gecko/intl/uconv/ucvcn/nsHZToUnicode.cpp

205 lines
6.5 KiB
C++

/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/**
* A character set converter from HZ to Unicode.
*
*
* @created 08/Sept/1999
* @author Yueheng Xu, Yueheng.Xu@intel.com
*
* Note: in this HZ-GB-2312 converter, we accept a string composed of 7-bit HZ
* encoded Chinese chars,as it is defined in RFC1843 available at
* http://www.cis.ohio-state.edu/htbin/rfc/rfc1843.html
* and RFC1842 available at http://www.cis.ohio-state.edu/htbin/rfc/rfc1842.html.
*
* In an effort to match the similar extended capability of Microsoft Internet Explorer
* 5.0. We also accept the 8-bit GB encoded chars mixed in a HZ string.
* But this should not be a recommendedd practice for HTML authors.
*
* The priority of converting are as follows: first convert 8-bit GB code; then,
* consume HZ ESC sequences such as '~{', '~}', '~~'; then, depending on the current
* state ( default to ASCII state ) of the string, each 7-bit char is converted as an
* ASCII, or two 7-bit chars are converted into a Chinese character.
*/
#include "nsUCvCnDll.h"
#include "nsHZToUnicode.h"
#include "gbku.h"
//----------------------------------------------------------------------
// Class nsHZToUnicode [implementation]
//----------------------------------------------------------------------
// Subclassing of nsTablesDecoderSupport class [implementation]
#define HZ_STATE_GB 1
#define HZ_STATE_ASCII 2
#define HZ_STATE_TILD 3
#define HZLEAD1 '~'
#define HZLEAD2 '{'
#define HZLEAD3 '}'
#define HZLEAD4 '\n'
nsHZToUnicode::nsHZToUnicode() : nsBufferDecoderSupport(1)
{
mHZState = HZ_STATE_ASCII; // per HZ spec, default to ASCII state
mRunLength = 0;
}
//Overwriting the ConvertNoBuff() in nsUCvCnSupport.cpp.
NS_IMETHODIMP nsHZToUnicode::ConvertNoBuff(
const char* aSrc,
PRInt32 * aSrcLength,
PRUnichar *aDest,
PRInt32 * aDestLength)
{
PRInt32 i=0;
PRInt32 iSrcLength = *aSrcLength;
PRInt32 iDestlen = 0;
PRUint8 ch1, ch2;
nsresult res = NS_OK;
*aSrcLength=0;
for (i=0;i<iSrcLength;i++)
{
if ( iDestlen >= (*aDestLength) )
{
res = NS_OK_UDEC_MOREOUTPUT;
break;
}
if ( *aSrc & 0x80 ) // if it is a 8-bit byte
{
if (UINT8_IN_RANGE(0x81, aSrc[0], 0xFE) &&
UINT8_IN_RANGE(0x40, aSrc[1], 0xFE)) {
// The source is a 8-bit GBCode
*aDest = mUtil.GBKCharToUnicode(aSrc[0], aSrc[1]);
} else {
*aDest = UCS2_NO_MAPPING;
}
aSrc += 2;
i++;
iDestlen++;
aDest++;
*aSrcLength = i+1;
continue;
}
// otherwise, it is a 7-bit byte
// The source will be an ASCII or a 7-bit HZ code depending on ch1
ch1 = *aSrc;
ch2 = *(aSrc+1);
if (ch1 == HZLEAD1 ) // if it is lead by '~'
{
switch (ch2)
{
case HZLEAD2:
// we got a '~{'
// we are switching to HZ state
mHZState = HZ_STATE_GB;
mRunLength = 0;
aSrc += 2;
i++;
break;
case HZLEAD3:
// we got a '~}'
// we are switching to ASCII state
mHZState = HZ_STATE_ASCII;
aSrc += 2;
i++;
if (mRunLength == 0) {
*aDest = UCS2_NO_MAPPING;
iDestlen++;
aDest++;
}
mRunLength = 0;
break;
case HZLEAD1:
// we got a '~~', process like an ASCII, but no state change
aSrc++;
*aDest = CAST_CHAR_TO_UNICHAR(*aSrc);
aSrc++;
i++;
iDestlen++;
aDest++;
mRunLength++;
break;
case HZLEAD4:
// we got a "~\n", it means maintain double byte mode cross lines, ignore the '~' itself
// mHZState = HZ_STATE_GB;
// I find that "~\n" should interpreted as line continuation without mode change
// It should not be interpreted as line continuation with double byte mode on
aSrc++;
break;
default:
// undefined ESC sequence '~X' are ignored since this is a illegal combination
aSrc += 2;
*aDest = UCS2_NO_MAPPING;
iDestlen++;
aDest++;
break;
};
continue;// go for next loop
}
// ch1 != '~'
switch (mHZState)
{
case HZ_STATE_GB:
// the following chars are HZ
*aDest = mUtil.GBKCharToUnicode(aSrc[0]|0x80, aSrc[1]|0x80);
aSrc += 2;
i++;
iDestlen++;
aDest++;
mRunLength++;
break;
case HZ_STATE_ASCII:
default:
// default behavior also like an ASCII
// when the source is an ASCII
*aDest = CAST_CHAR_TO_UNICHAR(*aSrc);
aSrc++;
iDestlen++;
aDest++;
break;
}
*aSrcLength = i+1;
}// for loop
*aDestLength = iDestlen;
return NS_OK;
}