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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 *
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package java.lang;

import java.text.BreakIterator;
import java.util.HashSet;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.Locale;
import sun.text.Normalizer;


This is a utility class for String.toLowerCase() and String.toUpperCase(), that handles special casing with conditions. In other words, it handles the mappings with conditions that are defined in Special
Casing Properties file.
 Note that the unconditional case mappings (including 1:M mappings) are handled in Character.toLower/UpperCase(). /**
 * This is a utility class for {@code String.toLowerCase()} and
 * {@code String.toUpperCase()}, that handles special casing with
 * conditions.  In other words, it handles the mappings with conditions
 * that are defined in
 * <a href="http://www.unicode.org/Public/UNIDATA/SpecialCasing.txt">Special
 * Casing Properties</a> file.
 * <p>
 * Note that the unconditional case mappings (including 1:M mappings)
 * are handled in {@code Character.toLower/UpperCase()}.
 */
final class ConditionalSpecialCasing {

    // context conditions.
    static final int FINAL_CASED =              1;
    static final int AFTER_SOFT_DOTTED =        2;
    static final int MORE_ABOVE =               3;
    static final int AFTER_I =                  4;
    static final int NOT_BEFORE_DOT =           5;

    // combining class definitions
    static final int COMBINING_CLASS_ABOVE = 230;

    // Special case mapping entries
    static Entry[] entry = {
        //# ================================================================================
        //# Conditional mappings
        //# ================================================================================
        new Entry(0x03A3, new char[]{0x03C2}, new char[]{0x03A3}, null, FINAL_CASED), // # GREEK CAPITAL LETTER SIGMA
        new Entry(0x0130, new char[]{0x0069, 0x0307}, new char[]{0x0130}, null, 0), // # LATIN CAPITAL LETTER I WITH DOT ABOVE

        //# ================================================================================
        //# Locale-sensitive mappings
        //# ================================================================================
        //# Lithuanian
        new Entry(0x0307, new char[]{0x0307}, new char[]{}, "lt",  AFTER_SOFT_DOTTED), // # COMBINING DOT ABOVE
        new Entry(0x0049, new char[]{0x0069, 0x0307}, new char[]{0x0049}, "lt", MORE_ABOVE), // # LATIN CAPITAL LETTER I
        new Entry(0x004A, new char[]{0x006A, 0x0307}, new char[]{0x004A}, "lt", MORE_ABOVE), // # LATIN CAPITAL LETTER J
        new Entry(0x012E, new char[]{0x012F, 0x0307}, new char[]{0x012E}, "lt", MORE_ABOVE), // # LATIN CAPITAL LETTER I WITH OGONEK
        new Entry(0x00CC, new char[]{0x0069, 0x0307, 0x0300}, new char[]{0x00CC}, "lt", 0), // # LATIN CAPITAL LETTER I WITH GRAVE
        new Entry(0x00CD, new char[]{0x0069, 0x0307, 0x0301}, new char[]{0x00CD}, "lt", 0), // # LATIN CAPITAL LETTER I WITH ACUTE
        new Entry(0x0128, new char[]{0x0069, 0x0307, 0x0303}, new char[]{0x0128}, "lt", 0), // # LATIN CAPITAL LETTER I WITH TILDE

        //# ================================================================================
        //# Turkish and Azeri
        new Entry(0x0130, new char[]{0x0069}, new char[]{0x0130}, "tr", 0), // # LATIN CAPITAL LETTER I WITH DOT ABOVE
        new Entry(0x0130, new char[]{0x0069}, new char[]{0x0130}, "az", 0), // # LATIN CAPITAL LETTER I WITH DOT ABOVE
        new Entry(0x0307, new char[]{}, new char[]{0x0307}, "tr", AFTER_I), // # COMBINING DOT ABOVE
        new Entry(0x0307, new char[]{}, new char[]{0x0307}, "az", AFTER_I), // # COMBINING DOT ABOVE
        new Entry(0x0049, new char[]{0x0131}, new char[]{0x0049}, "tr", NOT_BEFORE_DOT), // # LATIN CAPITAL LETTER I
        new Entry(0x0049, new char[]{0x0131}, new char[]{0x0049}, "az", NOT_BEFORE_DOT), // # LATIN CAPITAL LETTER I
        new Entry(0x0069, new char[]{0x0069}, new char[]{0x0130}, "tr", 0), // # LATIN SMALL LETTER I
        new Entry(0x0069, new char[]{0x0069}, new char[]{0x0130}, "az", 0)  // # LATIN SMALL LETTER I
    };

    // A hash table that contains the above entries
    static Hashtable<Integer, HashSet<Entry>> entryTable = new Hashtable<>();
    static {
        // create hashtable from the entry
        for (Entry cur : entry) {
            Integer cp = cur.getCodePoint();
            HashSet<Entry> set = entryTable.get(cp);
            if (set == null) {
                set = new HashSet<>();
                entryTable.put(cp, set);
            }
            set.add(cur);
        }
    }

    static int toLowerCaseEx(String src, int index, Locale locale) {
        char[] result = lookUpTable(src, index, locale, true);

        if (result != null) {
            if (result.length == 1) {
                return result[0];
            } else {
                return Character.ERROR;
            }
        } else {
            // default to Character class' one
            return Character.toLowerCase(src.codePointAt(index));
        }
    }

    static int toUpperCaseEx(String src, int index, Locale locale) {
        char[] result = lookUpTable(src, index, locale, false);

        if (result != null) {
            if (result.length == 1) {
                return result[0];
            } else {
                return Character.ERROR;
            }
        } else {
            // default to Character class' one
            return Character.toUpperCaseEx(src.codePointAt(index));
        }
    }

    static char[] toLowerCaseCharArray(String src, int index, Locale locale) {
        return lookUpTable(src, index, locale, true);
    }

    static char[] toUpperCaseCharArray(String src, int index, Locale locale) {
        char[] result = lookUpTable(src, index, locale, false);
        if (result != null) {
            return result;
        } else {
            return Character.toUpperCaseCharArray(src.codePointAt(index));
        }
    }

    private static char[] lookUpTable(String src, int index, Locale locale, boolean bLowerCasing) {
        HashSet<Entry> set = entryTable.get(src.codePointAt(index));
        char[] ret = null;

        if (set != null) {
            Iterator<Entry> iter = set.iterator();
            String currentLang = locale.getLanguage();
            while (iter.hasNext()) {
                Entry entry = iter.next();
                String conditionLang = entry.getLanguage();
                if (((conditionLang == null) || (conditionLang.equals(currentLang))) &&
                        isConditionMet(src, index, locale, entry.getCondition())) {
                    ret = bLowerCasing ? entry.getLowerCase() : entry.getUpperCase();
                    if (conditionLang != null) {
                        break;
                    }
                }
            }
        }

        return ret;
    }

    private static boolean isConditionMet(String src, int index, Locale locale, int condition) {
        return switch (condition) {
            case FINAL_CASED       -> isFinalCased(src, index, locale);
            case AFTER_SOFT_DOTTED -> isAfterSoftDotted(src, index);
            case MORE_ABOVE        -> isMoreAbove(src, index);
            case AFTER_I           -> isAfterI(src, index);
            case NOT_BEFORE_DOT    -> !isBeforeDot(src, index);
            default -> true;
        };
    }

    
Implements the "Final_Cased" condition
Specification: Within the closest word boundaries containing C, there is a cased
letter before C, and there is no cased letter after C.
Regular Expression:
  Before C: [{cased==true}][{wordBoundary!=true}]*
  After C: !([{wordBoundary!=true}]*[{cased}])
/**
     * Implements the "Final_Cased" condition
     *
     * Specification: Within the closest word boundaries containing C, there is a cased
     * letter before C, and there is no cased letter after C.
     *
     * Regular Expression:
     *   Before C: [{cased==true}][{wordBoundary!=true}]*
     *   After C: !([{wordBoundary!=true}]*[{cased}])
     */
    private static boolean isFinalCased(String src, int index, Locale locale) {
        BreakIterator wordBoundary = BreakIterator.getWordInstance(locale);
        wordBoundary.setText(src);
        int ch;

        // Look for a preceding 'cased' letter
        for (int i = index; (i >= 0) && !wordBoundary.isBoundary(i);
                i -= Character.charCount(ch)) {

            ch = src.codePointBefore(i);
            if (isCased(ch)) {

                int len = src.length();
                // Check that there is no 'cased' letter after the index
                for (i = index + Character.charCount(src.codePointAt(index));
                        (i < len) && !wordBoundary.isBoundary(i);
                        i += Character.charCount(ch)) {

                    ch = src.codePointAt(i);
                    if (isCased(ch)) {
                        return false;
                    }
                }

                return true;
            }
        }

        return false;
    }

    
Implements the "After_I" condition
Specification: The last preceding base character was an uppercase I,
and there is no intervening combining character class 230 (ABOVE).
Regular Expression:
  Before C: [I]([{cc!=230}&{cc!=0}])*
/**
     * Implements the "After_I" condition
     *
     * Specification: The last preceding base character was an uppercase I,
     * and there is no intervening combining character class 230 (ABOVE).
     *
     * Regular Expression:
     *   Before C: [I]([{cc!=230}&{cc!=0}])*
     */
    private static boolean isAfterI(String src, int index) {
        int ch;
        int cc;

        // Look for the last preceding base character
        for (int i = index; i > 0; i -= Character.charCount(ch)) {

            ch = src.codePointBefore(i);

            if (ch == 'I') {
                return true;
            } else {
                cc = Normalizer.getCombiningClass(ch);
                if ((cc == 0) || (cc == COMBINING_CLASS_ABOVE)) {
                    return false;
                }
            }
        }

        return false;
    }

    
Implements the "After_Soft_Dotted" condition
Specification: The last preceding character with combining class
of zero before C was Soft_Dotted, and there is no intervening
combining character class 230 (ABOVE).
Regular Expression:
  Before C: [{Soft_Dotted==true}]([{cc!=230}&{cc!=0}])*
/**
     * Implements the "After_Soft_Dotted" condition
     *
     * Specification: The last preceding character with combining class
     * of zero before C was Soft_Dotted, and there is no intervening
     * combining character class 230 (ABOVE).
     *
     * Regular Expression:
     *   Before C: [{Soft_Dotted==true}]([{cc!=230}&{cc!=0}])*
     */
    private static boolean isAfterSoftDotted(String src, int index) {
        int ch;
        int cc;

        // Look for the last preceding character
        for (int i = index; i > 0; i -= Character.charCount(ch)) {

            ch = src.codePointBefore(i);

            if (isSoftDotted(ch)) {
                return true;
            } else {
                cc = Normalizer.getCombiningClass(ch);
                if ((cc == 0) || (cc == COMBINING_CLASS_ABOVE)) {
                    return false;
                }
            }
        }

        return false;
    }

    
Implements the "More_Above" condition
Specification: C is followed by one or more characters of combining
class 230 (ABOVE) in the combining character sequence.
Regular Expression:
  After C: [{cc!=0}]*[{cc==230}]
/**
     * Implements the "More_Above" condition
     *
     * Specification: C is followed by one or more characters of combining
     * class 230 (ABOVE) in the combining character sequence.
     *
     * Regular Expression:
     *   After C: [{cc!=0}]*[{cc==230}]
     */
    private static boolean isMoreAbove(String src, int index) {
        int ch;
        int cc;
        int len = src.length();

        // Look for a following ABOVE combining class character
        for (int i = index + Character.charCount(src.codePointAt(index));
                i < len; i += Character.charCount(ch)) {

            ch = src.codePointAt(i);
            cc = Normalizer.getCombiningClass(ch);

            if (cc == COMBINING_CLASS_ABOVE) {
                return true;
            } else if (cc == 0) {
                return false;
            }
        }

        return false;
    }

    
Implements the "Before_Dot" condition Specification: C is followed by U+0307 COMBINING DOT ABOVE. Any sequence of characters with a combining class that is neither 0 nor 230 may intervene between the current character and the combining dot above. Regular Expression: After C: ([{cc!=230}&{cc!=0}])*[\u0307] /**
     * Implements the "Before_Dot" condition
     *
     * Specification: C is followed by {@code U+0307 COMBINING DOT ABOVE}.
     * Any sequence of characters with a combining class that is
     * neither 0 nor 230 may intervene between the current character
     * and the combining dot above.
     *
     * Regular Expression:
     *   After C: ([{cc!=230}&{cc!=0}])*[\u0307]
     */
    private static boolean isBeforeDot(String src, int index) {
        int ch;
        int cc;
        int len = src.length();

        // Look for a following COMBINING DOT ABOVE
        for (int i = index + Character.charCount(src.codePointAt(index));
                i < len; i += Character.charCount(ch)) {

            ch = src.codePointAt(i);

            if (ch == '\u0307') {
                return true;
            } else {
                cc = Normalizer.getCombiningClass(ch);
                if ((cc == 0) || (cc == COMBINING_CLASS_ABOVE)) {
                    return false;
                }
            }
        }

        return false;
    }

    
Examines whether a character is 'cased'.
A character C is defined to be 'cased' if and only if at least one of
following are true for C: uppercase==true, or lowercase==true, or
general_category==titlecase_letter.
The uppercase and lowercase property values are specified in the data
file DerivedCoreProperties.txt in the Unicode Character Database.
/**
     * Examines whether a character is 'cased'.
     *
     * A character C is defined to be 'cased' if and only if at least one of
     * following are true for C: uppercase==true, or lowercase==true, or
     * general_category==titlecase_letter.
     *
     * The uppercase and lowercase property values are specified in the data
     * file DerivedCoreProperties.txt in the Unicode Character Database.
     */
    private static boolean isCased(int ch) {
        int type = Character.getType(ch);
        if (type == Character.LOWERCASE_LETTER ||
                type == Character.UPPERCASE_LETTER ||
                type == Character.TITLECASE_LETTER) {
            return true;
        } else {
            // Check for Other_Lowercase and Other_Uppercase
            //
            if ((ch >= 0x02B0) && (ch <= 0x02B8)) {
                // MODIFIER LETTER SMALL H..MODIFIER LETTER SMALL Y
                return true;
            } else if ((ch >= 0x02C0) && (ch <= 0x02C1)) {
                // MODIFIER LETTER GLOTTAL STOP..MODIFIER LETTER REVERSED GLOTTAL STOP
                return true;
            } else if ((ch >= 0x02E0) && (ch <= 0x02E4)) {
                // MODIFIER LETTER SMALL GAMMA..MODIFIER LETTER SMALL REVERSED GLOTTAL STOP
                return true;
            } else if (ch == 0x0345) {
                // COMBINING GREEK YPOGEGRAMMENI
                return true;
            } else if (ch == 0x037A) {
                // GREEK YPOGEGRAMMENI
                return true;
            } else if ((ch >= 0x1D2C) && (ch <= 0x1D61)) {
                // MODIFIER LETTER CAPITAL A..MODIFIER LETTER SMALL CHI
                return true;
            } else if ((ch >= 0x2160) && (ch <= 0x217F)) {
                // ROMAN NUMERAL ONE..ROMAN NUMERAL ONE THOUSAND
                // SMALL ROMAN NUMERAL ONE..SMALL ROMAN NUMERAL ONE THOUSAND
                return true;
            } else if ((ch >= 0x24B6) && (ch <= 0x24E9)) {
                // CIRCLED LATIN CAPITAL LETTER A..CIRCLED LATIN CAPITAL LETTER Z
                // CIRCLED LATIN SMALL LETTER A..CIRCLED LATIN SMALL LETTER Z
                return true;
            } else {
                return false;
            }
        }
    }

    private static boolean isSoftDotted(int ch) {
        switch (ch) {
        case 0x0069: // Soft_Dotted # L&       LATIN SMALL LETTER I
        case 0x006A: // Soft_Dotted # L&       LATIN SMALL LETTER J
        case 0x012F: // Soft_Dotted # L&       LATIN SMALL LETTER I WITH OGONEK
        case 0x0268: // Soft_Dotted # L&       LATIN SMALL LETTER I WITH STROKE
        case 0x0456: // Soft_Dotted # L&       CYRILLIC SMALL LETTER BYELORUSSIAN-UKRAINIAN I
        case 0x0458: // Soft_Dotted # L&       CYRILLIC SMALL LETTER JE
        case 0x1D62: // Soft_Dotted # L&       LATIN SUBSCRIPT SMALL LETTER I
        case 0x1E2D: // Soft_Dotted # L&       LATIN SMALL LETTER I WITH TILDE BELOW
        case 0x1ECB: // Soft_Dotted # L&       LATIN SMALL LETTER I WITH DOT BELOW
        case 0x2071: // Soft_Dotted # L&       SUPERSCRIPT LATIN SMALL LETTER I
            return true;
        default:
            return false;
        }
    }

    
An internal class that represents an entry in the Special Casing Properties.
/**
     * An internal class that represents an entry in the Special Casing Properties.
     */
    static class Entry {
        int ch;
        char [] lower;
        char [] upper;
        String lang;
        int condition;

        Entry(int ch, char[] lower, char[] upper, String lang, int condition) {
            this.ch = ch;
            this.lower = lower;
            this.upper = upper;
            this.lang = lang;
            this.condition = condition;
        }

        int getCodePoint() {
            return ch;
        }

        char[] getLowerCase() {
            return lower;
        }

        char[] getUpperCase() {
            return upper;
        }

        String getLanguage() {
            return lang;
        }

        int getCondition() {
            return condition;
        }
    }
}