only based on their text, but ignores the language set
    360            // when adding new phonemes, check for equal phonemes and merge their language set, otherwise
    361            // phonemes with the same text but different language set get lost
    362            for (final Rule.Phoneme newPhoneme : subBuilder.getPhonemes()) {
    363                if (phonemes.containsKey(newPhoneme)) {
    364                    final Rule.Phoneme oldPhoneme = phonemes.remove(newPhoneme);
    365                    final Rule.Phoneme mergedPhoneme = oldPhoneme.mergeWithLanguage(newPhoneme.getLanguages());
    366                    phonemes.put(mergedPhoneme, mergedPhoneme);
    367                } else {
    368                    phonemes.put(newPhoneme, newPhoneme);
    369                }
    370            }
    371        }
    372
    373        return new PhonemeBuilder(phonemes.keySet());
    374    }
    375
    376    /**
    377     * Encodes a string to its phonetic representation.
    378     *
    379     * @param input
    380     *            the String to encode
    381     * @return the encoding of the input
    382     */
    383    public String encode(final String input) {
    384        final Languages.LanguageSet languageSet = this.lang.guessLanguages(input);
    385        return encode(input, languageSet);
    386    }
    387
    388    /**
    389     * Encodes an input string into an output phonetic representation, given a set of possible origin languages.
    390     *
    391     * @param input
    392     *            String to phoneticise; a String with dashes or spaces separating each word
    393     * @param languageSet
    394     *            set of possible origin languages
    395     * @return a phonetic representation of the input; a String containing '-'-separated phonetic representations of the
    396     *         input
    397     */
    398    public String encode(String input, final Languages.LanguageSet languageSet) {
    399        final Map<String, List<Rule>> rules = Rule.getInstanceMap(this.nameType, RuleType.RULES, languageSet);
    400        // rules common across many (all) languages
    401        final Map<String, List<Rule>> finalRules1 = Rule.getInstanceMap(this.nameType, this.ruleType, "common");
    402        // rules that apply to a specific language that may be ambiguous or wrong if applied to other languages
    403        final Map<String, List<Rule>> finalRules2 = Rule.getInstanceMap(this.nameType, this.ruleType, languageSet);
    404
    405        // tidy the input
    406        // lower case is a locale-dependent operation
    407        input = input.toLowerCase(Locale.ENGLISH).replace('-', ' ').trim();
    408
    409        if (this.nameType == NameType.GENERIC) {
    410            if (input.length() >= 2 && input.substring(0, 2).equals("d'")) { // check for d'
    411                final String remainder = input.substring(2);
    412                final String combined = "d" + remainder;
    413                return "(" + encode(remainder) + ")-(" + encode(combined) + ")";
    414            }
    415            for (final String l : NAME_PREFIXES.get(this.nameType)) {
    416                // handle generic prefixes
    417                if (input.startsWith(l + " ")) {
    418                    // check for any prefix in the words list
    419                    final String remainder = input.substring(l.length() + 1); // input without the prefix
    420                    final String combined = l + remainder; // input with prefix without space
    421                    return "(" + encode(remainder) + ")-(" + encode(combined) + ")";
    422                }
    423            }
    424        }
    425
    426        final List<String> words = Arrays.asList(input.split("\\s+"));
    427        final List<String> words2 = new ArrayList<>();
    428
    429        // special-case handling of word prefixes based upon the name type
    430        switch (this.nameType) {
    431        case SEPHARDIC:
    432            for (final String aWord : words) {
    433                final String[] parts = aWord.split("'");
    434                final String lastPart = parts[parts.length - 1];
    435                words2.add(lastPart);
    436            }
    437            words2.removeAll(NAME_PREFIXES.get(this.nameType));
    438            break;
    439        case ASHKENAZI:
    440            words2.addAll(words);
    441            words2.removeAll(NAME_PREFIXES.get(this.nameType));
    442            break;
    443        case GENERIC:
    444            words2.addAll(words);
    445            break;
    446        default:
    447            throw new IllegalStateException("Unreachable case: " + this.nameType);
    448        }
    449
    450        if (this.concat) {
    451            // concat mode enabled
    452            input = join(words2, " ");
    453        } else if (words2.size() == 1) {
    454            // not a multi-word name
    455            input = words.iterator().next();
    456        } else {
    457            // encode each word in a multi-word name separately (normally used for approx matches)
    458            final StringBuilder result = new StringBuilder();
    459            for (final String word : words2) {
    460                result.append("-").append(encode(word));
    461            }
    462            // return the result without the leading "-"
    463            return result.substring(1);
    464        }
    465
    466        PhonemeBuilder phonemeBuilder = PhonemeBuilder.empty(languageSet);
    467
    468        // loop over each char in the input - we will handle the increment manually
    469        for (int i = 0; i < input.length();) {
    470            final RulesApplication rulesApplication =
    471                    new RulesApplication(rules, input, phonemeBuilder, i, maxPhonemes).invoke();
    472            i = rulesApplication.getI();
    473            phonemeBuilder = rulesApplication.getPhonemeBuilder();
    474        }
    475
    476        // Apply the general rules
    477        phonemeBuilder = applyFinalRules(phonemeBuilder, finalRules1);
    478        // Apply the language-specific rules
    479        phonemeBuilder = applyFinalRules(phonemeBuilder, finalRules2);
    480
    481        return phonemeBuilder.makeString();
    482    }
    483
    484    /**
    485     * Gets the Lang language guessing rules being used.
    486     *
    487     * @return the Lang in use
    488     */
    489    public Lang getLang() {
    490        return this.lang;
    491    }
    492
    493    /**
    494     * Gets the NameType being used.
    495     *
    496     * @return the NameType in use
    497     */
    498    public NameType getNameType() {
    499        return this.nameType;
    500    }
    501
    502    /**
    503     * Gets the RuleType being used.
    504     *
    505     * @return the RuleType in use
    506     */
    507    public RuleType getRuleType() {
    508        return this.ruleType;
    509    }
    510
    511    /**
    512     * Gets if multiple phonetic encodings are concatenated or if just the first one is kept.
    513     *
    514     * @return true if multiple phonetic encodings are returned, false if just the first is
    515     */
    516    public boolean isConcat() {
    517        return this.concat;
    518    }
    519
    520    /**
    521     * Gets the maximum number of phonemes the engine will calculate for a given input.
    522     *
    523     * @return the maximum number of phonemes
    524     * @since 1.7
    525     */
    526    public int getMaxPhonemes() {
    527        return this.maxPhonemes;
    528    }
    529}