code: package zemberek.core.turkish;
  
  import static zemberek.core.turkish.TurkicLetter.builder;
  
  import com.google.common.collect.Lists;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Locale;
  import zemberek.core.collections.FixedBitVector;
  import zemberek.core.collections.IntIntMap;
  import zemberek.core.collections.IntMap;
  import zemberek.core.text.TextUtil;
  
  public class TurkishAlphabet {
  
    public static final Locale TR = new Locale("tr");
  
    private final String lowercase = "abcçdefgğhıijklmnoöprsştuüvyzxwqâîû";
    private final String uppercase = lowercase.toUpperCase(TR);
    private final String allLetters = lowercase + uppercase;
    private final FixedBitVector dictionaryLettersLookup =
        TextUtil.generateBitLookup(allLetters);
  
    private final String vowelsLowercase = "aeıioöuüâîû";
    private String vowelsUppercase = vowelsLowercase.toUpperCase(TR);
    private FixedBitVector vowelLookup =
        TextUtil.generateBitLookup(vowelsLowercase + vowelsUppercase);
  
    private final String circumflex = "âîû";
    private final String circumflexUpper = "ÂÎÛ";
    private FixedBitVector circumflexLookup =
        TextUtil.generateBitLookup(circumflex + circumflexUpper);
  
    private final String apostrophe = "\u2032´`’‘'";
    private FixedBitVector apostropheLookup = TextUtil.generateBitLookup(apostrophe);
  
    private final String stopConsonants = "çkpt";
    private FixedBitVector stopConsonantLookup =
        TextUtil.generateBitLookup(stopConsonants + stopConsonants.toUpperCase(TR));
  
    private String voicelessConsonants = "çfhkpsşt";
    private FixedBitVector voicelessConsonantsLookup =
        TextUtil.generateBitLookup(voicelessConsonants + voicelessConsonants.toUpperCase(TR));
  
    private String turkishSpecific = "çÇğĞıİöÖşŞüÜâîûÂÎÛ";
    private String turkishAscii = "cCgGiIoOsSuUaiuAIU";
    private IntIntMap turkishToAsciiMap = new IntIntMap();
    private FixedBitVector turkishSpecificLookup = TextUtil.generateBitLookup(turkishSpecific);
  
    private String asciiEqTr = "cCgGiIoOsSuUçÇğĞıİöÖşŞüÜ";
    private String asciiEq = "çÇğĞıİöÖşŞüÜcCgGiIoOsSuU";
    private IntIntMap asciiEqualMap = new IntIntMap();
    private FixedBitVector asciiTrLookup = TextUtil.generateBitLookup(asciiEqTr);
  
  
    private String foreignDiacritics = "ÀÁÂÃÄÅÈÉÊËÌÍÎÏÑÒÓÔÕÙÚÛàáâãäåèéêëìíîïñòóôõùúû";
    private String diacriticsToTurkish = "AAAAAAEEEEIIIINOOOOUUUaaaaaaeeeeiiiinoooouuu";
    private IntIntMap foreignDiacriticsMap = new IntIntMap();
    private FixedBitVector foreignDiacriticsLookup = TextUtil.generateBitLookup(foreignDiacritics);
  
    public static TurkishAlphabet INSTANCE = Singleton.Instance.alphabet;
  
    private enum Singleton {
      Instance;
      TurkishAlphabet alphabet = new TurkishAlphabet();
    }
  
    private IntMap<TurkicLetter> letterMap = new IntMap<>();
    private IntIntMap voicingMap = new IntIntMap();
    private IntIntMap devoicingMap = new IntIntMap();
    private IntIntMap circumflexMap = new IntIntMap();
  
    private TurkishAlphabet() {
      List<TurkicLetter> letters = generateLetters();
      for (TurkicLetter letter : letters) {
        letterMap.put(letter.charValue, letter);
      }
      generateVoicingDevoicingLookups();
  
      populateCharMap(turkishToAsciiMap, turkishSpecific, turkishAscii);
      populateCharMap(foreignDiacriticsMap, foreignDiacritics, diacriticsToTurkish);
  
      for (int i = 0; i < asciiEqTr.length(); i++) {
        char in = asciiEqTr.charAt(i);
        char out = asciiEq.charAt(i);
        asciiEqualMap.put(in, out);
      }
    }
  
    public String toAscii(String in) {
      StringBuilder sb = new StringBuilder(in.length());
      for (int i = 0; i < in.length(); i++) {
        char c = in.charAt(i);
        int res = turkishToAsciiMap.get(c);
        char map = res == IntIntMap.NO_RESULT ? c : (char) res;
        sb.append(map);
      }
      return sb.toString();
    }
  
    public String foreignDiacriticsToTurkish(String in) {
      StringBuilder sb = new StringBuilder(in.length());
      for (int i = 0; i < in.length(); i++) {
        char c = in.charAt(i);
        int res = foreignDiacriticsMap.get(c);
        char map = res == IntIntMap.NO_RESULT ? c : (char) res;
        sb.append(map);
      }
      return sb.toString();
    }
  
    private void generateVoicingDevoicingLookups() {
      String voicingIn = "çgkpt";
      String voicingOut = "cğğbd";
      String devoicingIn = "bcdgğ";
      String devoicingOut = "pçtkk";
  
      populateCharMap(voicingMap,
          voicingIn + voicingIn.toUpperCase(TR),
          voicingOut + voicingOut.toUpperCase(TR));
      populateCharMap(devoicingMap,
          devoicingIn + devoicingIn.toUpperCase(TR),
          devoicingOut + devoicingOut.toUpperCase(TR));
  
      String circumflexNormalized = "aiu";
      populateCharMap(circumflexMap,
          circumflex + circumflex.toUpperCase(TR),
          circumflexNormalized + circumflexNormalized.toUpperCase(TR));
    }
  
    private boolean lookup(FixedBitVector vector, char c) {
      return c < vector.length && vector.get(c);
    }
  
    public boolean containsAsciiRelated(String s) {
      for (int i = 0; i < s.length(); i++) {
        char c = s.charAt(i);
        if (c < asciiTrLookup.length && asciiTrLookup.get(c)) {
          return true;
        }
      }
      return false;
    }
  
    public IntIntMap getTurkishToAsciiMap() {
      return turkishToAsciiMap;
    }
  
    public char getAsciiEqual(char c) {
      int res = turkishToAsciiMap.get(c);
      return res == IntIntMap.NO_RESULT ? c : (char) res;
    }
  
    public boolean isAsciiEqual(char c1, char c2) {
      if (c1 == c2) {
        return true;
      }
      int a1 = asciiEqualMap.get(c1);
      if (a1 == IntIntMap.NO_RESULT) {
        return false;
      }
      return a1 == c2;
    }
  
  
    private void populateCharMap(IntIntMap map, String inStr, String outStr) {
      for (int i = 0; i < inStr.length(); i++) {
        char in = inStr.charAt(i);
        char out = outStr.charAt(i);
        map.put(in, out);
      }
    }
  
    private List<TurkicLetter> generateLetters() {
      List<TurkicLetter> letters = Lists.newArrayList(
          builder('a').vowel().build(),
          builder('e').vowel().frontalVowel().build(),
          builder('ı').vowel().build(),
          builder('i').vowel().frontalVowel().build(),
          builder('o').vowel().roundedVowel().build(),
          builder('ö').vowel().frontalVowel().roundedVowel().build(),
          builder('u').vowel().roundedVowel().build(),
          builder('ü').vowel().roundedVowel().frontalVowel().build(),
          // Circumflexed letters
          builder('â').vowel().build(),
          builder('î').vowel().frontalVowel().build(),
          builder('û').vowel().frontalVowel().roundedVowel().build(),
          // Consonants
          builder('b').build(),
          builder('c').build(),
          builder('ç').voiceless().build(),
          builder('d').build(),
          builder('f').continuant().voiceless().build(),
          builder('g').build(),
          builder('ğ').continuant().build(),
          builder('h').continuant().voiceless().build(),
          builder('j').continuant().build(),
          builder('k').voiceless().build(),
          builder('l').continuant().build(),
          builder('m').continuant().build(),
          builder('n').continuant().build(),
          builder('p').voiceless().build(),
          builder('r').continuant().build(),
          builder('s').continuant().voiceless().build(),
          builder('ş').continuant().voiceless().build(),
          builder('t').voiceless().build(),
          builder('v').continuant().build(),
          builder('y').continuant().build(),
          builder('z').continuant().build(),
          builder('q').build(),
          builder('w').build(),
          builder('x').build()
      );
      List<TurkicLetter> capitals = new ArrayList<>();
      for (TurkicLetter letter : letters) {
        char upper = String.valueOf(letter.charValue).toUpperCase(TR).charAt(0);
        capitals.add(letter.copyFor(upper));
      }
      letters.addAll(capitals);
      return letters;
    }
  
    public boolean allCapital(String input) {
      for (int i = 0; i < input.length(); i++) {
        if (!Character.isUpperCase(input.charAt(i))) {
          return false;
        }
      }
      return true;
    }
  
    // TODO: this should not be here,
    public String normalize(String input) {
      StringBuilder sb = new StringBuilder(input.length());
      input = TextUtil.normalizeApostrophes(input.toLowerCase(TR));
      for (char c : input.toCharArray()) {
        if (letterMap.containsKey(c) || c == '.' || c == '-') {
          sb.append(c);
        } else {
          sb.append("?");
        }
      }
      return sb.toString();
    }
  
    public char normalizeCircumflex(char c) {
      int res = circumflexMap.get(c);
      return res == IntIntMap.NO_RESULT ? c : (char) res;
    }
  
    public boolean containsCircumflex(String s) {
      return checkLookup(circumflexLookup, s);
    }
  
    public boolean isTurkishSpecific(char c) {
      return lookup(turkishSpecificLookup, c);
    }
  
    public boolean containsApostrophe(String s) {
      return checkLookup(apostropheLookup, s);
    }
  
    public boolean containsForeignDiacritics(String s) {
      return checkLookup(foreignDiacriticsLookup, s);
    }
  
    private boolean checkLookup(FixedBitVector lookup, String s) {
      for (int i = 0; i < s.length(); i++) {
        char c = s.charAt(i);
        if (lookup(lookup, c)) {
          return true;
        }
      }
      return false;
    }
  
    public String getAllLetters() {
      return allLetters;
    }
  
    public String getLowercaseLetters() {
      return lowercase;
    }
  
    public String getUppercaseLetters() {
      return uppercase;
    }
  
    /**
     * Converts Turkish letters with circumflex symbols to letters without circumflexes. â->a î->i
     * û->u
     */
    public String normalizeCircumflex(String s) {
      if (!containsCircumflex(s)) {
        return s;
      }
      StringBuilder sb = new StringBuilder();
      for (int i = 0; i < s.length(); i++) {
        char c = s.charAt(i);
        if (lookup(circumflexLookup, c)) {
          sb.append((char) circumflexMap.get(c));
        } else {
          sb.append(c);
        }
      }
      return sb.toString();
    }
  
    public String normalizeApostrophe(String s) {
      if (!containsApostrophe(s)) {
        return s;
      }
      StringBuilder sb = new StringBuilder();
      for (int i = 0; i < s.length(); i++) {
        char c = s.charAt(i);
        if (lookup(apostropheLookup, c)) {
          sb.append('\'');
        } else {
          sb.append(c);
        }
      }
      return sb.toString();
    }
  
    /**
     * If there is a voiced char for `c`, returns it. Otherwise Returns the original input. ç->c g->ğ
     * k->ğ p->b t->d
     */
    public char voice(char c) {
      int res = voicingMap.get(c);
      return res == IntIntMap.NO_RESULT ? c : (char) res;
    }
  
    /**
     * If there is a devoiced char for `c`, returns it. Otherwise Returns the original input. b->p
     * c->ç d->t g->k ğ->k
     */
    public char devoice(char c) {
      int res = devoicingMap.get(c);
      return res == IntIntMap.NO_RESULT ? c : (char) res;
    }
  
  
    /**
     * Returns the TurkicLetter object for a character. If it does not exist, returns
     * TurkicLetter.UNDEFINED
     */
    public TurkicLetter getLetter(char c) {
      TurkicLetter letter = letterMap.get(c);
      return letter == null ? TurkicLetter.UNDEFINED : letter;
    }
  
    /**
     * Returns the last letter of the input as "TurkicLetter". If input is empty or the last character
     * does not belong to alphabet, returns TurkicLetter.UNDEFINED.
     */
    public TurkicLetter getLastLetter(CharSequence s) {
      if (s.length() == 0) {
        return TurkicLetter.UNDEFINED;
      }
      return getLetter(s.charAt(s.length() - 1));
    }
  
    public char lastChar(CharSequence s) {
      return s.charAt(s.length() - 1);
    }
  
    /**
     * Returns the first letter of the input as "TurkicLetter". If input is empty or the first
     * character does not belong to alphabet, returns TurkicLetter.UNDEFINED.
     */
    public TurkicLetter getFirstLetter(CharSequence s) {
      if (s.length() == 0) {
        return TurkicLetter.UNDEFINED;
      }
      TurkicLetter letter = letterMap.get(s.charAt(0));
      return getLetter(s.charAt(0));
    }
  
    /**
     * Returns is `c` is a Turkish vowel. Input can be lower or upper case. Turkish letters with
     * circumflex are included.
     */
    public boolean isVowel(char c) {
      return lookup(vowelLookup, c);
    }
  
    /**
     * Returns true if `c` is a member of set Turkish alphabet and three english letters w,x and q.
     * Turkish letters with circumflex are included. Input can be lower or upper case.
     */
    public boolean isDictionaryLetter(char c) {
      return lookup(dictionaryLettersLookup, c);
    }
  
    /**
     * Returns true if `c` is a stop consonant. Stop consonants for Turkish are: `ç,k,p,t`. Input can
     * be lower or upper case.
     */
    public boolean isStopConsonant(char c) {
      return lookup(stopConsonantLookup, c);
    }
  
    /**
     * Returns true if `c` is a stop consonant. Voiceless consonants for Turkish are:
     * `ç,f,h,k,p,s,ş,t`. Input can be lower or upper case.
     */
    public boolean isVoicelessConsonant(char c) {
      return lookup(voicelessConsonantsLookup, c);
    }
  
    /**
     * Returns the last vowel of the input as "TurkicLetter". If input is empty or there is no vowel,
     * returns TurkicLetter.UNDEFINED.
     */
    public TurkicLetter getLastVowel(CharSequence s) {
      if (s.length() == 0) {
        return TurkicLetter.UNDEFINED;
      }
      for (int i = s.length() - 1; i >= 0; i--) {
        char c = s.charAt(i);
        if (isVowel(c)) {
          return getLetter(c);
        }
      }
      return TurkicLetter.UNDEFINED;
    }
  
    /**
     * Returns the first vowel of the input as "TurkicLetter". If input is empty or there is no vowel,
     * returns TurkicLetter.UNDEFINED.
     */
    public TurkicLetter getFirstVowel(CharSequence s) {
      if (s.length() == 0) {
        return TurkicLetter.UNDEFINED;
      }
      for (int i = 0; i < s.length(); i++) {
        char c = s.charAt(i);
        if (isVowel(c)) {
          return getLetter(c);
        }
      }
      return TurkicLetter.UNDEFINED;
    }
  
    /**
     * Returns true if target string matches source string with A-Type harmony
     * <pre>
     *   elma, ya -> true
     *   kedi, ye -> true
     *   kalem, a -> false
     * </pre>
     */
    public boolean checkVowelHarmonyA(CharSequence source, CharSequence target) {
      TurkicLetter sourceLastVowel = getLastVowel(source);
      TurkicLetter targetFirstVowel = getLastVowel(target);
      return checkVowelHarmonyA(sourceLastVowel, targetFirstVowel);
    }
  
    /**
     * Returns true if target string matches source string with I-Type harmony
     * <pre>
     *   elma, yı  -> true
     *   kedi, yi  -> true
     *   kalem, ü  -> false
     *   yogurt, u -> true
     * </pre>
     */
    public boolean checkVowelHarmonyI(CharSequence source, CharSequence target) {
      TurkicLetter sourceLastVowel = getLastVowel(source);
      TurkicLetter targetFirstVowel = getLastVowel(target);
      return checkVowelHarmonyI(sourceLastVowel, targetFirstVowel);
    }
  
    /**
     * Returns true if target letter matches source letter with A-Type harmony
     * <pre>
     *   i, e -> true
     *   i, a -> false
     *   u, a -> true
     *   c, b -> false
     * </pre>
     */
    public boolean checkVowelHarmonyA(TurkicLetter source, TurkicLetter target) {
      if (source == TurkicLetter.UNDEFINED || target == TurkicLetter.UNDEFINED) {
        return false;
      }
      if (!source.isVowel() || !target.isVowel()) {
        return false;
      }
      return (source.frontal && target.frontal) ||
          (!source.frontal && !target.frontal);
    }
  
    /**
     * Returns true if target letter matches source letter with I-Type harmony
     * <pre>
     *   e, i -> true
     *   a, i -> false
     *   o, u -> true
     *   c, b -> false
     * </pre>
     */
    public boolean checkVowelHarmonyI(TurkicLetter source, TurkicLetter target) {
      if (source == TurkicLetter.UNDEFINED || target == TurkicLetter.UNDEFINED) {
        return false;
      }
      if (!source.isVowel() || !target.isVowel()) {
        return false;
      }
      return ((source.frontal && target.frontal) ||
          (!source.frontal && !target.frontal)) &&
          ((source.rounded && target.rounded) ||
              (!source.rounded && !target.rounded));
    }
  
    /**
     * Returns tru if input contains a vowel.
     */
    public boolean containsVowel(CharSequence s) {
      if (s.length() == 0) {
        return false;
      }
      for (int i = 0; i < s.length(); i++) {
        if (isVowel(s.charAt(i))) {
          return true;
        }
      }
      return false;
    }
  
    /**
     * Returns the vowel count in a word. It only checks Turkish vowels.
     */
    public int vowelCount(String s) {
      int result = 0;
      for (int i = 0; i < s.length(); i++) {
        if (isVowel(s.charAt(i))) {
          result++;
        }
      }
      return result;
    }
  
    /**
     * Returns true if `s` contains a digit. If s is empty or has no digit, returns false.
     */
    public boolean containsDigit(String s) {
      if (s.isEmpty()) {
        return false;
      }
      for (int i = 0; i < s.length(); i++) {
        char c = s.charAt(i);
        if (c >= '0' && c <= '9') {
          return true;
        }
      }
      return false;
    }
  
    /**
     * Compares two strings ignoring diacritics symbols.
     * <pre>
     *   i, ı -> true
     *   i, î -> true
     *   s, ş -> true
     *   g, ğ -> true
     *   kişi, kışı -> true
     * </pre>
     */
    public boolean equalsIgnoreDiacritics(String s1, String s2) {
      if (s1 == null || s2 == null) {
        return false;
      }
      if (s1.length() != s2.length()) {
        return false;
      }
      for (int i = 0; i < s1.length(); i++) {
        char c1 = s1.charAt(i);
        char c2 = s2.charAt(i);
        if (!isAsciiEqual(c1, c2)) {
          return false;
        }
      }
      return true;
    }
  
    /**
     * Checks if s1 starts with s2 ignoring diacritics symbols.
     * <pre>
     *   kışı, kis -> true
     *   pîr, pi   -> true
     * </pre>
     */
    public boolean startsWithIgnoreDiacritics(String s1, String s2) {
      if (s1 == null || s2 == null) {
        return false;
      }
      if (s1.length() < s2.length()) {
        return false;
      }
      for (int i = 0; i < s2.length(); i++) {
        char c1 = s1.charAt(i);
        char c2 = s2.charAt(i);
        if (!isAsciiEqual(c1, c2)) {
          return false;
        }
      }
      return true;
    }
  
  }
  