java/11 : java.base/sun/text/normalizer/NormalizerBase.java

NormalizerBase
https://openjdk.java.net/
GPLv2 + Classpath Exception
/*
 * Copyright (c) 2005, 2015, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * 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).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/*
 *******************************************************************************
 * Copyright (C) 2000-2014, International Business Machines Corporation and
 * others. All Rights Reserved.
 *******************************************************************************
 */
package sun.text.normalizer;

import java.text.CharacterIterator;
import java.text.Normalizer;

Unicode Normalization
Unicode normalization API
normalize transforms Unicode text into an equivalent composed or
decomposed form, allowing for easier sorting and searching of text.
normalize supports the standard normalization forms described in

Unicode Standard Annex #15 — Unicode Normalization Forms.
Characters with accents or other adornments can be encoded in
several different ways in Unicode.  For example, take the character A-acute.
In Unicode, this can be encoded as a single character (the
"composed" form):
     00C1    LATIN CAPITAL LETTER A WITH ACUTE

or as two separate characters (the "decomposed" form):
     0041    LATIN CAPITAL LETTER A
     0301    COMBINING ACUTE ACCENT

To a user of your program, however, both of these sequences should be
treated as the same "user-level" character "A with acute accent".  When you
are searching or comparing text, you must ensure that these two sequences are
treated equivalently.  In addition, you must handle characters with more than
one accent.  Sometimes the order of a character's combining accents is
significant, while in other cases accent sequences in different orders are
really equivalent.
Similarly, the string "ffi" can be encoded as three separate letters:
     0066    LATIN SMALL LETTER F
     0066    LATIN SMALL LETTER F
     0069    LATIN SMALL LETTER I

or as the single character
     FB03    LATIN SMALL LIGATURE FFI

The ffi ligature is not a distinct semantic character, and strictly speaking
it shouldn't be in Unicode at all, but it was included for compatibility
with existing character sets that already provided it.  The Unicode standard
identifies such characters by giving them "compatibility" decompositions
into the corresponding semantic characters.  When sorting and searching, you
will often want to use these mappings.
normalize helps solve these problems by transforming text into
the canonical composed and decomposed forms as shown in the first example
above. In addition, you can have it perform compatibility decompositions so
that you can treat compatibility characters the same as their equivalents.
Finally, normalize rearranges accents into the proper canonical
order, so that you do not have to worry about accent rearrangement on your
own.
Form FCD, "Fast C or D", is also designed for collation.
It allows to work on strings that are not necessarily normalized
with an algorithm (like in collation) that works under "canonical closure",
i.e., it treats precomposed characters and their decomposed equivalents the
same.
It is not a normalization form because it does not provide for uniqueness of
representation. Multiple strings may be canonically equivalent (their NFDs
are identical) and may all conform to FCD without being identical themselves.
The form is defined such that the "raw decomposition", the recursive
canonical decomposition of each character, results in a string that is
canonically ordered. This means that precomposed characters are allowed for
as long as their decompositions do not need canonical reordering.
Its advantage for a process like collation is that all NFD and most NFC texts
- and many unnormalized texts - already conform to FCD and do not need to be
normalized (NFD) for such a process. The FCD quick check will return YES for
most strings in practice.
normalize(FCD) may be implemented with NFD.
For more details on FCD see Unicode Technical Note #5 (Canonical Equivalence in Applications):
http://www.unicode.org/notes/tn5/#FCD
ICU collation performs either NFD or FCD normalization automatically if
normalization is turned on for the collator object. Beyond collation and
string search, normalized strings may be useful for string equivalence
comparisons, transliteration/transcription, unique representations, etc.
The W3C generally recommends to exchange texts in NFC.
Note also that most legacy character encodings use only precomposed forms and
often do not encode any combining marks by themselves. For conversion to such
character encodings the Unicode text needs to be normalized to NFC.
For more usage examples, see the Unicode Standard Annex.
Note: The Normalizer class also provides API for iterative normalization.
While the setIndex() and getIndex() refer to indices in the
underlying Unicode input text, the next() and previous() methods
iterate through characters in the normalized output.
This means that there is not necessarily a one-to-one correspondence
between characters returned by next() and previous() and the indices
passed to and returned from setIndex() and getIndex().
It is for this reason that Normalizer does not implement the CharacterIterator interface.
@stable ICU 2.8/**
 * Unicode Normalization
 *
 * <h2>Unicode normalization API</h2>
 *
 * <code>normalize</code> transforms Unicode text into an equivalent composed or
 * decomposed form, allowing for easier sorting and searching of text.
 * <code>normalize</code> supports the standard normalization forms described in
 * <a href="http://www.unicode.org/unicode/reports/tr15/" target="unicode">
 * Unicode Standard Annex #15 &mdash; Unicode Normalization Forms</a>.
 *
 * Characters with accents or other adornments can be encoded in
 * several different ways in Unicode.  For example, take the character A-acute.
 * In Unicode, this can be encoded as a single character (the
 * "composed" form):
 *
 * <pre>
 *      00C1    LATIN CAPITAL LETTER A WITH ACUTE
 * </pre>
 *
 * or as two separate characters (the "decomposed" form):
 *
 * <pre>
 *      0041    LATIN CAPITAL LETTER A
 *      0301    COMBINING ACUTE ACCENT
 * </pre>
 *
 * To a user of your program, however, both of these sequences should be
 * treated as the same "user-level" character "A with acute accent".  When you
 * are searching or comparing text, you must ensure that these two sequences are
 * treated equivalently.  In addition, you must handle characters with more than
 * one accent.  Sometimes the order of a character's combining accents is
 * significant, while in other cases accent sequences in different orders are
 * really equivalent.
 *
 * Similarly, the string "ffi" can be encoded as three separate letters:
 *
 * <pre>
 *      0066    LATIN SMALL LETTER F
 *      0066    LATIN SMALL LETTER F
 *      0069    LATIN SMALL LETTER I
 * </pre>
 *
 * or as the single character
 *
 * <pre>
 *      FB03    LATIN SMALL LIGATURE FFI
 * </pre>
 *
 * The ffi ligature is not a distinct semantic character, and strictly speaking
 * it shouldn't be in Unicode at all, but it was included for compatibility
 * with existing character sets that already provided it.  The Unicode standard
 * identifies such characters by giving them "compatibility" decompositions
 * into the corresponding semantic characters.  When sorting and searching, you
 * will often want to use these mappings.
 *
 * <code>normalize</code> helps solve these problems by transforming text into
 * the canonical composed and decomposed forms as shown in the first example
 * above. In addition, you can have it perform compatibility decompositions so
 * that you can treat compatibility characters the same as their equivalents.
 * Finally, <code>normalize</code> rearranges accents into the proper canonical
 * order, so that you do not have to worry about accent rearrangement on your
 * own.
 *
 * Form FCD, "Fast C or D", is also designed for collation.
 * It allows to work on strings that are not necessarily normalized
 * with an algorithm (like in collation) that works under "canonical closure",
 * i.e., it treats precomposed characters and their decomposed equivalents the
 * same.
 *
 * It is not a normalization form because it does not provide for uniqueness of
 * representation. Multiple strings may be canonically equivalent (their NFDs
 * are identical) and may all conform to FCD without being identical themselves.
 *
 * The form is defined such that the "raw decomposition", the recursive
 * canonical decomposition of each character, results in a string that is
 * canonically ordered. This means that precomposed characters are allowed for
 * as long as their decompositions do not need canonical reordering.
 *
 * Its advantage for a process like collation is that all NFD and most NFC texts
 * - and many unnormalized texts - already conform to FCD and do not need to be
 * normalized (NFD) for such a process. The FCD quick check will return YES for
 * most strings in practice.
 *
 * normalize(FCD) may be implemented with NFD.
 *
 * For more details on FCD see Unicode Technical Note #5 (Canonical Equivalence in Applications):
 * http://www.unicode.org/notes/tn5/#FCD
 *
 * ICU collation performs either NFD or FCD normalization automatically if
 * normalization is turned on for the collator object. Beyond collation and
 * string search, normalized strings may be useful for string equivalence
 * comparisons, transliteration/transcription, unique representations, etc.
 *
 * The W3C generally recommends to exchange texts in NFC.
 * Note also that most legacy character encodings use only precomposed forms and
 * often do not encode any combining marks by themselves. For conversion to such
 * character encodings the Unicode text needs to be normalized to NFC.
 * For more usage examples, see the Unicode Standard Annex.
 *
 * Note: The Normalizer class also provides API for iterative normalization.
 * While the setIndex() and getIndex() refer to indices in the
 * underlying Unicode input text, the next() and previous() methods
 * iterate through characters in the normalized output.
 * This means that there is not necessarily a one-to-one correspondence
 * between characters returned by next() and previous() and the indices
 * passed to and returned from setIndex() and getIndex().
 * It is for this reason that Normalizer does not implement the CharacterIterator interface.
 *
 * @stable ICU 2.8
 */
// Original filename in ICU4J: Normalizer.java
public final class NormalizerBase implements Cloneable {

    // The input text and our position in it
    private UCharacterIterator  text;
    private Normalizer2         norm2;
    private Mode                mode;
    private int                 options;

    // The normalization buffer is the result of normalization
    // of the source in [currentIndex..nextIndex] .
    private int                 currentIndex;
    private int                 nextIndex;

    // A buffer for holding intermediate results
    private StringBuilder       buffer;
    private int                 bufferPos;

    // Helper classes to defer loading of normalization data.
    private static final class ModeImpl {
        private ModeImpl(Normalizer2 n2) {
            normalizer2 = n2;
        }
        private final Normalizer2 normalizer2;
    }

    private static final class NFDModeImpl {
        private static final ModeImpl INSTANCE = new ModeImpl(Normalizer2.getNFDInstance());
    }

    private static final class NFKDModeImpl {
        private static final ModeImpl INSTANCE = new ModeImpl(Normalizer2.getNFKDInstance());
    }

    private static final class NFCModeImpl {
        private static final ModeImpl INSTANCE = new ModeImpl(Normalizer2.getNFCInstance());
    }

    private static final class NFKCModeImpl {
        private static final ModeImpl INSTANCE = new ModeImpl(Normalizer2.getNFKCInstance());
    }

    private static final class Unicode32 {
        private static final UnicodeSet INSTANCE = new UnicodeSet("[:age=3.2:]").freeze();
    }

    private static final class NFD32ModeImpl {
        private static final ModeImpl INSTANCE =
            new ModeImpl(new FilteredNormalizer2(Normalizer2.getNFDInstance(),
                                                 Unicode32.INSTANCE));
    }

    private static final class NFKD32ModeImpl {
        private static final ModeImpl INSTANCE =
            new ModeImpl(new FilteredNormalizer2(Normalizer2.getNFKDInstance(),
                                                 Unicode32.INSTANCE));
    }

    private static final class NFC32ModeImpl {
        private static final ModeImpl INSTANCE =
            new ModeImpl(new FilteredNormalizer2(Normalizer2.getNFCInstance(),
                                                 Unicode32.INSTANCE));
    }

    private static final class NFKC32ModeImpl {
        private static final ModeImpl INSTANCE =
            new ModeImpl(new FilteredNormalizer2(Normalizer2.getNFKCInstance(),
                                                 Unicode32.INSTANCE));
    }

    Options bit set value to select Unicode 3.2 normalization
(except NormalizationCorrections).
At most one Unicode version can be selected at a time.
@stable ICU 2.6/**
     * Options bit set value to select Unicode 3.2 normalization
     * (except NormalizationCorrections).
     * At most one Unicode version can be selected at a time.
     * @stable ICU 2.6
     */
    public static final int UNICODE_3_2=0x20;

    public static final int UNICODE_3_2_0_ORIGINAL=UNICODE_3_2;

    /*
     * Default option for the latest Unicode normalization. This option is
     * provided mainly for testing.
     * The value zero means that normalization is done with the fixes for
     *   - Corrigendum 4 (Five CJK Canonical Mapping Errors)
     *   - Corrigendum 5 (Normalization Idempotency)
     */
    public static final int UNICODE_LATEST = 0x00;

    Constant indicating that the end of the iteration has been reached. This is guaranteed to have the same value as UCharacterIterator.DONE. 
@stable ICU 2.8/**
     * Constant indicating that the end of the iteration has been reached.
     * This is guaranteed to have the same value as {@link UCharacterIterator#DONE}.
     * @stable ICU 2.8
     */
    public static final int DONE = UCharacterIterator.DONE;

    Constants for normalization modes.

The Mode class is not intended for public subclassing.
Only the Mode constants provided by the Normalizer class should be used,
and any fields or methods should not be called or overridden by users.
@stable ICU 2.8/**
     * Constants for normalization modes.
     * <p>
     * The Mode class is not intended for public subclassing.
     * Only the Mode constants provided by the Normalizer class should be used,
     * and any fields or methods should not be called or overridden by users.
     * @stable ICU 2.8
     */
    public abstract static class Mode {

        Sole constructor
@internal 
Deprecated: This API is ICU internal only./**
         * Sole constructor
         * @internal
         * @deprecated This API is ICU internal only.
         */
        @Deprecated
        protected Mode() {
        }

        @internal 
Deprecated: This API is ICU internal only./**
         * @internal
         * @deprecated This API is ICU internal only.
         */
        @Deprecated
        protected abstract Normalizer2 getNormalizer2(int options);
    }

    private static Mode toMode(Normalizer.Form form) {
        switch (form) {
        case NFC :
            return NFC;
        case NFD :
            return NFD;
        case NFKC :
            return NFKC;
        case NFKD :
            return NFKD;
        }

        throw new IllegalArgumentException("Unexpected normalization form: " +
                                           form);
    }

    private static final class NONEMode extends Mode {
        protected Normalizer2 getNormalizer2(int options) { return Norm2AllModes.NOOP_NORMALIZER2; }
    }

    private static final class NFDMode extends Mode {
        protected Normalizer2 getNormalizer2(int options) {
            return (options&UNICODE_3_2) != 0 ?
                    NFD32ModeImpl.INSTANCE.normalizer2 :
                    NFDModeImpl.INSTANCE.normalizer2;
        }
    }

    private static final class NFKDMode extends Mode {
        protected Normalizer2 getNormalizer2(int options) {
            return (options&UNICODE_3_2) != 0 ?
                    NFKD32ModeImpl.INSTANCE.normalizer2 :
                    NFKDModeImpl.INSTANCE.normalizer2;
        }
    }

    private static final class NFCMode extends Mode {
        protected Normalizer2 getNormalizer2(int options) {
            return (options&UNICODE_3_2) != 0 ?
                    NFC32ModeImpl.INSTANCE.normalizer2 :
                    NFCModeImpl.INSTANCE.normalizer2;
        }
    }

    private static final class NFKCMode extends Mode {
        protected Normalizer2 getNormalizer2(int options) {
            return (options&UNICODE_3_2) != 0 ?
                    NFKC32ModeImpl.INSTANCE.normalizer2 :
                    NFKCModeImpl.INSTANCE.normalizer2;
        }
    }

    No decomposition/composition.
@stable ICU 2.8/**
     * No decomposition/composition.
     * @stable ICU 2.8
     */
    public static final Mode NONE = new NONEMode();

    Canonical decomposition.
@stable ICU 2.8/**
     * Canonical decomposition.
     * @stable ICU 2.8
     */
    public static final Mode NFD = new NFDMode();

    Compatibility decomposition.
@stable ICU 2.8/**
     * Compatibility decomposition.
     * @stable ICU 2.8
     */
    public static final Mode NFKD = new NFKDMode();

    Canonical decomposition followed by canonical composition.
@stable ICU 2.8/**
     * Canonical decomposition followed by canonical composition.
     * @stable ICU 2.8
     */
    public static final Mode NFC = new NFCMode();

    public static final Mode NFKC =new NFKCMode();

    //-------------------------------------------------------------------------
    // Iterator constructors
    //-------------------------------------------------------------------------

    Creates a new NormalizerBase object for iterating over the normalized form of a given string.  The options parameter specifies which optional NormalizerBase features are to be enabled for this object. 

Params: str –  The string to be normalized.  The normalization
             will start at the beginning of the string.
mode – The normalization mode.
opt – Any optional features to be enabled. Currently the only available option is UNICODE_3_2. If you want the default behavior corresponding to one of the standard Unicode Normalization Forms, use 0 for this argument.
@stable ICU 2.6/**
     * Creates a new {@code NormalizerBase} object for iterating over the
     * normalized form of a given string.
     * <p>
     * The {@code options} parameter specifies which optional
     * {@code NormalizerBase} features are to be enabled for this object.
     * <p>
     * @param str  The string to be normalized.  The normalization
     *              will start at the beginning of the string.
     *
     * @param mode The normalization mode.
     *
     * @param opt Any optional features to be enabled.
     *            Currently the only available option is {@link #UNICODE_3_2}.
     *            If you want the default behavior corresponding to one of the
     *            standard Unicode Normalization Forms, use 0 for this argument.
     * @stable ICU 2.6
     */
    public NormalizerBase(String str, Mode mode, int opt) {
        this.text = UCharacterIterator.getInstance(str);
        this.mode = mode;
        this.options=opt;
        norm2 = mode.getNormalizer2(opt);
        buffer = new StringBuilder();
    }

    public NormalizerBase(String str, Mode mode) {
       this(str, mode, 0);
    }


    Creates a new NormalizerBase object for iterating over the normalized form of the given text. 
Params: iter –  The input text to be normalized.  The normalization
             will start at the beginning of the string.
mode –  The normalization mode.
opt – Any optional features to be enabled. Currently the only available option is UNICODE_3_2. If you want the default behavior corresponding to one of the standard Unicode Normalization Forms, use 0 for this argument.
@stable ICU 2.6/**
     * Creates a new {@code NormalizerBase} object for iterating over the
     * normalized form of the given text.
     * <p>
     * @param iter  The input text to be normalized.  The normalization
     *              will start at the beginning of the string.
     *
     * @param mode  The normalization mode.
     *
     * @param opt Any optional features to be enabled.
     *            Currently the only available option is {@link #UNICODE_3_2}.
     *            If you want the default behavior corresponding to one of the
     *            standard Unicode Normalization Forms, use 0 for this argument.
     * @stable ICU 2.6
     */
    public NormalizerBase(CharacterIterator iter, Mode mode, int opt) {
        this.text = UCharacterIterator.getInstance((CharacterIterator)iter.clone());
        this.mode = mode;
        this.options = opt;
        norm2 = mode.getNormalizer2(opt);
        buffer = new StringBuilder();
    }

    public NormalizerBase(CharacterIterator iter, Mode mode) {
       this(iter, mode, 0);
    }

    Clones this NormalizerBase object. All properties of this object are duplicated in the new object, including the cloning of any CharacterIterator that was passed in to the constructor or to setText. However, the text storage underlying the CharacterIterator is not duplicated unless the iterator's clone method does so. 
@stable ICU 2.8/**
     * Clones this {@code NormalizerBase} object.  All properties of this
     * object are duplicated in the new object, including the cloning of any
     * {@link CharacterIterator} that was passed in to the constructor
     * or to {@link #setText(CharacterIterator) setText}.
     * However, the text storage underlying
     * the {@code CharacterIterator} is not duplicated unless the
     * iterator's {@code clone} method does so.
     * @stable ICU 2.8
     */
    public Object clone() {
        try {
            NormalizerBase copy = (NormalizerBase) super.clone();
            copy.text = (UCharacterIterator) text.clone();
            copy.mode = mode;
            copy.options = options;
            copy.norm2 = norm2;
            copy.buffer = new StringBuilder(buffer);
            copy.bufferPos = bufferPos;
            copy.currentIndex = currentIndex;
            copy.nextIndex = nextIndex;
            return copy;
        }
        catch (CloneNotSupportedException e) {
            throw new InternalError(e.toString(), e);
        }
    }

    Normalizes a String using the given normalization operation.  The options parameter specifies which optional NormalizerBase features are to be enabled for this operation. Currently the only available option is UNICODE_3_2. If you want the default behavior corresponding to one of the standard Unicode Normalization Forms, use 0 for this argument. 

Params: str –       the input string to be normalized.
mode –      the normalization mode
options –   the optional features to be enabled.
Returns: String   the normalized string
@stable ICU 2.6/**
     * Normalizes a {@code String} using the given normalization operation.
     * <p>
     * The {@code options} parameter specifies which optional
     * {@code NormalizerBase} features are to be enabled for this operation.
     * Currently the only available option is {@link #UNICODE_3_2}.
     * If you want the default behavior corresponding to one of the standard
     * Unicode Normalization Forms, use 0 for this argument.
     * <p>
     * @param str       the input string to be normalized.
     * @param mode      the normalization mode
     * @param options   the optional features to be enabled.
     * @return String   the normalized string
     * @stable ICU 2.6
     */
    public static String normalize(String str, Mode mode, int options) {
        return mode.getNormalizer2(options).normalize(str);
    }

    public static String normalize(String str, Normalizer.Form form) {
        return NormalizerBase.normalize(str, toMode(form), UNICODE_LATEST);
    }

    public static String normalize(String str, Normalizer.Form form, int options) {
        return NormalizerBase.normalize(str, toMode(form), options);
    }

    Test if a string is in a given normalization form.
This is semantically equivalent to source.equals(normalize(source, mode)).
Unlike quickCheck(), this function returns a definitive result,
never a "maybe".
For NFD, NFKD, and FCD, both functions work exactly the same.
For NFC and NFKC where quickCheck may return "maybe", this function will
perform further tests to arrive at a true/false result.
Params: str –       the input string to be checked to see if it is
                  normalized
mode –      the normalization mode
options –   Options for use with exclusion set and tailored Normalization
                 The only option that is currently recognized is UNICODE_3_2
See Also: isNormalized
@stable ICU 2.6/**
     * Test if a string is in a given normalization form.
     * This is semantically equivalent to source.equals(normalize(source, mode)).
     *
     * Unlike quickCheck(), this function returns a definitive result,
     * never a "maybe".
     * For NFD, NFKD, and FCD, both functions work exactly the same.
     * For NFC and NFKC where quickCheck may return "maybe", this function will
     * perform further tests to arrive at a true/false result.
     * @param str       the input string to be checked to see if it is
     *                   normalized
     * @param mode      the normalization mode
     * @param options   Options for use with exclusion set and tailored Normalization
     *                  The only option that is currently recognized is UNICODE_3_2
     * @see #isNormalized
     * @stable ICU 2.6
     */
    public static boolean isNormalized(String str, Mode mode, int options) {
        return mode.getNormalizer2(options).isNormalized(str);
    }

    public static boolean isNormalized(String str, Normalizer.Form form) {
        return NormalizerBase.isNormalized(str, toMode(form), UNICODE_LATEST);
    }

    public static boolean isNormalized(String str, Normalizer.Form form, int options) {
        return NormalizerBase.isNormalized(str, toMode(form), options);
    }

    //-------------------------------------------------------------------------
    // Iteration API
    //-------------------------------------------------------------------------

    Return the current character in the normalized text.
Returns: The codepoint as an int
@stable ICU 2.8/**
     * Return the current character in the normalized text.
     * @return The codepoint as an int
     * @stable ICU 2.8
     */
    public int current() {
        if(bufferPos<buffer.length() || nextNormalize()) {
            return buffer.codePointAt(bufferPos);
        } else {
            return DONE;
        }
    }

    Return the next character in the normalized text and advance the iteration position by one. If the end of the text has already been reached, DONE is returned. 
Returns: The codepoint as an int
@stable ICU 2.8/**
     * Return the next character in the normalized text and advance
     * the iteration position by one.  If the end
     * of the text has already been reached, {@link #DONE} is returned.
     * @return The codepoint as an int
     * @stable ICU 2.8
     */
    public int next() {
        if(bufferPos<buffer.length() ||  nextNormalize()) {
            int c=buffer.codePointAt(bufferPos);
            bufferPos+=Character.charCount(c);
            return c;
        } else {
            return DONE;
        }
    }

    Return the previous character in the normalized text and decrement the iteration position by one. If the beginning of the text has already been reached, DONE is returned. 
Returns: The codepoint as an int
@stable ICU 2.8/**
     * Return the previous character in the normalized text and decrement
     * the iteration position by one.  If the beginning
     * of the text has already been reached, {@link #DONE} is returned.
     * @return The codepoint as an int
     * @stable ICU 2.8
     */
    public int previous() {
        if(bufferPos>0 || previousNormalize()) {
            int c=buffer.codePointBefore(bufferPos);
            bufferPos-=Character.charCount(c);
            return c;
        } else {
            return DONE;
        }
    }

    Reset the index to the beginning of the text.
This is equivalent to setIndexOnly(startIndex)).
@stable ICU 2.8/**
     * Reset the index to the beginning of the text.
     * This is equivalent to setIndexOnly(startIndex)).
     * @stable ICU 2.8
     */
    public void reset() {
        text.setIndex(0);
        currentIndex=nextIndex=0;
        clearBuffer();
    }

    Set the iteration position in the input text that is being normalized,
without any immediate normalization.
After setIndexOnly(), getIndex() will return the same index that is
specified here.
Params: index – the desired index in the input text.
@stable ICU 2.8/**
     * Set the iteration position in the input text that is being normalized,
     * without any immediate normalization.
     * After setIndexOnly(), getIndex() will return the same index that is
     * specified here.
     *
     * @param index the desired index in the input text.
     * @stable ICU 2.8
     */
    public void setIndexOnly(int index) {
        text.setIndex(index);  // validates index
        currentIndex=nextIndex=index;
        clearBuffer();
    }

    Set the iteration position in the input text that is being normalized
and return the first normalized character at that position.

Note: This method sets the position in the input text, while next and previous iterate through characters in the normalized output. This means that there is not necessarily a one-to-one correspondence between characters returned by next and previous and the indices passed to and returned from setIndex and getIndex. 

Params: index – the desired index in the input text.
Throws: IllegalArgumentException – if the given index is less than getBeginIndex or greater than getEndIndex. deprecated ICU 3.2
Returns:   the first normalized character that is the result of iterating
           forward starting at the given index.
@obsolete ICU 3.2/**
     * Set the iteration position in the input text that is being normalized
     * and return the first normalized character at that position.
     * <p>
     * <b>Note:</b> This method sets the position in the <em>input</em> text,
     * while {@link #next} and {@link #previous} iterate through characters
     * in the normalized <em>output</em>.  This means that there is not
     * necessarily a one-to-one correspondence between characters returned
     * by {@code next} and {@code previous} and the indices passed to and
     * returned from {@code setIndex} and {@link #getIndex}.
     * <p>
     * @param index the desired index in the input text.
     *
     * @return   the first normalized character that is the result of iterating
     *            forward starting at the given index.
     *
     * @throws IllegalArgumentException if the given index is less than
     *          {@link #getBeginIndex} or greater than {@link #getEndIndex}.
     * deprecated ICU 3.2
     * @obsolete ICU 3.2
     */
     public int setIndex(int index) {
         setIndexOnly(index);
         return current();
     }

    Retrieve the index of the start of the input text. This is the begin index of the CharacterIterator or the start (i.e. 0) of the String over which this NormalizerBase is iterating 
See Also: startIndex
Deprecated: ICU 2.2. Use startIndex() instead.
Returns: The codepoint as an int/**
     * Retrieve the index of the start of the input text. This is the begin
     * index of the {@code CharacterIterator} or the start (i.e. 0) of the
     * {@code String} over which this {@code NormalizerBase} is iterating
     * @deprecated ICU 2.2. Use startIndex() instead.
     * @return The codepoint as an int
     * @see #startIndex
     */
    @Deprecated
    public int getBeginIndex() {
        return 0;
    }

    Retrieve the index of the end of the input text. This is the end index of the CharacterIterator or the length of the String over which this NormalizerBase is iterating 
See Also: endIndex
Deprecated: ICU 2.2. Use endIndex() instead.
Returns: The codepoint as an int/**
     * Retrieve the index of the end of the input text.  This is the end index
     * of the {@code CharacterIterator} or the length of the {@code String}
     * over which this {@code NormalizerBase} is iterating
     * @deprecated ICU 2.2. Use endIndex() instead.
     * @return The codepoint as an int
     * @see #endIndex
     */
    @Deprecated
    public int getEndIndex() {
        return endIndex();
    }

    Retrieve the current iteration position in the input text that is
being normalized.  This method is useful in applications such as
searching, where you need to be able to determine the position in
the input text that corresponds to a given normalized output character.

Note: This method sets the position in the input, while next and previous iterate through characters in the output. This means that there is not necessarily a one-to-one correspondence between characters returned by next and previous and the indices passed to and returned from setIndex and getIndex. 
Returns: The current iteration position
@stable ICU 2.8/**
     * Retrieve the current iteration position in the input text that is
     * being normalized.  This method is useful in applications such as
     * searching, where you need to be able to determine the position in
     * the input text that corresponds to a given normalized output character.
     * <p>
     * <b>Note:</b> This method sets the position in the <em>input</em>, while
     * {@link #next} and {@link #previous} iterate through characters in the
     * <em>output</em>.  This means that there is not necessarily a one-to-one
     * correspondence between characters returned by {@code next} and
     * {@code previous} and the indices passed to and returned from
     * {@code setIndex} and {@link #getIndex}.
     * @return The current iteration position
     * @stable ICU 2.8
     */
    public int getIndex() {
        if(bufferPos<buffer.length()) {
            return currentIndex;
        } else {
            return nextIndex;
        }
    }

    Retrieve the index of the end of the input text. This is the end index of the CharacterIterator or the length of the String over which this NormalizerBase is iterating 
Returns: The current iteration position
@stable ICU 2.8/**
     * Retrieve the index of the end of the input text.  This is the end index
     * of the {@code CharacterIterator} or the length of the {@code String}
     * over which this {@code NormalizerBase} is iterating
     * @return The current iteration position
     * @stable ICU 2.8
     */
    public int endIndex() {
        return text.getLength();
    }

    //-------------------------------------------------------------------------
    // Iterator attributes
    //-------------------------------------------------------------------------
    Set the normalization mode for this object.

Note:If the normalization mode is changed while iterating over a string, calls to next and previous may return previously buffers characters in the old normalization mode until the iteration is able to re-sync at the next base character. It is safest to call setText(), first, last, etc. after calling setMode. 

Params: newMode – the new mode for this NormalizerBase. The supported modes are: 
 NFC - Unicode canonical decompositiion followed by canonical composition. 
NFKC - Unicode compatibility decompositiion follwed by canonical composition. 
NFD - Unicode canonical decomposition 
NFKD - Unicode compatibility decomposition. 
NONE - Do nothing but return characters from the underlying input text. 
See Also: getMode
@stable ICU 2.8/**
     * Set the normalization mode for this object.
     * <p>
     * <b>Note:</b>If the normalization mode is changed while iterating
     * over a string, calls to {@link #next} and {@link #previous} may
     * return previously buffers characters in the old normalization mode
     * until the iteration is able to re-sync at the next base character.
     * It is safest to call {@link #setText setText()}, {@link #first},
     * {@link #last}, etc. after calling {@code setMode}.
     * <p>
     * @param newMode the new mode for this {@code NormalizerBase}.
     * The supported modes are:
     * <ul>
     *  <li>{@link #NFC}    - Unicode canonical decompositiion
     *                        followed by canonical composition.
     *  <li>{@link #NFKC}   - Unicode compatibility decompositiion
     *                        follwed by canonical composition.
     *  <li>{@link #NFD}    - Unicode canonical decomposition
     *  <li>{@link #NFKD}   - Unicode compatibility decomposition.
     *  <li>{@link #NONE}   - Do nothing but return characters
     *                        from the underlying input text.
     * </ul>
     *
     * @see #getMode
     * @stable ICU 2.8
     */
    public void setMode(Mode newMode) {
        mode = newMode;
        norm2 = mode.getNormalizer2(options);
    }

    Return the basic operation performed by this NormalizerBase 
See Also: setMode
@stable ICU 2.8/**
     * Return the basic operation performed by this {@code NormalizerBase}
     *
     * @see #setMode
     * @stable ICU 2.8
     */
    public Mode getMode() {
        return mode;
    }

    Set the input text over which this NormalizerBase will iterate. The iteration position is set to the beginning of the input text. 
Params: newText –   The new string to be normalized.
@stable ICU 2.8/**
     * Set the input text over which this {@code NormalizerBase} will iterate.
     * The iteration position is set to the beginning of the input text.
     * @param newText   The new string to be normalized.
     * @stable ICU 2.8
     */
    public void setText(String newText) {
        UCharacterIterator newIter = UCharacterIterator.getInstance(newText);
        if (newIter == null) {
            throw new IllegalStateException("Could not create a new UCharacterIterator");
        }
        text = newIter;
        reset();
    }

    Set the input text over which this NormalizerBase will iterate. The iteration position is set to the beginning of the input text. 
Params: newText –   The new string to be normalized.
@stable ICU 2.8/**
     * Set the input text over which this {@code NormalizerBase} will iterate.
     * The iteration position is set to the beginning of the input text.
     * @param newText   The new string to be normalized.
     * @stable ICU 2.8
     */
    public void setText(CharacterIterator newText) {
        UCharacterIterator newIter = UCharacterIterator.getInstance(newText);
        if (newIter == null) {
            throw new IllegalStateException("Could not create a new UCharacterIterator");
        }
        text = newIter;
        currentIndex=nextIndex=0;
        clearBuffer();
    }

    private void clearBuffer() {
        buffer.setLength(0);
        bufferPos=0;
    }

    private boolean nextNormalize() {
        clearBuffer();
        currentIndex=nextIndex;
        text.setIndex(nextIndex);
        // Skip at least one character so we make progress.
        int c=text.nextCodePoint();
        if(c<0) {
            return false;
        }
        StringBuilder segment=new StringBuilder().appendCodePoint(c);
        while((c=text.nextCodePoint())>=0) {
            if(norm2.hasBoundaryBefore(c)) {
                text.moveCodePointIndex(-1);
                break;
            }
            segment.appendCodePoint(c);
        }
        nextIndex=text.getIndex();
        norm2.normalize(segment, buffer);
        return buffer.length()!=0;
    }

    private boolean previousNormalize() {
        clearBuffer();
        nextIndex=currentIndex;
        text.setIndex(currentIndex);
        StringBuilder segment=new StringBuilder();
        int c;
        while((c=text.previousCodePoint())>=0) {
            if(c<=0xffff) {
                segment.insert(0, (char)c);
            } else {
                segment.insert(0, Character.toChars(c));
            }
            if(norm2.hasBoundaryBefore(c)) {
                break;
            }
        }
        currentIndex=text.getIndex();
        norm2.normalize(segment, buffer);
        bufferPos=buffer.length();
        return buffer.length()!=0;
    }

}
Params:	str – The string to be normalized. The normalization will start at the beginning of the string. mode – The normalization mode. opt – Any optional features to be enabled. Currently the only available option is `UNICODE_3_2`. If you want the default behavior corresponding to one of the standard Unicode Normalization Forms, use 0 for this argument.
@stable	ICU 2.6
Params:	iter – The input text to be normalized. The normalization will start at the beginning of the string. mode – The normalization mode. opt – Any optional features to be enabled. Currently the only available option is `UNICODE_3_2`. If you want the default behavior corresponding to one of the standard Unicode Normalization Forms, use 0 for this argument.
@stable	ICU 2.6
Params:	str – the input string to be normalized. mode – the normalization mode options – the optional features to be enabled.
Returns:	String the normalized string
@stable	ICU 2.6
Params:	str – the input string to be checked to see if it is normalized mode – the normalization mode options – Options for use with exclusion set and tailored Normalization The only option that is currently recognized is UNICODE_3_2
See Also:	isNormalized
@stable	ICU 2.6
Params:	index – the desired index in the input text.
@stable	ICU 2.8
Params:	index – the desired index in the input text.
Throws:	IllegalArgumentException – if the given index is less than `getBeginIndex` or greater than `getEndIndex`. deprecated ICU 3.2
Returns:	the first normalized character that is the result of iterating forward starting at the given index.
@obsolete	ICU 3.2
See Also:	startIndex
Deprecated:	ICU 2.2. Use startIndex() instead.
Returns:	The codepoint as an int
See Also:	endIndex
Deprecated:	ICU 2.2. Use endIndex() instead.
Returns:	The codepoint as an int
Params:	newMode – the new mode for this `NormalizerBase`. The supported modes are: `NFC` - Unicode canonical decompositiion followed by canonical composition. `NFKC` - Unicode compatibility decompositiion follwed by canonical composition. `NFD` - Unicode canonical decomposition `NFKD` - Unicode compatibility decomposition. `NONE` - Do nothing but return characters from the underlying input text.
See Also:	getMode
@stable	ICU 2.8
Params:	newText – The new string to be normalized.
@stable	ICU 2.8
/

java/ 11/ java.base/sun/text/normalizer/NormalizerBase.java

Unicode normalization API
