/*
 ********************************************************************
 * COPYRIGHT: 
 * Copyright (c) 1996-1999, International Business Machines Corporation and
 * others. All Rights Reserved.
 ********************************************************************
 */

/*
* Modification history
* 
* Date      Name      Description
* 02/02/01  synwee    Added converters from EMode to UNormalizationMode, 
*                     getUNormalizationMode and getNormalizerEMode,
*                     useful in tbcoll and unorm.
*                     Added quickcheck method and incorporated it into 
*                     normalize()
*/

#include "ucmp16.h"
#include "dcmpdata.h"
#include "compdata.h"

#include "unicode/normlzr.h"
#include "unicode/utypes.h"
#include "unicode/unistr.h"
#include "unicode/chariter.h"
#include "unicode/schriter.h"
#include "unicode/unicode.h"
#include "mutex.h"


#define ARRAY_LENGTH(array) (sizeof (array) / sizeof (*array))
/**
* Maximum initial buffer size.
* Used in quickCheck to declare initial array.
*/
const uint32_t StackBufferLen = 1024;

inline static void insert(UnicodeString& dest, 
                          UTextOffset pos, 
                          UChar ch)
{
    dest.replace(pos, 0, &ch, 1);
}

//-------------------------------------------------------------------------
// Constructors and other boilerplate
//-------------------------------------------------------------------------

Normalizer::Normalizer(const UnicodeString& str, 
                       EMode mode)
{
    init(new StringCharacterIterator(str), mode, 0);
}

Normalizer::Normalizer(const UnicodeString& str, 
                       EMode mode, 
                       int32_t opt)
{
    init(new StringCharacterIterator(str), mode, opt);
}

Normalizer::Normalizer(const UChar* str, int32_t length, EMode mode) 
{
    init(new StringCharacterIterator(UnicodeString(str, length)), mode, 0);
}

Normalizer::Normalizer(const CharacterIterator& iter, 
                       EMode mode)
{
    init(iter.clone(), mode, 0);
}

Normalizer::Normalizer(const CharacterIterator& iter, 
                       EMode mode, 
                       int32_t opt)
{
    init(iter.clone(), mode, opt);
}

void Normalizer::init(CharacterIterator* adoptIter, 
                      EMode mode, 
                      int32_t options)
{
    bufferPos = 0;
    bufferLimit = 0;
    fOptions = options;
    currentChar = DONE;
    fMode = mode;
    text = adoptIter;
  
    minDecomp = (int16_t)((fMode & COMPAT_BIT) ? 0 : DecompData::MAX_COMPAT);
}

Normalizer::Normalizer(const Normalizer& copy)
{
    init(copy.text->clone(), copy.fMode, copy.fOptions);
  
    buffer      = copy.buffer;
    bufferPos   = copy.bufferPos;
    bufferLimit = copy.bufferLimit;
    explodeBuf  = copy.explodeBuf;
    currentChar = copy.currentChar;
}

Normalizer::~Normalizer()
{
    delete text;
}

Normalizer* 
Normalizer::clone() const
{
    if(this!=0) {
        return new Normalizer(*this);
    } else {
        return 0;
    }
}

/**
 * Generates a hash code for this iterator.
 */
int32_t Normalizer::hashCode() const
{
    return text->hashCode() + fMode + fOptions + bufferPos + bufferLimit;
}
    
UBool Normalizer::operator==(const Normalizer& that) const
{
    return *text == *(that.text)
        && currentChar == that.currentChar
        && buffer == that.buffer
        && explodeBuf == that.explodeBuf
        && bufferPos == that.bufferPos
        && bufferLimit == that.bufferLimit;
}

//-------------------------------------------------------------------------
// Static utility methods
//-------------------------------------------------------------------------

void 
Normalizer::normalize(const UnicodeString& source, 
                      EMode mode, 
                      int32_t options,
                      UnicodeString& result, 
                      UErrorCode &status)
{
  if (quickCheck(source, mode, status) == UNORM_YES)
  {
    result = source;
    return;
  }

  switch (mode) {
  case NO_OP:
    result = source;
    break;
  case COMPOSE:
  case COMPOSE_COMPAT:
    compose(source, (mode & COMPAT_BIT) != 0, options, result, status);
    break;
  case DECOMP:
  case DECOMP_COMPAT:
    decompose(source, (mode & COMPAT_BIT) != 0, options, result, status);
    break;
  }
}

UNormalizationCheckResult
Normalizer::quickCheck(const UnicodeString& source,
                       Normalizer::EMode mode, 
                       UErrorCode &status)
{
  if (U_FAILURE(status))
    return UNORM_MAYBE;

  const UChar *ps = source.getUChars();
  return unorm_quickCheck(ps, source.length(), 
                          getUNormalizationMode(mode, status), &status);
}

//-------------------------------------------------------------------------
// Inline functions for 64-bit bitmasks (array of 2 uint32_t)
//-------------------------------------------------------------------------

// Clear all bits of the mask
inline void emptyBitmask64(uint32_t* mask) {
    mask[0] = mask[1] = 0;
}

// Return TRUE if all bits are clear in the mask
inline UBool isEmptyBitmask64(uint32_t* mask) {
    return (mask[0] == 0) && (mask[1] == 0);
}

// Set a single bit (0..63) of the mask
inline void setBitmask64(uint32_t* mask, int32_t bit) {
    mask[bit >> 5] |= (1L << (bit & 31));
}

// Return TRUE if a single bit (0..63) is set in the mask
inline UBool isSetBitmask64(uint32_t* mask, int32_t bit) {
    return (mask[bit >> 5] & (1L << (bit & 31))) != 0;
}

//-------------------------------------------------------------------------
// Compose methods
//-------------------------------------------------------------------------

void
Normalizer::compose(const UnicodeString& source, 
                    UBool compat,
                    int32_t,
                    UnicodeString& result, 
                    UErrorCode &status)
{
    if (U_FAILURE(status)) {
        return;
    }
    result.truncate(0);
    UnicodeString explodeBuf;
  
    UTextOffset explodePos = EMPTY;         // Position in input buffer
    UTextOffset basePos = 0;                // Position of last base in output string
    uint16_t    baseIndex = 0;              // Index of last base in "actions" array
    uint32_t    classesSeen[2];             // Combining classes seen since last base
    uint16_t    action;
    
    // Compatibility explosions have lower indices; skip them if necessary
    uint16_t minExplode = (uint16_t)(compat ? 0 : ComposeData::MAX_COMPAT);
    uint16_t minDecompLocal = (uint16_t)(compat ? 0 : DecompData::MAX_COMPAT);
  
    UTextOffset i = 0;

    emptyBitmask64(classesSeen);
    while (i < source.length() || explodePos != EMPTY) {
        // Get the next char from either the buffer or the source
        UChar ch;
        if (explodePos == EMPTY) {
            ch = source[i++];
        } else {
            ch = explodeBuf[explodePos++];
            if (explodePos >= explodeBuf.length()) {
                explodePos = EMPTY;
                explodeBuf.truncate(0);
            }
        }
      
        // Get the basic info for the character
        uint16_t charInfo = composeLookup(ch);
        uint16_t type = (uint16_t)(charInfo & ComposeData::TYPE_MASK);
        uint16_t index = (uint16_t)(charInfo >> ComposeData::INDEX_SHIFT);
      
        if (type == ComposeData::BASE ||
            (type == ComposeData::NON_COMPOSING_COMBINING && index < minExplode)) {
            emptyBitmask64(classesSeen);
            baseIndex = index;
            basePos = result.length();
            result += ch;
        }
        else if (type == ComposeData::COMBINING)
        {
            uint32_t cclass = ComposeData::typeBit[index]; // 0..63
      
            // We can only combine a character with the base if we haven't
            // already seen a combining character with the same canonical class.
            // We also only combine characters with an index from
            // 1..COMBINING_COUNT-1.  Indices >= COMBINING_COUNT are
            // non-combining; these formerly had an index of zero.
            if (index < ComposeData::COMBINING_COUNT
                && !isSetBitmask64(classesSeen, cclass)
                && (action = composeAction(baseIndex, index)) > 0)
            {
                if (action > ComposeData::MAX_COMPOSED) {
                    // Pairwise explosion.  Actions above this value are really
                    // indices into an array that in turn contains indices
                    // into the exploding string table
                    // TODO: What if there are unprocessed chars in the explode buffer?
                    UChar newBase = pairExplode(explodeBuf, action);
                    explodePos = 0;
                    result[basePos] = newBase;
        
                    baseIndex = (uint16_t)(composeLookup(newBase) >> ComposeData::INDEX_SHIFT);
                } else {
                    // Normal pairwise combination.  Replace the base char
                    UChar newBase = (UChar) action;
                    result[basePos] = newBase;
        
                    baseIndex = (uint16_t)(composeLookup(newBase) >> ComposeData::INDEX_SHIFT);
                }
                //
                // Since there are Unicode characters that cannot be combined in arbitrary
                // order, we have to re-process any combining marks that go with this
                // base character.  There are only four characters in Unicode that have
                // this problem.  If they are fixed in Unicode 3.0, this code can go away.
                //
                UTextOffset len = result.length();
                if (len - basePos > 1) {
                    for (UTextOffset j = basePos+1; j < len; j++) {
                        explodeBuf += result[j];
                    }
                    result.truncate(basePos+1);
                    emptyBitmask64(classesSeen);
                    if (explodePos == EMPTY) explodePos = 0;
                }
            } else {
                // No combination with this character
                bubbleAppend(result, ch, cclass);
                setBitmask64(classesSeen, cclass);
            }
        }
        else if (index > minExplode) {
            // Single exploding character
            explode(explodeBuf, index);
            explodePos = 0;
        }
        else if (type == ComposeData::HANGUL && minExplode == 0) {
            // If we're in compatibility mode we need to decompose Hangul to Jamo,
            // because some of the Jamo might have compatibility decompositions.
            hangulToJamo(ch, explodeBuf, minDecompLocal);
            explodePos = 0;
        }
        else if (type == ComposeData::INITIAL_JAMO) {
            emptyBitmask64(classesSeen);
            baseIndex = ComposeData::INITIAL_JAMO_INDEX;
            basePos = result.length();
            result += ch;
        }
        else if (type == ComposeData::MEDIAL_JAMO
                 && isEmptyBitmask64(classesSeen)
                 && baseIndex == ComposeData::INITIAL_JAMO_INDEX) {
            // If the last character was an initial jamo, we can combine it with this
            // one to create a Hangul character.
            uint16_t l = (uint16_t)(result[basePos] - (UChar)JAMO_LBASE);
            uint16_t v = (uint16_t)(ch - JAMO_VBASE);
            result[basePos] = (UChar)(HANGUL_BASE + (l*JAMO_VCOUNT + v) * JAMO_TCOUNT);
    
            baseIndex = ComposeData::MEDIAL_JAMO_INDEX;
        }
        else if (type == ComposeData::FINAL_JAMO
                 && isEmptyBitmask64(classesSeen)
                 && baseIndex == ComposeData::MEDIAL_JAMO_INDEX) {
            // If the last character was a medial jamo that we turned into Hangul,
            // we can add this character too.
            result[basePos] = (UChar)(result[basePos] + (ch - JAMO_TBASE));
    
            baseIndex = 0;
            basePos = -1;
            emptyBitmask64(classesSeen);
        } else {
            baseIndex = 0;
            basePos = -1;
            emptyBitmask64(classesSeen);
            result += ch;
        }
    }
}

/**
 * Compose starting with current input character and continuing
 * until just before the next base char.
 * <p>
 * <b>Input</b>:
 * <ul>
 *  <li>underlying char iter points to first character to decompose
 * </ul>
 * <p>
 * <b>Output:</b>
 * <ul>
 *  <li>returns first char of decomposition or DONE if at end
 *  <li>Underlying char iter is pointing at next base char or past end
 * </ul>
 */
UChar Normalizer::nextCompose() 
{
    UTextOffset explodePos = EMPTY;  // Position in input buffer
    UTextOffset basePos = 0;         // Position of last base in output string
    uint16_t    baseIndex = 0;       // Index of last base in "actions" array
    uint32_t    classesSeen[2];      // Combining classes seen since last base
    uint16_t    action;
    UChar       lastBase = 0;
    UBool       chFromText = TRUE;
    
    // Compatibility explosions have lower indices; skip them if necessary
    uint16_t minExplode = (uint16_t)((fMode & COMPAT_BIT) ? 0 : ComposeData::MAX_COMPAT);
    uint16_t minDecompLocal = (uint16_t)((fMode & COMPAT_BIT) ? 0 : DecompData::MAX_COMPAT);
    
    emptyBitmask64(classesSeen);
    initBuffer();
    explodeBuf.truncate(0);
    
    UChar ch = curForward();

    while (ch != DONE) {
        // Get the basic info for the character
        uint16_t charInfo = composeLookup(ch);
        uint16_t type = (uint16_t)(charInfo & ComposeData::TYPE_MASK);
        uint16_t index = (uint16_t)(charInfo >> ComposeData::INDEX_SHIFT);
        
        if (type == ComposeData::BASE || (type == ComposeData::NON_COMPOSING_COMBINING && index < minExplode)) {
            if (buffer.length() > 0 && chFromText && explodePos == EMPTY) {
                // When we hit a base char in the source text, we can return the text
                // that's been composed so far.  We'll re-process this char next time hrough.
                break;
            }
            emptyBitmask64(classesSeen);
            baseIndex = index;
            basePos = buffer.length();
            buffer += ch;
            lastBase = ch;
        }
        else if (type == ComposeData::COMBINING)
        {
            uint32_t cclass = ComposeData::typeBit[index]; // 0..63
            
            // We can only combine a character with the base if we haven't
            // already seen a combining character with the same canonical class.
            if (index < ComposeData::COMBINING_COUNT
                && !isSetBitmask64(classesSeen, cclass)
                && (action = composeAction(baseIndex, index)) > 0)
            {
                if (action > ComposeData::MAX_COMPOSED) {
                    // Pairwise explosion.  Actions above this value are really
                    // indices into an array that in turn contains indices
                    // into the exploding string table
                    // TODO: What if there are unprocessed chars in the explode buffer?
                    UChar newBase = pairExplode(explodeBuf, action);
                    explodePos = 0;
                    buffer[basePos] = newBase;

                    baseIndex = (uint16_t)(composeLookup(newBase) >> ComposeData::INDEX_SHIFT);
                    lastBase = newBase;
                } else {
                    // Normal pairwise combination.  Replace the base char
                    UChar newBase = (UChar) action;
                    buffer[basePos] = newBase;
                                            
                    baseIndex = (uint16_t)(composeLookup(newBase) >> ComposeData::INDEX_SHIFT);
                    lastBase = newBase;
                }
                //
                // Since there are Unicode characters that cannot be combined in arbitrary
                // order, we have to re-process any combining marks that go with this
                // base character.  There are only four characters in Unicode that have
                // this problem.  If they are fixed in Unicode 3.0, this code can go away.
                //
                UTextOffset len = buffer.length();
                if (len - basePos > 1) {
                    for (UTextOffset j = basePos+1; j < len; j++) {
                        explodeBuf += buffer[j];
                    }
                    buffer.truncate(basePos+1);
                    emptyBitmask64(classesSeen);
                    if (explodePos == EMPTY) explodePos = 0;
                }
            } else {
                // No combination with this character
                bubbleAppend(buffer, ch, cclass);
                setBitmask64(classesSeen, cclass); //[cclass >> 5] |= (1L << (cclass & 31));
            }
        }
        else if (index > minExplode) {
            // Single exploding character
            explode(explodeBuf, index);
            explodePos = 0;
        }
        else if (type == ComposeData::HANGUL && minExplode == 0) {
            // If we're in compatibility mode we need to decompose Hangul to Jamo,
            // because some of the Jamo might have compatibility decompositions.
            hangulToJamo(ch, explodeBuf, minDecompLocal);
            explodePos = 0;
        }
        else if (type == ComposeData::INITIAL_JAMO) {
            if (buffer.length() > 0 && chFromText && explodePos == EMPTY) {
                // When we hit a base char in the source text, we can return the text
                // that's been composed so far.  We'll re-process this char next time through.
                break;
            }
            emptyBitmask64(classesSeen);
            baseIndex = ComposeData::INITIAL_JAMO_INDEX;
            basePos = buffer.length();
            buffer += ch;
        }
        else if (type == ComposeData::MEDIAL_JAMO
                 && isEmptyBitmask64(classesSeen)
                 && baseIndex == ComposeData::INITIAL_JAMO_INDEX) {
            // If the last character was an initial jamo, we can combine it with this
            // one to create a Hangul character.
            uint16_t l = (uint16_t)(buffer[basePos] - (UChar)JAMO_LBASE);
            uint16_t v = (uint16_t)(ch - JAMO_VBASE);
            buffer[basePos] = (UChar)(HANGUL_BASE + (l*JAMO_VCOUNT + v) * JAMO_TCOUNT);
            
            baseIndex = ComposeData::MEDIAL_JAMO_INDEX;
        }
        else if (type == ComposeData::FINAL_JAMO
                 && isEmptyBitmask64(classesSeen)
                 && baseIndex == ComposeData::MEDIAL_JAMO_INDEX) {
            // If the last character was a medial jamo that we turned into Hangul,
            // we can add this character too.
            buffer[basePos] = (UChar)(buffer[basePos] + (ch - JAMO_TBASE));

            baseIndex = 0;
            basePos = -1;
            emptyBitmask64(classesSeen);
        } else {
            // TODO: deal with JAMO character types
            baseIndex = 0;
            basePos = -1;
            emptyBitmask64(classesSeen);
            buffer += ch;
        }
        
        if (explodePos == EMPTY) {
            ch = text->next();
            chFromText = TRUE;
        } else {
            ch = explodeBuf[explodePos++];
            if (explodePos >= explodeBuf.length()) {
                explodePos = EMPTY;
                explodeBuf.truncate(0);
            }
            chFromText = FALSE;
        }
    }
    if (buffer.length() > 0) {
        bufferLimit = buffer.length() - 1;
        ch = buffer[0];
    } else {
        ch = DONE;
        bufferLimit = 0;
    }
    return ch;
}

/**
 * Compose starting with the input UChar just before the current position
 * and continuing backward until (and including) the previous base char.
 * <p>
 * <b>Input</b>:
 * <ul>
 *  <li>underlying char iter points just after last char to decompose
 * </ul>
 * <p>
 * <b>Output:</b>
 * <ul>
 *  <li>returns last char of resulting decomposition sequence
 *  <li>underlying iter points to lowest-index char we decomposed, i.e. the base char
 * </ul>
 */
UChar Normalizer::prevCompose()
{
    UErrorCode status = U_ZERO_ERROR;

    // Compatibility explosions have lower indices; skip them if necessary
    uint16_t minExplode = (uint16_t)((fMode & COMPAT_BIT) ? 0 : ComposeData::MAX_COMPAT);

    initBuffer();
    
    // Slurp up characters until we hit a base char or an initial Jamo
    UChar ch;
    while ((ch = curBackward()) != DONE) {
        insert(buffer, 0, ch);
        
        // Get the basic info for the character
        uint16_t charInfo = composeLookup(ch);
        uint16_t type = (uint16_t)(charInfo & ComposeData::TYPE_MASK);
        uint16_t index = (uint16_t)(charInfo >> ComposeData::INDEX_SHIFT);
        
        if (type == ComposeData::BASE
            || (type == ComposeData::NON_COMPOSING_COMBINING && index < minExplode)
            || type == ComposeData::HANGUL 
            || type == ComposeData::INITIAL_JAMO)
        {
            break;
        }
    }
    // If there's more than one character in the buffer, compose it all at once....
    if (buffer.length() > 0) {
        // TODO: The performance of this is awful; add a way to compose
        // a UnicodeString& in place.
        UnicodeString composed;
        compose(buffer, (fMode & COMPAT_BIT) != 0, fOptions, composed, status);
        buffer.truncate(0);
        buffer += composed;
        
        if (buffer.length() > 1) {
            bufferLimit = bufferPos = buffer.length() - 1;
            ch = buffer[bufferPos];
        } else {
            ch = buffer[0];
        }
    }
    else {
        ch = DONE;
    }
    
    return ch;
}

void Normalizer::bubbleAppend(UnicodeString& target, UChar ch, uint32_t cclass) {
    UTextOffset i;
    for (i = target.length() - 1; i > 0; --i) {
        uint32_t iClass = getComposeClass(target[i]);

        if (iClass == 1 || iClass <= cclass) {      // 1 means combining class 0
            // We've hit something we can't bubble this character past, so insert here
            break;
        }
    }
    // We need to insert just after character "i"
    insert(target, i+1, ch);
}
    
/**
 * Return the composing class of a character, as stored in the ComposeData
 * table.  This is not the composing class as listed in the raw Unicode
 * database, but an equivalent remapped value.  Values are remapped so they
 * fit in a sequential range from 0..n, where n < 64, and relative order
 * is preserved.
 * @return the composing class of ch, from 0..63
 */
uint32_t Normalizer::getComposeClass(UChar ch) {
    uint32_t cclass = 0;
    uint16_t charInfo = composeLookup(ch);
    uint16_t type = (uint16_t)(charInfo & ComposeData::TYPE_MASK);
    if (type == ComposeData::COMBINING) {
        cclass = ComposeData::typeBit[charInfo >> ComposeData::INDEX_SHIFT];
    }
    return cclass;
}

uint16_t Normalizer::composeLookup(UChar ch) {
    return ucmp16_getu(ComposeData::lookup, ch);
}

uint16_t Normalizer::composeAction(uint16_t baseIndex, uint16_t comIndex) 
{
    return ucmp16_getu(ComposeData::actions,
                       ((UChar)(baseIndex + ComposeData::MAX_BASES*comIndex)));
}

void Normalizer::explode(UnicodeString& target, uint16_t index) {
    UChar ch;
    while ((ch = ComposeData::replace[index++]) != 0) {
        target += ch;
    }
}

UChar Normalizer::pairExplode(UnicodeString& target, uint16_t action) {
    uint16_t index = ComposeData::actionIndex[action - ComposeData::MAX_COMPOSED];
    explode(target, (uint16_t)(index + 1));
    return ComposeData::replace[index];   // New base char
}

//-------------------------------------------------------------------------
// Decompose methods
//-------------------------------------------------------------------------

void
Normalizer::decompose(const UnicodeString& source, 
                      UBool compat,
                      int32_t options,
                      UnicodeString& result, 
                      UErrorCode &status)
{
    if (U_FAILURE(status)) {
        return;
    }
    UBool     hangul = (options & IGNORE_HANGUL) == 0;
    uint16_t  minDecompLocal = (uint16_t)(compat ? 0 : DecompData::MAX_COMPAT);
    UnicodeString buffer;
    int32_t i = 0, bufPtr = -1;

    result.truncate(0);
  
    // Rewritten - Liu
    while (i < source.length() || bufPtr >= 0) {
        UChar ch;
    
        if (bufPtr >= 0) {
            ch = buffer.charAt(bufPtr++);
            if (bufPtr == buffer.length()) {
                bufPtr = -1;
            }
        } else {
            ch = source[i++];
        }

        uint16_t offset = ucmp16_getu(DecompData::offsets, ch);
        uint16_t index = (uint16_t)(offset & DecompData::DECOMP_MASK);
    
        if (index > minDecompLocal) {
            if ((offset & DecompData::DECOMP_RECURSE) != 0) {
                buffer.truncate(0);
                doAppend((const UChar*)DecompData::contents, index, buffer);
                bufPtr = 0;
            } else {
                doAppend((const UChar*)DecompData::contents, index, result);
            }
        } else if (ch >= HANGUL_BASE && ch < HANGUL_LIMIT && hangul) {
            hangulToJamo(ch, result, minDecompLocal);
        } else {
            result += ch;
        }
    }
    fixCanonical(result);
}

/**
 * Decompose starting with current input character and continuing
 * until just before the next base char.
 * <p>
 * <b>Input</b>:
 * <ul>
 *  <li>underlying char iter points to first character to decompose
 * </ul>
 * <p>
 * <b>Output:</b>
 * <ul>
 *  <li>returns first char of decomposition or DONE if at end
 *  <li>Underlying char iter is pointing at next base char or past end
 * </ul>
 */
UChar Normalizer::nextDecomp()
{
    UBool hangul = ((fOptions & IGNORE_HANGUL) == 0);
    UChar ch = curForward();
    int32_t i;
    uint16_t offset = ucmp16_getu(DecompData::offsets, ch);
    int16_t index = (uint16_t)(offset & DecompData::DECOMP_MASK);
  
    if (index > minDecomp ||
        ucmp8_get(DecompData::canonClass, ch) != DecompData::BASE)
    {
        initBuffer();
      
        if (index > minDecomp) {
            doAppend((const UChar*)(DecompData::contents), index, buffer);

            if ((offset & DecompData::DECOMP_RECURSE) != 0) {
                // Need to decompose the output of this decomposition recursively.
                for (i = 0; i < buffer.length(); i++) {
                    ch = buffer.charAt(i);
                    int16_t index = (int16_t)(ucmp16_getu(DecompData::offsets, ch)
                        & DecompData::DECOMP_MASK);
                    if (index > minDecomp) {
                        i += doReplace((const UChar*)(DecompData::contents), index, buffer, i);
                    }
                }
            }
        } else {
            buffer += ch;
        }
        UBool needToReorder = FALSE;
      
        // Any other combining chacters that immediately follow the decomposed
        // character must be included in the buffer too, because they're
        // conceptually part of the same logical character.
        while ((ch = text->next()) != DONE
               && ucmp8_get(DecompData::canonClass, ch) != DecompData::BASE)
        {
            needToReorder = TRUE;
            // Decompose any of these characters that need it - Liu
            index = (int16_t)(ucmp16_getu(DecompData::offsets, ch)
                    & DecompData::DECOMP_MASK);
            if (index > minDecomp) {
                doAppend((const UChar*)DecompData::contents, index, buffer);
            } else {
                buffer += ch;
            }
        }
        
        if (buffer.length() > 1 && needToReorder) {
            // If there is more than one combining character in the buffer,
            // put them into the canonical order.
            // But we don't need to sort if only characters are the ones that
            // resulted from decomosing the base character.
            fixCanonical(buffer);
        }
        bufferLimit = buffer.length() - 1;
        ch = buffer[0];
    } else {
        // Just use this character, but first advance to the next one
        text->next();
      
        // Do Hangul -> Jamo decomposition if necessary
        if (hangul && ch >= HANGUL_BASE && ch < HANGUL_LIMIT) {
            initBuffer();
            hangulToJamo(ch, buffer, minDecomp);
            bufferLimit = buffer.length() - 1;
            ch = buffer[0];
        }
    }
    return ch;
}


/**
 * Decompose starting with the input char just before the current position
 * and continuing backward until (and including) the previous base char.
 * <p>
 * <b>Input</b>:
 * <ul>
 *  <li>underlying char iter points just after last char to decompose
 * </ul>
 * <p>
 * <b>Output:</b>
 * <ul>
 *  <li>returns last char of resulting decomposition sequence
 *  <li>underlying iter points to lowest-index char we decomposed, i.e. the base char
 * </ul>
 */
UChar Normalizer::prevDecomp() {
    UBool hangul = (fOptions & IGNORE_HANGUL) == 0;

    UChar ch = curBackward();

    uint16_t offset = ucmp16_getu(DecompData::offsets, ch);

    if (offset > minDecomp ||
        ucmp8_get(DecompData::canonClass, ch) != DecompData::BASE)
    {
        initBuffer();

        // This method rewritten to pass conformance tests. - Liu
        // Collect all characters up to the previous base char
        while (ch != DONE) {
            buffer.insert(0, ch);
            if (ucmp8_get(DecompData::canonClass, ch) == DecompData::BASE) break;
            ch = text->previous();
        }
        
        // Decompose the buffer
        int32_t i;
        for (i = 0; i < buffer.length(); i++) {
            ch = buffer.charAt(i);
            offset = ucmp16_getu(DecompData::offsets, ch);
            int16_t index = (int16_t)(offset & DecompData::DECOMP_MASK);
            
            if (index > minDecomp) {
                int j = doReplace((const UChar*)(DecompData::contents), index, buffer, i);
                if ((offset & DecompData::DECOMP_RECURSE) != 0) {
                    // Need to decompose this recursively
                    for (; i < j; ++i) {
                        ch = buffer.charAt(i);
                        index = (int16_t)(ucmp16_getu(DecompData::offsets, ch)
                            & DecompData::DECOMP_MASK);
                        if (index > minDecomp) {
                            i += doReplace((const UChar*)(DecompData::contents), index, buffer, i);
                        }
                    }
                }
                i = j;
            }
        }


        if (buffer.length() > 1) {
            // If there is more than one combining character in the buffer,
            // put them into the canonical order.
            fixCanonical(buffer);
        }
        bufferLimit = bufferPos = buffer.length() - 1;
        ch = buffer[bufferPos];
    }
    else if (hangul && ch >= HANGUL_BASE && ch < HANGUL_LIMIT) {
        initBuffer();
        hangulToJamo(ch, buffer, minDecomp);
        bufferLimit = bufferPos = buffer.length() - 1;
        ch = buffer[bufferPos];
    }
    return ch;
}

uint8_t Normalizer::getClass(UChar ch) {
    return  ucmp8_get(DecompData::canonClass, ch);
}
 
/**
 * Fixes the sorting sequence of non-spacing characters according to
 * their combining class.  The algorithm is listed on p.3-11 in the
 * Unicode Standard 2.0.  The table of combining classes is on p.4-2
 * in the Unicode Standard 2.0.
 * @param result the string to fix.
 */
void Normalizer::fixCanonical(UnicodeString& result) {
    UTextOffset i = result.length() - 1;
    uint8_t currentType = getClass(result[i]);
    uint8_t lastType;
    
    for (--i; i >= 0; --i) {
        lastType = currentType;
        currentType = getClass(result[i]);
        
        //
        // a swap is presumed to be rare (and a double-swap very rare),
        // so don't worry about efficiency here.
        //
        if (currentType > lastType && lastType != DecompData::BASE) {
            // swap characters
            UChar temp = result[i];
            result[i] = result[i+1];
            result[i+1] = temp;

            // if not at end, backup (one further, to compensate for for-loop)
            if (i < result.length() - 2) {
                i += 2;
            }
            // reset type, since we swapped.
            currentType = getClass(result[i]);
        }
    }
}

    
//-------------------------------------------------------------------------
// CharacterIterator overrides
//-------------------------------------------------------------------------

/**
 * Return the current character in the normalized text.
 */
UChar32 Normalizer:: current() const
{
    // TODO: make this method const and guarantee that currentChar is always set?
    Normalizer *nonConst = (Normalizer*)this;
  
    if (currentChar == DONE) {
        switch (fMode) {
        case NO_OP:
            nonConst->currentChar = text->current();            
            break;
        case COMPOSE:
        case COMPOSE_COMPAT:
            nonConst->currentChar = nonConst->nextCompose();    
            break;
        case DECOMP:    
        case DECOMP_COMPAT:
            nonConst->currentChar = nonConst->nextDecomp();        
            break;
        }
    }
    return currentChar;
}

/**
 * Return the first character in the normalized text.  This resets
 * the <tt>Normalizer's</tt> position to the beginning of the text.
 */
UChar32 Normalizer::first() {
    return setIndex(text->startIndex());
}

/**
 * Return the last character in the normalized text.  This resets
 * the <tt>Normalizer's</tt> position to be just before the
 * the input text corresponding to that normalized character.
 */
UChar32 Normalizer::last() {
    text->setIndex(text->endIndex());
  
    currentChar = DONE;                     // The current char hasn't been processed
    clearBuffer();                          // The buffer is empty too
    return previous();
}

/**
 * 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.
 */
UChar32 Normalizer::next() {
    if (bufferPos < bufferLimit) {
        // There are output characters left in the buffer
        currentChar = buffer[++bufferPos];
    }
    else {
        bufferLimit = bufferPos = 0;    // Buffer is now out of date
        switch (fMode) {
        case NO_OP:
            currentChar = text->next();        
            break;
        case COMPOSE:        
        case COMPOSE_COMPAT:
            currentChar = nextCompose();    
            break;
        case DECOMP:    
        case DECOMP_COMPAT:
            currentChar = nextDecomp();        
            break;
        }
    }
    return currentChar;
}

/**
 * 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.
 */
UChar32 Normalizer::previous()
{
    if (bufferPos > 0) {
        // There are output characters left in the buffer
        currentChar = buffer[--bufferPos];
    }
    else {
        bufferLimit = bufferPos = 0;    // Buffer is now out of date
        switch (fMode) {
        case NO_OP:        
            currentChar = text->previous();    
            break;
        case COMPOSE:        
        case COMPOSE_COMPAT:
            currentChar = prevCompose();    
            break;
        case DECOMP:    
        case DECOMP_COMPAT:
            currentChar = prevDecomp();        
            break;
        }
    }
    return currentChar;
}

void Normalizer::reset() 
{
    text->setIndex(text->startIndex());
    currentChar = DONE;     // The current char hasn't been processed
    clearBuffer();          // The buffer is empty too
}

/**
 * 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 <tt>next</tt> and <tt>previous</tt> and the indices passed to and
 * returned from <tt>setIndex</tt> 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}.
 */
UChar32 Normalizer::setIndex(UTextOffset index)
{
    text->setIndex(index);   // Checks range
    currentChar = DONE;     // The current char hasn't been processed
    clearBuffer();          // The buffer is empty too

    return current();
}

/**
 * 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 <tt>next</tt> and
 * <tt>previous</tt> and the indices passed to and returned from
 * <tt>setIndex</tt> and {@link #getIndex}.
 *
 */
UTextOffset Normalizer::getIndex() const {
    return text->getIndex();
}

/**
 * Retrieve the index of the start of the input text.  This is the begin index
 * of the <tt>CharacterIterator</tt> or the start (i.e. 0) of the <tt>String</tt>
 * over which this <tt>Normalizer</tt> is iterating
 */
UTextOffset Normalizer::startIndex() const {
    return text->startIndex();
}

/**
 * Retrieve the index of the end of the input text.  This is the end index
 * of the <tt>CharacterIterator</tt> or the length of the <tt>String</tt>
 * over which this <tt>Normalizer</tt> is iterating
 */
UTextOffset Normalizer::endIndex() const {
    return text->endIndex();
}

//-------------------------------------------------------------------------
// Property access methods
//-------------------------------------------------------------------------

void
Normalizer::setMode(EMode newMode) 
{
    fMode = newMode;
    minDecomp = (int16_t)(((fMode & COMPAT_BIT) != 0) ? 0 : DecompData::MAX_COMPAT);
}

Normalizer::EMode 
Normalizer::getMode() const
{
    return fMode;
}

void
Normalizer::setOption(int32_t option, 
                      UBool value) 
{
    if (value) {
        fOptions |= option;
    } else {
        fOptions &= (~option);
    }
}

UBool
Normalizer::getOption(int32_t option) const
{
    return (fOptions & option) != 0;
}

/**
 * Set the input text over which this <tt>Normalizer</tt> will iterate.
 * The iteration position is set to the beginning of the input text.
 */
void
Normalizer::setText(const UnicodeString& newText, 
                    UErrorCode &status)
{
    if (U_FAILURE(status)) {
        return;
    }
    CharacterIterator *newIter = new StringCharacterIterator(newText);
    if (newIter == NULL) {
        status = U_MEMORY_ALLOCATION_ERROR;
        return;
    }
    delete text;
    text = newIter;
    reset();
}

/**
 * Set the input text over which this <tt>Normalizer</tt> will iterate.
 * The iteration position is set to the beginning of the string.
 */
void
Normalizer::setText(const CharacterIterator& newText, 
                    UErrorCode &status) 
{
    if (U_FAILURE(status)) {
        return;
    }
    CharacterIterator *newIter = newText.clone();
    if (newIter == NULL) {
        status = U_MEMORY_ALLOCATION_ERROR;
        return;
    }
    delete text;
    text = newIter;
    reset();
}

void
Normalizer::setText(const UChar* newText,
                    int32_t length,
                    UErrorCode &status)
{
    setText(UnicodeString(newText, length), status);
}

/**
 * Copies the text under iteration into the UnicodeString referred to by "result".
 * @param result Receives a copy of the text under iteration.
 */
void
Normalizer::getText(UnicodeString&  result) 
{
    text->getText(result);
}


//-------------------------------------------------------------------------
// Private utility methods
//-------------------------------------------------------------------------


UChar Normalizer::curForward() {
    UChar ch = text->current();
    return ch;
}

UChar Normalizer::curBackward() {
    UChar ch = text->previous();
    return ch;
}

void Normalizer::doAppend(const UChar source[], uint16_t offset, UnicodeString& dest) {
    uint16_t index = (int16_t)(offset >> STR_INDEX_SHIFT);
    uint16_t length = (int16_t)(offset & STR_LENGTH_MASK);

    if (length == 0) {
        UChar ch;
        while ((ch = source[index++]) != 0x0000) {
            dest += ch;
        }
    } else {
        while (length-- > 0) {
            dest += source[index++];
        }
    }
}

void Normalizer::doInsert(const UChar source[], uint16_t offset, UnicodeString& dest, UTextOffset pos)
{
    uint16_t index = (int16_t)(offset >> STR_INDEX_SHIFT);
    uint16_t length = (int16_t)(offset & STR_LENGTH_MASK);

    if (length == 0) {
        UChar ch;
        while ((ch = source[index++]) != 0x0000) {
            insert(dest, pos++, ch);
        }
    } else {
        while (length-- > 0) {
            insert(dest, pos++, source[index++]);
        }
    }
}

uint16_t Normalizer::doReplace(const UChar source[], uint16_t offset, UnicodeString& dest, UTextOffset pos) {

    uint16_t index = (int16_t)(offset >> STR_INDEX_SHIFT);
    uint16_t length = (int16_t)(offset & STR_LENGTH_MASK);
    uint16_t i;
    
    dest.setCharAt(pos++, source[index++]);
    if (length == 0) {
        UChar ch;
        while ((ch = source[index++]) != 0x0000) {
            insert(dest, pos++, ch);
            length++;
        }
    } else {
        for (i = 1; i < length; i++) {
            dest.insert(pos++, source[index++]);
        }
    }
    return length;
}

void Normalizer::initBuffer() {
    buffer.truncate(0);
    clearBuffer();
}

void Normalizer::clearBuffer() {
    bufferLimit = bufferPos = 0;
}

//-----------------------------------------------------------------------------
// Hangul / Jamo conversion utilities for internal use
// See section 3.10 of The Unicode Standard, v 2.0.
//
/**
 * Convert a single Hangul syllable into one or more Jamo characters.
 * 
 * @param conjoin If TRUE, decompose Jamo into conjoining Jamo.
 */
void Normalizer::hangulToJamo(UChar ch, UnicodeString& result, uint16_t decompLimit)
{
    UChar sIndex  = (UChar)(ch - HANGUL_BASE);
    UChar leading = (UChar)(JAMO_LBASE + sIndex / JAMO_NCOUNT);
    UChar vowel   = (UChar)(JAMO_VBASE +
                            (sIndex % JAMO_NCOUNT) / JAMO_TCOUNT);
    UChar trailing= (UChar)(JAMO_TBASE + (sIndex % JAMO_TCOUNT));

    jamoAppend(leading, decompLimit, result);
    jamoAppend(vowel, decompLimit, result);
    if (trailing != JAMO_TBASE) {
        jamoAppend(trailing, decompLimit, result);
    }
}

void Normalizer::jamoAppend(UChar ch, uint16_t decompLimit, UnicodeString& dest) {
    uint16_t offset = ucmp16_getu(DecompData::offsets, ch);
    if (offset > decompLimit) {
        /* HSYS: Be sure to check this for later.  UChar may not always be
           uint16_t*/
        doAppend((const UChar*)(DecompData::contents), offset, dest);
    } else {
        dest += ch;
    }
}

void Normalizer::jamoToHangul(UnicodeString& buffer, UTextOffset start) {
    UTextOffset out = start;
    UTextOffset limit = buffer.length() - 1;

    UTextOffset in;
    int16_t l, v = 0, t;

    for (in = start; in < limit; in++) {
        UChar ch = buffer[in];

        if ((l = (int16_t)(ch - JAMO_LBASE)) >= 0 && l < JAMO_LCOUNT
            && (v = (int16_t)(buffer[in+1] - (UChar)JAMO_VBASE)) >= 0 && v < JAMO_VCOUNT) {
            //
            // We've found a pair of Jamo characters to compose.
            // Snarf the Jamo vowel and see if there's also a trailing char
            //
            in++;   // Snarf the Jamo vowel too.

            t = (int16_t)((in < limit) ? buffer.charAt(in+1) : 0);
            t -= JAMO_TBASE;

            if (t >= 0 && t < JAMO_TCOUNT) {
                in++;   // Snarf the trailing consonant too
            } else {
                t = 0;  // No trailing consonant
            }
            buffer[out++] = (UChar)((l*JAMO_VCOUNT + v) * JAMO_TCOUNT + t + HANGUL_BASE);
        } else {
            buffer[out++] = ch;
        }
    }
    while (in < buffer.length()) {
        buffer[out++] = buffer[in++];
    }

    buffer.truncate(out);
}