utf_conversion.cpp

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/*****************************************************************************\
*                                                                             *
 *  Name   : utf_conversion                                                    *
 *  Author : Unicode, Inc. (C conversion functions)                            *
 *  Author : Chris Koeritz (C++ conversion classes)                            *
 *                                                                             *
 *******************************************************************************
 * Copyright (c) 2006-$now By Author.  This program is free software; you can  *
 * redistribute it and/or modify it under the terms of the GNU General Public  *
 * License as published by the Free Software Foundation; either version 2 of   *
 * the License or (at your option) any later version.  This is online at:      *
 *     http://www.fsf.org/copyleft/gpl.html                                    *
 * Please send any updates to: fred@gruntose.com                               *
 \*****************************************************************************/
 
//copyright below is relevant to UTF conversion methods only.
/*
 * Copyright 2001-$now Unicode, Inc.
 * 
 * Disclaimer
 * 
 * This source code is provided as is by Unicode, Inc. No claims are
 * made as to fitness for any particular purpose. No warranties of any
 * kind are expressed or implied. The recipient agrees to determine
 * applicability of information provided. If this file has been
 * purchased on magnetic or optical media from Unicode, Inc., the
 * sole remedy for any claim will be exchange of defective media
 * within 90 days of receipt.
 * 
 * Limitations on Rights to Redistribute This Code
 * 
 * Unicode, Inc. hereby grants the right to freely use the information
 * supplied in this file in the creation of products supporting the
 * Unicode Standard, and to make copies of this file in any form
 * for internal or external distribution as long as this notice
 * remains attached.
 */
 
/* ---------------------------------------------------------------------
 
 Conversions between UTF32, UTF-16, and UTF-8. Source code file.
 Author: Mark E. Davis, 1994.
 Rev History: Rick McGowan, fixes & updates May 2001.
 Sept 2001: fixed const & error conditions per
 mods suggested by S. Parent & A. Lillich.
 June 2002: Tim Dodd added detection and handling of incomplete
 source sequences, enhanced error detection, added casts
 to eliminate compiler warnings.
 July 2003: slight mods to back out aggressive FFFE detection.
 Jan 2004: updated switches in from-UTF8 conversions.
 Oct 2004: updated to use UNI_MAX_LEGAL_UTF32 in UTF-32 conversions.
 
 See the header file "ConvertUTF.h" for complete documentation.
 
 ------------------------------------------------------------------------ */
 
#include "astring.h"
#include "utf_conversion.h"
 
#include <string.h>
#include <wchar.h>
#ifdef CVTUTF_DEBUG
#include <stdio.h>
#endif
 
namespace basis {
 
  static const int halfShift = 10; /* used for shifting by 10 bits */
 
  static const UTF32 halfBase = 0x0010000UL;
  static const UTF32 halfMask = 0x3FFUL;
 
#define UNI_SUR_HIGH_START  (UTF32)0xD800
#define UNI_SUR_HIGH_END    (UTF32)0xDBFF
#define UNI_SUR_LOW_START   (UTF32)0xDC00
#define UNI_SUR_LOW_END     (UTF32)0xDFFF
 
  /* --------------------------------------------------------------------- */
 
  ConversionResult ConvertUTF32toUTF16(const UTF32** sourceStart, const UTF32* sourceEnd,
    UTF16** targetStart, UTF16* targetEnd, ConversionFlags flags)
  {
    ConversionResult result = conversionOK;
    const UTF32* source = *sourceStart;
    UTF16* target = *targetStart;
    while (source < sourceEnd) {
      UTF32 ch;
      if (target >= targetEnd) {
        result = targetExhausted;
        break;
      }
      ch = *source++;
      if (ch <= UNI_MAX_BMP) { /* Target is a character <= 0xFFFF */
        /* UTF-16 surrogate values are illegal in UTF-32; 0xffff or 0xfffe are both reserved values */
        if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END) {
          if (flags == strictConversion) {
            --source; /* return to the illegal value itself */
            result = sourceIllegal;
            break;
          } else {
            *target++ = UNI_REPLACEMENT_CHAR;
          }
        } else {
          *target++ = (UTF16)ch; /* normal case */
        }
      } else if (ch > UNI_MAX_LEGAL_UTF32) {
        if (flags == strictConversion) {
          result = sourceIllegal;
        } else {
          *target++ = UNI_REPLACEMENT_CHAR;
        }
      } else {
        /* target is a character in range 0xFFFF - 0x10FFFF. */
        if (target + 1 >= targetEnd) {
          --source; /* Back up source pointer! */
          result = targetExhausted;
          break;
        }
        ch -= halfBase;
        *target++ = (UTF16)((ch >> halfShift) + UNI_SUR_HIGH_START );
        *target++ = (UTF16)((ch & halfMask) + UNI_SUR_LOW_START );
      }
    }
    *sourceStart = source;
    *targetStart = target;
    return result;
  }
 
  /* --------------------------------------------------------------------- */
 
  ConversionResult ConvertUTF16toUTF32(const UTF16** sourceStart, const UTF16* sourceEnd,
    UTF32** targetStart, UTF32* targetEnd, ConversionFlags flags)
  {
    ConversionResult result = conversionOK;
    const UTF16* source = *sourceStart;
    UTF32* target = *targetStart;
    UTF32 ch, ch2;
    while (source < sourceEnd) {
      const UTF16* oldSource = source; /*  In case we have to back up because of target overflow. */
      ch = *source++;
      /* If we have a surrogate pair, convert to UTF32 first. */
      if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_HIGH_END) {
        /* If the 16 bits following the high surrogate are in the source buffer... */
        if (source < sourceEnd) {
          ch2 = *source;
          /* If it's a low surrogate, convert to UTF32. */
          if (ch2 >= UNI_SUR_LOW_START && ch2 <= UNI_SUR_LOW_END) {
            ch = ((ch - UNI_SUR_HIGH_START ) << halfShift) + (ch2 - UNI_SUR_LOW_START )
                + halfBase;
            ++source;
          } else if (flags == strictConversion) { /* it's an unpaired high surrogate */
            --source; /* return to the illegal value itself */
            result = sourceIllegal;
            break;
          }
        } else { /* We don't have the 16 bits following the high surrogate. */
          --source; /* return to the high surrogate */
          result = sourceExhausted;
          break;
        }
      } else if (flags == strictConversion) {
        /* UTF-16 surrogate values are illegal in UTF-32 */
        if (ch >= UNI_SUR_LOW_START && ch <= UNI_SUR_LOW_END) {
          --source; /* return to the illegal value itself */
          result = sourceIllegal;
          break;
        }
      }
      if (target >= targetEnd) {
        source = oldSource; /* Back up source pointer! */
        result = targetExhausted;
        break;
      }
      *target++ = ch;
    }
    *sourceStart = source;
    *targetStart = target;
#ifdef CVTUTF_DEBUG
    if (result == sourceIllegal) {
      fprintf(stderr, "ConvertUTF16toUTF32 illegal seq 0x%04x,%04x\n", ch, ch2);
      fflush(stderr);
    }
#endif
    return result;
  }
 
  /* --------------------------------------------------------------------- */
 
  /*
   * Index into the table below with the first byte of a UTF-8 sequence to
   * get the number of trailing bytes that are supposed to follow it.
   * Note that *legal* UTF-8 values can't have 4 or 5-bytes. The table is
   * left as-is for anyone who may want to do such conversion, which was
   * allowed in earlier algorithms.
   */
  static const char trailingBytesForUTF8[256] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
      1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2,
      2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5 };
 
  /*
   * Magic values subtracted from a buffer value during UTF8 conversion.
   * This table contains as many values as there might be trailing bytes
   * in a UTF-8 sequence.
   */
  static const UTF32 offsetsFromUTF8[6] = { 0x00000000UL, 0x00003080UL, 0x000E2080UL,
      0x03C82080UL, 0xFA082080UL, 0x82082080UL };
 
  /*
   * Once the bits are split out into bytes of UTF-8, this is a mask OR-ed
   * into the first byte, depending on how many bytes follow.  There are
   * as many entries in this table as there are UTF-8 sequence types.
   * (I.e., one byte sequence, two byte... etc.). Remember that sequencs
   * for *legal* UTF-8 will be 4 or fewer bytes total.
   */
  static const UTF8 firstByteMark[7] = { 0x00, 0x00, 0xC0, 0xE0, 0xF0, 0xF8, 0xFC };
 
  /* --------------------------------------------------------------------- */
 
  /* The interface converts a whole buffer to avoid function-call overhead.
   * Constants have been gathered. Loops & conditionals have been removed as
   * much as possible for efficiency, in favor of drop-through switches.
   * (See "Note A" at the bottom of the file for equivalent code.)
   * If your compiler supports it, the "isLegalUTF8" call can be turned
   * into an inline function.
   */
 
  /* --------------------------------------------------------------------- */
 
  ConversionResult ConvertUTF16toUTF8(const UTF16** sourceStart, const UTF16* sourceEnd,
    UTF8** targetStart, UTF8* targetEnd, ConversionFlags flags)
  {
    ConversionResult result = conversionOK;
    const UTF16* source = *sourceStart;
    UTF8* target = *targetStart;
    while (source < sourceEnd) {
      UTF32 ch;
      unsigned short bytesToWrite = 0;
      const UTF32 byteMask = 0xBF;
      const UTF32 byteMark = 0x80;
      const UTF16* oldSource = source; /* In case we have to back up because of target overflow. */
      ch = *source++;
      /* If we have a surrogate pair, convert to UTF32 first. */
      if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_HIGH_END) {
        /* If the 16 bits following the high surrogate are in the source buffer... */
        if (source < sourceEnd) {
          UTF32 ch2 = *source;
          /* If it's a low surrogate, convert to UTF32. */
          if (ch2 >= UNI_SUR_LOW_START && ch2 <= UNI_SUR_LOW_END) {
            ch = ((ch - UNI_SUR_HIGH_START ) << halfShift) + (ch2 - UNI_SUR_LOW_START )
                + halfBase;
            ++source;
          } else if (flags == strictConversion) { /* it's an unpaired high surrogate */
            --source; /* return to the illegal value itself */
            result = sourceIllegal;
            break;
          }
        } else { /* We don't have the 16 bits following the high surrogate. */
          --source; /* return to the high surrogate */
          result = sourceExhausted;
          break;
        }
      } else if (flags == strictConversion) {
        /* UTF-16 surrogate values are illegal in UTF-32 */
        if (ch >= UNI_SUR_LOW_START && ch <= UNI_SUR_LOW_END) {
          --source; /* return to the illegal value itself */
          result = sourceIllegal;
          break;
        }
      }
      /* Figure out how many bytes the result will require */
      if (ch < (UTF32)0x80) {
        bytesToWrite = 1;
      } else if (ch < (UTF32)0x800) {
        bytesToWrite = 2;
      } else if (ch < (UTF32)0x10000) {
        bytesToWrite = 3;
      } else if (ch < (UTF32)0x110000) {
        bytesToWrite = 4;
      } else {
        bytesToWrite = 3;
        ch = UNI_REPLACEMENT_CHAR;
      }
 
      target += bytesToWrite;
      if (target > targetEnd) {
        source = oldSource; /* Back up source pointer! */
        target -= bytesToWrite;
        result = targetExhausted;
        break;
      }
      switch (bytesToWrite) { /* note: everything falls through. */
        case 4:
          *--target = (UTF8)((ch | byteMark) & byteMask);
          ch >>= 6;
          // no break
        case 3:
          *--target = (UTF8)((ch | byteMark) & byteMask);
          ch >>= 6;
          // no break.
        case 2:
          *--target = (UTF8)((ch | byteMark) & byteMask);
          ch >>= 6;
          // no break.
        case 1:
          *--target = (UTF8)(ch | firstByteMark[bytesToWrite]);
          // no break.
      }
      target += bytesToWrite;
    }
    *sourceStart = source;
    *targetStart = target;
    return result;
  }
 
  /* --------------------------------------------------------------------- */
 
  /*
   * Utility routine to tell whether a sequence of bytes is legal UTF-8.
   * This must be called with the length pre-determined by the first byte.
   * If not calling this from ConvertUTF8to*, then the length can be set by:
   *  length = trailingBytesForUTF8[*source]+1;
   * and the sequence is illegal right away if there aren't that many bytes
   * available.
   * If presented with a length > 4, this returns false.  The Unicode
   * definition of UTF-8 goes up to 4-byte sequences.
   */
 
  static Booleano isLegalUTF8(const UTF8 *source, int length)
  {
    UTF8 a;
    const UTF8 *srcptr = source + length;
    switch (length) {
      /* Everything else falls through when "true"... */
      case 4: {
        if ((a = (*--srcptr)) < 0x80 || a > 0xBF) return false;
      }
        /* no break */
      case 3: {
        if ((a = (*--srcptr)) < 0x80 || a > 0xBF) return false;
      }
        /* no break */
      case 2: {
        if ((a = (*--srcptr)) > 0xBF) return false;
 
        switch (*source) {
          /* no fall-through in this inner switch */
          case 0xE0:
            if (a < 0xA0) return false;
            break;
          case 0xED:
            if (a > 0x9F) return false;
            break;
          case 0xF0:
            if (a < 0x90) return false;
            break;
          case 0xF4:
            if (a > 0x8F) return false;
            break;
          default:
            if (a < 0x80) return false;
            break;
        }
      }
        /* no break */
      case 1: {
        if (*source >= 0x80 && *source < 0xC2) return false;
      }
        /* no break */
      default: {
        return false;
      }
    }
    if (*source > 0xF4) return false;
    return true;
  }
 
  /* --------------------------------------------------------------------- */
 
  /*
   * Exported function to return whether a UTF-8 sequence is legal or not.
   * This is not used here; it's just exported.
   */
  Booleano isLegalUTF8Sequence(const UTF8 *source, const UTF8 *sourceEnd)
  {
    int length = trailingBytesForUTF8[*source] + 1;
    if (source + length > sourceEnd) {
      return false;
    }
    return isLegalUTF8(source, length);
  }
 
  /* --------------------------------------------------------------------- */
 
  ConversionResult ConvertUTF8toUTF16(const UTF8** sourceStart, const UTF8* sourceEnd,
    UTF16** targetStart, UTF16* targetEnd, ConversionFlags flags)
  {
    ConversionResult result = conversionOK;
    const UTF8* source = *sourceStart;
    UTF16* target = *targetStart;
    while (source < sourceEnd) {
      UTF32 ch = 0;
      unsigned short extraBytesToRead = trailingBytesForUTF8[*source];
      if (source + extraBytesToRead >= sourceEnd) {
        result = sourceExhausted;
        break;
      }
      /* Do this check whether lenient or strict */
      if (!isLegalUTF8(source, extraBytesToRead + 1)) {
        result = sourceIllegal;
        break;
      }
      /*
       * The cases all fall through. See "Note A" below.
       */
      switch (extraBytesToRead) {
        case 5:
          ch += *source++;
          ch <<= 6; /* remember, illegal UTF-8 */
          /* no break */
        case 4:
          ch += *source++;
          ch <<= 6; /* remember, illegal UTF-8 */
          /* no break */
        case 3:
          ch += *source++;
          ch <<= 6;
          /* no break */
        case 2:
          ch += *source++;
          ch <<= 6;
          /* no break */
        case 1:
          ch += *source++;
          ch <<= 6;
          /* no break */
        case 0:
          ch += *source++;
          /* no break */
      }
      ch -= offsetsFromUTF8[extraBytesToRead];
 
      if (target >= targetEnd) {
        source -= (extraBytesToRead + 1); /* Back up source pointer! */
        result = targetExhausted;
        break;
      }
      if (ch <= UNI_MAX_BMP) { /* Target is a character <= 0xFFFF */
        /* UTF-16 surrogate values are illegal in UTF-32 */
        if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END) {
          if (flags == strictConversion) {
            source -= (extraBytesToRead + 1); /* return to the illegal value itself */
            result = sourceIllegal;
            break;
          } else {
            *target++ = UNI_REPLACEMENT_CHAR;
          }
        } else {
          *target++ = (UTF16)ch; /* normal case */
        }
      } else if (ch > UNI_MAX_UTF16) {
        if (flags == strictConversion) {
          result = sourceIllegal;
          source -= (extraBytesToRead + 1); /* return to the start */
          break; /* Bail out; shouldn't continue */
        } else {
          *target++ = UNI_REPLACEMENT_CHAR;
        }
      } else {
        /* target is a character in range 0xFFFF - 0x10FFFF. */
        if (target + 1 >= targetEnd) {
          source -= (extraBytesToRead + 1); /* Back up source pointer! */
          result = targetExhausted;
          break;
        }
        ch -= halfBase;
        *target++ = (UTF16)((ch >> halfShift) + UNI_SUR_HIGH_START );
        *target++ = (UTF16)((ch & halfMask) + UNI_SUR_LOW_START );
      }
    }
    *sourceStart = source;
    *targetStart = target;
    return result;
  }
 
  /* --------------------------------------------------------------------- */
 
  ConversionResult ConvertUTF32toUTF8(const UTF32** sourceStart, const UTF32* sourceEnd,
    UTF8** targetStart, UTF8* targetEnd, ConversionFlags flags)
  {
    ConversionResult result = conversionOK;
    const UTF32* source = *sourceStart;
    UTF8* target = *targetStart;
    while (source < sourceEnd) {
      UTF32 ch;
      unsigned short bytesToWrite = 0;
      const UTF32 byteMask = 0xBF;
      const UTF32 byteMark = 0x80;
      ch = *source++;
      if (flags == strictConversion) {
        /* UTF-16 surrogate values are illegal in UTF-32 */
        if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END) {
          --source; /* return to the illegal value itself */
          result = sourceIllegal;
          break;
        }
      }
      /*
       * Figure out how many bytes the result will require. Turn any
       * illegally large UTF32 things (> Plane 17) into replacement chars.
       */
      if (ch < (UTF32)0x80) {
        bytesToWrite = 1;
      } else if (ch < (UTF32)0x800) {
        bytesToWrite = 2;
      } else if (ch < (UTF32)0x10000) {
        bytesToWrite = 3;
      } else if (ch <= UNI_MAX_LEGAL_UTF32) {
        bytesToWrite = 4;
      } else {
        bytesToWrite = 3;
        ch = UNI_REPLACEMENT_CHAR;
        result = sourceIllegal;
      }
 
      target += bytesToWrite;
      if (target > targetEnd) {
        --source; /* Back up source pointer! */
        target -= bytesToWrite;
        result = targetExhausted;
        break;
      }
      switch (bytesToWrite) { /* note: everything falls through. */
        case 4:
          *--target = (UTF8)((ch | byteMark) & byteMask);
          ch >>= 6;
          /* no break */
        case 3:
          *--target = (UTF8)((ch | byteMark) & byteMask);
          ch >>= 6;
          /* no break */
        case 2:
          *--target = (UTF8)((ch | byteMark) & byteMask);
          ch >>= 6;
          /* no break */
        case 1:
          *--target = (UTF8)(ch | firstByteMark[bytesToWrite]);
          /* no break */
      }
      target += bytesToWrite;
    }
    *sourceStart = source;
    *targetStart = target;
    return result;
  }
 
  /* --------------------------------------------------------------------- */
 
  ConversionResult ConvertUTF8toUTF32(const UTF8** sourceStart, const UTF8* sourceEnd,
    UTF32** targetStart, UTF32* targetEnd, ConversionFlags flags)
  {
    ConversionResult result = conversionOK;
    const UTF8* source = *sourceStart;
    UTF32* target = *targetStart;
    while (source < sourceEnd) {
      UTF32 ch = 0;
      unsigned short extraBytesToRead = trailingBytesForUTF8[*source];
      if (source + extraBytesToRead >= sourceEnd) {
        result = sourceExhausted;
        break;
      }
      /* Do this check whether lenient or strict */
      if (!isLegalUTF8(source, extraBytesToRead + 1)) {
        result = sourceIllegal;
        break;
      }
      /*
       * The cases all fall through. See "Note A" below.
       */
      switch (extraBytesToRead) {
        case 5:
          ch += *source++;
          ch <<= 6;
          /* no break */
        case 4:
          ch += *source++;
          ch <<= 6;
          /* no break */
        case 3:
          ch += *source++;
          ch <<= 6;
          /* no break */
        case 2:
          ch += *source++;
          ch <<= 6;
          /* no break */
        case 1:
          ch += *source++;
          ch <<= 6;
          /* no break */
        case 0:
          ch += *source++;
          /* no break */
      }
      ch -= offsetsFromUTF8[extraBytesToRead];
 
      if (target >= targetEnd) {
        source -= (extraBytesToRead + 1); /* Back up the source pointer! */
        result = targetExhausted;
        break;
      }
      if (ch <= UNI_MAX_LEGAL_UTF32) {
        /*
         * UTF-16 surrogate values are illegal in UTF-32, and anything
         * over Plane 17 (> 0x10FFFF) is illegal.
         */
        if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END) {
          if (flags == strictConversion) {
            source -= (extraBytesToRead + 1); /* return to the illegal value itself */
            result = sourceIllegal;
            break;
          } else {
            *target++ = UNI_REPLACEMENT_CHAR;
          }
        } else {
          *target++ = ch;
        }
      } else { /* i.e., ch > UNI_MAX_LEGAL_UTF32 */
        result = sourceIllegal;
        *target++ = UNI_REPLACEMENT_CHAR;
      }
    }
    *sourceStart = source;
    *targetStart = target;
    return result;
  }
 
  /* ---------------------------------------------------------------------
 
   Note A.
   The fall-through switches in UTF-8 reading code save a
   temp variable, some decrements & conditionals.  The switches
   are equivalent to the following loop:
   {
   int tmpBytesToRead = extraBytesToRead+1;
   do {
   ch += *source++;
   --tmpBytesToRead;
   if (tmpBytesToRead) ch <<= 6;
   } while (tmpBytesToRead > 0);
   }
   In UTF-8 writing code, the switches on "bytesToWrite" are
   similarly unrolled loops.
 
   --------------------------------------------------------------------- */
 
#ifdef __cplusplus
 
  transcode_to_utf16::transcode_to_utf16(const char *utf8_input)
      : _orig_length(int(strlen(utf8_input)) + 1), _converted(new UTF16[_orig_length + 1])
  // we don't ever expect the string to get longer going to the larger data
  // type, so the current length should be enough.
  {
    _result = conversionOK;
    if (_orig_length == 1) {
      // no length, so only provide a blank string.
      _converted[0] = 0;
      return;
    }
    memset((abyte *)_converted, 0, 2 * _orig_length);
    // we use these temporary pointers since the converter resets the source
    // and target pointers to the end of the conversion.  the same pattern
    // is used in the code below.
    const UTF8 *temp_in = (const UTF8 *)utf8_input;
    UTF16 *temp_out = _converted;
    _result = ConvertUTF8toUTF16(&temp_in, temp_in + _orig_length, &temp_out,
        temp_out + _orig_length, lenientConversion);
  }
 
  transcode_to_utf16::transcode_to_utf16(const astring &utf8_input)
      : _orig_length(utf8_input.length() + 1), _converted(new UTF16[_orig_length])
  {
    _result = conversionOK;
    if (_orig_length == 1) {
      // no length, so only provide a blank string.
      _converted[0] = 0;
      return;
    }
    memset((abyte *)_converted, 0, 2 * _orig_length);
    const UTF8 *temp_in = (const UTF8 *)utf8_input.observe();
    UTF16 *temp_out = _converted;
    _result = ConvertUTF8toUTF16(&temp_in, temp_in + _orig_length, &temp_out,
        temp_out + _orig_length, lenientConversion);
  }
 
  transcode_to_utf16::~transcode_to_utf16()
  {
    delete[] _converted;
    _converted = NULL_POINTER;
  }
 
  int transcode_to_utf16::length() const
  {
    return int(wcslen((wchar_t *)_converted));
  }
 
 
  transcode_to_utf8::transcode_to_utf8(const UTF16 *utf16_input)
      : _orig_length(int(wcslen((const wchar_t *)utf16_input))),
          _new_length(_orig_length * 2 + _orig_length / 2 + 1),
          // this is just an estimate.  it may be appropriate most of the time.
          // whatever doesn't fit will get truncated.
          _converted(new UTF8[_new_length])
  {
    _result = conversionOK;
    if (_orig_length == 0) {
      // no length, so only provide a blank string.
      _converted[0] = 0;
      return;
    }
    memset(_converted, 0, _new_length);
    const UTF16 *temp_in = (const UTF16 *)utf16_input;
    UTF8 *temp_out = _converted;
    _result = ConvertUTF16toUTF8(&temp_in, temp_in + _orig_length, &temp_out,
        temp_out + _new_length, lenientConversion);
  }
 
  transcode_to_utf8::transcode_to_utf8(const wchar_t *utf16_input)
      : _orig_length(int(wcslen(utf16_input))),
          _new_length(_orig_length * 2 + _orig_length / 2 + 1),
          // this is just an estimate.  it may be appropriate most of the time.
          // whatever doesn't fit will get truncated.
          _converted(new UTF8[_new_length > 0 ? _new_length : 1])
  {
    _result = conversionOK;
    if (_orig_length == 0) {
      // no length, so only provide a blank string.
      _converted[0] = 0;
      return;
    }
    memset(_converted, 0, _new_length);
    const UTF16 *temp_in = (const UTF16 *)utf16_input;
    UTF8 *temp_out = _converted;
    _result = ConvertUTF16toUTF8(&temp_in, temp_in + _orig_length, &temp_out,
        temp_out + _new_length, lenientConversion);
  }
 
  transcode_to_utf8::~transcode_to_utf8()
  {
    delete[] _converted;
    _converted = NULL_POINTER;
  }
 
  int transcode_to_utf8::length() const
  {
    return int(strlen((char *)_converted));
  }
 
  transcode_to_utf8::operator astring() const
  {
    return astring((char *)_converted);
  }
 
 
  null_transcoder::null_transcoder(const char *utf8_input, bool make_own_copy)
      : _make_own_copy(make_own_copy),
          _converted(make_own_copy ? new UTF8[strlen(utf8_input) + 1] : (const UTF8 *)utf8_input)
  {
    if (_make_own_copy) {
      strcpy((char *)_converted, utf8_input);
    }
  }
 
  null_transcoder::null_transcoder(const astring &utf8_input, bool make_own_copy)
      : _make_own_copy(make_own_copy),
          _converted(
              make_own_copy ? new UTF8[utf8_input.length() + 1] : (const UTF8 *)utf8_input.s())
  {
    if (_make_own_copy) {
      strcpy((char *)_converted, utf8_input.s());
    }
  }
 
  int null_transcoder::length() const
  {
    return int(strlen((char *)_converted));
  }
 
#endif //_cplusplus
}  //namespace.