Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2030 insertions, 0 deletions

diff --git a/intl/icu/source/common/unistr.cpp b/intl/icu/source/common/unistr.cpp
new file mode 100644
index 0000000000..04f01cfa16
--- /dev/null
+++ b/intl/icu/source/common/unistr.cpp
@@ -0,0 +1,2030 @@
+// © 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+/*
+******************************************************************************
+* Copyright (C) 1999-2016, 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/appendable.h"
+#include "unicode/putil.h"
+#include "cstring.h"
+#include "cmemory.h"
+#include "unicode/ustring.h"
+#include "unicode/unistr.h"
+#include "unicode/utf.h"
+#include "unicode/utf16.h"
+#include "uelement.h"
+#include "ustr_imp.h"
+#include "umutex.h"
+#include "uassert.h"
+
+#if 0
+
+#include <iostream>
+using namespace std;
+
+//DEBUGGING
+void
+print(const UnicodeString& s,
+      const char *name)
+{
+  char16_t 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 char16_t *s,
+      int32_t len,
+      const char *name)
+{
+  char16_t 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 char16_t *src, int32_t srcStart,
+         char16_t *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 char16_t from a UnicodeString
+U_CDECL_BEGIN
+static char16_t U_CALLCONV
+UnicodeString_charAt(int32_t offset, void *context) {
+    return ((icu::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() {}
+
+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((u_atomic_int32_t *)fUnion.fFields.fArray - 1);
+}
+
+int32_t
+UnicodeString::removeRef() {
+  return umtx_atomic_dec((u_atomic_int32_t *)fUnion.fFields.fArray - 1);
+}
+
+int32_t
+UnicodeString::refCount() const {
+  return umtx_loadAcquire(*((u_atomic_int32_t *)fUnion.fFields.fArray - 1));
+}
+
+void
+UnicodeString::releaseArray() {
+  if((fUnion.fFields.fLengthAndFlags & kRefCounted) && removeRef() == 0) {
+    uprv_free((int32_t *)fUnion.fFields.fArray - 1);
+  }
+}
+
+
+
+//========================================
+// Constructors
+//========================================
+
+// The default constructor is inline in unistr.h.
+
+UnicodeString::UnicodeString(int32_t capacity, UChar32 c, int32_t count) {
+  fUnion.fFields.fLengthAndFlags = 0;
+  if(count <= 0 || (uint32_t)c > 0x10ffff) {
+    // just allocate and do not do anything else
+    allocate(capacity);
+  } else if(c <= 0xffff) {
+    int32_t length = count;
+    if(capacity < length) {
+      capacity = length;
+    }
+    if(allocate(capacity)) {
+      char16_t *array = getArrayStart();
+      char16_t unit = (char16_t)c;
+      for(int32_t i = 0; i < length; ++i) {
+        array[i] = unit;
+      }
+      setLength(length);
+    }
+  } else {  // supplementary code point, write surrogate pairs
+    if(count > (INT32_MAX / 2)) {
+      // We would get more than 2G UChars.
+      allocate(capacity);
+      return;
+    }
+    int32_t length = count * 2;
+    if(capacity < length) {
+      capacity = length;
+    }
+    if(allocate(capacity)) {
+      char16_t *array = getArrayStart();
+      char16_t lead = U16_LEAD(c);
+      char16_t trail = U16_TRAIL(c);
+      for(int32_t i = 0; i < length; i += 2) {
+        array[i] = lead;
+        array[i + 1] = trail;
+      }
+      setLength(length);
+    }
+  }
+}
+
+UnicodeString::UnicodeString(char16_t ch) {
+  fUnion.fFields.fLengthAndFlags = kLength1 | kShortString;
+  fUnion.fStackFields.fBuffer[0] = ch;
+}
+
+UnicodeString::UnicodeString(UChar32 ch) {
+  fUnion.fFields.fLengthAndFlags = kShortString;
+  int32_t i = 0;
+  UBool isError = false;
+  U16_APPEND(fUnion.fStackFields.fBuffer, i, US_STACKBUF_SIZE, ch, isError);
+  // We test isError so that the compiler does not complain that we don't.
+  // If isError then i==0 which is what we want anyway.
+  if(!isError) {
+    setShortLength(i);
+  }
+}
+
+UnicodeString::UnicodeString(const char16_t *text) {
+  fUnion.fFields.fLengthAndFlags = kShortString;
+  doAppend(text, 0, -1);
+}
+
+UnicodeString::UnicodeString(const char16_t *text,
+                             int32_t textLength) {
+  fUnion.fFields.fLengthAndFlags = kShortString;
+  doAppend(text, 0, textLength);
+}
+
+UnicodeString::UnicodeString(UBool isTerminated,
+                             ConstChar16Ptr textPtr,
+                             int32_t textLength) {
+  fUnion.fFields.fLengthAndFlags = kReadonlyAlias;
+  const char16_t *text = textPtr;
+  if(text == nullptr) {
+    // treat as an empty string, do not alias
+    setToEmpty();
+  } 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
+      textLength = u_strlen(text);
+    }
+    setArray(const_cast<char16_t *>(text), textLength,
+             isTerminated ? textLength + 1 : textLength);
+  }
+}
+
+UnicodeString::UnicodeString(char16_t *buff,
+                             int32_t buffLength,
+                             int32_t buffCapacity) {
+  fUnion.fFields.fLengthAndFlags = kWritableAlias;
+  if(buff == nullptr) {
+    // treat as an empty string, do not alias
+    setToEmpty();
+  } else if(buffLength < -1 || buffCapacity < 0 || buffLength > buffCapacity) {
+    setToBogus();
+  } else {
+    if(buffLength == -1) {
+      // fLength = u_strlen(buff); but do not look beyond buffCapacity
+      const char16_t *p = buff, *limit = buff + buffCapacity;
+      while(p != limit && *p != 0) {
+        ++p;
+      }
+      buffLength = (int32_t)(p - buff);
+    }
+    setArray(buff, buffLength, buffCapacity);
+  }
+}
+
+UnicodeString::UnicodeString(const char *src, int32_t length, EInvariant) {
+  fUnion.fFields.fLengthAndFlags = kShortString;
+  if(src==nullptr) {
+    // treat as an empty string
+  } else {
+    if(length<0) {
+      length=(int32_t)uprv_strlen(src);
+    }
+    if(cloneArrayIfNeeded(length, length, false)) {
+      u_charsToUChars(src, getArrayStart(), length);
+      setLength(length);
+    } else {
+      setToBogus();
+    }
+  }
+}
+
+#if U_CHARSET_IS_UTF8
+
+UnicodeString::UnicodeString(const char *codepageData) {
+  fUnion.fFields.fLengthAndFlags = kShortString;
+  if(codepageData != 0) {
+    setToUTF8(codepageData);
+  }
+}
+
+UnicodeString::UnicodeString(const char *codepageData, int32_t dataLength) {
+  fUnion.fFields.fLengthAndFlags = kShortString;
+  // if there's nothing to convert, do nothing
+  if(codepageData == 0 || dataLength == 0 || dataLength < -1) {
+    return;
+  }
+  if(dataLength == -1) {
+    dataLength = (int32_t)uprv_strlen(codepageData);
+  }
+  setToUTF8(StringPiece(codepageData, dataLength));
+}
+
+// else see unistr_cnv.cpp
+#endif
+
+UnicodeString::UnicodeString(const UnicodeString& that) {
+  fUnion.fFields.fLengthAndFlags = kShortString;
+  copyFrom(that);
+}
+
+UnicodeString::UnicodeString(UnicodeString &&src) noexcept {
+  copyFieldsFrom(src, true);
+}
+
+UnicodeString::UnicodeString(const UnicodeString& that,
+                             int32_t srcStart) {
+  fUnion.fFields.fLengthAndFlags = kShortString;
+  setTo(that, srcStart);
+}
+
+UnicodeString::UnicodeString(const UnicodeString& that,
+                             int32_t srcStart,
+                             int32_t srcLength) {
+  fUnion.fFields.fLengthAndFlags = kShortString;
+  setTo(that, srcStart, srcLength);
+}
+
+// Replaceable base class clone() default implementation, does not clone
+Replaceable *
+Replaceable::clone() const {
+  return nullptr;
+}
+
+// UnicodeString overrides clone() with a real implementation
+UnicodeString *
+UnicodeString::clone() const {
+  LocalPointer<UnicodeString> clonedString(new UnicodeString(*this));
+  return clonedString.isValid() && !clonedString->isBogus() ? clonedString.orphan() : nullptr;
+}
+
+//========================================
+// array allocation
+//========================================
+
+namespace {
+
+const int32_t kGrowSize = 128;
+
+// The number of bytes for one int32_t reference counter and capacity UChars
+// must fit into a 32-bit size_t (at least when on a 32-bit platform).
+// We also add one for the NUL terminator, to avoid reallocation in getTerminatedBuffer(),
+// and round up to a multiple of 16 bytes.
+// This means that capacity must be at most (0xfffffff0 - 4) / 2 - 1 = 0x7ffffff5.
+// (With more complicated checks we could go up to 0x7ffffffd without rounding up,
+// but that does not seem worth it.)
+const int32_t kMaxCapacity = 0x7ffffff5;
+
+int32_t getGrowCapacity(int32_t newLength) {
+  int32_t growSize = (newLength >> 2) + kGrowSize;
+  if(growSize <= (kMaxCapacity - newLength)) {
+    return newLength + growSize;
+  } else {
+    return kMaxCapacity;
+  }
+}
+
+}  // namespace
+
+UBool
+UnicodeString::allocate(int32_t capacity) {
+  if(capacity <= US_STACKBUF_SIZE) {
+    fUnion.fFields.fLengthAndFlags = kShortString;
+    return true;
+  }
+  if(capacity <= kMaxCapacity) {
+    ++capacity;  // for the NUL
+    // Switch to size_t which is unsigned so that we can allocate up to 4GB.
+    // Reference counter + UChars.
+    size_t numBytes = sizeof(int32_t) + (size_t)capacity * U_SIZEOF_UCHAR;
+    // Round up to a multiple of 16.
+    numBytes = (numBytes + 15) & ~15;
+    int32_t *array = (int32_t *) uprv_malloc(numBytes);
+    if(array != nullptr) {
+      // set initial refCount and point behind the refCount
+      *array++ = 1;
+      numBytes -= sizeof(int32_t);
+
+      // have fArray point to the first char16_t
+      fUnion.fFields.fArray = (char16_t *)array;
+      fUnion.fFields.fCapacity = (int32_t)(numBytes / U_SIZEOF_UCHAR);
+      fUnion.fFields.fLengthAndFlags = kLongString;
+      return true;
+    }
+  }
+  fUnion.fFields.fLengthAndFlags = kIsBogus;
+  fUnion.fFields.fArray = 0;
+  fUnion.fFields.fCapacity = 0;
+  return false;
+}
+
+//========================================
+// Destructor
+//========================================
+
+#ifdef UNISTR_COUNT_FINAL_STRING_LENGTHS
+static u_atomic_int32_t finalLengthCounts[0x400];  // UnicodeString::kMaxShortLength+1
+static u_atomic_int32_t beyondCount(0);
+
+U_CAPI void unistr_printLengths() {
+  int32_t i;
+  for(i = 0; i <= 59; ++i) {
+    printf("%2d,  %9d\n", i, (int32_t)finalLengthCounts[i]);
+  }
+  int32_t beyond = beyondCount;
+  for(; i < UPRV_LENGTHOF(finalLengthCounts); ++i) {
+    beyond += finalLengthCounts[i];
+  }
+  printf(">59, %9d\n", beyond);
+}
+#endif
+
+UnicodeString::~UnicodeString()
+{
+#ifdef UNISTR_COUNT_FINAL_STRING_LENGTHS
+  // Count lengths of strings at the end of their lifetime.
+  // Useful for discussion of a desirable stack buffer size.
+  // Count the contents length, not the optional NUL terminator nor further capacity.
+  // Ignore open-buffer strings and strings which alias external storage.
+  if((fUnion.fFields.fLengthAndFlags&(kOpenGetBuffer|kReadonlyAlias|kWritableAlias)) == 0) {
+    if(hasShortLength()) {
+      umtx_atomic_inc(finalLengthCounts + getShortLength());
+    } else {
+      umtx_atomic_inc(&beyondCount);
+    }
+  }
+#endif
+
+  releaseArray();
+}
+
+//========================================
+// Factory methods
+//========================================
+
+UnicodeString UnicodeString::fromUTF8(StringPiece utf8) {
+  UnicodeString result;
+  result.setToUTF8(utf8);
+  return result;
+}
+
+UnicodeString UnicodeString::fromUTF32(const UChar32 *utf32, int32_t length) {
+  UnicodeString result;
+  int32_t capacity;
+  // Most UTF-32 strings will be BMP-only and result in a same-length
+  // UTF-16 string. We overestimate the capacity just slightly,
+  // just in case there are a few supplementary characters.
+  if(length <= US_STACKBUF_SIZE) {
+    capacity = US_STACKBUF_SIZE;
+  } else {
+    capacity = length + (length >> 4) + 4;
+  }
+  do {
+    char16_t *utf16 = result.getBuffer(capacity);
+    int32_t length16;
+    UErrorCode errorCode = U_ZERO_ERROR;
+    u_strFromUTF32WithSub(utf16, result.getCapacity(), &length16,
+        utf32, length,
+        0xfffd,  // Substitution character.
+        nullptr,    // Don't care about number of substitutions.
+        &errorCode);
+    result.releaseBuffer(length16);
+    if(errorCode == U_BUFFER_OVERFLOW_ERROR) {
+      capacity = length16 + 1;  // +1 for the terminating NUL.
+      continue;
+    } else if(U_FAILURE(errorCode)) {
+      result.setToBogus();
+    }
+    break;
+  } while(true);
+  return result;
+}
+
+//========================================
+// 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 == &src) {
+    return *this;
+  }
+
+  // is the right side bogus?
+  if(src.isBogus()) {
+    setToBogus();
+    return *this;
+  }
+
+  // delete the current contents
+  releaseArray();
+
+  if(src.isEmpty()) {
+    // empty string - use the stack buffer
+    setToEmpty();
+    return *this;
+  }
+
+  // fLength>0 and not an "open" src.getBuffer(minCapacity)
+  fUnion.fFields.fLengthAndFlags = src.fUnion.fFields.fLengthAndFlags;
+  switch(src.fUnion.fFields.fLengthAndFlags & kAllStorageFlags) {
+  case kShortString:
+    // short string using the stack buffer, do the same
+    uprv_memcpy(fUnion.fStackFields.fBuffer, src.fUnion.fStackFields.fBuffer,
+                getShortLength() * 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 actually change it
+    const_cast<UnicodeString &>(src).addRef();
+    // copy all fields, share the reference-counted buffer
+    fUnion.fFields.fArray = src.fUnion.fFields.fArray;
+    fUnion.fFields.fCapacity = src.fUnion.fFields.fCapacity;
+    if(!hasShortLength()) {
+      fUnion.fFields.fLength = src.fUnion.fFields.fLength;
+    }
+    break;
+  case kReadonlyAlias:
+    if(fastCopy) {
+      // src is a readonly alias, do the same
+      // -> maintain the readonly alias as such
+      fUnion.fFields.fArray = src.fUnion.fFields.fArray;
+      fUnion.fFields.fCapacity = src.fUnion.fFields.fCapacity;
+      if(!hasShortLength()) {
+        fUnion.fFields.fLength = src.fUnion.fFields.fLength;
+      }
+      break;
+    }
+    // else if(!fastCopy) fall through to case kWritableAlias
+    // -> allocate a new buffer and copy the contents
+    U_FALLTHROUGH;
+  case kWritableAlias: {
+    // src is a writable alias; we make a copy of that instead
+    int32_t srcLength = src.length();
+    if(allocate(srcLength)) {
+      u_memcpy(getArrayStart(), src.getArrayStart(), srcLength);
+      setLength(srcLength);
+      break;
+    }
+    // if there is not enough memory, then fall through to setting to bogus
+    U_FALLTHROUGH;
+  }
+  default:
+    // if src is bogus, set ourselves to bogus
+    // do not call setToBogus() here because fArray and flags are not consistent here
+    fUnion.fFields.fLengthAndFlags = kIsBogus;
+    fUnion.fFields.fArray = 0;
+    fUnion.fFields.fCapacity = 0;
+    break;
+  }
+
+  return *this;
+}
+
+UnicodeString &UnicodeString::operator=(UnicodeString &&src) noexcept {
+  // No explicit check for self move assignment, consistent with standard library.
+  // Self move assignment causes no crash nor leak but might make the object bogus.
+  releaseArray();
+  copyFieldsFrom(src, true);
+  return *this;
+}
+
+// Same as move assignment except without memory management.
+void UnicodeString::copyFieldsFrom(UnicodeString &src, UBool setSrcToBogus) noexcept {
+  int16_t lengthAndFlags = fUnion.fFields.fLengthAndFlags = src.fUnion.fFields.fLengthAndFlags;
+  if(lengthAndFlags & kUsingStackBuffer) {
+    // Short string using the stack buffer, copy the contents.
+    // Check for self assignment to prevent "overlap in memcpy" warnings,
+    // although it should be harmless to copy a buffer to itself exactly.
+    if(this != &src) {
+      uprv_memcpy(fUnion.fStackFields.fBuffer, src.fUnion.fStackFields.fBuffer,
+                  getShortLength() * U_SIZEOF_UCHAR);
+    }
+  } else {
+    // In all other cases, copy all fields.
+    fUnion.fFields.fArray = src.fUnion.fFields.fArray;
+    fUnion.fFields.fCapacity = src.fUnion.fFields.fCapacity;
+    if(!hasShortLength()) {
+      fUnion.fFields.fLength = src.fUnion.fFields.fLength;
+    }
+    if(setSrcToBogus) {
+      // Set src to bogus without releasing any memory.
+      src.fUnion.fFields.fLengthAndFlags = kIsBogus;
+      src.fUnion.fFields.fArray = nullptr;
+      src.fUnion.fFields.fCapacity = 0;
+    }
+  }
+}
+
+void UnicodeString::swap(UnicodeString &other) noexcept {
+  UnicodeString temp;  // Empty short string: Known not to need releaseArray().
+  // Copy fields without resetting source values in between.
+  temp.copyFieldsFrom(*this, false);
+  this->copyFieldsFrom(other, false);
+  other.copyFieldsFrom(temp, false);
+  // Set temp to an empty string so that other's memory is not released twice.
+  temp.fUnion.fFields.fLengthAndFlags = kShortString;
+}
+
+//========================================
+// Miscellaneous operations
+//========================================
+
+UnicodeString UnicodeString::unescape() const {
+    UnicodeString result(length(), (UChar32)0, (int32_t)0); // construct with capacity
+    if (result.isBogus()) {
+        return result;
+    }
+    const char16_t *array = getBuffer();
+    int32_t len = length();
+    int32_t prev = 0;
+    for (int32_t i=0;;) {
+        if (i == len) {
+            result.append(array, prev, len - prev);
+            break;
+        }
+        if (array[i++] == 0x5C /*'\\'*/) {
+            result.append(array, prev, (i - 1) - prev);
+            UChar32 c = unescapeAt(i); // advances i
+            if (c < 0) {
+                result.remove(); // return empty string
+                break; // invalid escape sequence
+            }
+            result.append(c);
+            prev = i;
+        }
+    }
+    return result;
+}
+
+UChar32 UnicodeString::unescapeAt(int32_t &offset) const {
+    return u_unescapeAt(UnicodeString_charAt, &offset, length(), (void*)this);
+}
+
+//========================================
+// Read-only implementation
+//========================================
+UBool
+UnicodeString::doEquals(const UnicodeString &text, int32_t len) const {
+  // Requires: this & text not bogus and have same lengths.
+  // Byte-wise comparison works for equality regardless of endianness.
+  return uprv_memcmp(getArrayStart(), text.getArrayStart(), len * U_SIZEOF_UCHAR) == 0;
+}
+
+UBool
+UnicodeString::doEqualsSubstring( int32_t start,
+              int32_t length,
+              const char16_t *srcChars,
+              int32_t srcStart,
+              int32_t srcLength) const
+{
+  // compare illegal string values
+  if(isBogus()) {
+    return false;
+  }
+  
+  // pin indices to legal values
+  pinIndices(start, length);
+
+  if(srcChars == nullptr) {
+    // treat const char16_t *srcChars==nullptr as an empty string
+    return length == 0 ? true : false;
+  }
+
+  // get the correct pointer
+  const char16_t *chars = getArrayStart();
+
+  chars += start;
+  srcChars += srcStart;
+
+  // get the srcLength if necessary
+  if(srcLength < 0) {
+    srcLength = u_strlen(srcChars + srcStart);
+  }
+
+  if (length != srcLength) {
+    return false;
+  }
+
+  if(length == 0 || chars == srcChars) {
+    return true;
+  }
+
+  return u_memcmp(chars, srcChars, srcLength) == 0;
+}
+
+int8_t
+UnicodeString::doCompare( int32_t start,
+              int32_t length,
+              const char16_t *srcChars,
+              int32_t srcStart,
+              int32_t srcLength) const
+{
+  // compare illegal string values
+  if(isBogus()) {
+    return -1;
+  }
+  
+  // pin indices to legal values
+  pinIndices(start, length);
+
+  if(srcChars == nullptr) {
+    // treat const char16_t *srcChars==nullptr as an empty string
+    return length == 0 ? 0 : 1;
+  }
+
+  // get the correct pointer
+  const char16_t *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(char16_t));
+      if(result != 0) {
+        return (int8_t)(result >> 15 | 1);
+      }
+#   else
+      // little-endian: compare char16_t 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 char16_t *srcChars,
+                                       int32_t srcStart,
+                                       int32_t srcLength) const
+{
+  // compare illegal string values
+  // treat const char16_t *srcChars==nullptr as an empty string
+  if(isBogus()) {
+    return -1;
+  }
+
+  // pin indices to legal values
+  pinIndices(start, length);
+
+  if(srcChars == nullptr) {
+    srcStart = srcLength = 0;
+  }
+
+  int32_t diff = uprv_strCompare(getArrayStart() + start, length, (srcChars!=nullptr)?(srcChars + srcStart):nullptr, 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();
+}
+
+char16_t
+UnicodeString::getCharAt(int32_t offset) const {
+  return charAt(offset);
+}
+
+UChar32
+UnicodeString::getChar32At(int32_t offset) const {
+  return char32At(offset);
+}
+
+UChar32
+UnicodeString::char32At(int32_t offset) const
+{
+  int32_t len = length();
+  if((uint32_t)offset < (uint32_t)len) {
+    const char16_t *array = getArrayStart();
+    UChar32 c;
+    U16_GET(array, 0, offset, len, c);
+    return c;
+  } else {
+    return kInvalidUChar;
+  }
+}
+
+int32_t
+UnicodeString::getChar32Start(int32_t offset) const {
+  if((uint32_t)offset < (uint32_t)length()) {
+    const char16_t *array = getArrayStart();
+    U16_SET_CP_START(array, 0, offset);
+    return offset;
+  } else {
+    return 0;
+  }
+}
+
+int32_t
+UnicodeString::getChar32Limit(int32_t offset) const {
+  int32_t len = length();
+  if((uint32_t)offset < (uint32_t)len) {
+    const char16_t *array = getArrayStart();
+    U16_SET_CP_LIMIT(array, 0, offset, len);
+    return offset;
+  } else {
+    return len;
+  }
+}
+
+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 nullptr
+  return u_countChar32(getArrayStart()+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 nullptr
+  return u_strHasMoreChar32Than(getArrayStart()+start, length, number);
+}
+
+int32_t
+UnicodeString::moveIndex32(int32_t index, int32_t delta) const {
+  // pin index
+  int32_t len = length();
+  if(index<0) {
+    index=0;
+  } else if(index>len) {
+    index=len;
+  }
+
+  const char16_t *array = getArrayStart();
+  if(delta>0) {
+    U16_FWD_N(array, index, len, delta);
+  } else {
+    U16_BACK_N(array, 0, index, -delta);
+  }
+
+  return index;
+}
+
+void
+UnicodeString::doExtract(int32_t start,
+             int32_t length,
+             char16_t *dst,
+             int32_t dstStart) const
+{
+  // pin indices to legal values
+  pinIndices(start, length);
+
+  // do not copy anything if we alias dst itself
+  const char16_t *array = getArrayStart();
+  if(array + start != dst + dstStart) {
+    us_arrayCopy(array, start, dst, dstStart, length);
+  }
+}
+
+int32_t
+UnicodeString::extract(Char16Ptr dest, int32_t destCapacity,
+                       UErrorCode &errorCode) const {
+  int32_t len = length();
+  if(U_SUCCESS(errorCode)) {
+    if(isBogus() || destCapacity<0 || (destCapacity>0 && dest==0)) {
+      errorCode=U_ILLEGAL_ARGUMENT_ERROR;
+    } else {
+      const char16_t *array = getArrayStart();
+      if(len>0 && len<=destCapacity && array!=dest) {
+        u_memcpy(dest, array, len);
+      }
+      return u_terminateUChars(dest, destCapacity, len, &errorCode);
+    }
+  }
+
+  return len;
+}
+
+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 == nullptr)) {
+    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);
+}
+
+UnicodeString
+UnicodeString::tempSubString(int32_t start, int32_t len) const {
+  pinIndices(start, len);
+  const char16_t *array = getBuffer();  // not getArrayStart() to check kIsBogus & kOpenGetBuffer
+  if(array==nullptr) {
+    array=fUnion.fStackFields.fBuffer;  // anything not nullptr because that would make an empty string
+    len=-2;  // bogus result string
+  }
+  return UnicodeString(false, array + start, len);
+}
+
+int32_t
+UnicodeString::toUTF8(int32_t start, int32_t len,
+                      char *target, int32_t capacity) const {
+  pinIndices(start, len);
+  int32_t length8;
+  UErrorCode errorCode = U_ZERO_ERROR;
+  u_strToUTF8WithSub(target, capacity, &length8,
+                     getBuffer() + start, len,
+                     0xFFFD,  // Standard substitution character.
+                     nullptr,    // Don't care about number of substitutions.
+                     &errorCode);
+  return length8;
+}
+
+#if U_CHARSET_IS_UTF8
+
+int32_t
+UnicodeString::extract(int32_t start, int32_t len,
+                       char *target, uint32_t dstSize) const {
+  // if the arguments are illegal, then do nothing
+  if(/*dstSize < 0 || */(dstSize > 0 && target == 0)) {
+    return 0;
+  }
+  return toUTF8(start, len, target, dstSize <= 0x7fffffff ? (int32_t)dstSize : 0x7fffffff);
+}
+
+// else see unistr_cnv.cpp
+#endif
+
+void 
+UnicodeString::extractBetween(int32_t start,
+                  int32_t limit,
+                  UnicodeString& target) const {
+  pinIndex(start);
+  pinIndex(limit);
+  doExtract(start, limit - start, target);
+}
+
+// When converting from UTF-16 to UTF-8, the result will have at most 3 times
+// as many bytes as the source has UChars.
+// The "worst cases" are writing systems like Indic, Thai and CJK with
+// 3:1 bytes:UChars.
+void
+UnicodeString::toUTF8(ByteSink &sink) const {
+  int32_t length16 = length();
+  if(length16 != 0) {
+    char stackBuffer[1024];
+    int32_t capacity = (int32_t)sizeof(stackBuffer);
+    UBool utf8IsOwned = false;
+    char *utf8 = sink.GetAppendBuffer(length16 < capacity ? length16 : capacity,
+                                      3*length16,
+                                      stackBuffer, capacity,
+                                      &capacity);
+    int32_t length8 = 0;
+    UErrorCode errorCode = U_ZERO_ERROR;
+    u_strToUTF8WithSub(utf8, capacity, &length8,
+                       getBuffer(), length16,
+                       0xFFFD,  // Standard substitution character.
+                       nullptr,    // Don't care about number of substitutions.
+                       &errorCode);
+    if(errorCode == U_BUFFER_OVERFLOW_ERROR) {
+      utf8 = (char *)uprv_malloc(length8);
+      if(utf8 != nullptr) {
+        utf8IsOwned = true;
+        errorCode = U_ZERO_ERROR;
+        u_strToUTF8WithSub(utf8, length8, &length8,
+                           getBuffer(), length16,
+                           0xFFFD,  // Standard substitution character.
+                           nullptr,    // Don't care about number of substitutions.
+                           &errorCode);
+      } else {
+        errorCode = U_MEMORY_ALLOCATION_ERROR;
+      }
+    }
+    if(U_SUCCESS(errorCode)) {
+      sink.Append(utf8, length8);
+      sink.Flush();
+    }
+    if(utf8IsOwned) {
+      uprv_free(utf8);
+    }
+  }
+}
+
+int32_t
+UnicodeString::toUTF32(UChar32 *utf32, int32_t capacity, UErrorCode &errorCode) const {
+  int32_t length32=0;
+  if(U_SUCCESS(errorCode)) {
+    // getBuffer() and u_strToUTF32WithSub() check for illegal arguments.
+    u_strToUTF32WithSub(utf32, capacity, &length32,
+        getBuffer(), length(),
+        0xfffd,  // Substitution character.
+        nullptr,    // Don't care about number of substitutions.
+        &errorCode);
+  }
+  return length32;
+}
+
+int32_t 
+UnicodeString::indexOf(const char16_t *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 char16_t *array = getArrayStart();
+  const char16_t *match = u_strFindFirst(array + start, length, srcChars + srcStart, srcLength);
+  if(match == nullptr) {
+    return -1;
+  } else {
+    return (int32_t)(match - array);
+  }
+}
+
+int32_t
+UnicodeString::doIndexOf(char16_t c,
+             int32_t start,
+             int32_t length) const
+{
+  // pin indices
+  pinIndices(start, length);
+
+  // find the first occurrence of c
+  const char16_t *array = getArrayStart();
+  const char16_t *match = u_memchr(array + start, c, length);
+  if(match == nullptr) {
+    return -1;
+  } else {
+    return (int32_t)(match - array);
+  }
+}
+
+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 char16_t *array = getArrayStart();
+  const char16_t *match = u_memchr32(array + start, c, length);
+  if(match == nullptr) {
+    return -1;
+  } else {
+    return (int32_t)(match - array);
+  }
+}
+
+int32_t 
+UnicodeString::lastIndexOf(const char16_t *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 char16_t *array = getArrayStart();
+  const char16_t *match = u_strFindLast(array + start, length, srcChars + srcStart, srcLength);
+  if(match == nullptr) {
+    return -1;
+  } else {
+    return (int32_t)(match - array);
+  }
+}
+
+int32_t
+UnicodeString::doLastIndexOf(char16_t c,
+                 int32_t start,
+                 int32_t length) const
+{
+  if(isBogus()) {
+    return -1;
+  }
+
+  // pin indices
+  pinIndices(start, length);
+
+  // find the last occurrence of c
+  const char16_t *array = getArrayStart();
+  const char16_t *match = u_memrchr(array + start, c, length);
+  if(match == nullptr) {
+    return -1;
+  } else {
+    return (int32_t)(match - array);
+  }
+}
+
+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 char16_t *array = getArrayStart();
+  const char16_t *match = u_memrchr32(array + start, c, length);
+  if(match == nullptr) {
+    return -1;
+  } else {
+    return (int32_t)(match - array);
+  }
+}
+
+//========================================
+// 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();
+
+  fUnion.fFields.fLengthAndFlags = kIsBogus;
+  fUnion.fFields.fArray = 0;
+  fUnion.fFields.fCapacity = 0;
+}
+
+// turn a bogus string into an empty one
+void
+UnicodeString::unBogus() {
+  if(fUnion.fFields.fLengthAndFlags & kIsBogus) {
+    setToEmpty();
+  }
+}
+
+const char16_t *
+UnicodeString::getTerminatedBuffer() {
+  if(!isWritable()) {
+    return nullptr;
+  }
+  char16_t *array = getArrayStart();
+  int32_t len = length();
+  if(len < getCapacity()) {
+    if(fUnion.fFields.fLengthAndFlags & kBufferIsReadonly) {
+      // If len<capacity on a read-only alias, then array[len] is
+      // either the original NUL (if constructed with (true, s, length))
+      // or one of the original string contents characters (if later truncated),
+      // therefore we can assume that array[len] is initialized memory.
+      if(array[len] == 0) {
+        return array;
+      }
+    } else if(((fUnion.fFields.fLengthAndFlags & kRefCounted) == 0 || refCount() == 1)) {
+      // kRefCounted: Do not write the NUL if the buffer is shared.
+      // That is mostly safe, except when the length of one copy was modified
+      // without copy-on-write, e.g., via truncate(newLength) or remove().
+      // Then the NUL would be written into the middle of another copy's string.
+
+      // Otherwise, the buffer is fully writable and it is anyway safe to write the NUL.
+      // Do not test if there is a NUL already because it might be uninitialized memory.
+      // (That would be safe, but tools like valgrind & Purify would complain.)
+      array[len] = 0;
+      return array;
+    }
+  }
+  if(len<INT32_MAX && cloneArrayIfNeeded(len+1)) {
+    array = getArrayStart();
+    array[len] = 0;
+    return array;
+  } else {
+    return nullptr;
+  }
+}
+
+// setTo() analogous to the readonly-aliasing constructor with the same signature
+UnicodeString &
+UnicodeString::setTo(UBool isTerminated,
+                     ConstChar16Ptr textPtr,
+                     int32_t textLength)
+{
+  if(fUnion.fFields.fLengthAndFlags & kOpenGetBuffer) {
+    // do not modify a string that has an "open" getBuffer(minCapacity)
+    return *this;
+  }
+
+  const char16_t *text = textPtr;
+  if(text == nullptr) {
+    // treat as an empty string, do not alias
+    releaseArray();
+    setToEmpty();
+    return *this;
+  }
+
+  if( textLength < -1 ||
+      (textLength == -1 && !isTerminated) ||
+      (textLength >= 0 && isTerminated && text[textLength] != 0)
+  ) {
+    setToBogus();
+    return *this;
+  }
+
+  releaseArray();
+
+  if(textLength == -1) {
+    // text is terminated, or else it would have failed the above test
+    textLength = u_strlen(text);
+  }
+  fUnion.fFields.fLengthAndFlags = kReadonlyAlias;
+  setArray((char16_t *)text, textLength, isTerminated ? textLength + 1 : textLength);
+  return *this;
+}
+
+// setTo() analogous to the writable-aliasing constructor with the same signature
+UnicodeString &
+UnicodeString::setTo(char16_t *buffer,
+                     int32_t buffLength,
+                     int32_t buffCapacity) {
+  if(fUnion.fFields.fLengthAndFlags & kOpenGetBuffer) {
+    // do not modify a string that has an "open" getBuffer(minCapacity)
+    return *this;
+  }
+
+  if(buffer == nullptr) {
+    // treat as an empty string, do not alias
+    releaseArray();
+    setToEmpty();
+    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 char16_t *p = buffer, *limit = buffer + buffCapacity;
+    while(p != limit && *p != 0) {
+      ++p;
+    }
+    buffLength = (int32_t)(p - buffer);
+  }
+
+  releaseArray();
+
+  fUnion.fFields.fLengthAndFlags = kWritableAlias;
+  setArray(buffer, buffLength, buffCapacity);
+  return *this;
+}
+
+UnicodeString &UnicodeString::setToUTF8(StringPiece utf8) {
+  unBogus();
+  int32_t length = utf8.length();
+  int32_t capacity;
+  // The UTF-16 string will be at most as long as the UTF-8 string.
+  if(length <= US_STACKBUF_SIZE) {
+    capacity = US_STACKBUF_SIZE;
+  } else {
+    capacity = length + 1;  // +1 for the terminating NUL.
+  }
+  char16_t *utf16 = getBuffer(capacity);
+  int32_t length16;
+  UErrorCode errorCode = U_ZERO_ERROR;
+  u_strFromUTF8WithSub(utf16, getCapacity(), &length16,
+      utf8.data(), length,
+      0xfffd,  // Substitution character.
+      nullptr,    // Don't care about number of substitutions.
+      &errorCode);
+  releaseBuffer(length16);
+  if(U_FAILURE(errorCode)) {
+    setToBogus();
+  }
+  return *this;
+}
+
+UnicodeString&
+UnicodeString::setCharAt(int32_t offset,
+             char16_t c)
+{
+  int32_t len = length();
+  if(cloneArrayIfNeeded() && len > 0) {
+    if(offset < 0) {
+      offset = 0;
+    } else if(offset >= len) {
+      offset = len - 1;
+    }
+
+    getArrayStart()[offset] = c;
+  }
+  return *this;
+}
+
+UnicodeString&
+UnicodeString::replace(int32_t start,
+               int32_t _length,
+               UChar32 srcChar) {
+  char16_t buffer[U16_MAX_LENGTH];
+  int32_t count = 0;
+  UBool isError = false;
+  U16_APPEND(buffer, count, U16_MAX_LENGTH, srcChar, isError);
+  // We test isError so that the compiler does not complain that we don't.
+  // If isError (srcChar is not a valid code point) then count==0 which means
+  // we remove the source segment rather than replacing it with srcChar.
+  return doReplace(start, _length, buffer, 0, isError ? 0 : count);
+}
+
+UnicodeString&
+UnicodeString::append(UChar32 srcChar) {
+  char16_t buffer[U16_MAX_LENGTH];
+  int32_t _length = 0;
+  UBool isError = false;
+  U16_APPEND(buffer, _length, U16_MAX_LENGTH, srcChar, isError);
+  // We test isError so that the compiler does not complain that we don't.
+  // If isError then _length==0 which turns the doAppend() into a no-op anyway.
+  return isError ? *this : doAppend(buffer, 0, _length);
+}
+
+UnicodeString&
+UnicodeString::doReplace( int32_t start,
+              int32_t length,
+              const UnicodeString& src,
+              int32_t srcStart,
+              int32_t srcLength)
+{
+  // 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);
+}
+
+UnicodeString&
+UnicodeString::doReplace(int32_t start,
+             int32_t length,
+             const char16_t *srcChars,
+             int32_t srcStart,
+             int32_t srcLength)
+{
+  if(!isWritable()) {
+    return *this;
+  }
+
+  int32_t oldLength = this->length();
+
+  // optimize (read-only alias).remove(0, start) and .remove(start, end)
+  if((fUnion.fFields.fLengthAndFlags&kBufferIsReadonly) && srcLength == 0) {
+    if(start == 0) {
+      // remove prefix by adjusting the array pointer
+      pinIndex(length);
+      fUnion.fFields.fArray += length;
+      fUnion.fFields.fCapacity -= length;
+      setLength(oldLength - length);
+      return *this;
+    } else {
+      pinIndex(start);
+      if(length >= (oldLength - start)) {
+        // remove suffix by reducing the length (like truncate())
+        setLength(start);
+        fUnion.fFields.fCapacity = start;  // not NUL-terminated any more
+        return *this;
+      }
+    }
+  }
+
+  if(start == oldLength) {
+    return doAppend(srcChars, srcStart, srcLength);
+  }
+
+  if(srcChars == 0) {
+    srcLength = 0;
+  } else {
+    // Perform all remaining operations relative to srcChars + srcStart.
+    // From this point forward, do not use srcStart.
+    srcChars += srcStart;
+    if (srcLength < 0) {
+      // get the srcLength if necessary
+      srcLength = u_strlen(srcChars);
+    }
+  }
+
+  // pin the indices to legal values
+  pinIndices(start, length);
+
+  // Calculate the size of the string after the replace.
+  // Avoid int32_t overflow.
+  int32_t newLength = oldLength - length;
+  if(srcLength > (INT32_MAX - newLength)) {
+    setToBogus();
+    return *this;
+  }
+  newLength += srcLength;
+
+  // Check for insertion into ourself
+  const char16_t *oldArray = getArrayStart();
+  if (isBufferWritable() &&
+      oldArray < srcChars + srcLength &&
+      srcChars < oldArray + oldLength) {
+    // Copy into a new UnicodeString and start over
+    UnicodeString copy(srcChars, srcLength);
+    if (copy.isBogus()) {
+      setToBogus();
+      return *this;
+    }
+    return doReplace(start, length, copy.getArrayStart(), 0, srcLength);
+  }
+
+  // cloneArrayIfNeeded(doCopyArray=false) may change fArray but will not copy the current contents;
+  // therefore we need to keep the current fArray
+  char16_t oldStackBuffer[US_STACKBUF_SIZE];
+  if((fUnion.fFields.fLengthAndFlags&kUsingStackBuffer) && (newLength > US_STACKBUF_SIZE)) {
+    // copy the stack buffer contents because it will be overwritten with
+    // fUnion.fFields values
+    u_memcpy(oldStackBuffer, oldArray, oldLength);
+    oldArray = oldStackBuffer;
+  }
+
+  // clone our array and allocate a bigger array if needed
+  int32_t *bufferToDelete = 0;
+  if(!cloneArrayIfNeeded(newLength, getGrowCapacity(newLength),
+                         false, &bufferToDelete)
+  ) {
+    return *this;
+  }
+
+  // now do the replace
+
+  char16_t *newArray = getArrayStart();
+  if(newArray != oldArray) {
+    // if fArray changed, then we need to copy everything except what will change
+    us_arrayCopy(oldArray, 0, newArray, 0, start);
+    us_arrayCopy(oldArray, start + length,
+                 newArray, 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,
+                 newArray, start + srcLength,
+                 oldLength - (start + length));
+  }
+
+  // now fill in the hole with the new string
+  us_arrayCopy(srcChars, 0, newArray, start, srcLength);
+
+  setLength(newLength);
+
+  // 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;
+}
+
+// Versions of doReplace() only for append() variants.
+// doReplace() and doAppend() optimize for different cases.
+
+UnicodeString&
+UnicodeString::doAppend(const UnicodeString& src, int32_t srcStart, int32_t srcLength) {
+  if(srcLength == 0) {
+    return *this;
+  }
+
+  // pin the indices to legal values
+  src.pinIndices(srcStart, srcLength);
+  return doAppend(src.getArrayStart(), srcStart, srcLength);
+}
+
+UnicodeString&
+UnicodeString::doAppend(const char16_t *srcChars, int32_t srcStart, int32_t srcLength) {
+  if(!isWritable() || srcLength == 0 || srcChars == nullptr) {
+    return *this;
+  }
+
+  // Perform all remaining operations relative to srcChars + srcStart.
+  // From this point forward, do not use srcStart.
+  srcChars += srcStart;
+
+  if(srcLength < 0) {
+    // get the srcLength if necessary
+    if((srcLength = u_strlen(srcChars)) == 0) {
+      return *this;
+    }
+  }
+
+  int32_t oldLength = length();
+  int32_t newLength;
+  if (uprv_add32_overflow(oldLength, srcLength, &newLength)) {
+    setToBogus();
+    return *this;
+  }
+
+  // Check for append onto ourself
+  const char16_t* oldArray = getArrayStart();
+  if (isBufferWritable() &&
+      oldArray < srcChars + srcLength &&
+      srcChars < oldArray + oldLength) {
+    // Copy into a new UnicodeString and start over
+    UnicodeString copy(srcChars, srcLength);
+    if (copy.isBogus()) {
+      setToBogus();
+      return *this;
+    }
+    return doAppend(copy.getArrayStart(), 0, srcLength);
+  }
+
+  // optimize append() onto a large-enough, owned string
+  if((newLength <= getCapacity() && isBufferWritable()) ||
+      cloneArrayIfNeeded(newLength, getGrowCapacity(newLength))) {
+    char16_t *newArray = getArrayStart();
+    // Do not copy characters when
+    //   char16_t *buffer=str.getAppendBuffer(...);
+    // is followed by
+    //   str.append(buffer, length);
+    // or
+    //   str.appendString(buffer, length)
+    // or similar.
+    if(srcChars != newArray + oldLength) {
+      us_arrayCopy(srcChars, 0, newArray, oldLength, srcLength);
+    }
+    setLength(newLength);
+  }
+  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
+    }
+    char16_t* text = (char16_t*) uprv_malloc( sizeof(char16_t) * (limit - start) );
+    // Check to make sure text is not null.
+    if (text != nullptr) {
+	    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(length <= 1 || !cloneArrayIfNeeded()) {
+    return *this;
+  }
+
+  // pin the indices to legal values
+  pinIndices(start, length);
+  if(length <= 1) {  // pinIndices() might have shrunk the length
+    return *this;
+  }
+
+  char16_t *left = getArrayStart() + start;
+  char16_t *right = left + length - 1;  // -1 for inclusive boundary (length>=2)
+  char16_t swap;
+  UBool hasSupplementary = false;
+
+  // Before the loop we know left<right because length>=2.
+  do {
+    hasSupplementary |= (UBool)U16_IS_LEAD(swap = *left);
+    hasSupplementary |= (UBool)U16_IS_LEAD(*left++ = *right);
+    *right-- = swap;
+  } while(left < right);
+  // Make sure to test the middle code unit of an odd-length string.
+  // Redundant if the length is even.
+  hasSupplementary |= (UBool)U16_IS_LEAD(*left);
+
+  /* if there are supplementary code points in the reversed range, then re-swap their surrogates */
+  if(hasSupplementary) {
+    char16_t swap2;
+
+    left = getArrayStart() + start;
+    right = left + length - 1; // -1 so that we can look at *(left+1) if left<right
+    while(left < right) {
+      if(U16_IS_TRAIL(swap = *left) && U16_IS_LEAD(swap2 = *(left + 1))) {
+        *left++ = swap2;
+        *left++ = swap;
+      } else {
+        ++left;
+      }
+    }
+  }
+
+  return *this;
+}
+
+UBool 
+UnicodeString::padLeading(int32_t targetLength,
+                          char16_t padChar)
+{
+  int32_t oldLength = length();
+  if(oldLength >= targetLength || !cloneArrayIfNeeded(targetLength)) {
+    return false;
+  } else {
+    // move contents up by padding width
+    char16_t *array = getArrayStart();
+    int32_t start = targetLength - oldLength;
+    us_arrayCopy(array, 0, array, start, oldLength);
+
+    // fill in padding character
+    while(--start >= 0) {
+      array[start] = padChar;
+    }
+    setLength(targetLength);
+    return true;
+  }
+}
+
+UBool 
+UnicodeString::padTrailing(int32_t targetLength,
+                           char16_t padChar)
+{
+  int32_t oldLength = length();
+  if(oldLength >= targetLength || !cloneArrayIfNeeded(targetLength)) {
+    return false;
+  } else {
+    // fill in padding character
+    char16_t *array = getArrayStart();
+    int32_t length = targetLength;
+    while(--length >= oldLength) {
+      array[length] = padChar;
+    }
+    setLength(targetLength);
+    return true;
+  }
+}
+
+//========================================
+// Hashing
+//========================================
+int32_t
+UnicodeString::doHashCode() const
+{
+    /* Delegate hash computation to uhash.  This makes UnicodeString
+     * hashing consistent with char16_t* hashing.  */
+    int32_t hashCode = ustr_hashUCharsN(getArrayStart(), length());
+    if (hashCode == kInvalidHashCode) {
+        hashCode = kEmptyHashCode;
+    }
+    return hashCode;
+}
+
+//========================================
+// External Buffer
+//========================================
+
+char16_t *
+UnicodeString::getBuffer(int32_t minCapacity) {
+  if(minCapacity>=-1 && cloneArrayIfNeeded(minCapacity)) {
+    fUnion.fFields.fLengthAndFlags|=kOpenGetBuffer;
+    setZeroLength();
+    return getArrayStart();
+  } else {
+    return nullptr;
+  }
+}
+
+void
+UnicodeString::releaseBuffer(int32_t newLength) {
+  if(fUnion.fFields.fLengthAndFlags&kOpenGetBuffer && newLength>=-1) {
+    // set the new fLength
+    int32_t capacity=getCapacity();
+    if(newLength==-1) {
+      // the new length is the string length, capped by fCapacity
+      const char16_t *array=getArrayStart(), *p=array, *limit=array+capacity;
+      while(p<limit && *p!=0) {
+        ++p;
+      }
+      newLength=(int32_t)(p-array);
+    } else if(newLength>capacity) {
+      newLength=capacity;
+    }
+    setLength(newLength);
+    fUnion.fFields.fLengthAndFlags&=~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 = getCapacity();
+  }
+
+  // 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(!isWritable()) {
+    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 ||
+     fUnion.fFields.fLengthAndFlags & kBufferIsReadonly ||
+     (fUnion.fFields.fLengthAndFlags & kRefCounted && refCount() > 1) ||
+     newCapacity > getCapacity()
+  ) {
+    // check growCapacity for default value and use of the stack buffer
+    if(growCapacity < 0) {
+      growCapacity = newCapacity;
+    } else if(newCapacity <= US_STACKBUF_SIZE && growCapacity > US_STACKBUF_SIZE) {
+      growCapacity = US_STACKBUF_SIZE;
+    }
+
+    // save old values
+    char16_t oldStackBuffer[US_STACKBUF_SIZE];
+    char16_t *oldArray;
+    int32_t oldLength = length();
+    int16_t flags = fUnion.fFields.fLengthAndFlags;
+
+    if(flags&kUsingStackBuffer) {
+      U_ASSERT(!(flags&kRefCounted)); /* kRefCounted and kUsingStackBuffer are mutally exclusive */
+      if(doCopyArray && growCapacity > US_STACKBUF_SIZE) {
+        // copy the stack buffer contents because it will be overwritten with
+        // fUnion.fFields values
+        us_arrayCopy(fUnion.fStackFields.fBuffer, 0, oldStackBuffer, 0, oldLength);
+        oldArray = oldStackBuffer;
+      } else {
+        oldArray = nullptr; // no need to copy from the stack buffer to itself
+      }
+    } else {
+      oldArray = fUnion.fFields.fArray;
+      U_ASSERT(oldArray!=nullptr); /* when stack buffer is not used, oldArray must have a non-nullptr reference */
+    }
+
+    // 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
+        int32_t minLength = oldLength;
+        newCapacity = getCapacity();
+        if(newCapacity < minLength) {
+          minLength = newCapacity;
+        }
+        if(oldArray != nullptr) {
+          us_arrayCopy(oldArray, 0, getArrayStart(), 0, minLength);
+        }
+        setLength(minLength);
+      } else {
+        setZeroLength();
+      }
+
+      // release the old array
+      if(flags & kRefCounted) {
+        // the array is refCounted; decrement and release if 0
+        u_atomic_int32_t *pRefCount = ((u_atomic_int32_t *)oldArray - 1);
+        if(umtx_atomic_dec(pRefCount) == 0) {
+          if(pBufferToDelete == 0) {
+              // Note: cast to (void *) is needed with MSVC, where u_atomic_int32_t
+              // is defined as volatile. (Volatile has useful non-standard behavior
+              //   with this compiler.)
+            uprv_free((void *)pRefCount);
+          } else {
+            // the caller requested to delete it himself
+            *pBufferToDelete = (int32_t *)pRefCount;
+          }
+        }
+      }
+    } else {
+      // not enough memory for growCapacity and not even for the smaller newCapacity
+      // reset the old values for setToBogus() to release the array
+      if(!(flags&kUsingStackBuffer)) {
+        fUnion.fFields.fArray = oldArray;
+      }
+      fUnion.fFields.fLengthAndFlags = flags;
+      setToBogus();
+      return false;
+    }
+  }
+  return true;
+}
+
+// UnicodeStringAppendable ------------------------------------------------- ***
+
+UnicodeStringAppendable::~UnicodeStringAppendable() {}
+
+UBool
+UnicodeStringAppendable::appendCodeUnit(char16_t c) {
+  return str.doAppend(&c, 0, 1).isWritable();
+}
+
+UBool
+UnicodeStringAppendable::appendCodePoint(UChar32 c) {
+  char16_t buffer[U16_MAX_LENGTH];
+  int32_t cLength = 0;
+  UBool isError = false;
+  U16_APPEND(buffer, cLength, U16_MAX_LENGTH, c, isError);
+  return !isError && str.doAppend(buffer, 0, cLength).isWritable();
+}
+
+UBool
+UnicodeStringAppendable::appendString(const char16_t *s, int32_t length) {
+  return str.doAppend(s, 0, length).isWritable();
+}
+
+UBool
+UnicodeStringAppendable::reserveAppendCapacity(int32_t appendCapacity) {
+  return str.cloneArrayIfNeeded(str.length() + appendCapacity);
+}
+
+char16_t *
+UnicodeStringAppendable::getAppendBuffer(int32_t minCapacity,
+                                         int32_t desiredCapacityHint,
+                                         char16_t *scratch, int32_t scratchCapacity,
+                                         int32_t *resultCapacity) {
+  if(minCapacity < 1 || scratchCapacity < minCapacity) {
+    *resultCapacity = 0;
+    return nullptr;
+  }
+  int32_t oldLength = str.length();
+  if(minCapacity <= (kMaxCapacity - oldLength) &&
+      desiredCapacityHint <= (kMaxCapacity - oldLength) &&
+      str.cloneArrayIfNeeded(oldLength + minCapacity, oldLength + desiredCapacityHint)) {
+    *resultCapacity = str.getCapacity() - oldLength;
+    return str.getArrayStart() + oldLength;
+  }
+  *resultCapacity = scratchCapacity;
+  return scratch;
+}
+
+U_NAMESPACE_END
+
+U_NAMESPACE_USE
+
+U_CAPI int32_t U_EXPORT2
+uhash_hashUnicodeString(const UElement key) {
+    const UnicodeString *str = (const UnicodeString*) key.pointer;
+    return (str == nullptr) ? 0 : str->hashCode();
+}
+
+// Moved here from uhash_us.cpp so that using a UVector of UnicodeString*
+// does not depend on hashtable code.
+U_CAPI UBool U_EXPORT2
+uhash_compareUnicodeString(const UElement key1, const UElement key2) {
+    const UnicodeString *str1 = (const UnicodeString*) key1.pointer;
+    const UnicodeString *str2 = (const UnicodeString*) key2.pointer;
+    if (str1 == str2) {
+        return true;
+    }
+    if (str1 == nullptr || str2 == nullptr) {
+        return false;
+    }
+    return *str1 == *str2;
+}
+
+#ifdef U_STATIC_IMPLEMENTATION
+/*
+This should never be called. It is defined here to make sure that the
+virtual vector deleting destructor is defined within unistr.cpp.
+The vector deleting destructor is already a part of UObject,
+but defining it here makes sure that it is included with this object file.
+This makes sure that static library dependencies are kept to a minimum.
+*/
+#if defined(__clang__) || U_GCC_MAJOR_MINOR >= 1100
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-function"
+static void uprv_UnicodeStringDummy() {
+    delete [] (new UnicodeString[2]);
+}
+#pragma GCC diagnostic pop
+#endif
+#endif