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 * 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
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/*
 *******************************************************************************
 *   Copyright (C) 2009-2014, International Business Machines
 *   Corporation and others.  All Rights Reserved.
 *******************************************************************************
 */

package sun.text.normalizer;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.text.Normalizer;

// Original filename in ICU4J: Normalizer2Impl.java
public final class NormalizerImpl {

    public static final class Hangul {
        /* Korean Hangul and Jamo constants */
        public static final int JAMO_L_BASE=0x1100;     /* "lead" jamo */
        public static final int JAMO_V_BASE=0x1161;     /* "vowel" jamo */
        public static final int JAMO_T_BASE=0x11a7;     /* "trail" jamo */

        public static final int HANGUL_BASE=0xac00;
        public static final int HANGUL_END=0xd7a3;

        public static final int JAMO_L_COUNT=19;
        public static final int JAMO_V_COUNT=21;
        public static final int JAMO_T_COUNT=28;

        public static final int HANGUL_COUNT=JAMO_L_COUNT*JAMO_V_COUNT*JAMO_T_COUNT;
        public static final int HANGUL_LIMIT=HANGUL_BASE+HANGUL_COUNT;

        public static boolean isHangul(int c) {
            return HANGUL_BASE<=c && c<HANGUL_LIMIT;
        }

        public static boolean isHangulWithoutJamoT(char c) {
            c-=HANGUL_BASE;
            return c<HANGUL_COUNT && c%JAMO_T_COUNT==0;
        }

        
Decomposes c, which must be a Hangul syllable, into buffer
and returns the length of the decomposition (2 or 3).
/**
         * Decomposes c, which must be a Hangul syllable, into buffer
         * and returns the length of the decomposition (2 or 3).
         */
        public static int decompose(int c, Appendable buffer) {
            try {
                c-=HANGUL_BASE;
                int c2=c%JAMO_T_COUNT;
                c/=JAMO_T_COUNT;
                buffer.append((char)(JAMO_L_BASE+c/JAMO_V_COUNT));
                buffer.append((char)(JAMO_V_BASE+c%JAMO_V_COUNT));
                if(c2==0) {
                    return 2;
                } else {
                    buffer.append((char)(JAMO_T_BASE+c2));
                    return 3;
                }
            } catch(IOException e) {
                throw new InternalError(e);
            }
        }
    }

    
Writable buffer that takes care of canonical ordering.
Its Appendable methods behave like the C++ implementation's
appendZeroCC() methods.

If dest is a StringBuilder, then the buffer writes directly to it.
Otherwise, the buffer maintains a StringBuilder for intermediate text segments
until no further changes are necessary and whole segments are appended.
append() methods that take combining-class values always write to the StringBuilder.
Other append() methods flush and append to the Appendable.
/**
     * Writable buffer that takes care of canonical ordering.
     * Its Appendable methods behave like the C++ implementation's
     * appendZeroCC() methods.
     * <p>
     * If dest is a StringBuilder, then the buffer writes directly to it.
     * Otherwise, the buffer maintains a StringBuilder for intermediate text segments
     * until no further changes are necessary and whole segments are appended.
     * append() methods that take combining-class values always write to the StringBuilder.
     * Other append() methods flush and append to the Appendable.
     */
    public static final class ReorderingBuffer implements Appendable {
        public ReorderingBuffer(NormalizerImpl ni, Appendable dest, int destCapacity) {
            impl=ni;
            app=dest;
            if (app instanceof StringBuilder) {
                appIsStringBuilder=true;
                str=(StringBuilder)dest;
                // In Java, the constructor subsumes public void init(int destCapacity)
                str.ensureCapacity(destCapacity);
                reorderStart=0;
                if(str.length()==0) {
                    lastCC=0;
                } else {
                    setIterator();
                    lastCC=previousCC();
                    // Set reorderStart after the last code point with cc<=1 if there is one.
                    if(lastCC>1) {
                        while(previousCC()>1) {}
                    }
                    reorderStart=codePointLimit;
                }
            } else {
                appIsStringBuilder=false;
                str=new StringBuilder();
                reorderStart=0;
                lastCC=0;
            }
        }

        public boolean isEmpty() { return str.length()==0; }
        public int length() { return str.length(); }
        public int getLastCC() { return lastCC; }

        public StringBuilder getStringBuilder() { return str; }

        public boolean equals(CharSequence s, int start, int limit) {
            return UTF16Plus.equal(str, 0, str.length(), s, start, limit);
        }

        // For Hangul composition, replacing the Leading consonant Jamo with the syllable.
        public void setLastChar(char c) {
            str.setCharAt(str.length()-1, c);
        }

        public void append(int c, int cc) {
            if(lastCC<=cc || cc==0) {
                str.appendCodePoint(c);
                lastCC=cc;
                if(cc<=1) {
                    reorderStart=str.length();
                }
            } else {
                insert(c, cc);
            }
        }

        // s must be in NFD, otherwise change the implementation.
        public void append(CharSequence s, int start, int limit,
                           int leadCC, int trailCC) {
            if(start==limit) {
                return;
            }
            if(lastCC<=leadCC || leadCC==0) {
                if(trailCC<=1) {
                    reorderStart=str.length()+(limit-start);
                } else if(leadCC<=1) {
                    reorderStart=str.length()+1;  // Ok if not a code point boundary.
                }
                str.append(s, start, limit);
                lastCC=trailCC;
            } else {
                int c=Character.codePointAt(s, start);
                start+=Character.charCount(c);
                insert(c, leadCC);  // insert first code point
                while(start<limit) {
                    c=Character.codePointAt(s, start);
                    start+=Character.charCount(c);
                    if(start<limit) {
                        // s must be in NFD, otherwise we need to use getCC().
                        leadCC=getCCFromYesOrMaybe(impl.getNorm16(c));
                    } else {
                        leadCC=trailCC;
                    }
                    append(c, leadCC);
                }
            }
        }

        // The following append() methods work like C++ appendZeroCC().
        // They assume that the cc or trailCC of their input is 0.
        // Most of them implement Appendable interface methods.
        // @Override when we switch to Java 6
        public ReorderingBuffer append(char c) {
            str.append(c);
            lastCC=0;
            reorderStart=str.length();
            return this;
        }

        public void appendZeroCC(int c) {
            str.appendCodePoint(c);
            lastCC=0;
            reorderStart=str.length();
        }

        // @Override when we switch to Java 6
        public ReorderingBuffer append(CharSequence s) {
            if(s.length()!=0) {
                str.append(s);
                lastCC=0;
                reorderStart=str.length();
            }
            return this;
        }

        // @Override when we switch to Java 6
        public ReorderingBuffer append(CharSequence s, int start, int limit) {
            if(start!=limit) {
                str.append(s, start, limit);
                lastCC=0;
                reorderStart=str.length();
            }
            return this;
        }

        
Flushes from the intermediate StringBuilder to the Appendable,
if they are different objects.
Used after recomposition.
Must be called at the end when writing to a non-StringBuilder Appendable.
/**
         * Flushes from the intermediate StringBuilder to the Appendable,
         * if they are different objects.
         * Used after recomposition.
         * Must be called at the end when writing to a non-StringBuilder Appendable.
         */
        public void flush() {
            if(appIsStringBuilder) {
                reorderStart=str.length();
            } else {
                try {
                    app.append(str);
                    str.setLength(0);
                    reorderStart=0;
                } catch(IOException e) {
                    throw new InternalError(e);  // Avoid declaring "throws IOException".
                }
            }
            lastCC=0;
        }

        
Flushes from the intermediate StringBuilder to the Appendable,
if they are different objects.
Then appends the new text to the Appendable or StringBuilder.
Normally used after quick check loops find a non-empty sequence.
/**
         * Flushes from the intermediate StringBuilder to the Appendable,
         * if they are different objects.
         * Then appends the new text to the Appendable or StringBuilder.
         * Normally used after quick check loops find a non-empty sequence.
         */
        public ReorderingBuffer flushAndAppendZeroCC(CharSequence s, int start, int limit) {
            if(appIsStringBuilder) {
                str.append(s, start, limit);
                reorderStart=str.length();
            } else {
                try {
                    app.append(str).append(s, start, limit);
                    str.setLength(0);
                    reorderStart=0;
                } catch(IOException e) {
                    throw new InternalError(e);  // Avoid declaring "throws IOException".
                }
            }
            lastCC=0;
            return this;
        }

        public void remove() {
            str.setLength(0);
            lastCC=0;
            reorderStart=0;
        }

        public void removeSuffix(int suffixLength) {
            int oldLength=str.length();
            str.delete(oldLength-suffixLength, oldLength);
            lastCC=0;
            reorderStart=str.length();
        }

        // Inserts c somewhere before the last character.
        // Requires 0<cc<lastCC which implies reorderStart<limit.
        private void insert(int c, int cc) {
            for(setIterator(), skipPrevious(); previousCC()>cc;) {}
            // insert c at codePointLimit, after the character with prevCC<=cc
            if(c<=0xffff) {
                str.insert(codePointLimit, (char)c);
                if(cc<=1) {
                    reorderStart=codePointLimit+1;
                }
            } else {
                str.insert(codePointLimit, Character.toChars(c));
                if(cc<=1) {
                    reorderStart=codePointLimit+2;
                }
            }
        }

        private final NormalizerImpl impl;
        private final Appendable app;
        private final StringBuilder str;
        private final boolean appIsStringBuilder;
        private int reorderStart;
        private int lastCC;

        // private backward iterator
        private void setIterator() { codePointStart=str.length(); }
        private void skipPrevious() {  // Requires 0<codePointStart.
            codePointLimit=codePointStart;
            codePointStart=str.offsetByCodePoints(codePointStart, -1);
        }
        private int previousCC() {  // Returns 0 if there is no previous character.
            codePointLimit=codePointStart;
            if(reorderStart>=codePointStart) {
                return 0;
            }
            int c=str.codePointBefore(codePointStart);
            codePointStart-=Character.charCount(c);
            if(c<MIN_CCC_LCCC_CP) {
                return 0;
            }
            return getCCFromYesOrMaybe(impl.getNorm16(c));
        }

        private int codePointStart, codePointLimit;
    }

    // TODO: Propose as public API on the UTF16 class.
    // TODO: Propose widening UTF16 methods that take char to take int.
    // TODO: Propose widening UTF16 methods that take String to take CharSequence.
    public static final class UTF16Plus {
        
Assuming c is a surrogate code point (UTF16.isSurrogate(c)),
is it a lead surrogate?
Params:
c – code unit or code point
Returns:
true or false/**
         * Assuming c is a surrogate code point (UTF16.isSurrogate(c)),
         * is it a lead surrogate?
         * @param c code unit or code point
         * @return true or false
         */
        public static boolean isSurrogateLead(int c) { return (c&0x400)==0; }

        
Compares two CharSequence subsequences for binary equality.
Params:
s1 – first sequence
start1 – start offset in first sequence
limit1 – limit offset in first sequence
s2 – second sequence
start2 – start offset in second sequence
limit2 – limit offset in second sequence
Returns:
true if s1.subSequence(start1, limit1) contains the same text
             as s2.subSequence(start2, limit2)/**
         * Compares two CharSequence subsequences for binary equality.
         * @param s1 first sequence
         * @param start1 start offset in first sequence
         * @param limit1 limit offset in first sequence
         * @param s2 second sequence
         * @param start2 start offset in second sequence
         * @param limit2 limit offset in second sequence
         * @return true if s1.subSequence(start1, limit1) contains the same text
         *              as s2.subSequence(start2, limit2)
         */
        public static boolean equal(CharSequence s1, int start1, int limit1,
                                    CharSequence s2, int start2, int limit2) {
            if((limit1-start1)!=(limit2-start2)) {
                return false;
            }
            if(s1==s2 && start1==start2) {
                return true;
            }
            while(start1<limit1) {
                if(s1.charAt(start1++)!=s2.charAt(start2++)) {
                    return false;
                }
            }
            return true;
        }
    }

    public NormalizerImpl() {}

    private static final class IsAcceptable implements ICUBinary.Authenticate {
        // @Override when we switch to Java 6
        public boolean isDataVersionAcceptable(byte version[]) {
            return version[0]==2;
        }
    }

    private static final IsAcceptable IS_ACCEPTABLE = new IsAcceptable();
    private static final int DATA_FORMAT = 0x4e726d32;  // "Nrm2"

    public NormalizerImpl load(ByteBuffer bytes) {
        try {
            dataVersion=ICUBinary.readHeaderAndDataVersion(bytes, DATA_FORMAT, IS_ACCEPTABLE);
            int indexesLength=bytes.getInt()/4;  // inIndexes[IX_NORM_TRIE_OFFSET]/4
            if(indexesLength<=IX_MIN_MAYBE_YES) {
                throw new IOException("Normalizer2 data: not enough indexes");
            }
            int[] inIndexes=new int[indexesLength];
            inIndexes[0]=indexesLength*4;
            for(int i=1; i<indexesLength; ++i) {
                inIndexes[i]=bytes.getInt();
            }

            minDecompNoCP=inIndexes[IX_MIN_DECOMP_NO_CP];
            minCompNoMaybeCP=inIndexes[IX_MIN_COMP_NO_MAYBE_CP];

            minYesNo=inIndexes[IX_MIN_YES_NO];
            minYesNoMappingsOnly=inIndexes[IX_MIN_YES_NO_MAPPINGS_ONLY];
            minNoNo=inIndexes[IX_MIN_NO_NO];
            limitNoNo=inIndexes[IX_LIMIT_NO_NO];
            minMaybeYes=inIndexes[IX_MIN_MAYBE_YES];

            // Read the normTrie.
            int offset=inIndexes[IX_NORM_TRIE_OFFSET];
            int nextOffset=inIndexes[IX_EXTRA_DATA_OFFSET];
            normTrie=Trie2_16.createFromSerialized(bytes);
            int trieLength=normTrie.getSerializedLength();
            if(trieLength>(nextOffset-offset)) {
                throw new IOException("Normalizer2 data: not enough bytes for normTrie");
            }
            ICUBinary.skipBytes(bytes, (nextOffset-offset)-trieLength);  // skip padding after trie bytes

            // Read the composition and mapping data.
            offset=nextOffset;
            nextOffset=inIndexes[IX_SMALL_FCD_OFFSET];
            int numChars=(nextOffset-offset)/2;
            char[] chars;
            if(numChars!=0) {
                chars=new char[numChars];
                for(int i=0; i<numChars; ++i) {
                    chars[i]=bytes.getChar();
                }
                maybeYesCompositions=new String(chars);
                extraData=maybeYesCompositions.substring(MIN_NORMAL_MAYBE_YES-minMaybeYes);
            }

            // smallFCD: new in formatVersion 2
            offset=nextOffset;
            smallFCD=new byte[0x100];
            for(int i=0; i<0x100; ++i) {
                smallFCD[i]=bytes.get();
            }

            // Build tccc180[].
            // gennorm2 enforces lccc=0 for c<MIN_CCC_LCCC_CP=U+0300.
            tccc180=new int[0x180];
            int bits=0;
            for(int c=0; c<0x180; bits>>=1) {
                if((c&0xff)==0) {
                    bits=smallFCD[c>>8];  // one byte per 0x100 code points
                }
                if((bits&1)!=0) {
                    for(int i=0; i<0x20; ++i, ++c) {
                        tccc180[c]=getFCD16FromNormData(c)&0xff;
                    }
                } else {
                    c+=0x20;
                }
            }

            return this;
        } catch(IOException e) {
            throw new InternalError(e);
        }
    }

    public NormalizerImpl load(String name) {
        return load(ICUBinary.getRequiredData(name));
    }

    public int getNorm16(int c) {
        return normTrie.get(c);
    }

    public boolean isDecompYes(int norm16) { return norm16<minYesNo || minMaybeYes<=norm16; }

    public int getCC(int norm16) {
        if(norm16>=MIN_NORMAL_MAYBE_YES) {
            return norm16&0xff;
        }
        if(norm16<minNoNo || limitNoNo<=norm16) {
            return 0;
        }
        return getCCFromNoNo(norm16);
    }

    public static int getCCFromYesOrMaybe(int norm16) {
        return norm16>=MIN_NORMAL_MAYBE_YES ? norm16&0xff : 0;
    }

    
Returns the FCD data for code point c.
Params:
c – A Unicode code point.
Returns:
The lccc(c) in bits 15..8 and tccc(c) in bits 7..0./**
     * Returns the FCD data for code point c.
     * @param c A Unicode code point.
     * @return The lccc(c) in bits 15..8 and tccc(c) in bits 7..0.
     */
    public int getFCD16(int c) {
        if(c<0) {
            return 0;
        } else if(c<0x180) {
            return tccc180[c];
        } else if(c<=0xffff) {
            if(!singleLeadMightHaveNonZeroFCD16(c)) { return 0; }
        }
        return getFCD16FromNormData(c);
    }

    
Returns the FCD data for U+0000<=c/** Returns the FCD data for U+0000<=c<U+0180. */
    public int getFCD16FromBelow180(int c) { return tccc180[c]; }
    
Returns true if the single-or-lead code unit c might have non-zero FCD data. /** Returns true if the single-or-lead code unit c might have non-zero FCD data. */
    public boolean singleLeadMightHaveNonZeroFCD16(int lead) {
        // 0<=lead<=0xffff
        byte bits=smallFCD[lead>>8];
        if(bits==0) { return false; }
        return ((bits>>((lead>>5)&7))&1)!=0;
    }

    
Gets the FCD value from the regular normalization data. /** Gets the FCD value from the regular normalization data. */
    public int getFCD16FromNormData(int c) {
        // Only loops for 1:1 algorithmic mappings.
        for(;;) {
            int norm16=getNorm16(c);
            if(norm16<=minYesNo) {
                // no decomposition or Hangul syllable, all zeros
                return 0;
            } else if(norm16>=MIN_NORMAL_MAYBE_YES) {
                // combining mark
                norm16&=0xff;
                return norm16|(norm16<<8);
            } else if(norm16>=minMaybeYes) {
                return 0;
            } else if(isDecompNoAlgorithmic(norm16)) {
                c=mapAlgorithmic(c, norm16);
            } else {
                // c decomposes, get everything from the variable-length extra data
                int firstUnit=extraData.charAt(norm16);
                if((firstUnit&MAPPING_LENGTH_MASK)==0) {
                    // A character that is deleted (maps to an empty string) must
                    // get the worst-case lccc and tccc values because arbitrary
                    // characters on both sides will become adjacent.
                    return 0x1ff;
                } else {
                    int fcd16=firstUnit>>8;  // tccc
                    if((firstUnit&MAPPING_HAS_CCC_LCCC_WORD)!=0) {
                        fcd16|=extraData.charAt(norm16-1)&0xff00;  // lccc
                    }
                    return fcd16;
                }
            }
        }
    }

    
Gets the decomposition for one code point.
Params:
c – code point
Returns:
c's decomposition, if it has one; returns null if it does not have a decomposition/**
     * Gets the decomposition for one code point.
     * @param c code point
     * @return c's decomposition, if it has one; returns null if it does not have a decomposition
     */
    public String getDecomposition(int c) {
        int decomp=-1;
        int norm16;
        for(;;) {
            if(c<minDecompNoCP || isDecompYes(norm16=getNorm16(c))) {
                // c does not decompose
            } else if(isHangul(norm16)) {
                // Hangul syllable: decompose algorithmically
                StringBuilder buffer=new StringBuilder();
                Hangul.decompose(c, buffer);
                return buffer.toString();
            } else if(isDecompNoAlgorithmic(norm16)) {
                decomp=c=mapAlgorithmic(c, norm16);
                continue;
            } else {
                // c decomposes, get everything from the variable-length extra data
                int length=extraData.charAt(norm16++)&MAPPING_LENGTH_MASK;
                return extraData.substring(norm16, norm16+length);
            }
            if(decomp<0) {
                return null;
            } else {
                return UTF16.valueOf(decomp);
            }
        }
    }

    public static final int MIN_CCC_LCCC_CP=0x300;

    public static final int MIN_YES_YES_WITH_CC=0xff01;
    public static final int JAMO_VT=0xff00;
    public static final int MIN_NORMAL_MAYBE_YES=0xfe00;
    public static final int MAX_DELTA=0x40;

    // Byte offsets from the start of the data, after the generic header.
    public static final int IX_NORM_TRIE_OFFSET=0;
    public static final int IX_EXTRA_DATA_OFFSET=1;
    public static final int IX_SMALL_FCD_OFFSET=2;

    // Code point thresholds for quick check codes.
    public static final int IX_MIN_DECOMP_NO_CP=8;
    public static final int IX_MIN_COMP_NO_MAYBE_CP=9;

    // Norm16 value thresholds for quick check combinations and types of extra data.
    // Mappings & compositions in [minYesNo..minYesNoMappingsOnly[.
    public static final int IX_MIN_YES_NO=10;
    public static final int IX_MIN_NO_NO=11;
    public static final int IX_LIMIT_NO_NO=12;
    public static final int IX_MIN_MAYBE_YES=13;

    // Mappings only in [minYesNoMappingsOnly..minNoNo[.
    public static final int IX_MIN_YES_NO_MAPPINGS_ONLY=14;

    public static final int MAPPING_HAS_CCC_LCCC_WORD=0x80;
    public static final int MAPPING_LENGTH_MASK=0x1f;

    public static final int COMP_1_LAST_TUPLE=0x8000;
    public static final int COMP_1_TRIPLE=1;
    public static final int COMP_1_TRAIL_LIMIT=0x3400;
    public static final int COMP_1_TRAIL_MASK=0x7ffe;
    public static final int COMP_1_TRAIL_SHIFT=9;  // 10-1 for the "triple" bit
    public static final int COMP_2_TRAIL_SHIFT=6;
    public static final int COMP_2_TRAIL_MASK=0xffc0;

    // higher-level functionality ------------------------------------------ ***

    
Decomposes s[src, limit[ and writes the result to dest.
limit can be NULL if src is NUL-terminated.
destLengthEstimate is the initial dest buffer capacity and can be -1.
/**
     * Decomposes s[src, limit[ and writes the result to dest.
     * limit can be NULL if src is NUL-terminated.
     * destLengthEstimate is the initial dest buffer capacity and can be -1.
     */
    public void decompose(CharSequence s, int src, int limit, StringBuilder dest,
                   int destLengthEstimate) {
        if(destLengthEstimate<0) {
            destLengthEstimate=limit-src;
        }
        dest.setLength(0);
        ReorderingBuffer buffer=new ReorderingBuffer(this, dest, destLengthEstimate);
        decompose(s, src, limit, buffer);
    }

    // Dual functionality:
    // buffer!=NULL: normalize
    // buffer==NULL: isNormalized/quickCheck/spanQuickCheckYes
    public int decompose(CharSequence s, int src, int limit,
                         ReorderingBuffer buffer) {
        int minNoCP=minDecompNoCP;

        int prevSrc;
        int c=0;
        int norm16=0;

        // only for quick check
        int prevBoundary=src;
        int prevCC=0;

        for(;;) {
            // count code units below the minimum or with irrelevant data for the quick check
            for(prevSrc=src; src!=limit;) {
                if( (c=s.charAt(src))<minNoCP ||
                    isMostDecompYesAndZeroCC(norm16=normTrie.getFromU16SingleLead((char)c))
                ) {
                    ++src;
                } else if(!UTF16.isSurrogate((char)c)) {
                    break;
                } else {
                    char c2;
                    if(UTF16Plus.isSurrogateLead(c)) {
                        if((src+1)!=limit && Character.isLowSurrogate(c2=s.charAt(src+1))) {
                            c=Character.toCodePoint((char)c, c2);
                        }
                    } else /* trail surrogate */ {
                        if(prevSrc<src && Character.isHighSurrogate(c2=s.charAt(src-1))) {
                            --src;
                            c=Character.toCodePoint(c2, (char)c);
                        }
                    }
                    if(isMostDecompYesAndZeroCC(norm16=getNorm16(c))) {
                        src+=Character.charCount(c);
                    } else {
                        break;
                    }
                }
            }
            // copy these code units all at once
            if(src!=prevSrc) {
                if(buffer!=null) {
                    buffer.flushAndAppendZeroCC(s, prevSrc, src);
                } else {
                    prevCC=0;
                    prevBoundary=src;
                }
            }
            if(src==limit) {
                break;
            }

            // Check one above-minimum, relevant code point.
            src+=Character.charCount(c);
            if(buffer!=null) {
                decompose(c, norm16, buffer);
            } else {
                if(isDecompYes(norm16)) {
                    int cc=getCCFromYesOrMaybe(norm16);
                    if(prevCC<=cc || cc==0) {
                        prevCC=cc;
                        if(cc<=1) {
                            prevBoundary=src;
                        }
                        continue;
                    }
                }
                return prevBoundary;  // "no" or cc out of order
            }
        }
        return src;
    }

    public void decomposeAndAppend(CharSequence s, boolean doDecompose, ReorderingBuffer buffer) {
        int limit=s.length();
        if(limit==0) {
            return;
        }
        if(doDecompose) {
            decompose(s, 0, limit, buffer);
            return;
        }
        // Just merge the strings at the boundary.
        int c=Character.codePointAt(s, 0);
        int src=0;
        int firstCC, prevCC, cc;
        firstCC=prevCC=cc=getCC(getNorm16(c));
        while(cc!=0) {
            prevCC=cc;
            src+=Character.charCount(c);
            if(src>=limit) {
                break;
            }
            c=Character.codePointAt(s, src);
            cc=getCC(getNorm16(c));
        };
        buffer.append(s, 0, src, firstCC, prevCC);
        buffer.append(s, src, limit);
    }

    // Very similar to composeQuickCheck(): Make the same changes in both places if relevant.
    // doCompose: normalize
    // !doCompose: isNormalized (buffer must be empty and initialized)
    public boolean compose(CharSequence s, int src, int limit,
                           boolean onlyContiguous,
                           boolean doCompose,
                           ReorderingBuffer buffer) {
        int minNoMaybeCP=minCompNoMaybeCP;

        /*
         * prevBoundary points to the last character before the current one
         * that has a composition boundary before it with ccc==0 and quick check "yes".
         * Keeping track of prevBoundary saves us looking for a composition boundary
         * when we find a "no" or "maybe".
         *
         * When we back out from prevSrc back to prevBoundary,
         * then we also remove those same characters (which had been simply copied
         * or canonically-order-inserted) from the ReorderingBuffer.
         * Therefore, at all times, the [prevBoundary..prevSrc[ source units
         * must correspond 1:1 to destination units at the end of the destination buffer.
         */
        int prevBoundary=src;
        int prevSrc;
        int c=0;
        int norm16=0;

        // only for isNormalized
        int prevCC=0;

        for(;;) {
            // count code units below the minimum or with irrelevant data for the quick check
            for(prevSrc=src; src!=limit;) {
                if( (c=s.charAt(src))<minNoMaybeCP ||
                    isCompYesAndZeroCC(norm16=normTrie.getFromU16SingleLead((char)c))
                ) {
                    ++src;
                } else if(!UTF16.isSurrogate((char)c)) {
                    break;
                } else {
                    char c2;
                    if(UTF16Plus.isSurrogateLead(c)) {
                        if((src+1)!=limit && Character.isLowSurrogate(c2=s.charAt(src+1))) {
                            c=Character.toCodePoint((char)c, c2);
                        }
                    } else /* trail surrogate */ {
                        if(prevSrc<src && Character.isHighSurrogate(c2=s.charAt(src-1))) {
                            --src;
                            c=Character.toCodePoint(c2, (char)c);
                        }
                    }
                    if(isCompYesAndZeroCC(norm16=getNorm16(c))) {
                        src+=Character.charCount(c);
                    } else {
                        break;
                    }
                }
            }
            // copy these code units all at once
            if(src!=prevSrc) {
                if(src==limit) {
                    if(doCompose) {
                        buffer.flushAndAppendZeroCC(s, prevSrc, src);
                    }
                    break;
                }
                // Set prevBoundary to the last character in the quick check loop.
                prevBoundary=src-1;
                if( Character.isLowSurrogate(s.charAt(prevBoundary)) && prevSrc<prevBoundary &&
                    Character.isHighSurrogate(s.charAt(prevBoundary-1))
                ) {
                    --prevBoundary;
                }
                if(doCompose) {
                    // The last "quick check yes" character is excluded from the
                    // flush-and-append call in case it needs to be modified.
                    buffer.flushAndAppendZeroCC(s, prevSrc, prevBoundary);
                    buffer.append(s, prevBoundary, src);
                } else {
                    prevCC=0;
                }
                // The start of the current character (c).
                prevSrc=src;
            } else if(src==limit) {
                break;
            }

            src+=Character.charCount(c);
            /*
             * isCompYesAndZeroCC(norm16) is false, that is, norm16>=minNoNo.
             * c is either a "noNo" (has a mapping) or a "maybeYes" (combines backward)
             * or has ccc!=0.
             * Check for Jamo V/T, then for regular characters.
             * c is not a Hangul syllable or Jamo L because those have "yes" properties.
             */
            if(isJamoVT(norm16) && prevBoundary!=prevSrc) {
                char prev=s.charAt(prevSrc-1);
                boolean needToDecompose=false;
                if(c<Hangul.JAMO_T_BASE) {
                    // c is a Jamo Vowel, compose with previous Jamo L and following Jamo T.
                    prev-=Hangul.JAMO_L_BASE;
                    if(prev<Hangul.JAMO_L_COUNT) {
                        if(!doCompose) {
                            return false;
                        }
                        char syllable=(char)
                            (Hangul.HANGUL_BASE+
                             (prev*Hangul.JAMO_V_COUNT+(c-Hangul.JAMO_V_BASE))*
                             Hangul.JAMO_T_COUNT);
                        char t;
                        if(src!=limit && (t=(char)(s.charAt(src)-Hangul.JAMO_T_BASE))<Hangul.JAMO_T_COUNT) {
                            ++src;
                            syllable+=t;  // The next character was a Jamo T.
                            prevBoundary=src;
                            buffer.setLastChar(syllable);
                            continue;
                        }
                        // If we see L+V+x where x!=T then we drop to the slow path,
                        // decompose and recompose.
                        // This is to deal with NFKC finding normal L and V but a
                        // compatibility variant of a T. We need to either fully compose that
                        // combination here (which would complicate the code and may not work
                        // with strange custom data) or use the slow path -- or else our replacing
                        // two input characters (L+V) with one output character (LV syllable)
                        // would violate the invariant that [prevBoundary..prevSrc[ has the same
                        // length as what we appended to the buffer since prevBoundary.
                        needToDecompose=true;
                    }
                } else if(Hangul.isHangulWithoutJamoT(prev)) {
                    // c is a Jamo Trailing consonant,
                    // compose with previous Hangul LV that does not contain a Jamo T.
                    if(!doCompose) {
                        return false;
                    }
                    buffer.setLastChar((char)(prev+c-Hangul.JAMO_T_BASE));
                    prevBoundary=src;
                    continue;
                }
                if(!needToDecompose) {
                    // The Jamo V/T did not compose into a Hangul syllable.
                    if(doCompose) {
                        buffer.append((char)c);
                    } else {
                        prevCC=0;
                    }
                    continue;
                }
            }
            /*
             * Source buffer pointers:
             *
             *  all done      quick check   current char  not yet
             *                "yes" but     (c)           processed
             *                may combine
             *                forward
             * [-------------[-------------[-------------[-------------[
             * |             |             |             |             |
             * orig. src     prevBoundary  prevSrc       src           limit
             *
             *
             * Destination buffer pointers inside the ReorderingBuffer:
             *
             *  all done      might take    not filled yet
             *                characters for
             *                reordering
             * [-------------[-------------[-------------[
             * |             |             |             |
             * start         reorderStart  limit         |
             *                             +remainingCap.+
             */
            if(norm16>=MIN_YES_YES_WITH_CC) {
                int cc=norm16&0xff;  // cc!=0
                if( onlyContiguous &&  // FCC
                    (doCompose ? buffer.getLastCC() : prevCC)==0 &&
                    prevBoundary<prevSrc &&
                    // buffer.getLastCC()==0 && prevBoundary<prevSrc tell us that
                    // [prevBoundary..prevSrc[ (which is exactly one character under these conditions)
                    // passed the quick check "yes && ccc==0" test.
                    // Check whether the last character was a "yesYes" or a "yesNo".
                    // If a "yesNo", then we get its trailing ccc from its
                    // mapping and check for canonical order.
                    // All other cases are ok.
                    getTrailCCFromCompYesAndZeroCC(s, prevBoundary, prevSrc)>cc
                ) {
                    // Fails FCD test, need to decompose and contiguously recompose.
                    if(!doCompose) {
                        return false;
                    }
                } else if(doCompose) {
                    buffer.append(c, cc);
                    continue;
                } else if(prevCC<=cc) {
                    prevCC=cc;
                    continue;
                } else {
                    return false;
                }
            } else if(!doCompose && !isMaybeOrNonZeroCC(norm16)) {
                return false;
            }

            /*
             * Find appropriate boundaries around this character,
             * decompose the source text from between the boundaries,
             * and recompose it.
             *
             * We may need to remove the last few characters from the ReorderingBuffer
             * to account for source text that was copied or appended
             * but needs to take part in the recomposition.
             */

            /*
             * Find the last composition boundary in [prevBoundary..src[.
             * It is either the decomposition of the current character (at prevSrc),
             * or prevBoundary.
             */
            if(hasCompBoundaryBefore(c, norm16)) {
                prevBoundary=prevSrc;
            } else if(doCompose) {
                buffer.removeSuffix(prevSrc-prevBoundary);
            }

            // Find the next composition boundary in [src..limit[ -
            // modifies src to point to the next starter.
            src=findNextCompBoundary(s, src, limit);

            // Decompose [prevBoundary..src[ into the buffer and then recompose that part of it.
            int recomposeStartIndex=buffer.length();
            decomposeShort(s, prevBoundary, src, buffer);
            recompose(buffer, recomposeStartIndex, onlyContiguous);
            if(!doCompose) {
                if(!buffer.equals(s, prevBoundary, src)) {
                    return false;
                }
                buffer.remove();
                prevCC=0;
            }

            // Move to the next starter. We never need to look back before this point again.
            prevBoundary=src;
        }
        return true;
    }

    
Very similar to compose(): Make the same changes in both places if relevant.
doSpan: spanQuickCheckYes (ignore bit 0 of the return value)
!doSpan: quickCheck
Returns:
bits 31..1: spanQuickCheckYes (==s.length() if "yes") and
        bit 0: set if "maybe"; otherwise, if the span length<s.length()
        then the quick check result is "no"/**
     * Very similar to compose(): Make the same changes in both places if relevant.
     * doSpan: spanQuickCheckYes (ignore bit 0 of the return value)
     * !doSpan: quickCheck
     * @return bits 31..1: spanQuickCheckYes (==s.length() if "yes") and
     *         bit 0: set if "maybe"; otherwise, if the span length&lt;s.length()
     *         then the quick check result is "no"
     */
    public int composeQuickCheck(CharSequence s, int src, int limit,
                                 boolean onlyContiguous, boolean doSpan) {
        int qcResult=0;
        int minNoMaybeCP=minCompNoMaybeCP;

        /*
         * prevBoundary points to the last character before the current one
         * that has a composition boundary before it with ccc==0 and quick check "yes".
         */
        int prevBoundary=src;
        int prevSrc;
        int c=0;
        int norm16=0;
        int prevCC=0;

        for(;;) {
            // count code units below the minimum or with irrelevant data for the quick check
            for(prevSrc=src;;) {
                if(src==limit) {
                    return (src<<1)|qcResult;  // "yes" or "maybe"
                }
                if( (c=s.charAt(src))<minNoMaybeCP ||
                    isCompYesAndZeroCC(norm16=normTrie.getFromU16SingleLead((char)c))
                ) {
                    ++src;
                } else if(!UTF16.isSurrogate((char)c)) {
                    break;
                } else {
                    char c2;
                    if(UTF16Plus.isSurrogateLead(c)) {
                        if((src+1)!=limit && Character.isLowSurrogate(c2=s.charAt(src+1))) {
                            c=Character.toCodePoint((char)c, c2);
                        }
                    } else /* trail surrogate */ {
                        if(prevSrc<src && Character.isHighSurrogate(c2=s.charAt(src-1))) {
                            --src;
                            c=Character.toCodePoint(c2, (char)c);
                        }
                    }
                    if(isCompYesAndZeroCC(norm16=getNorm16(c))) {
                        src+=Character.charCount(c);
                    } else {
                        break;
                    }
                }
            }
            if(src!=prevSrc) {
                // Set prevBoundary to the last character in the quick check loop.
                prevBoundary=src-1;
                if( Character.isLowSurrogate(s.charAt(prevBoundary)) && prevSrc<prevBoundary &&
                        Character.isHighSurrogate(s.charAt(prevBoundary-1))
                ) {
                    --prevBoundary;
                }
                prevCC=0;
                // The start of the current character (c).
                prevSrc=src;
            }

            src+=Character.charCount(c);
            /*
             * isCompYesAndZeroCC(norm16) is false, that is, norm16>=minNoNo.
             * c is either a "noNo" (has a mapping) or a "maybeYes" (combines backward)
             * or has ccc!=0.
             */
            if(isMaybeOrNonZeroCC(norm16)) {
                int cc=getCCFromYesOrMaybe(norm16);
                if( onlyContiguous &&  // FCC
                    cc!=0 &&
                    prevCC==0 &&
                    prevBoundary<prevSrc &&
                    // prevCC==0 && prevBoundary<prevSrc tell us that
                    // [prevBoundary..prevSrc[ (which is exactly one character under these conditions)
                    // passed the quick check "yes && ccc==0" test.
                    // Check whether the last character was a "yesYes" or a "yesNo".
                    // If a "yesNo", then we get its trailing ccc from its
                    // mapping and check for canonical order.
                    // All other cases are ok.
                    getTrailCCFromCompYesAndZeroCC(s, prevBoundary, prevSrc)>cc
                ) {
                    // Fails FCD test.
                } else if(prevCC<=cc || cc==0) {
                    prevCC=cc;
                    if(norm16<MIN_YES_YES_WITH_CC) {
                        if(!doSpan) {
                            qcResult=1;
                        } else {
                            return prevBoundary<<1;  // spanYes does not care to know it's "maybe"
                        }
                    }
                    continue;
                }
            }
            return prevBoundary<<1;  // "no"
        }
    }

    public void composeAndAppend(CharSequence s,
                                 boolean doCompose,
                                 boolean onlyContiguous,
                                 ReorderingBuffer buffer) {
        int src=0, limit=s.length();
        if(!buffer.isEmpty()) {
            int firstStarterInSrc=findNextCompBoundary(s, 0, limit);
            if(0!=firstStarterInSrc) {
                int lastStarterInDest=findPreviousCompBoundary(buffer.getStringBuilder(),
                                                               buffer.length());
                StringBuilder middle=new StringBuilder((buffer.length()-lastStarterInDest)+
                                                       firstStarterInSrc+16);
                middle.append(buffer.getStringBuilder(), lastStarterInDest, buffer.length());
                buffer.removeSuffix(buffer.length()-lastStarterInDest);
                middle.append(s, 0, firstStarterInSrc);
                compose(middle, 0, middle.length(), onlyContiguous, true, buffer);
                src=firstStarterInSrc;
            }
        }
        if(doCompose) {
            compose(s, src, limit, onlyContiguous, true, buffer);
        } else {
            buffer.append(s, src, limit);
        }
    }

    // Dual functionality:
    // buffer!=NULL: normalize
    // buffer==NULL: isNormalized/quickCheck/spanQuickCheckYes
    public int makeFCD(CharSequence s, int src, int limit, ReorderingBuffer buffer) {
        // Note: In this function we use buffer->appendZeroCC() because we track
        // the lead and trail combining classes here, rather than leaving it to
        // the ReorderingBuffer.
        // The exception is the call to decomposeShort() which uses the buffer
        // in the normal way.

        // Tracks the last FCD-safe boundary, before lccc=0 or after properly-ordered tccc<=1.
        // Similar to the prevBoundary in the compose() implementation.
        int prevBoundary=src;
        int prevSrc;
        int c=0;
        int prevFCD16=0;
        int fcd16=0;

        for(;;) {
            // count code units with lccc==0
            for(prevSrc=src; src!=limit;) {
                if((c=s.charAt(src))<MIN_CCC_LCCC_CP) {
                    prevFCD16=~c;
                    ++src;
                } else if(!singleLeadMightHaveNonZeroFCD16(c)) {
                    prevFCD16=0;
                    ++src;
                } else {
                    if(UTF16.isSurrogate((char)c)) {
                        char c2;
                        if(UTF16Plus.isSurrogateLead(c)) {
                            if((src+1)!=limit && Character.isLowSurrogate(c2=s.charAt(src+1))) {
                                c=Character.toCodePoint((char)c, c2);
                            }
                        } else /* trail surrogate */ {
                            if(prevSrc<src && Character.isHighSurrogate(c2=s.charAt(src-1))) {
                                --src;
                                c=Character.toCodePoint(c2, (char)c);
                            }
                        }
                    }
                    if((fcd16=getFCD16FromNormData(c))<=0xff) {
                        prevFCD16=fcd16;
                        src+=Character.charCount(c);
                    } else {
                        break;
                    }
              }
            }
            // copy these code units all at once
            if(src!=prevSrc) {
                if(src==limit) {
                    if(buffer!=null) {
                        buffer.flushAndAppendZeroCC(s, prevSrc, src);
                    }
                    break;
                }
                prevBoundary=src;
                // We know that the previous character's lccc==0.
                if(prevFCD16<0) {
                    // Fetching the fcd16 value was deferred for this below-U+0300 code point.
                    int prev=~prevFCD16;
                    prevFCD16= prev<0x180 ? tccc180[prev] : getFCD16FromNormData(prev);
                    if(prevFCD16>1) {
                        --prevBoundary;
                    }
                } else {
                    int p=src-1;
                    if( Character.isLowSurrogate(s.charAt(p)) && prevSrc<p &&
                        Character.isHighSurrogate(s.charAt(p-1))
                    ) {
                        --p;
                        // Need to fetch the previous character's FCD value because
                        // prevFCD16 was just for the trail surrogate code point.
                        prevFCD16=getFCD16FromNormData(Character.toCodePoint(s.charAt(p), s.charAt(p+1)));
                        // Still known to have lccc==0 because its lead surrogate unit had lccc==0.
                    }
                    if(prevFCD16>1) {
                        prevBoundary=p;
                    }
                }
                if(buffer!=null) {
                    // The last lccc==0 character is excluded from the
                    // flush-and-append call in case it needs to be modified.
                    buffer.flushAndAppendZeroCC(s, prevSrc, prevBoundary);
                    buffer.append(s, prevBoundary, src);
                }
                // The start of the current character (c).
                prevSrc=src;
            } else if(src==limit) {
                break;
            }

            src+=Character.charCount(c);
            // The current character (c) at [prevSrc..src[ has a non-zero lead combining class.
            // Check for proper order, and decompose locally if necessary.
            if((prevFCD16&0xff)<=(fcd16>>8)) {
                // proper order: prev tccc <= current lccc
                if((fcd16&0xff)<=1) {
                    prevBoundary=src;
                }
                if(buffer!=null) {
                    buffer.appendZeroCC(c);
                }
                prevFCD16=fcd16;
                continue;
            } else if(buffer==null) {
                return prevBoundary;  // quick check "no"
            } else {
                /*
                 * Back out the part of the source that we copied or appended
                 * already but is now going to be decomposed.
                 * prevSrc is set to after what was copied/appended.
                 */
                buffer.removeSuffix(prevSrc-prevBoundary);
                /*
                 * Find the part of the source that needs to be decomposed,
                 * up to the next safe boundary.
                 */
                src=findNextFCDBoundary(s, src, limit);
                /*
                 * The source text does not fulfill the conditions for FCD.
                 * Decompose and reorder a limited piece of the text.
                 */
                decomposeShort(s, prevBoundary, src, buffer);
                prevBoundary=src;
                prevFCD16=0;
            }
        }
        return src;
    }

    // Note: hasDecompBoundary() could be implemented as aliases to
    // hasFCDBoundaryBefore() and hasFCDBoundaryAfter()
    // at the cost of building the FCD trie for a decomposition normalizer.
    public boolean hasDecompBoundary(int c, boolean before) {
        for(;;) {
            if(c<minDecompNoCP) {
                return true;
            }
            int norm16=getNorm16(c);
            if(isHangul(norm16) || isDecompYesAndZeroCC(norm16)) {
                return true;
            } else if(norm16>MIN_NORMAL_MAYBE_YES) {
                return false;  // ccc!=0
            } else if(isDecompNoAlgorithmic(norm16)) {
                c=mapAlgorithmic(c, norm16);
            } else {
                // c decomposes, get everything from the variable-length extra data
                int firstUnit=extraData.charAt(norm16);
                if((firstUnit&MAPPING_LENGTH_MASK)==0) {
                    return false;
                }
                if(!before) {
                    // decomp after-boundary: same as hasFCDBoundaryAfter(),
                    // fcd16<=1 || trailCC==0
                    if(firstUnit>0x1ff) {
                        return false;  // trailCC>1
                    }
                    if(firstUnit<=0xff) {
                        return true;  // trailCC==0
                    }
                    // if(trailCC==1) test leadCC==0, same as checking for before-boundary
                }
                // true if leadCC==0 (hasFCDBoundaryBefore())
                return (firstUnit&MAPPING_HAS_CCC_LCCC_WORD)==0 || (extraData.charAt(norm16-1)&0xff00)==0;
            }
        }
    }

    public boolean hasCompBoundaryBefore(int c) {
        return c<minCompNoMaybeCP || hasCompBoundaryBefore(c, getNorm16(c));
    }

    private boolean isMaybe(int norm16) { return minMaybeYes<=norm16 && norm16<=JAMO_VT; }
    private boolean isMaybeOrNonZeroCC(int norm16) { return norm16>=minMaybeYes; }
    private static boolean isJamoVT(int norm16) { return norm16==JAMO_VT; }
    private boolean isHangul(int norm16) { return norm16==minYesNo; }
    private boolean isCompYesAndZeroCC(int norm16) { return norm16<minNoNo; }

    // UBool isCompYes(uint16_t norm16) const {
    //     return norm16>=MIN_YES_YES_WITH_CC || norm16<minNoNo;
    // }
    // UBool isCompYesOrMaybe(uint16_t norm16) const {
    //     return norm16<minNoNo || minMaybeYes<=norm16;
    // }
    // private boolean hasZeroCCFromDecompYes(int norm16) {
    //     return norm16<=MIN_NORMAL_MAYBE_YES || norm16==JAMO_VT;
    // }
    private boolean isDecompYesAndZeroCC(int norm16) {
        return norm16<minYesNo ||
               norm16==JAMO_VT ||
               (minMaybeYes<=norm16 && norm16<=MIN_NORMAL_MAYBE_YES);
    }

    
A little faster and simpler than isDecompYesAndZeroCC() but does not include
the MaybeYes which combine-forward and have ccc=0.
(Standard Unicode 5.2 normalization does not have such characters.)
/**
     * A little faster and simpler than isDecompYesAndZeroCC() but does not include
     * the MaybeYes which combine-forward and have ccc=0.
     * (Standard Unicode 5.2 normalization does not have such characters.)
     */
    private boolean isMostDecompYesAndZeroCC(int norm16) {
        return norm16<minYesNo || norm16==MIN_NORMAL_MAYBE_YES || norm16==JAMO_VT;
    }

    private boolean isDecompNoAlgorithmic(int norm16) { return norm16>=limitNoNo; }

    // For use with isCompYes().
    // Perhaps the compiler can combine the two tests for MIN_YES_YES_WITH_CC.
    // static uint8_t getCCFromYes(uint16_t norm16) {
    //     return norm16>=MIN_YES_YES_WITH_CC ? (uint8_t)norm16 : 0;
    // }
    private int getCCFromNoNo(int norm16) {
        if((extraData.charAt(norm16)&MAPPING_HAS_CCC_LCCC_WORD)!=0) {
            return extraData.charAt(norm16-1)&0xff;
        } else {
            return 0;
        }
    }

    // requires that the [cpStart..cpLimit[ character passes isCompYesAndZeroCC()
    int getTrailCCFromCompYesAndZeroCC(CharSequence s, int cpStart, int cpLimit) {
        int c;
        if(cpStart==(cpLimit-1)) {
            c=s.charAt(cpStart);
        } else {
            c=Character.codePointAt(s, cpStart);
        }
        int prevNorm16=getNorm16(c);
        if(prevNorm16<=minYesNo) {
            return 0;  // yesYes and Hangul LV/LVT have ccc=tccc=0
        } else {
            return extraData.charAt(prevNorm16)>>8;  // tccc from yesNo
        }
    }

    // Requires algorithmic-NoNo.
    private int mapAlgorithmic(int c, int norm16) {
        return c+norm16-(minMaybeYes-MAX_DELTA-1);
    }

    // Requires minYesNo<norm16<limitNoNo.
    // private int getMapping(int norm16) { return /*extraData+*/norm16; }

    
Returns:
index into maybeYesCompositions, or -1/**
     * @return index into maybeYesCompositions, or -1
     */
    private int getCompositionsListForDecompYes(int norm16) {
        if(norm16==0 || MIN_NORMAL_MAYBE_YES<=norm16) {
            return -1;
        } else {
            if((norm16-=minMaybeYes)<0) {
                // norm16<minMaybeYes: index into extraData which is a substring at
                //     maybeYesCompositions[MIN_NORMAL_MAYBE_YES-minMaybeYes]
                // same as (MIN_NORMAL_MAYBE_YES-minMaybeYes)+norm16
                norm16+=MIN_NORMAL_MAYBE_YES;  // for yesYes; if Jamo L: harmless empty list
            }
            return norm16;
        }
    }

    
Returns:
index into maybeYesCompositions/**
     * @return index into maybeYesCompositions
     */
    private int getCompositionsListForComposite(int norm16) {
        // composite has both mapping & compositions list
        int firstUnit=extraData.charAt(norm16);
        return (MIN_NORMAL_MAYBE_YES-minMaybeYes)+norm16+  // mapping in maybeYesCompositions
            1+  // +1 to skip the first unit with the mapping lenth
            (firstUnit&MAPPING_LENGTH_MASK);  // + mapping length
    }

    // Decompose a short piece of text which is likely to contain characters that
    // fail the quick check loop and/or where the quick check loop's overhead
    // is unlikely to be amortized.
    // Called by the compose() and makeFCD() implementations.
    // Public in Java for collation implementation code.
    public void decomposeShort(CharSequence s, int src, int limit,
                               ReorderingBuffer buffer) {
        while(src<limit) {
            int c=Character.codePointAt(s, src);
            src+=Character.charCount(c);
            decompose(c, getNorm16(c), buffer);
        }
    }

    private void decompose(int c, int norm16,
                           ReorderingBuffer buffer) {
        // Only loops for 1:1 algorithmic mappings.
        for(;;) {
            // get the decomposition and the lead and trail cc's
            if(isDecompYes(norm16)) {
                // c does not decompose
                buffer.append(c, getCCFromYesOrMaybe(norm16));
            } else if(isHangul(norm16)) {
                // Hangul syllable: decompose algorithmically
                Hangul.decompose(c, buffer);
            } else if(isDecompNoAlgorithmic(norm16)) {
                c=mapAlgorithmic(c, norm16);
                norm16=getNorm16(c);
                continue;
            } else {
                // c decomposes, get everything from the variable-length extra data
                int firstUnit=extraData.charAt(norm16);
                int length=firstUnit&MAPPING_LENGTH_MASK;
                int leadCC, trailCC;
                trailCC=firstUnit>>8;
                if((firstUnit&MAPPING_HAS_CCC_LCCC_WORD)!=0) {
                    leadCC=extraData.charAt(norm16-1)>>8;
                } else {
                    leadCC=0;
                }
                ++norm16;  // skip over the firstUnit
                buffer.append(extraData, norm16, norm16+length, leadCC, trailCC);
            }
            return;
        }
    }

    
Finds the recomposition result for
a forward-combining "lead" character,
specified with a pointer to its compositions list,
and a backward-combining "trail" character.
If the lead and trail characters combine, then this function returns
the following "compositeAndFwd" value:
Bits 21..1  composite character
Bit      0  set if the composite is a forward-combining starter

otherwise it returns -1.
The compositions list has (trail, compositeAndFwd) pair entries,
encoded as either pairs or triples of 16-bit units.
The last entry has the high bit of its first unit set.
The list is sorted by ascending trail characters (there are no duplicates).
A linear search is used.
See normalizer2impl.h for a more detailed description
of the compositions list format.
/**
     * Finds the recomposition result for
     * a forward-combining "lead" character,
     * specified with a pointer to its compositions list,
     * and a backward-combining "trail" character.
     *
     * <p>If the lead and trail characters combine, then this function returns
     * the following "compositeAndFwd" value:
     * <pre>
     * Bits 21..1  composite character
     * Bit      0  set if the composite is a forward-combining starter
     * </pre>
     * otherwise it returns -1.
     *
     * <p>The compositions list has (trail, compositeAndFwd) pair entries,
     * encoded as either pairs or triples of 16-bit units.
     * The last entry has the high bit of its first unit set.
     *
     * <p>The list is sorted by ascending trail characters (there are no duplicates).
     * A linear search is used.
     *
     * <p>See normalizer2impl.h for a more detailed description
     * of the compositions list format.
     */
    private static int combine(String compositions, int list, int trail) {
        int key1, firstUnit;
        if(trail<COMP_1_TRAIL_LIMIT) {
            // trail character is 0..33FF
            // result entry may have 2 or 3 units
            key1=(trail<<1);
            while(key1>(firstUnit=compositions.charAt(list))) {
                list+=2+(firstUnit&COMP_1_TRIPLE);
            }
            if(key1==(firstUnit&COMP_1_TRAIL_MASK)) {
                if((firstUnit&COMP_1_TRIPLE)!=0) {
                    return ((int)compositions.charAt(list+1)<<16)|compositions.charAt(list+2);
                } else {
                    return compositions.charAt(list+1);
                }
            }
        } else {
            // trail character is 3400..10FFFF
            // result entry has 3 units
            key1=COMP_1_TRAIL_LIMIT+(((trail>>COMP_1_TRAIL_SHIFT))&~COMP_1_TRIPLE);
            int key2=(trail<<COMP_2_TRAIL_SHIFT)&0xffff;
            int secondUnit;
            for(;;) {
                if(key1>(firstUnit=compositions.charAt(list))) {
                    list+=2+(firstUnit&COMP_1_TRIPLE);
                } else if(key1==(firstUnit&COMP_1_TRAIL_MASK)) {
                    if(key2>(secondUnit=compositions.charAt(list+1))) {
                        if((firstUnit&COMP_1_LAST_TUPLE)!=0) {
                            break;
                        } else {
                            list+=3;
                        }
                    } else if(key2==(secondUnit&COMP_2_TRAIL_MASK)) {
                        return ((secondUnit&~COMP_2_TRAIL_MASK)<<16)|compositions.charAt(list+2);
                    } else {
                        break;
                    }
                } else {
                    break;
                }
            }
        }
        return -1;
    }

    /*
     * Recomposes the buffer text starting at recomposeStartIndex
     * (which is in NFD - decomposed and canonically ordered),
     * and truncates the buffer contents.
     *
     * Note that recomposition never lengthens the text:
     * Any character consists of either one or two code units;
     * a composition may contain at most one more code unit than the original starter,
     * while the combining mark that is removed has at least one code unit.
     */
    private void recompose(ReorderingBuffer buffer, int recomposeStartIndex,
                           boolean onlyContiguous) {
        StringBuilder sb=buffer.getStringBuilder();
        int p=recomposeStartIndex;
        if(p==sb.length()) {
            return;
        }

        int starter, pRemove;
        int compositionsList;
        int c, compositeAndFwd;
        int norm16;
        int cc, prevCC;
        boolean starterIsSupplementary;

        // Some of the following variables are not used until we have a forward-combining starter
        // and are only initialized now to avoid compiler warnings.
        compositionsList=-1;  // used as indicator for whether we have a forward-combining starter
        starter=-1;
        starterIsSupplementary=false;
        prevCC=0;

        for(;;) {
            c=sb.codePointAt(p);
            p+=Character.charCount(c);
            norm16=getNorm16(c);
            cc=getCCFromYesOrMaybe(norm16);
            if( // this character combines backward and
                isMaybe(norm16) &&
                // we have seen a starter that combines forward and
                compositionsList>=0 &&
                // the backward-combining character is not blocked
                (prevCC<cc || prevCC==0)) {
                if(isJamoVT(norm16)) {
                    // c is a Jamo V/T, see if we can compose it with the previous character.
                    if(c<Hangul.JAMO_T_BASE) {
                        // c is a Jamo Vowel, compose with previous Jamo L and following Jamo T.
                        char prev=(char)(sb.charAt(starter)-Hangul.JAMO_L_BASE);
                        if(prev<Hangul.JAMO_L_COUNT) {
                            pRemove=p-1;
                            char syllable=(char)
                                (Hangul.HANGUL_BASE+
                                 (prev*Hangul.JAMO_V_COUNT+(c-Hangul.JAMO_V_BASE))*
                                 Hangul.JAMO_T_COUNT);
                            char t;
                            if(p!=sb.length() && (t=(char)(sb.charAt(p)-Hangul.JAMO_T_BASE))<Hangul.JAMO_T_COUNT) {
                                ++p;
                                syllable+=t;  // The next character was a Jamo T.
                            }
                            sb.setCharAt(starter, syllable);
                            // remove the Jamo V/T
                            sb.delete(pRemove, p);
                            p=pRemove;
                        }
                    }
                    /*
                     * No "else" for Jamo T:
                     * Since the input is in NFD, there are no Hangul LV syllables that
                     * a Jamo T could combine with.
                     * All Jamo Ts are combined above when handling Jamo Vs.
                     */
                    if(p==sb.length()) {
                        break;
                    }
                    compositionsList=-1;
                    continue;
                } else if((compositeAndFwd=combine(maybeYesCompositions, compositionsList, c))>=0) {
                    // The starter and the combining mark (c) do combine.
                    int composite=compositeAndFwd>>1;

                    // Remove the combining mark.
                    pRemove=p-Character.charCount(c);  // pRemove & p: start & limit of the combining mark
                    sb.delete(pRemove, p);
                    p=pRemove;
                    // Replace the starter with the composite.
                    if(starterIsSupplementary) {
                        if(composite>0xffff) {
                            // both are supplementary
                            sb.setCharAt(starter, UTF16.getLeadSurrogate(composite));
                            sb.setCharAt(starter+1, UTF16.getTrailSurrogate(composite));
                        } else {
                            sb.setCharAt(starter, (char)c);
                            sb.deleteCharAt(starter+1);
                            // The composite is shorter than the starter,
                            // move the intermediate characters forward one.
                            starterIsSupplementary=false;
                            --p;
                        }
                    } else if(composite>0xffff) {
                        // The composite is longer than the starter,
                        // move the intermediate characters back one.
                        starterIsSupplementary=true;
                        sb.setCharAt(starter, UTF16.getLeadSurrogate(composite));
                        sb.insert(starter+1, UTF16.getTrailSurrogate(composite));
                        ++p;
                    } else {
                        // both are on the BMP
                        sb.setCharAt(starter, (char)composite);
                    }

                    // Keep prevCC because we removed the combining mark.

                    if(p==sb.length()) {
                        break;
                    }
                    // Is the composite a starter that combines forward?
                    if((compositeAndFwd&1)!=0) {
                        compositionsList=
                            getCompositionsListForComposite(getNorm16(composite));
                    } else {
                        compositionsList=-1;
                    }

                    // We combined; continue with looking for compositions.
                    continue;
                }
            }

            // no combination this time
            prevCC=cc;
            if(p==sb.length()) {
                break;
            }

            // If c did not combine, then check if it is a starter.
            if(cc==0) {
                // Found a new starter.
                if((compositionsList=getCompositionsListForDecompYes(norm16))>=0) {
                    // It may combine with something, prepare for it.
                    if(c<=0xffff) {
                        starterIsSupplementary=false;
                        starter=p-1;
                    } else {
                        starterIsSupplementary=true;
                        starter=p-2;
                    }
                }
            } else if(onlyContiguous) {
                // FCC: no discontiguous compositions; any intervening character blocks.
                compositionsList=-1;
            }
        }
        buffer.flush();
    }

    
Does c have a composition boundary before it?
True if its decomposition begins with a character that has
ccc=0 && NFC_QC=Yes (isCompYesAndZeroCC()).
As a shortcut, this is true if c itself has ccc=0 && NFC_QC=Yes
(isCompYesAndZeroCC()) so we need not decompose.
/**
     * Does c have a composition boundary before it?
     * True if its decomposition begins with a character that has
     * ccc=0 && NFC_QC=Yes (isCompYesAndZeroCC()).
     * As a shortcut, this is true if c itself has ccc=0 && NFC_QC=Yes
     * (isCompYesAndZeroCC()) so we need not decompose.
     */
    private boolean hasCompBoundaryBefore(int c, int norm16) {
        for(;;) {
            if(isCompYesAndZeroCC(norm16)) {
                return true;
            } else if(isMaybeOrNonZeroCC(norm16)) {
                return false;
            } else if(isDecompNoAlgorithmic(norm16)) {
                c=mapAlgorithmic(c, norm16);
                norm16=getNorm16(c);
            } else {
                // c decomposes, get everything from the variable-length extra data
                int firstUnit=extraData.charAt(norm16);
                if((firstUnit&MAPPING_LENGTH_MASK)==0) {
                    return false;
                }
                if((firstUnit&MAPPING_HAS_CCC_LCCC_WORD)!=0 && (extraData.charAt(norm16-1)&0xff00)!=0) {
                    return false;  // non-zero leadCC
                }
                return isCompYesAndZeroCC(getNorm16(Character.codePointAt(extraData, norm16+1)));
            }
        }
    }

    private int findPreviousCompBoundary(CharSequence s, int p) {
        while(p>0) {
            int c=Character.codePointBefore(s, p);
            p-=Character.charCount(c);
            if(hasCompBoundaryBefore(c)) {
                break;
            }
            // We could also test hasCompBoundaryAfter() and return iter.codePointLimit,
            // but that's probably not worth the extra cost.
        }
        return p;
    }

    private int findNextCompBoundary(CharSequence s, int p, int limit) {
        while(p<limit) {
            int c=Character.codePointAt(s, p);
            int norm16=normTrie.get(c);
            if(hasCompBoundaryBefore(c, norm16)) {
                break;
            }
            p+=Character.charCount(c);
        }
        return p;
    }

    private int findNextFCDBoundary(CharSequence s, int p, int limit) {
        while(p<limit) {
            int c=Character.codePointAt(s, p);
            if(c<MIN_CCC_LCCC_CP || getFCD16(c)<=0xff) {
                break;
            }
            p+=Character.charCount(c);
        }
        return p;
    }

    
Get the canonical decomposition
sherman  for ComposedCharIter
/**
     * Get the canonical decomposition
     * sherman  for ComposedCharIter
     */
    public static int getDecompose(int chars[], String decomps[]) {
        Normalizer2 impl = Normalizer2.getNFDInstance();

        int length=0;
        int norm16 = 0;
        int ch = -1;
        int i = 0;

        while (++ch < 0x2fa1e) {   //no cannoical above 0x3ffff
            //TBD !!!! the hack code heres save us about 50ms for startup
            //need a better solution/lookup
            if (ch == 0x30ff)
                ch = 0xf900;
            else if (ch == 0x115bc)
                ch = 0x1d15e;
            else if (ch == 0x1d1c1)
                ch = 0x2f800;

            String s = impl.getDecomposition(ch);

            if(s != null && i < chars.length) {
                chars[i] = ch;
                decomps[i++] = s;
            }
        }
        return i;
    }

    //------------------------------------------------------
    // special method for Collation (RBTableBuilder.build())
    //------------------------------------------------------
    private static boolean needSingleQuotation(char c) {
        return (c >= 0x0009 && c <= 0x000D) ||
               (c >= 0x0020 && c <= 0x002F) ||
               (c >= 0x003A && c <= 0x0040) ||
               (c >= 0x005B && c <= 0x0060) ||
               (c >= 0x007B && c <= 0x007E);
    }

    public static String canonicalDecomposeWithSingleQuotation(String string) {
       Normalizer2 impl = Normalizer2.getNFDInstance();
       char[] src = string.toCharArray();
       int    srcIndex = 0;
       int    srcLimit = src.length;
       char[] dest = new char[src.length * 3];  //MAX_BUF_SIZE_DECOMPOSE = 3
       int    destIndex = 0;
       int    destLimit = dest.length;

        int prevSrc;
        String norm;
        int reorderStartIndex, length;
        char c1, c2;
        int cp;
        int minNoMaybe = 0x00c0;
        int cc, prevCC, trailCC;
        char[] p;
        int pStart;

        // initialize
        reorderStartIndex = 0;
        prevCC = 0;
        norm = null;
        cp = 0;
        pStart = 0;

        cc = trailCC = -1; // initialize to bogus value
        c1 = 0;
        for (;;) {
            prevSrc=srcIndex;
            //quick check (1)less than minNoMaybe (2)no decomp (3)hangual
            while (srcIndex != srcLimit &&
                   ((c1 = src[srcIndex]) < minNoMaybe ||
                    (norm = impl.getDecomposition(cp = string.codePointAt(srcIndex))) == null ||
                    (c1 >= '\uac00' && c1 <= '\ud7a3'))) { // Hangul Syllables
                prevCC = 0;
                srcIndex += (cp < 0x10000) ? 1 : 2;
            }

            // copy these code units all at once
            if (srcIndex != prevSrc) {
                length = srcIndex - prevSrc;
                if ((destIndex + length) <= destLimit) {
                    System.arraycopy(src,prevSrc,dest,destIndex,length);
                }

                destIndex += length;
                reorderStartIndex = destIndex;
            }

            // end of source reached?
            if (srcIndex == srcLimit) {
                break;
            }

            // cp already contains *src and norm32 is set for it, increment src
            srcIndex += (cp < 0x10000) ? 1 : 2;

            if (cp < Character.MIN_SUPPLEMENTARY_CODE_POINT) {
                c2 = 0;
                length = 1;

                if (Character.isHighSurrogate(c1)
                    || Character.isLowSurrogate(c1)) {
                    norm = null;
                }
            } else {
                length = 2;
                c2 = src[srcIndex-1];
            }

          // get the decomposition and the lead and trail cc's
          if (norm == null) {
              // cp does not decompose
              cc = trailCC = UCharacter.getCombiningClass(cp);
              p = null;
              pStart = -1;
          } else {

                pStart = 0;
                p = norm.toCharArray();
                length = p.length;
                int cpNum = norm.codePointCount(0, length);
                cc= UCharacter.getCombiningClass(norm.codePointAt(0));
                trailCC= UCharacter.getCombiningClass(norm.codePointAt(cpNum-1));
                if (length == 1) {
                    // fastpath a single code unit from decomposition
                    c1 = p[pStart];
                    c2 = 0;
                    p = null;
                    pStart = -1;
                }
            }

            if((destIndex + length * 3) >= destLimit) {  // 2 SingleQuotations
                // buffer overflow
                char[] tmpBuf = new char[destLimit * 2];
                System.arraycopy(dest, 0, tmpBuf, 0, destIndex);
                dest = tmpBuf;
                destLimit = dest.length;
            }

            // append the decomposition to the destination buffer, assume length>0
            {
                int reorderSplit = destIndex;
                if (p == null) {
                    // fastpath: single code point
                    if (needSingleQuotation(c1)) {
                        //if we need single quotation, no need to consider "prevCC"
                        //and it must NOT be a supplementary pair
                        dest[destIndex++] = '\'';
                        dest[destIndex++] = c1;
                        dest[destIndex++] = '\'';
                        trailCC = 0;
                    } else if(cc != 0 && cc < prevCC) {
                        // (c1, c2) is out of order with respect to the preceding
                        //  text
                        destIndex += length;
                        trailCC = insertOrdered(dest, reorderStartIndex,
                                                reorderSplit, destIndex, c1, c2, cc);
                    } else {
                        // just append (c1, c2)
                        dest[destIndex++] = c1;
                        if(c2 != 0) {
                            dest[destIndex++] = c2;
                        }
                    }
                } else {
                    // general: multiple code points (ordered by themselves)
                    // from decomposition
                    if (needSingleQuotation(p[pStart])) {
                        dest[destIndex++] = '\'';
                        dest[destIndex++] = p[pStart++];
                        dest[destIndex++] = '\'';
                        length--;
                        do {
                            dest[destIndex++] = p[pStart++];
                        } while(--length > 0);
                    } else if (cc != 0 && cc < prevCC) {
                        destIndex += length;
                        trailCC = mergeOrdered(dest, reorderStartIndex,
                                               reorderSplit, p, pStart,
                                               pStart+length);
                    } else {
                        // just append the decomposition
                        do {
                            dest[destIndex++] = p[pStart++];
                        } while (--length > 0);
                    }
                }
            }
            prevCC = trailCC;
            if(prevCC == 0) {
                reorderStartIndex = destIndex;
            }
        }

        return new String(dest, 0, destIndex);
    }

    
simpler, single-character version of mergeOrdered() -
bubble-insert one single code point into the preceding string
which is already canonically ordered
(c, c2) may or may not yet have been inserted at src[current]..src[p]
it must be p=current+lengthof(c, c2) i.e. p=current+(c2==0 ? 1 : 2)
before: src[start]..src[current] is already ordered, and
        src[current]..src[p]     may or may not hold (c, c2) but
                         must be exactly the same length as (c, c2)
after: src[start]..src[p] is ordered
Returns:
the trailing combining class/**
     * simpler, single-character version of mergeOrdered() -
     * bubble-insert one single code point into the preceding string
     * which is already canonically ordered
     * (c, c2) may or may not yet have been inserted at src[current]..src[p]
     *
     * it must be p=current+lengthof(c, c2) i.e. p=current+(c2==0 ? 1 : 2)
     *
     * before: src[start]..src[current] is already ordered, and
     *         src[current]..src[p]     may or may not hold (c, c2) but
     *                          must be exactly the same length as (c, c2)
     * after: src[start]..src[p] is ordered
     *
     * @return the trailing combining class
     */
    private static int/*unsigned byte*/ insertOrdered(char[] source,
                                                      int start,
                                                      int current, int p,
                                                      char c1, char c2,
                                                      int/*unsigned byte*/ cc) {
        int back, preBack;
        int r;
        int prevCC, trailCC=cc;

        if (start<current && cc!=0) {
            // search for the insertion point where cc>=prevCC
            preBack=back=current;

            PrevArgs prevArgs = new PrevArgs();
            prevArgs.current  = current;
            prevArgs.start    = start;
            prevArgs.src      = source;
            prevArgs.c1       = c1;
            prevArgs.c2       = c2;

            // get the prevCC
            prevCC=getPrevCC(prevArgs);
            preBack = prevArgs.current;

            if(cc<prevCC) {
                // this will be the last code point, so keep its cc
                trailCC=prevCC;
                back=preBack;
                while(start<preBack) {
                    prevCC=getPrevCC(prevArgs);
                    preBack=prevArgs.current;
                    if(cc>=prevCC) {
                        break;
                    }
                    back=preBack;
                }

                // this is where we are right now with all these indicies:
                // [start]..[pPreBack] 0..? code points that we can ignore
                // [pPreBack]..[pBack] 0..1 code points with prevCC<=cc
                // [pBack]..[current] 0..n code points with >cc, move up to insert (c, c2)
                // [current]..[p]         1 code point (c, c2) with cc

                // move the code units in between up
                r=p;
                do {
                    source[--r]=source[--current];
                } while (back!=current);
            }
        }

        // insert (c1, c2)
        source[current] = c1;
        if (c2!=0) {
            source[(current+1)] = c2;
        }

        // we know the cc of the last code point
        return trailCC;
    }

    
merge two UTF-16 string parts together
to canonically order (order by combining classes) their concatenation
the two strings may already be adjacent, so that the merging is done
in-place if the two strings are not adjacent, then the buffer holding the
first one must be large enough
the second string may or may not be ordered in itself
before: [start]..[current] is already ordered, and
        [next]..[limit]    may be ordered in itself, but
                         is not in relation to [start..current[
after: [start..current+(limit-next)[ is ordered
the algorithm is a simple bubble-sort that takes the characters from
src[next++] and inserts them in correct combining class order into the
preceding part of the string
since this function is called much less often than the single-code point
insertOrdered(), it just uses that for easier maintenance
Returns:
the trailing combining class/**
     * merge two UTF-16 string parts together
     * to canonically order (order by combining classes) their concatenation
     *
     * the two strings may already be adjacent, so that the merging is done
     * in-place if the two strings are not adjacent, then the buffer holding the
     * first one must be large enough
     * the second string may or may not be ordered in itself
     *
     * before: [start]..[current] is already ordered, and
     *         [next]..[limit]    may be ordered in itself, but
     *                          is not in relation to [start..current[
     * after: [start..current+(limit-next)[ is ordered
     *
     * the algorithm is a simple bubble-sort that takes the characters from
     * src[next++] and inserts them in correct combining class order into the
     * preceding part of the string
     *
     * since this function is called much less often than the single-code point
     * insertOrdered(), it just uses that for easier maintenance
     *
     * @return the trailing combining class
     */
    private static int /*unsigned byte*/ mergeOrdered(char[] source,
                                                      int start,
                                                      int current,
                                                      char[] data,
                                                        int next,
                                                        int limit) {
            int r;
            int /*unsigned byte*/ cc, trailCC=0;
            boolean adjacent;

            adjacent= current==next;
            NextCCArgs ncArgs = new NextCCArgs();
            ncArgs.source = data;
            ncArgs.next   = next;
            ncArgs.limit  = limit;

            if(start!=current) {

                while(ncArgs.next<ncArgs.limit) {
                    cc=getNextCC(ncArgs);
                    if(cc==0) {
                        // does not bubble back
                        trailCC=0;
                        if(adjacent) {
                            current=ncArgs.next;
                        } else {
                            data[current++]=ncArgs.c1;
                            if(ncArgs.c2!=0) {
                                data[current++]=ncArgs.c2;
                            }
                        }
                        break;
                    } else {
                        r=current+(ncArgs.c2==0 ? 1 : 2);
                        trailCC=insertOrdered(source,start, current, r,
                                              ncArgs.c1, ncArgs.c2, cc);
                        current=r;
                    }
                }
            }

            if(ncArgs.next==ncArgs.limit) {
                // we know the cc of the last code point
                return trailCC;
            } else {
                if(!adjacent) {
                    // copy the second string part
                    do {
                        source[current++]=data[ncArgs.next++];
                    } while(ncArgs.next!=ncArgs.limit);
                    ncArgs.limit=current;
                }
                PrevArgs prevArgs = new PrevArgs();
                prevArgs.src   = data;
                prevArgs.start = start;
                prevArgs.current =  ncArgs.limit;
                return getPrevCC(prevArgs);
            }

    }

    private static final class PrevArgs{
        char[] src;
        int start;
        int current;
        char c1;
        char c2;
    }

    private static final class NextCCArgs{
        char[] source;
        int next;
        int limit;
        char c1;
        char c2;
    }

    private static int /*unsigned*/ getPrevCC(PrevArgs args) {
        args.c1=args.src[--args.current];
        args.c2=0;

        if (args.c1 < MIN_CCC_LCCC_CP) {
            return 0;
        } else if (UTF16.isLeadSurrogate(args.c1)) {
            /* unpaired first surrogate */
            return 0;
        } else if (!UTF16.isTrailSurrogate(args.c1)) {
            return UCharacter.getCombiningClass(args.c1);
        } else if (args.current!=args.start &&
                    UTF16.isLeadSurrogate(args.c2=args.src[args.current-1])) {
            --args.current;
            return UCharacter.getCombiningClass(Character.toCodePoint(args.c2, args.c1));
        } else {
            /* unpaired second surrogate */
            args.c2=0;
            return 0;
        }
    }

    private static int /*unsigned byte*/ getNextCC(NextCCArgs args) {
        args.c1=args.source[args.next++];
        args.c2=0;

        if (UTF16.isTrailSurrogate(args.c1)) {
            /* unpaired second surrogate */
            return 0;
        } else if (!UTF16.isLeadSurrogate(args.c1)) {
            return UCharacter.getCombiningClass(args.c1);
        } else if (args.next!=args.limit &&
                        UTF16.isTrailSurrogate(args.c2=args.source[args.next])){
            ++args.next;
            return UCharacter.getCombiningClass(Character.toCodePoint(args.c1, args.c2));
        } else {
            /* unpaired first surrogate */
            args.c2=0;
            return 0;
        }
    }

    private VersionInfo dataVersion;

    // Code point thresholds for quick check codes.
    private int minDecompNoCP;
    private int minCompNoMaybeCP;

    // Norm16 value thresholds for quick check combinations and types of extra data.
    private int minYesNo;
    private int minYesNoMappingsOnly;
    private int minNoNo;
    private int limitNoNo;
    private int minMaybeYes;

    private Trie2_16 normTrie;
    private String maybeYesCompositions;
    private String extraData;  // mappings and/or compositions for yesYes, yesNo & noNo characters
    private byte[] smallFCD;  // [0x100] one bit per 32 BMP code points, set if any FCD!=0
    private int[] tccc180;  // [0x180] tccc values for U+0000..U+017F

}