textcodecicu.cpp

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    }

    err = U_ZERO_ERROR;
    m_converterICU = ucnv_open(m_encoding.name(), &err);
#if !LOG_DISABLED
    if (err == U_AMBIGUOUS_ALIAS_WARNING)
        LOG_ERROR("ICU ambiguous alias warning for encoding: %s", m_encoding.name());
#endif
    if (m_converterICU)
        ucnv_setFallback(m_converterICU, TRUE);
}

int TextCodecICU::decodeToBuffer(UChar* target, UChar* targetLimit, const char*& source, const char* sourceLimit, int32_t* offsets, bool flush, UErrorCode& err)
{
    UChar* targetStart = target;
    err = U_ZERO_ERROR;
    ucnv_toUnicode(m_converterICU, &target, targetLimit, &source, sourceLimit, offsets, flush, &err);
    return target - targetStart;
}

class ErrorCallbackSetter {
public:
    ErrorCallbackSetter(UConverter* converter, bool stopOnError)
        : m_converter(converter)
        , m_shouldStopOnEncodingErrors(stopOnError)
    {
        if (m_shouldStopOnEncodingErrors) {
            UErrorCode err = U_ZERO_ERROR;
            ucnv_setToUCallBack(m_converter, UCNV_TO_U_CALLBACK_SUBSTITUTE,
                           UCNV_SUB_STOP_ON_ILLEGAL, &m_savedAction,
                           &m_savedContext, &err);
            ASSERT(err == U_ZERO_ERROR);
        }
    }
    ~ErrorCallbackSetter()
    {
        if (m_shouldStopOnEncodingErrors) {
            UErrorCode err = U_ZERO_ERROR;
            const void* oldContext;
            UConverterToUCallback oldAction;
            ucnv_setToUCallBack(m_converter, m_savedAction,
                   m_savedContext, &oldAction,
                   &oldContext, &err);
            ASSERT(oldAction == UCNV_TO_U_CALLBACK_SUBSTITUTE);
            ASSERT(!strcmp(static_cast<const char*>(oldContext), UCNV_SUB_STOP_ON_ILLEGAL));
            ASSERT(err == U_ZERO_ERROR);
        }
    }
private:
    UConverter* m_converter;
    bool m_shouldStopOnEncodingErrors;
    const void* m_savedContext;
    UConverterToUCallback m_savedAction;
};

String TextCodecICU::decode(const char* bytes, size_t length, bool flush, bool stopOnError, bool& sawError)
{
    // Get a converter for the passed-in encoding.
    if (!m_converterICU) {
        createICUConverter();
        ASSERT(m_converterICU);
        if (!m_converterICU) {
            LOG_ERROR("error creating ICU encoder even though encoding was in table");
            return String();
        }
    }
    
    ErrorCallbackSetter callbackSetter(m_converterICU, stopOnError);

    Vector<UChar> result;

    UChar buffer[ConversionBufferSize];
    UChar* bufferLimit = buffer + ConversionBufferSize;
    const char* source = reinterpret_cast<const char*>(bytes);
    const char* sourceLimit = source + length;
    int32_t* offsets = NULL;
    UErrorCode err = U_ZERO_ERROR;

    do {
        int ucharsDecoded = decodeToBuffer(buffer, bufferLimit, source, sourceLimit, offsets, flush, err);
        result.append(buffer, ucharsDecoded);
    } while (err == U_BUFFER_OVERFLOW_ERROR);

    if (U_FAILURE(err)) {
        // flush the converter so it can be reused, and not be bothered by this error.
        do {
            decodeToBuffer(buffer, bufferLimit, source, sourceLimit, offsets, true, err);
        } while (source < sourceLimit);
        sawError = true;
    }

    String resultString = String::adopt(result);

    // <http://bugs.webkit.org/show_bug.cgi?id=17014>
    // Simplified Chinese pages use the code A3A0 to mean "full-width space", but ICU decodes it as U+E5E5.
    if (strcmp(m_encoding.name(), "GBK") == 0 || strcmp(m_encoding.name(), "gb18030") == 0)
        resultString.replace(0xE5E5, ideographicSpace);

    return resultString;
}

// We need to apply these fallbacks ourselves as they are not currently supported by ICU and
// they were provided by the old TEC encoding path
// Needed to fix <rdar://problem/4708689>
static UChar getGbkEscape(UChar32 codePoint)
{
    switch (codePoint) {
        case 0x01F9:
            return 0xE7C8;
        case 0x1E3F:
            return 0xE7C7;
        case 0x22EF:
            return 0x2026;
        case 0x301C:
            return 0xFF5E;
        default:
            return 0;
    }
}

// Invalid character handler when writing escaped entities for unrepresentable
// characters. See the declaration of TextCodec::encode for more.
static void urlEscapedEntityCallback(const void* context, UConverterFromUnicodeArgs* fromUArgs, const UChar* codeUnits, int32_t length,
                                     UChar32 codePoint, UConverterCallbackReason reason, UErrorCode* err)
{
    if (reason == UCNV_UNASSIGNED) {
        *err = U_ZERO_ERROR;

        UnencodableReplacementArray entity;
        int entityLen = TextCodec::getUnencodableReplacement(codePoint, URLEncodedEntitiesForUnencodables, entity);
        ucnv_cbFromUWriteBytes(fromUArgs, entity, entityLen, 0, err);
    } else
        UCNV_FROM_U_CALLBACK_ESCAPE(context, fromUArgs, codeUnits, length, codePoint, reason, err);
}

// Substitutes special GBK characters, escaping all other unassigned entities.
static void gbkCallbackEscape(const void* context, UConverterFromUnicodeArgs* fromUArgs, const UChar* codeUnits, int32_t length,
                              UChar32 codePoint, UConverterCallbackReason reason, UErrorCode* err) 
{
    UChar outChar;
    if (reason == UCNV_UNASSIGNED && (outChar = getGbkEscape(codePoint))) {
        const UChar* source = &outChar;
        *err = U_ZERO_ERROR;
        ucnv_cbFromUWriteUChars(fromUArgs, &source, source + 1, 0, err);
        return;
    }
    UCNV_FROM_U_CALLBACK_ESCAPE(context, fromUArgs, codeUnits, length, codePoint, reason, err);
}

// Combines both gbkUrlEscapedEntityCallback and GBK character substitution.
static void gbkUrlEscapedEntityCallack(const void* context, UConverterFromUnicodeArgs* fromUArgs, const UChar* codeUnits, int32_t length,
                                       UChar32 codePoint, UConverterCallbackReason reason, UErrorCode* err) 
{
    if (reason == UCNV_UNASSIGNED) {
        if (UChar outChar = getGbkEscape(codePoint)) {
            const UChar* source = &outChar;
            *err = U_ZERO_ERROR;
            ucnv_cbFromUWriteUChars(fromUArgs, &source, source + 1, 0, err);
            return;
        }
        urlEscapedEntityCallback(context, fromUArgs, codeUnits, length, codePoint, reason, err);
        return;
    }
    UCNV_FROM_U_CALLBACK_ESCAPE(context, fromUArgs, codeUnits, length, codePoint, reason, err);
}

static void gbkCallbackSubstitute(const void* context, UConverterFromUnicodeArgs* fromUArgs, const UChar* codeUnits, int32_t length,
                                  UChar32 codePoint, UConverterCallbackReason reason, UErrorCode* err) 
{
    UChar outChar;
    if (reason == UCNV_UNASSIGNED && (outChar = getGbkEscape(codePoint))) {
        const UChar* source = &outChar;
        *err = U_ZERO_ERROR;
        ucnv_cbFromUWriteUChars(fromUArgs, &source, source + 1, 0, err);
        return;
    }
    UCNV_FROM_U_CALLBACK_SUBSTITUTE(context, fromUArgs, codeUnits, length, codePoint, reason, err);
}

CString TextCodecICU::encode(const UChar* characters, size_t length, UnencodableHandling handling)
{
    if (!length)
        return "";

    if (!m_converterICU)
        createICUConverter();
    if (!m_converterICU)
        return CString();

    // FIXME: We should see if there is "force ASCII range" mode in ICU;
    // until then, we change the backslash into a yen sign.
    // Encoding will change the yen sign back into a backslash.
    String copy(characters, length);
    copy = m_encoding.displayString(copy.impl());

    const UChar* source = copy.characters();
    const UChar* sourceLimit = source + copy.length();

    UErrorCode err = U_ZERO_ERROR;

    switch (handling) {
        case QuestionMarksForUnencodables:
            ucnv_setSubstChars(m_converterICU, "?", 1, &err);
            ucnv_setFromUCallBack(m_converterICU, m_needsGBKFallbacks ? gbkCallbackSubstitute : UCNV_FROM_U_CALLBACK_SUBSTITUTE, 0, 0, 0, &err);
            break;
        case EntitiesForUnencodables:
            ucnv_setFromUCallBack(m_converterICU, m_needsGBKFallbacks ? gbkCallbackEscape : UCNV_FROM_U_CALLBACK_ESCAPE, UCNV_ESCAPE_XML_DEC, 0, 0, &err);
            break;
        case URLEncodedEntitiesForUnencodables:
            ucnv_setFromUCallBack(m_converterICU, m_needsGBKFallbacks ? gbkUrlEscapedEntityCallack : urlEscapedEntityCallback, 0, 0, 0, &err);
            break;
    }

    ASSERT(U_SUCCESS(err));
    if (U_FAILURE(err))
        return CString();

    Vector<char> result;
    size_t size = 0;
    do {
        char buffer[ConversionBufferSize];
        char* target = buffer;
        char* targetLimit = target + ConversionBufferSize;
        err = U_ZERO_ERROR;
        ucnv_fromUnicode(m_converterICU, &target, targetLimit, &source, sourceLimit, 0, true, &err);
        size_t count = target - buffer;
        result.grow(size + count);
        memcpy(result.data() + size, buffer, count);
        size += count;
    } while (err == U_BUFFER_OVERFLOW_ERROR);

    return CString(result.data(), size);
}


} // namespace WebCore