unistr.cpp   [plain text]

/*
******************************************************************************
* Copyright (C) 1999-2004, International Business Machines Corporation and   *
* others. All Rights Reserved.                                               *
******************************************************************************
*
* File unistr.cpp
*
* Modification History:
*
*   Date        Name        Description
*   09/25/98    stephen     Creation.
*   04/20/99    stephen     Overhauled per 4/16 code review.
*   07/09/99    stephen     Renamed {hi,lo},{byte,word} to icu_X for HP/UX
*   11/18/99    aliu        Added handleReplaceBetween() to make inherit from
*                           Replaceable.
*   06/25/01    grhoten     Removed the dependency on iostream
******************************************************************************
*/

#include "unicode/utypes.h"
#include "unicode/putil.h"
#include "cstring.h"
#include "cmemory.h"
#include "unicode/ustring.h"
#include "unicode/unistr.h"
#include "uhash.h"
#include "ustr_imp.h"
#include "umutex.h"

#if 0

#if U_IOSTREAM_SOURCE >= 199711
#include <iostream>
using namespace std;
#elif U_IOSTREAM_SOURCE >= 198506
#include <iostream.h>
#endif

//DEBUGGING
void
print(const UnicodeString& s,
      const char *name)
{
  UChar c;
  cout << name << ":|";
  for(int i = 0; i < s.length(); ++i) {
    c = s[i];
    if(c>= 0x007E || c < 0x0020)
      cout << "[0x" << hex << s[i] << "]";
    else
      cout << (char) s[i];
  }
  cout << '|' << endl;
}

void
print(const UChar *s,
      int32_t len,
      const char *name)
{
  UChar c;
  cout << name << ":|";
  for(int i = 0; i < len; ++i) {
    c = s[i];
    if(c>= 0x007E || c < 0x0020)
      cout << "[0x" << hex << s[i] << "]";
    else
      cout << (char) s[i];
  }
  cout << '|' << endl;
}
// END DEBUGGING
#endif

// Local function definitions for now

// need to copy areas that may overlap
static
inline void
us_arrayCopy(const UChar *src, int32_t srcStart,
         UChar *dst, int32_t dstStart, int32_t count)
{
  if(count>0) {
    uprv_memmove(dst+dstStart, src+srcStart, (size_t)(count*sizeof(*src)));
  }
}

// u_unescapeAt() callback to get a UChar from a UnicodeString
U_CDECL_BEGIN
static UChar U_CALLCONV
UnicodeString_charAt(int32_t offset, void *context) {
    return ((UnicodeString*) context)->charAt(offset);
}
U_CDECL_END

U_NAMESPACE_BEGIN

/* The Replaceable virtual destructor can't be defined in the header
   due to how AIX works with multiple definitions of virtual functions.
*/
Replaceable::~Replaceable() {}
Replaceable::Replaceable() {}
UOBJECT_DEFINE_RTTI_IMPLEMENTATION(UnicodeString)

UnicodeString U_EXPORT2
operator+ (const UnicodeString &s1, const UnicodeString &s2) {
    return
        UnicodeString(s1.length()+s2.length()+1, (UChar32)0, 0).
            append(s1).
                append(s2);
}

//========================================
// Reference Counting functions, put at top of file so that optimizing compilers
//                               have a chance to automatically inline.
//========================================

void
UnicodeString::addRef()
{  umtx_atomic_inc((int32_t *)fArray - 1);}

int32_t
UnicodeString::removeRef()
{ return umtx_atomic_dec((int32_t *)fArray - 1);}

int32_t
UnicodeString::refCount() const 
{ 
    umtx_lock(NULL);
    // Note: without the lock to force a memory barrier, we might see a very
    //       stale value on some multi-processor systems.
    int32_t  count = *((int32_t *)fArray - 1);
    umtx_unlock(NULL);
    return count;
 }

void
UnicodeString::releaseArray() {
  if((fFlags & kRefCounted) && removeRef() == 0) {
    uprv_free((int32_t *)fArray - 1);
  }
}



//========================================
// Constructors
//========================================
UnicodeString::UnicodeString()
  : fLength(0),
    fCapacity(US_STACKBUF_SIZE),
    fArray(fStackBuffer),
    fFlags(kShortString)
{}

UnicodeString::UnicodeString(int32_t capacity, UChar32 c, int32_t count)
  : fLength(0),
    fCapacity(US_STACKBUF_SIZE),
    fArray(0),
    fFlags(0)
{
  if(count <= 0 || (uint32_t)c > 0x10ffff) {
    // just allocate and do not do anything else
    allocate(capacity);
  } else {
    // count > 0, allocate and fill the new string with count c's
    int32_t unitCount = UTF_CHAR_LENGTH(c), length = count * unitCount;
    if(capacity < length) {
      capacity = length;
    }
    if(allocate(capacity)) {
      int32_t i = 0;

      // fill the new string with c
      if(unitCount == 1) {
        // fill with length UChars
        while(i < length) {
          fArray[i++] = (UChar)c;
        }
      } else {
        // get the code units for c
        UChar units[UTF_MAX_CHAR_LENGTH];
        UTF_APPEND_CHAR_UNSAFE(units, i, c);

        // now it must be i==unitCount
        i = 0;

        // for Unicode, unitCount can only be 1, 2, 3, or 4
        // 1 is handled above
        while(i < length) {
          int32_t unitIdx = 0;
          while(unitIdx < unitCount) {
            fArray[i++]=units[unitIdx++];
          }
        }
      }
    }
    fLength = length;
  }
}

UnicodeString::UnicodeString(UChar ch)
  : fLength(1),
    fCapacity(US_STACKBUF_SIZE),
    fArray(fStackBuffer),
    fFlags(kShortString)
{
  fStackBuffer[0] = ch;
}

UnicodeString::UnicodeString(UChar32 ch)
  : fLength(1),
    fCapacity(US_STACKBUF_SIZE),
    fArray(fStackBuffer),
    fFlags(kShortString)
{
  int32_t i = 0;
  UBool isError = FALSE;
  U16_APPEND(fStackBuffer, i, US_STACKBUF_SIZE, ch, isError);
  fLength = i;
}

UnicodeString::UnicodeString(const UChar *text)
  : fLength(0),
    fCapacity(US_STACKBUF_SIZE),
    fArray(fStackBuffer),
    fFlags(kShortString)
{
  doReplace(0, 0, text, 0, -1);
}

UnicodeString::UnicodeString(const UChar *text,
                             int32_t textLength)
  : fLength(0),
    fCapacity(US_STACKBUF_SIZE),
    fArray(fStackBuffer),
    fFlags(kShortString)
{
  doReplace(0, 0, text, 0, textLength);
}

UnicodeString::UnicodeString(UBool isTerminated,
                             const UChar *text,
                             int32_t textLength)
  : fLength(textLength),
    fCapacity(isTerminated ? textLength + 1 : textLength),
    fArray((UChar *)text),
    fFlags(kReadonlyAlias)
{
  if(text == NULL) {
    // treat as an empty string, do not alias
    fLength = 0;
    fCapacity = US_STACKBUF_SIZE;
    fArray = fStackBuffer;
    fFlags = kShortString;
  } else if(textLength < -1 ||
            (textLength == -1 && !isTerminated) ||
            (textLength >= 0 && isTerminated && text[textLength] != 0)
  ) {
    setToBogus();
  } else if(textLength == -1) {
    // text is terminated, or else it would have failed the above test
    fLength = u_strlen(text);
    fCapacity = fLength + 1;
  }
}

UnicodeString::UnicodeString(UChar *buff,
                             int32_t buffLength,
                             int32_t buffCapacity)
  : fLength(buffLength),
    fCapacity(buffCapacity),
    fArray(buff),
    fFlags(kWritableAlias)
{
  if(buff == NULL) {
    // treat as an empty string, do not alias
    fLength = 0;
    fCapacity = US_STACKBUF_SIZE;
    fArray = fStackBuffer;
    fFlags = kShortString;
  } else if(buffLength < -1 || buffCapacity < 0 || buffLength > buffCapacity) {
    setToBogus();
  } else if(buffLength == -1) {
    // fLength = u_strlen(buff); but do not look beyond buffCapacity
    const UChar *p = buff, *limit = buff + buffCapacity;
    while(p != limit && *p != 0) {
      ++p;
    }
    fLength = (int32_t)(p - buff);
  }
}

UnicodeString::UnicodeString(const char *src, int32_t length, EInvariant)
  : fLength(0),
    fCapacity(US_STACKBUF_SIZE),
    fArray(fStackBuffer),
    fFlags(kShortString)
{
  if(src==NULL) {
    // treat as an empty string
  } else {
    if(length<0) {
      length=uprv_strlen(src);
    }
    if(cloneArrayIfNeeded(length, length, FALSE)) {
      u_charsToUChars(src, getArrayStart(), length);
      fLength = length;
    } else {
      setToBogus();
    }
  }
}

UnicodeString::UnicodeString(const UnicodeString& that)
  : Replaceable(),
    fLength(0),
    fCapacity(US_STACKBUF_SIZE),
    fArray(fStackBuffer),
    fFlags(kShortString)
{
  copyFrom(that);
}

UnicodeString::UnicodeString(const UnicodeString& that,
                             int32_t srcStart)
  : Replaceable(),
    fLength(0),
    fCapacity(US_STACKBUF_SIZE),
    fArray(fStackBuffer),
    fFlags(kShortString)
{
  setTo(that, srcStart);
}

UnicodeString::UnicodeString(const UnicodeString& that,
                             int32_t srcStart,
                             int32_t srcLength)
  : Replaceable(),
    fLength(0),
    fCapacity(US_STACKBUF_SIZE),
    fArray(fStackBuffer),
    fFlags(kShortString)
{
  setTo(that, srcStart, srcLength);
}

// Replaceable base class clone() default implementation, does not clone
Replaceable *
Replaceable::clone() const {
  return NULL;
}

// UnicodeString overrides clone() with a real implementation
Replaceable *
UnicodeString::clone() const {
  return new UnicodeString(*this);
}

//========================================
// array allocation
//========================================

UBool
UnicodeString::allocate(int32_t capacity) {
  if(capacity <= US_STACKBUF_SIZE) {
    fArray = fStackBuffer;
    fCapacity = US_STACKBUF_SIZE;
    fFlags = kShortString;
  } else {
    // count bytes for the refCounter and the string capacity, and
    // round up to a multiple of 16; then divide by 4 and allocate int32_t's
    // to be safely aligned for the refCount
    int32_t words = (int32_t)(((sizeof(int32_t) + capacity * U_SIZEOF_UCHAR + 15) & ~15) >> 2);
    int32_t *array = (int32_t*) uprv_malloc( sizeof(int32_t) * words );
    if(array != 0) {
      // set initial refCount and point behind the refCount
      *array++ = 1;

      // have fArray point to the first UChar
      fArray = (UChar *)array;
      fCapacity = (int32_t)((words - 1) * (sizeof(int32_t) / U_SIZEOF_UCHAR));
      fFlags = kLongString;
    } else {
      fLength = 0;
      fCapacity = 0;
      fFlags = kIsBogus;
      return FALSE;
    }
  }
  return TRUE;
}

//========================================
// Destructor
//========================================
UnicodeString::~UnicodeString()
{
  releaseArray();
}


//========================================
// Assignment
//========================================

UnicodeString &
UnicodeString::operator=(const UnicodeString &src) {
  return copyFrom(src);
}

UnicodeString &
UnicodeString::fastCopyFrom(const UnicodeString &src) {
  return copyFrom(src, TRUE);
}

UnicodeString &
UnicodeString::copyFrom(const UnicodeString &src, UBool fastCopy) {
  // if assigning to ourselves, do nothing
  if(this == 0 || this == &src) {
    return *this;
  }

  // is the right side bogus?
  if(&src == 0 || src.isBogus()) {
    setToBogus();
    return *this;
  }

  // delete the current contents
  releaseArray();

  // we always copy the length
  fLength = src.fLength;
  if(fLength == 0) {
    // empty string - use the stack buffer
    fArray = fStackBuffer;
    fCapacity = US_STACKBUF_SIZE;
    fFlags = kShortString;
    return *this;
  }

  // fLength>0 and not an "open" src.getBuffer(minCapacity)
  switch(src.fFlags) {
  case kShortString:
    // short string using the stack buffer, do the same
    fArray = fStackBuffer;
    fCapacity = US_STACKBUF_SIZE;
    fFlags = kShortString;
    uprv_memcpy(fStackBuffer, src.fArray, fLength * U_SIZEOF_UCHAR);
    break;
  case kLongString:
    // src uses a refCounted string buffer, use that buffer with refCount
    // src is const, use a cast - we don't really change it
    ((UnicodeString &)src).addRef();
    // copy all fields, share the reference-counted buffer
    fArray = src.fArray;
    fCapacity = src.fCapacity;
    fFlags = src.fFlags;
    break;
  case kReadonlyAlias:
    if(fastCopy) {
      // src is a readonly alias, do the same
      // -> maintain the readonly alias as such
      fArray = src.fArray;
      fCapacity = src.fCapacity;
      fFlags = src.fFlags;
      break;
    }
    // else if(!fastCopy) fall through to case kWritableAlias
    // -> allocate a new buffer and copy the contents
  case kWritableAlias:
    // src is a writable alias; we make a copy of that instead
    if(allocate(fLength)) {
      uprv_memcpy(fArray, src.fArray, fLength * U_SIZEOF_UCHAR);
      break;
    }
    // if there is not enough memory, then fall through to setting to bogus
  default:
    // if src is bogus, set ourselves to bogus
    // do not call setToBogus() here because fArray and fFlags are not consistent here
    fArray = 0;
    fLength = 0;
    fCapacity = 0;
    fFlags = kIsBogus;
    break;
  }

  return *this;
}

//========================================
// Miscellaneous operations
//========================================

UnicodeString UnicodeString::unescape() const {
    UnicodeString result;
    for (int32_t i=0; i<length(); ) {
        UChar32 c = charAt(i++);
        if (c == 0x005C /*'\\'*/) {
            c = unescapeAt(i); // advances i
            if (c == (UChar32)0xFFFFFFFF) {
                result.remove(); // return empty string
                break; // invalid escape sequence
            }
        }
        result.append(c);
    }
    return result;
}

UChar32 UnicodeString::unescapeAt(int32_t &offset) const {
    return u_unescapeAt(UnicodeString_charAt, &offset, length(), (void*)this);
}

//========================================
// Read-only implementation
//========================================
int8_t
UnicodeString::doCompare( int32_t start,
              int32_t length,
              const UChar *srcChars,
              int32_t srcStart,
              int32_t srcLength) const
{
  // compare illegal string values
  // treat const UChar *srcChars==NULL as an empty string
  if(isBogus()) {
    return -1;
  }
  
  // pin indices to legal values
  pinIndices(start, length);

  if(srcChars == NULL) {
    srcStart = srcLength = 0;
  }

  // get the correct pointer
  const UChar *chars = getArrayStart();

  chars += start;
  srcChars += srcStart;

  int32_t minLength;
  int8_t lengthResult;

  // get the srcLength if necessary
  if(srcLength < 0) {
    srcLength = u_strlen(srcChars + srcStart);
  }

  // are we comparing different lengths?
  if(length != srcLength) {
    if(length < srcLength) {
      minLength = length;
      lengthResult = -1;
    } else {
      minLength = srcLength;
      lengthResult = 1;
    }
  } else {
    minLength = length;
    lengthResult = 0;
  }

  /*
   * note that uprv_memcmp() returns an int but we return an int8_t;
   * we need to take care not to truncate the result -
   * one way to do this is to right-shift the value to
   * move the sign bit into the lower 8 bits and making sure that this
   * does not become 0 itself
   */

  if(minLength > 0 && chars != srcChars) {
    int32_t result;

#   if U_IS_BIG_ENDIAN 
      // big-endian: byte comparison works
      result = uprv_memcmp(chars, srcChars, minLength * sizeof(UChar));
      if(result != 0) {
        return (int8_t)(result >> 15 | 1);
      }
#   else
      // little-endian: compare UChar units
      do {
        result = ((int32_t)*(chars++) - (int32_t)*(srcChars++));
        if(result != 0) {
          return (int8_t)(result >> 15 | 1);
        }
      } while(--minLength > 0);
#   endif
  }
  return lengthResult;
}

/* String compare in code point order - doCompare() compares in code unit order. */
int8_t
UnicodeString::doCompareCodePointOrder(int32_t start,
                                       int32_t length,
                                       const UChar *srcChars,
                                       int32_t srcStart,
                                       int32_t srcLength) const
{
  // compare illegal string values
  // treat const UChar *srcChars==NULL as an empty string
  if(isBogus()) {
    return -1;
  }

  // pin indices to legal values
  pinIndices(start, length);

  if(srcChars == NULL) {
    srcStart = srcLength = 0;
  }

  int32_t diff = uprv_strCompare(fArray + start, length, srcChars + srcStart, srcLength, FALSE, TRUE);
  /* translate the 32-bit result into an 8-bit one */
  if(diff!=0) {
    return (int8_t)(diff >> 15 | 1);
  } else {
    return 0;
  }
}

int32_t
UnicodeString::getLength() const {
    return length();
}

UChar
UnicodeString::getCharAt(int32_t offset) const {
  return charAt(offset);
}

UChar32
UnicodeString::getChar32At(int32_t offset) const {
  return char32At(offset);
}

int32_t
UnicodeString::countChar32(int32_t start, int32_t length) const {
  pinIndices(start, length);
  // if(isBogus()) then fArray==0 and start==0 - u_countChar32() checks for NULL
  return u_countChar32(fArray+start, length);
}

UBool
UnicodeString::hasMoreChar32Than(int32_t start, int32_t length, int32_t number) const {
  pinIndices(start, length);
  // if(isBogus()) then fArray==0 and start==0 - u_strHasMoreChar32Than() checks for NULL
  return u_strHasMoreChar32Than(fArray+start, length, number);
}

int32_t
UnicodeString::moveIndex32(int32_t index, int32_t delta) const {
  // pin index
  if(index<0) {
    index=0;
  } else if(index>fLength) {
    index=fLength;
  }

  if(delta>0) {
    UTF_FWD_N(fArray, index, fLength, delta);
  } else {
    UTF_BACK_N(fArray, 0, index, -delta);
  }

  return index;
}

void
UnicodeString::doExtract(int32_t start,
             int32_t length,
             UChar *dst,
             int32_t dstStart) const
{
  // pin indices to legal values
  pinIndices(start, length);

  // do not copy anything if we alias dst itself
  if(fArray + start != dst + dstStart) {
    us_arrayCopy(getArrayStart(), start, dst, dstStart, length);
  }
}

int32_t
UnicodeString::extract(UChar *dest, int32_t destCapacity,
                       UErrorCode &errorCode) const {
  if(U_SUCCESS(errorCode)) {
    if(isBogus() || destCapacity<0 || (destCapacity>0 && dest==0)) {
      errorCode=U_ILLEGAL_ARGUMENT_ERROR;
    } else {
      if(fLength>0 && fLength<=destCapacity && fArray!=dest) {
        uprv_memcpy(dest, fArray, fLength*U_SIZEOF_UCHAR);
      }
      return u_terminateUChars(dest, destCapacity, fLength, &errorCode);
    }
  }

  return fLength;
}

int32_t
UnicodeString::extract(int32_t start,
                       int32_t length,
                       char *target,
                       int32_t targetCapacity,
                       enum EInvariant) const
{
  // if the arguments are illegal, then do nothing
  if(targetCapacity < 0 || (targetCapacity > 0 && target == NULL)) {
    return 0;
  }

  // pin the indices to legal values
  pinIndices(start, length);

  if(length <= targetCapacity) {
    u_UCharsToChars(getArrayStart() + start, target, length);
  }
  UErrorCode status = U_ZERO_ERROR;
  return u_terminateChars(target, targetCapacity, length, &status);
}

void 
UnicodeString::extractBetween(int32_t start,
                  int32_t limit,
                  UnicodeString& target) const {
  pinIndex(start);
  pinIndex(limit);
  doExtract(start, limit - start, target);
}

int32_t 
UnicodeString::indexOf(const UChar *srcChars,
               int32_t srcStart,
               int32_t srcLength,
               int32_t start,
               int32_t length) const
{
  if(isBogus() || srcChars == 0 || srcStart < 0 || srcLength == 0) {
    return -1;
  }

  // UnicodeString does not find empty substrings
  if(srcLength < 0 && srcChars[srcStart] == 0) {
    return -1;
  }

  // get the indices within bounds
  pinIndices(start, length);

  // find the first occurrence of the substring
  const UChar *match = u_strFindFirst(fArray + start, length, srcChars + srcStart, srcLength);
  if(match == NULL) {
    return -1;
  } else {
    return match - fArray;
  }
}

int32_t
UnicodeString::doIndexOf(UChar c,
             int32_t start,
             int32_t length) const
{
  // pin indices
  pinIndices(start, length);

  // find the first occurrence of c
  const UChar *match = u_memchr(fArray + start, c, length);
  if(match == NULL) {
    return -1;
  } else {
    return match - fArray;
  }
}

int32_t
UnicodeString::doIndexOf(UChar32 c,
                         int32_t start,
                         int32_t length) const {
  // pin indices
  pinIndices(start, length);

  // find the first occurrence of c
  const UChar *match = u_memchr32(fArray + start, c, length);
  if(match == NULL) {
    return -1;
  } else {
    return match - fArray;
  }
}

int32_t 
UnicodeString::lastIndexOf(const UChar *srcChars,
               int32_t srcStart,
               int32_t srcLength,
               int32_t start,
               int32_t length) const
{
  if(isBogus() || srcChars == 0 || srcStart < 0 || srcLength == 0) {
    return -1;
  }

  // UnicodeString does not find empty substrings
  if(srcLength < 0 && srcChars[srcStart] == 0) {
    return -1;
  }

  // get the indices within bounds
  pinIndices(start, length);

  // find the last occurrence of the substring
  const UChar *match = u_strFindLast(fArray + start, length, srcChars + srcStart, srcLength);
  if(match == NULL) {
    return -1;
  } else {
    return match - fArray;
  }
}

int32_t
UnicodeString::doLastIndexOf(UChar c,
                 int32_t start,
                 int32_t length) const
{
  if(isBogus()) {
    return -1;
  }

  // pin indices
  pinIndices(start, length);

  // find the last occurrence of c
  const UChar *match = u_memrchr(fArray + start, c, length);
  if(match == NULL) {
    return -1;
  } else {
    return match - fArray;
  }
}

int32_t
UnicodeString::doLastIndexOf(UChar32 c,
                             int32_t start,
                             int32_t length) const {
  // pin indices
  pinIndices(start, length);

  // find the last occurrence of c
  const UChar *match = u_memrchr32(fArray + start, c, length);
  if(match == NULL) {
    return -1;
  } else {
    return match - fArray;
  }
}

//========================================
// Write implementation
//========================================

UnicodeString& 
UnicodeString::findAndReplace(int32_t start,
                  int32_t length,
                  const UnicodeString& oldText,
                  int32_t oldStart,
                  int32_t oldLength,
                  const UnicodeString& newText,
                  int32_t newStart,
                  int32_t newLength)
{
  if(isBogus() || oldText.isBogus() || newText.isBogus()) {
    return *this;
  }

  pinIndices(start, length);
  oldText.pinIndices(oldStart, oldLength);
  newText.pinIndices(newStart, newLength);

  if(oldLength == 0) {
    return *this;
  }

  while(length > 0 && length >= oldLength) {
    int32_t pos = indexOf(oldText, oldStart, oldLength, start, length);
    if(pos < 0) {
      // no more oldText's here: done
      break;
    } else {
      // we found oldText, replace it by newText and go beyond it
      replace(pos, oldLength, newText, newStart, newLength);
      length -= pos + oldLength - start;
      start = pos + newLength;
    }
  }

  return *this;
}


void
UnicodeString::setToBogus()
{
  releaseArray();

  fArray = 0;
  fCapacity = fLength = 0;
  fFlags = kIsBogus;
}

// turn a bogus string into an empty one
void
UnicodeString::unBogus() {
  if(fFlags & kIsBogus) {
    fArray = fStackBuffer;
    fLength = 0;
    fCapacity = US_STACKBUF_SIZE;
    fFlags = kShortString;
  }
}

// setTo() analogous to the readonly-aliasing constructor with the same signature
UnicodeString &
UnicodeString::setTo(UBool isTerminated,
                     const UChar *text,
                     int32_t textLength)
{
  if(fFlags & kOpenGetBuffer) {
    // do not modify a string that has an "open" getBuffer(minCapacity)
    return *this;
  }

  if(text == NULL) {
    // treat as an empty string, do not alias
    releaseArray();
    fLength = 0;
    fCapacity = US_STACKBUF_SIZE;
    fArray = fStackBuffer;
    fFlags = kShortString;
    return *this;
  }

  if( textLength < -1 ||
      (textLength == -1 && !isTerminated) ||
      (textLength >= 0 && isTerminated && text[textLength] != 0)
  ) {
    setToBogus();
    return *this;
  }

  releaseArray();

  fArray = (UChar *)text;
  if(textLength != -1) {
    fLength = textLength;
    fCapacity = isTerminated ? fLength + 1 : fLength;
  } else {
    // text is terminated, or else it would have failed the above test
    fLength = u_strlen(text);
    fCapacity = fLength + 1;
  }

  fFlags = kReadonlyAlias;
  return *this;
}

// setTo() analogous to the writable-aliasing constructor with the same signature
UnicodeString &
UnicodeString::setTo(UChar *buffer,
                     int32_t buffLength,
                     int32_t buffCapacity) {
  if(fFlags & kOpenGetBuffer) {
    // do not modify a string that has an "open" getBuffer(minCapacity)
    return *this;
  }

  if(buffer == NULL) {
    // treat as an empty string, do not alias
    releaseArray();
    fLength = 0;
    fCapacity = US_STACKBUF_SIZE;
    fArray = fStackBuffer;
    fFlags = kShortString;
    return *this;
  }

  if(buffLength < -1 || buffCapacity < 0 || buffLength > buffCapacity) {
    setToBogus();
    return *this;
  } else if(buffLength == -1) {
    // buffLength = u_strlen(buff); but do not look beyond buffCapacity
    const UChar *p = buffer, *limit = buffer + buffCapacity;
    while(p != limit && *p != 0) {
      ++p;
    }
    buffLength = (int32_t)(p - buffer);
  }

  releaseArray();

  fArray = buffer;
  fLength = buffLength;
  fCapacity = buffCapacity;
  fFlags = kWritableAlias;
  return *this;
}

UnicodeString&
UnicodeString::setCharAt(int32_t offset,
             UChar c)
{
  if(cloneArrayIfNeeded() && fLength > 0) {
    if(offset < 0) {
      offset = 0;
    } else if(offset >= fLength) {
      offset = fLength - 1;
    }

    fArray[offset] = c;
  }
  return *this;
}

UnicodeString&
UnicodeString::doReplace( int32_t start,
              int32_t length,
              const UnicodeString& src,
              int32_t srcStart,
              int32_t srcLength)
{
  if(!src.isBogus()) {
    // pin the indices to legal values
    src.pinIndices(srcStart, srcLength);

    // get the characters from src
    // and replace the range in ourselves with them
    return doReplace(start, length, src.getArrayStart(), srcStart, srcLength);
  } else {
    // remove the range
    return doReplace(start, length, 0, 0, 0);
  }
}

UnicodeString&
UnicodeString::doReplace(int32_t start,
             int32_t length,
             const UChar *srcChars,
             int32_t srcStart,
             int32_t srcLength)
{
  if(isBogus()) {
    return *this;
  }

  if(srcChars == 0) {
    srcStart = srcLength = 0;
  } else if(srcLength < 0) {
    // get the srcLength if necessary
    srcLength = u_strlen(srcChars + srcStart);
  }

  int32_t *bufferToDelete = 0;

  // the following may change fArray but will not copy the current contents;
  // therefore we need to keep the current fArray
  UChar *oldArray = fArray;
  int32_t oldLength = fLength;

  // pin the indices to legal values
  pinIndices(start, length);

  // calculate the size of the string after the replace
  int32_t newSize = oldLength - length + srcLength;

  // clone our array and allocate a bigger array if needed
  if(!cloneArrayIfNeeded(newSize, newSize + (newSize >> 2) + kGrowSize,
                         FALSE, &bufferToDelete)
  ) {
    return *this;
  }

  // now do the replace

  if(fArray != oldArray) {
    // if fArray changed, then we need to copy everything except what will change
    us_arrayCopy(oldArray, 0, fArray, 0, start);
    us_arrayCopy(oldArray, start + length,
                 fArray, start + srcLength,
                 oldLength - (start + length));
  } else if(length != srcLength) {
    // fArray did not change; copy only the portion that isn't changing, leaving a hole
    us_arrayCopy(oldArray, start + length,
                 fArray, start + srcLength,
                 oldLength - (start + length));
  }

  // now fill in the hole with the new string
  us_arrayCopy(srcChars, srcStart, getArrayStart(), start, srcLength);

  fLength = newSize;

  // delayed delete in case srcChars == fArray when we started, and
  // to keep oldArray alive for the above operations
  if (bufferToDelete) {
    uprv_free(bufferToDelete);
  }

  return *this;
}

/**
 * Replaceable API
 */
void
UnicodeString::handleReplaceBetween(int32_t start,
                                    int32_t limit,
                                    const UnicodeString& text) {
    replaceBetween(start, limit, text);
}

/**
 * Replaceable API
 */
void 
UnicodeString::copy(int32_t start, int32_t limit, int32_t dest) {
    if (limit <= start) {
        return; // Nothing to do; avoid bogus malloc call
    }
    UChar* text = (UChar*) uprv_malloc( sizeof(UChar) * (limit - start) );
    extractBetween(start, limit, text, 0);
    insert(dest, text, 0, limit - start);    
    uprv_free(text);
}

/**
 * Replaceable API
 *
 * NOTE: This is for the Replaceable class.  There is no rep.cpp,
 * so we implement this function here.
 */
UBool Replaceable::hasMetaData() const {
    return TRUE;
}

/**
 * Replaceable API
 */
UBool UnicodeString::hasMetaData() const {
    return FALSE;
}

UnicodeString&
UnicodeString::doReverse(int32_t start,
             int32_t length)
{
  if(fLength <= 1 || !cloneArrayIfNeeded()) {
    return *this;
  }

  // pin the indices to legal values
  pinIndices(start, length);

  UChar *left = getArrayStart() + start;
  UChar *right = getArrayStart() + start + length;
  UChar swap;
  UBool hasSupplementary = FALSE;

  while(left < --right) {
    hasSupplementary |= (UBool)UTF_IS_LEAD(swap = *left);
    hasSupplementary |= (UBool)UTF_IS_LEAD(*left++ = *right);
    *right = swap;
  }

  /* if there are supplementary code points in the reversed range, then re-swap their surrogates */
  if(hasSupplementary) {
    UChar swap2;

    left = getArrayStart() + start;
    right = getArrayStart() + start + length - 1; // -1 so that we can look at *(left+1) if left<right
    while(left < right) {
      if(UTF_IS_TRAIL(swap = *left) && UTF_IS_LEAD(swap2 = *(left + 1))) {
        *left++ = swap2;
        *left++ = swap;
      } else {
        ++left;
      }
    }
  }

  return *this;
}

UBool 
UnicodeString::padLeading(int32_t targetLength,
                          UChar padChar)
{
  if(fLength >= targetLength || !cloneArrayIfNeeded(targetLength)) {
    return FALSE;
  } else {
    // move contents up by padding width
    int32_t start = targetLength - fLength;
    us_arrayCopy(fArray, 0, fArray, start, fLength);

    // fill in padding character
    while(--start >= 0) {
      fArray[start] = padChar;
    }
    fLength = targetLength;
    return TRUE;
  }
}

UBool 
UnicodeString::padTrailing(int32_t targetLength,
                           UChar padChar)
{
  if(fLength >= targetLength || !cloneArrayIfNeeded(targetLength)) {
    return FALSE;
  } else {
    // fill in padding character
    int32_t length = targetLength;
    while(--length >= fLength) {
      fArray[length] = padChar;
    }
    fLength = targetLength;
    return TRUE;
  }
}

//========================================
// Hashing
//========================================
int32_t
UnicodeString::doHashCode() const
{
    /* Delegate hash computation to uhash.  This makes UnicodeString
     * hashing consistent with UChar* hashing.  */
    int32_t hashCode = uhash_hashUCharsN(getArrayStart(), fLength);
    if (hashCode == kInvalidHashCode) {
        hashCode = kEmptyHashCode;
    }
    return hashCode;
}

//========================================
// External Buffer
//========================================

UChar *
UnicodeString::getBuffer(int32_t minCapacity) {
  if(minCapacity>=-1 && cloneArrayIfNeeded(minCapacity)) {
    fFlags|=kOpenGetBuffer;
    fLength=0;
    return fArray;
  } else {
    return 0;
  }
}

void
UnicodeString::releaseBuffer(int32_t newLength) {
  if(fFlags&kOpenGetBuffer && newLength>=-1) {
    // set the new fLength
    if(newLength==-1) {
      // the new length is the string length, capped by fCapacity
      const UChar *p=fArray, *limit=fArray+fCapacity;
      while(p<limit && *p!=0) {
        ++p;
      }
      fLength=(int32_t)(p-fArray);
    } else if(newLength<=fCapacity) {
      fLength=newLength;
    } else {
      fLength=fCapacity;
    }
    fFlags&=~kOpenGetBuffer;
  }
}

//========================================
// Miscellaneous
//========================================
UBool
UnicodeString::cloneArrayIfNeeded(int32_t newCapacity,
                                  int32_t growCapacity,
                                  UBool doCopyArray,
                                  int32_t **pBufferToDelete,
                                  UBool forceClone) {
  // default parameters need to be static, therefore
  // the defaults are -1 to have convenience defaults
  if(newCapacity == -1) {
    newCapacity = fCapacity;
  }

  // while a getBuffer(minCapacity) is "open",
  // prevent any modifications of the string by returning FALSE here
  // if the string is bogus, then only an assignment or similar can revive it
  if((fFlags&(kOpenGetBuffer|kIsBogus))!=0) {
    return FALSE;
  }

  /*
   * We need to make a copy of the array if
   * the buffer is read-only, or
   * the buffer is refCounted (shared), and refCount>1, or
   * the buffer is too small.
   * Return FALSE if memory could not be allocated.
   */
  if(forceClone ||
     fFlags & kBufferIsReadonly ||
     fFlags & kRefCounted && refCount() > 1 ||
     newCapacity > fCapacity
  ) {
    // save old values
    UChar *array = fArray;
    uint16_t flags = fFlags;

    // check growCapacity for default value and use of the stack buffer
    if(growCapacity == -1) {
      growCapacity = newCapacity;
    } else if(newCapacity <= US_STACKBUF_SIZE && growCapacity > US_STACKBUF_SIZE) {
      growCapacity = US_STACKBUF_SIZE;
    }

    // allocate a new array
    if(allocate(growCapacity) ||
       newCapacity < growCapacity && allocate(newCapacity)
    ) {
      if(doCopyArray) {
        // copy the contents
        // do not copy more than what fits - it may be smaller than before
        if(fCapacity < fLength) {
          fLength = fCapacity;
        }
        us_arrayCopy(array, 0, fArray, 0, fLength);
      } else {
        fLength = 0;
      }

      // release the old array
      if(flags & kRefCounted) {
        // the array is refCounted; decrement and release if 0
        int32_t *pRefCount = ((int32_t *)array - 1);
        if(umtx_atomic_dec(pRefCount) == 0) {
          if(pBufferToDelete == 0) {
            uprv_free(pRefCount);
          } else {
            // the caller requested to delete it himself
            *pBufferToDelete = pRefCount;
          }
        }
      }
    } else {
      // not enough memory for growCapacity and not even for the smaller newCapacity
      // reset the old values for setToBogus() to release the array
      fArray = array;
      fFlags = flags;
      setToBogus();
      return FALSE;
    }
  }
  return TRUE;
}
U_NAMESPACE_END