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qtextcodec.cpp

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**
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#include "qplatformdefs.h"
#include "qtextcodec.h"

#ifndef QT_NO_TEXTCODEC

#include "qlist.h"
#include "qfile.h"
#ifndef QT_NO_LIBRARY
# include "qcoreapplication.h"
# include "qtextcodecplugin.h"
# include "private/qfactoryloader_p.h"
#endif
#include "qstringlist.h"

#ifdef Q_OS_UNIX
#  include "qiconvcodec_p.h"
#endif

#include "qutfcodec_p.h"
#include "qsimplecodec_p.h"
#include "qlatincodec_p.h"
#ifndef QT_NO_CODECS
#  include "qtsciicodec_p.h"
#  include "qisciicodec_p.h"
#  if defined(QT_NO_ICONV) && !defined(QT_BOOTSTRAPPED)
// no iconv(3) support, must build all codecs into the library
#    include "../../plugins/codecs/cn/qgb18030codec.h"
#    include "../../plugins/codecs/jp/qeucjpcodec.h"
#    include "../../plugins/codecs/jp/qjiscodec.h"
#    include "../../plugins/codecs/jp/qsjiscodec.h"
#    include "../../plugins/codecs/kr/qeuckrcodec.h"
#    include "../../plugins/codecs/tw/qbig5codec.h"
#  endif // QT_NO_ICONV
#  if defined(Q_WS_X11) && !defined(QT_BOOTSTRAPPED)
#    include "qfontlaocodec_p.h"
#    include "../../plugins/codecs/jp/qfontjpcodec.h"
#  endif
#endif // QT_NO_CODECS
#include "qlocale.h"
#include "private/qmutexpool_p.h"

#include <stdlib.h>
#include <ctype.h>
#ifndef Q_OS_TEMP
#include <locale.h>
#endif
#if defined (_XOPEN_UNIX) && !defined(Q_OS_QNX6) && !defined(Q_OS_OSF)
#include <langinfo.h>
#endif


#ifndef QT_NO_TEXTCODECPLUGIN
Q_GLOBAL_STATIC_WITH_ARGS(QFactoryLoader, loader,
    (QTextCodecFactoryInterface_iid, QCoreApplication::libraryPaths(), QLatin1String("/codecs")))
#endif


static bool nameMatch(const QByteArray &name, const QByteArray &test)
{
    // if they're the same, return a perfect score
    if (qstricmp(name, test) == 0)
        return true;

    const char *n = name.constData();
    const char *h = test.constData();

    // if the letters and numbers are the same, we have a match
    while (*n != '\0') {
        if (isalnum((uchar)*n)) {
            for (;;) {
                if (*h == '\0')
                    return false;
                if (isalnum((uchar)*h))
                    break;
                ++h;
            }
            if (tolower((uchar)*n) != tolower((uchar)*h))
                return false;
            ++h;
        }
        ++n;
    }
    while (*h && !isalnum((uchar)*h))
           ++h;
    return (*h == '\0');
}


static QTextCodec *createForName(const QByteArray &name)
{
#ifndef QT_NO_TEXTCODECPLUGIN
    QFactoryLoader *l = loader();
    QStringList keys = l->keys();
    for (int i = 0; i < keys.size(); ++i) {
        if (nameMatch(name, keys.at(i).toLatin1())) {
            QString realName = keys.at(i);
            if (QTextCodecFactoryInterface *factory
                = qobject_cast<QTextCodecFactoryInterface*>(l->instance(realName))) {
                return factory->create(realName);
            }
        }
    }
#else
    Q_UNUSED(name);
#endif
    return 0;
}

static QTextCodec *createForMib(int mib)
{
#ifndef QT_NO_TEXTCODECPLUGIN
    QString name = QLatin1String("MIB: ") + QString::number(mib);
    if (QTextCodecFactoryInterface *factory
        = qobject_cast<QTextCodecFactoryInterface*>(loader()->instance(name)))
        return factory->create(name);
#else
    Q_UNUSED(mib);
#endif
    return 0;
}

static QList<QTextCodec*> *all = 0;
static bool destroying_is_ok = false;

static QTextCodec *localeMapper = 0;
QTextCodec *QTextCodec::cftr = 0;


class QTextCodecCleanup
{
public:
    ~QTextCodecCleanup();
};

/*
    Deletes all the created codecs. This destructor is called just
    before exiting to delete any QTextCodec objects that may be lying
    around.
*/
QTextCodecCleanup::~QTextCodecCleanup()
{
    if (!all)
        return;

    destroying_is_ok = true;

    while (all->size())
        delete all->takeFirst();
    delete all;
    all = 0;
    localeMapper = 0;

    destroying_is_ok = false;
}

Q_GLOBAL_STATIC(QTextCodecCleanup, createQTextCodecCleanup)

#ifdef Q_OS_WIN32
class QWindowsLocalCodec: public QTextCodec
{
public:
    QWindowsLocalCodec();
    ~QWindowsLocalCodec();

    QString convertToUnicode(const char *, int, ConverterState *) const;
    QByteArray convertFromUnicode(const QChar *, int, ConverterState *) const;

    QByteArray name() const;
    int mibEnum() const;

};

QWindowsLocalCodec::QWindowsLocalCodec()
{
}

QWindowsLocalCodec::~QWindowsLocalCodec()
{
}


QString QWindowsLocalCodec::convertToUnicode(const char *chars, int len, ConverterState * /*state*/) const
{
    return qt_winMB2QString(chars, len);
}

QByteArray QWindowsLocalCodec::convertFromUnicode(const QChar *uc, int len, ConverterState *) const
{
    return qt_winQString2MB(uc, len);
}


QByteArray QWindowsLocalCodec::name() const
{
    return "System";
}

int QWindowsLocalCodec::mibEnum() const
{
    return 0;
}

#else

/* locale names mostly copied from XFree86 */
static const char * const iso8859_2locales[] = {
    "croatian", "cs", "cs_CS", "cs_CZ","cz", "cz_CZ", "czech", "hr",
    "hr_HR", "hu", "hu_HU", "hungarian", "pl", "pl_PL", "polish", "ro",
    "ro_RO", "rumanian", "serbocroatian", "sh", "sh_SP", "sh_YU", "sk",
    "sk_SK", "sl", "sl_CS", "sl_SI", "slovak", "slovene", "sr_SP", 0 };

static const char * const iso8859_3locales[] = {
    "eo", 0 };

static const char * const iso8859_4locales[] = {
    "ee", "ee_EE", 0 };

static const char * const iso8859_5locales[] = {
    "mk", "mk_MK", "sp", "sp_YU", 0 };

static const char * const cp_1251locales[] = {
    "be", "be_BY", "bg", "bg_BG", "bulgarian", 0 };

static const char * const pt_154locales[] = {
    "ba_RU", "ky", "ky_KG", "kk", "kk_KZ", 0 };

static const char * const iso8859_6locales[] = {
    "ar_AA", "ar_SA", "arabic", 0 };

static const char * const iso8859_7locales[] = {
    "el", "el_GR", "greek", 0 };

static const char * const iso8859_8locales[] = {
    "hebrew", "he", "he_IL", "iw", "iw_IL", 0 };

static const char * const iso8859_9locales[] = {
    "tr", "tr_TR", "turkish", 0 };

static const char * const iso8859_13locales[] = {
    "lt", "lt_LT", "lv", "lv_LV", 0 };

static const char * const iso8859_15locales[] = {
    "et", "et_EE",
    // Euro countries
    "br_FR", "ca_ES", "de", "de_AT", "de_BE", "de_DE", "de_LU", "en_IE",
    "es", "es_ES", "eu_ES", "fi", "fi_FI", "finnish", "fr", "fr_FR",
    "fr_BE", "fr_LU", "french", "ga_IE", "gl_ES", "it", "it_IT", "oc_FR",
    "nl", "nl_BE", "nl_NL", "pt", "pt_PT", "sv_FI", "wa_BE",
    0 };

static const char * const koi8_ulocales[] = {
    "uk", "uk_UA", "ru_UA", "ukrainian", 0 };

static const char * const tis_620locales[] = {
    "th", "th_TH", "thai", 0 };

// static const char * const tcvnlocales[] = {
//     "vi", "vi_VN", 0 };

static bool try_locale_list(const char * const locale[], const char * lang)
{
    int i;
    for(i=0; locale[i] && *locale[i] && strcmp(locale[i], lang); i++)
        ;
    return locale[i] != 0;
}

// For the probably_koi8_locales we have to look. the standard says
// these are 8859-5, but almost all Russian users use KOI8-R and
// incorrectly set $LANG to ru_RU. We'll check tolower() to see what
// it thinks ru_RU means.

// If you read the history, it seems that many Russians blame ISO and
// Perestroika for the confusion.
//
// The real bug is that some programs break if the user specifies
// ru_RU.KOI8-R.

static const char * const probably_koi8_rlocales[] = {
    "ru", "ru_SU", "ru_RU", "russian", 0 };

static QTextCodec * ru_RU_hack(const char * i) {
    QTextCodec * ru_RU_codec = 0;

    QByteArray origlocale(setlocale(LC_CTYPE, i));
    // unicode   koi8r   latin5   name
    // 0x044E    0xC0    0xEE     CYRILLIC SMALL LETTER YU
    // 0x042E    0xE0    0xCE     CYRILLIC CAPITAL LETTER YU
    int latin5 = tolower(0xCE);
    int koi8r = tolower(0xE0);
    if (koi8r == 0xC0 && latin5 != 0xEE) {
        ru_RU_codec = QTextCodec::codecForName("KOI8-R");
    } else if (koi8r != 0xC0 && latin5 == 0xEE) {
        ru_RU_codec = QTextCodec::codecForName("ISO 8859-5");
    } else {
        // something else again... let's assume... *throws dice*
        ru_RU_codec = QTextCodec::codecForName("KOI8-R");
        qWarning("QTextCodec: Using KOI8-R, probe failed (%02x %02x %s)",
                  koi8r, latin5, i);
    }
    setlocale(LC_CTYPE, origlocale);

    return ru_RU_codec;
}

#endif

#ifndef Q_OS_WIN32
static QTextCodec *checkForCodec(const char *name) {
    QTextCodec *c = QTextCodec::codecForName(name);
    if (!c) {
        const char *at = strchr(name, '@');
        if (at) {
            QByteArray n(name, at - name);
            c = QTextCodec::codecForName(n.data());
        }
    }
    return c;
}
#endif

/* the next two functions are implicitely thread safe,
   as they are only called by setup() which uses a mutex.
*/
static void setupLocaleMapper()
{
#ifdef Q_OS_WIN32
    localeMapper = QTextCodec::codecForName("System");
#else

#ifndef QT_NO_ICONV
    localeMapper = QTextCodec::codecForName("System");
#endif

#if defined (_XOPEN_UNIX) && !defined(Q_OS_QNX6) && !defined(Q_OS_OSF)
    if (!localeMapper) {
        char *charset = nl_langinfo (CODESET);
        if (charset)
            localeMapper = QTextCodec::codecForName(charset);
    }
#endif

    if (!localeMapper) {
        // Very poorly defined and followed standards causes lots of
        // code to try to get all the cases... This logic is
        // duplicated in QIconvCodec, so if you change it here, change
        // it there too.

        // Try to determine locale codeset from locale name assigned to
        // LC_CTYPE category.

        // First part is getting that locale name.  First try setlocale() which
        // definitely knows it, but since we cannot fully trust it, get ready
        // to fall back to environment variables.
        char * ctype = qstrdup(setlocale(LC_CTYPE, 0));

        // Get the first nonempty value from $LC_ALL, $LC_CTYPE, and $LANG
        // environment variables.
        char * lang = qstrdup(qgetenv("LC_ALL").constData());
        if (!lang || lang[0] == 0 || strcmp(lang, "C") == 0) {
            if (lang) delete [] lang;
            lang = qstrdup(qgetenv("LC_CTYPE").constData());
        }
        if (!lang || lang[0] == 0 || strcmp(lang, "C") == 0) {
            if (lang) delete [] lang;
            lang = qstrdup(qgetenv("LANG").constData());
        }

        // Now try these in order:
        // 1. CODESET from ctype if it contains a .CODESET part (e.g. en_US.ISO8859-15)
        // 2. CODESET from lang if it contains a .CODESET part
        // 3. ctype (maybe the locale is named "ISO-8859-1" or something)
        // 4. locale (ditto)
        // 5. check for "@euro"
        // 6. guess locale from ctype unless ctype is "C"
        // 7. guess locale from lang

        // 1. CODESET from ctype if it contains a .CODESET part (e.g. en_US.ISO8859-15)
        char * codeset = ctype ? strchr(ctype, '.') : 0;
        if (codeset && *codeset == '.')
            localeMapper = checkForCodec(codeset + 1);

        // 2. CODESET from lang if it contains a .CODESET part
        codeset = lang ? strchr(lang, '.') : 0;
        if (!localeMapper && codeset && *codeset == '.')
            localeMapper = checkForCodec(codeset + 1);

        // 3. ctype (maybe the locale is named "ISO-8859-1" or something)
        if (!localeMapper && ctype && *ctype != 0 && strcmp (ctype, "C") != 0)
            localeMapper = checkForCodec(ctype);

        // 4. locale (ditto)
        if (!localeMapper && lang && *lang != 0)
            localeMapper = checkForCodec(lang);

        // 5. "@euro"
        if (!localeMapper && ctype && strstr(ctype, "@euro") || lang && strstr(lang, "@euro"))
            localeMapper = checkForCodec("ISO 8859-15");

        // 6. guess locale from ctype unless ctype is "C"
        // 7. guess locale from lang
        char * try_by_name = ctype;
        if (ctype && *ctype != 0 && strcmp (ctype, "C") != 0)
            try_by_name = lang;

        // Now do the guessing.
        if (lang && *lang && !localeMapper && try_by_name && *try_by_name) {
            if (try_locale_list(iso8859_15locales, lang))
                localeMapper = QTextCodec::codecForName("ISO 8859-15");
            else if (try_locale_list(iso8859_2locales, lang))
                localeMapper = QTextCodec::codecForName("ISO 8859-2");
            else if (try_locale_list(iso8859_3locales, lang))
                localeMapper = QTextCodec::codecForName("ISO 8859-3");
            else if (try_locale_list(iso8859_4locales, lang))
                localeMapper = QTextCodec::codecForName("ISO 8859-4");
            else if (try_locale_list(iso8859_5locales, lang))
                localeMapper = QTextCodec::codecForName("ISO 8859-5");
            else if (try_locale_list(iso8859_6locales, lang))
                localeMapper = QTextCodec::codecForName("ISO 8859-6");
            else if (try_locale_list(iso8859_7locales, lang))
                localeMapper = QTextCodec::codecForName("ISO 8859-7");
            else if (try_locale_list(iso8859_8locales, lang))
                localeMapper = QTextCodec::codecForName("ISO 8859-8-I");
            else if (try_locale_list(iso8859_9locales, lang))
                localeMapper = QTextCodec::codecForName("ISO 8859-9");
            else if (try_locale_list(iso8859_13locales, lang))
                localeMapper = QTextCodec::codecForName("ISO 8859-13");
            else if (try_locale_list(tis_620locales, lang))
                localeMapper = QTextCodec::codecForName("ISO 8859-11");
            else if (try_locale_list(koi8_ulocales, lang))
                localeMapper = QTextCodec::codecForName("KOI8-U");
            else if (try_locale_list(cp_1251locales, lang))
                localeMapper = QTextCodec::codecForName("CP 1251");
            else if (try_locale_list(pt_154locales, lang))
                localeMapper = QTextCodec::codecForName("PT 154");
            else if (try_locale_list(probably_koi8_rlocales, lang))
                localeMapper = ru_RU_hack(lang);
        }

        delete [] ctype;
        delete [] lang;
    }

    // If everything failed, we default to 8859-1
    // We could perhaps default to 8859-15.
    if (!localeMapper)
        localeMapper = QTextCodec::codecForName("ISO 8859-1");
#endif
}


static void setup()
{
#ifndef QT_NO_THREAD
    QMutexLocker locker(QMutexPool::globalInstanceGet(&all));
#endif

    if (all)
        return;

    if (destroying_is_ok)
        qWarning("QTextCodec: Creating new codec during codec cleanup");
    all = new QList<QTextCodec*>;
    // create the cleanup object to cleanup all codecs on exit
    (void) createQTextCodecCleanup();

#ifndef QT_NO_CODECS
#  if defined(Q_WS_X11) && !defined(QT_BOOTSTRAPPED)
    // no font codecs when bootstrapping
    (void)new QFontLaoCodec;
#    if defined(QT_NO_ICONV)
    // no iconv(3) support, must build all codecs into the library
    (void)new QFontGb2312Codec;
    (void)new QFontGbkCodec;
    (void)new QFontGb18030_0Codec;
    (void)new QFontJis0208Codec;
    (void)new QFontJis0201Codec;
    (void)new QFontKsc5601Codec;
    (void)new QFontBig5hkscsCodec;
    (void)new QFontBig5Codec;
#    endif // QT_NO_ICONV && !QT_BOOTSTRAPPED
#  endif // Q_WS_X11

    (void)new QTsciiCodec;

    for (int i = 0; i < 9; ++i)
        (void)new QIsciiCodec(i);

    for (int i = 0; i < QSimpleTextCodec::numSimpleCodecs; ++i)
        (void)new QSimpleTextCodec(i);

#  if defined(QT_NO_ICONV) && !defined(QT_BOOTSTRAPPED)
    // no asian codecs when bootstrapping, sorry
    (void)new QGb18030Codec;
    (void)new QGbkCodec;
    (void)new QGb2312Codec;
    (void)new QEucJpCodec;
    (void)new QJisCodec;
    (void)new QSjisCodec;
    (void)new QEucKrCodec;
    (void)new QBig5Codec;
    (void)new QBig5hkscsCodec;
#  endif // QT_NO_ICONV && !QT_BOOTSTRAPPED
#endif // QT_NO_CODECS

#ifdef Q_OS_WIN32
    (void) new QWindowsLocalCodec;
#endif // Q_OS_WIN32

    (void)new QUtf16Codec;
    (void)new QUtf16BECodec;
    (void)new QUtf16LECodec;
    (void)new QLatin15Codec;
    (void)new QLatin1Codec;
    (void)new QUtf8Codec;

#if defined(Q_OS_UNIX) && !defined(QT_NO_ICONV) && !defined(QT_BOOTSTRAPPED)
    // QIconvCodec depends on the UTF-16 codec, so it needs to be created last
    (void) new QIconvCodec();
#endif

    if (!localeMapper)
        setupLocaleMapper();
}



/*!
    \class QTextCodec
    \brief The QTextCodec class provides conversions between text encodings.
    \reentrant
    \ingroup i18n

    Qt uses Unicode to store, draw and manipulate strings. In many
    situations you may wish to deal with data that uses a different
    encoding. For example, most Japanese documents are still stored
    in Shift-JIS or ISO 2022-JP, while Russian users often have their
    documents in KOI8-R or Windows-1251.

    Qt provides a set of QTextCodec classes to help with converting
    non-Unicode formats to and from Unicode. You can also create your
    own codec classes.

    The supported encodings are:

    \list
    \o Apple Roman
    \o \l{Big5 Text Codec}{Big5}
    \o \l{Big5-HKSCS Text Codec}{Big5-HKSCS}
    \o \l{EUC-JP Text Codec}{EUC-JP}
    \o \l{EUC-KR Text Codec}{EUC-KR}
    \o \l{GBK Text Codec}{GB18030-0}
    \o IBM 850
    \o IBM 866
    \o IBM 874
    \o \l{ISO 2022-JP (JIS) Text Codec}{ISO 2022-JP}
    \o ISO 8859-1 to 10
    \o ISO 8859-13 to 16
    \o Iscii-Bng, Dev, Gjr, Knd, Mlm, Ori, Pnj, Tlg, and Tml
    \o JIS X 0201
    \o JIS X 0208
    \o KOI8-R
    \o KOI8-U
    \o MuleLao-1
    \o ROMAN8
    \o \l{Shift-JIS Text Codec}{Shift-JIS}
    \o TIS-620
    \o \l{TSCII Text Codec}{TSCII}
    \o UTF-8
    \o UTF-16
    \o UTF-16BE
    \o UTF-16LE
    \o Windows-1250 to 1258
    \o WINSAMI2
    \endlist

    QTextCodecs can be used as follows to convert some locally encoded
    string to Unicode. Suppose you have some string encoded in Russian
    KOI8-R encoding, and want to convert it to Unicode. The simple way
    to do it is like this:

    \code
        QByteArray encodedString = "...";
        QTextCodec *codec = QTextCodec::codecForName("KOI8-R");
        QString string = codec->toUnicode(encodedString);
    \endcode

    After this, \c string holds the text converted to Unicode.
    Converting a string from Unicode to the local encoding is just as
    easy:

    \code
        QString string = "...";
        QTextCodec *codec = QTextCodec::codecForName("KOI8-R");
        QByteArray encodedString = codec->fromUnicode(string);
    \endcode

    To read or write files in various encodings, use QTextStream and
    its \l{QTextStream::setCodec()}{setCodec()} function. See the
    \l{tools/codecs}{Codecs} example for an application of QTextCodec
    to file I/O.

    Some care must be taken when trying to convert the data in chunks,
    for example, when receiving it over a network. In such cases it is
    possible that a multi-byte character will be split over two
    chunks. At best this might result in the loss of a character and
    at worst cause the entire conversion to fail.

    The approach to use in these situations is to create a QTextDecoder
    object for the codec and use this QTextDecoder for the whole
    decoding process, as shown below:

    \code
        QTextCodec *codec = QTextCodec::codecForName("Shift-JIS");
        QTextDecoder *decoder = codec->makeDecoder();

        QString string;
        while (new_data_available()) {
            QByteArray chunk = get_new_data();
            string += decoder->toUnicode(chunk);
        }
    \endcode

    The QTextDecoder object maintains state between chunks and therefore
    works correctly even if a multi-byte character is split between
    chunks.

    \section1 Creating Your Own Codec Class

    Support for new text encodings can be added to Qt by creating
    QTextCodec subclasses.

    The pure virtual functions describe the encoder to the system and
    the coder is used as required in the different text file formats
    supported by QTextStream, and under X11, for the locale-specific
    character input and output.

    To add support for another encoding to Qt, make a subclass of
    QTextCodec and implement the functions listed in the table below.

    \table
    \header \o Function \o Description

    \row \o name()
         \o Returns the official name for the encoding. If the
            ncoding is listed in the
            \l{http://www.iana.org/assignments/character-sets}{IANA
            character-sets encoding file}, the name should be the
            preferred MIME name for the encoding.

    \row \o aliases()
         \o Returns a list of alternative names for the encoding.
            QTextCodec provides a default implementation that returns
            an empty list. For example, "ISO-8859-1" has "latin1",
          "CP819", "IBM819", and "iso-ir-100" as aliases.

    \row \o mibEnum()
         \o Return the MIB enum for the encoding if it is listed in
            the \l{http://www.iana.org/assignments/character-sets}{IANA
            character-sets encoding file}.

    \row \o convertToUnicode()
         \o Converts an 8-bit character string to Unicode.

    \row \o convertFromUnicode()
         \o Converts a Unicode string to an 8-bit character string.
    \endtable

    You may find it more convenient to make your codec class
    available as a plugin; see \l{How to Create Qt Plugins} for
    details.

    \sa QTextStream, QTextDecoder, QTextEncoder, {Codecs Example}
*/

/*!
    \enum QTextCodec::ConversionFlag

    \value DefaultConversion  No flag is set.
    \value ConvertInvalidToNull  If this flag is set, invalid input results in
           an empty string.
    \value IgnoreHeader  Ignore any Unicode byte-order mark and don't generate any.
*/

/*!
    \fn QTextCodec::ConverterState::ConverterState(ConversionFlags flags)

    Constructs a ConverterState object initialized with the given \a flags.
*/

/*!
    \fn QTextCodec::ConverterState::~ConverterState()

    Destroys the ConverterState object.
*/

/*!
    \nonreentrant

    Constructs a QTextCodec, and gives it the highest precedence. The
    QTextCodec should always be constructed on the heap (i.e. with \c
    new). Qt takes ownership and will delete it when the application
    terminates.
*/
00748 QTextCodec::QTextCodec()
{
    setup();
    all->prepend(this);
}


/*!
    \nonreentrant

    Destroys the QTextCodec. Note that you should not delete codecs
    yourself: once created they become Qt's responsibility.
*/
00761 QTextCodec::~QTextCodec()
{
    if (!destroying_is_ok)
        qWarning("QTextCodec::~QTextCodec: Called by application");
    if (all)
        all->removeAll(this);
}

/*!
    \fn QTextCodec *QTextCodec::codecForName(const char *name)

    Searches all installed QTextCodec objects and returns the one
    which best matches \a name; the match is case-insensitive. Returns
    0 if no codec matching the name \a name could be found.
*/

/*!
    Searches all installed QTextCodec objects and returns the one
    which best matches \a name; the match is case-insensitive. Returns
    0 if no codec matching the name \a name could be found.
*/
00782 QTextCodec *QTextCodec::codecForName(const QByteArray &name)
{
    if (name.isEmpty())
        return 0;

    setup();

    for (int i = 0; i < all->size(); ++i) {
        QTextCodec *cursor = all->at(i);
        if (nameMatch(cursor->name(), name))
            return cursor;
        QList<QByteArray> aliases = cursor->aliases();
        for (int i = 0; i < aliases.size(); ++i)
            if (nameMatch(aliases.at(i), name))
                return cursor;
    }

    return createForName(name);
}


/*!
    Returns the QTextCodec which matches the \link
    QTextCodec::mibEnum() MIBenum\endlink \a mib.
*/
00807 QTextCodec* QTextCodec::codecForMib(int mib)
{
    setup();

    // Qt 3 used 1000 (mib for UCS2) as it's identifier for the utf16 codec. Map
    // this correctly for compatibility.
    if (mib == 1000)
        mib = 1015;

    QList<QTextCodec*>::ConstIterator i;
    for (int i = 0; i < all->size(); ++i) {
        QTextCodec *cursor = all->at(i);
        if (cursor->mibEnum() == mib)
            return cursor;
    }

    return createForMib(mib);
}

/*!
    Returns the list of all available codecs, by name. Call
    QTextCodec::codecForName() to obtain the QTextCodec for the name.

    The list may contain many mentions of the same codec
    if the codec has aliases.

    \sa availableMibs(), name(), aliases()
*/
00835 QList<QByteArray> QTextCodec::availableCodecs()
{
    setup();

    QList<QByteArray> codecs;
    for (int i = 0; i < all->size(); ++i) {
        codecs += all->at(i)->name();
        codecs += all->at(i)->aliases();
    }
#ifndef QT_NO_TEXTCODECPLUGIN
    QFactoryLoader *l = loader();
    QStringList keys = l->keys();
    for (int i = 0; i < keys.size(); ++i) {
        if (!keys.at(i).startsWith(QLatin1String("MIB: "))) {
            QByteArray name = keys.at(i).toLatin1();
            if (!codecs.contains(name))
                codecs += name;
        }
    }
#endif

    return codecs;
}

/*!
    Returns the list of MIBs for all available codecs. Call
    QTextCodec::codecForMib() to obtain the QTextCodec for the MIB.

    \sa availableCodecs(), mibEnum()
*/
00865 QList<int> QTextCodec::availableMibs()
{
    setup();

    QList<int> codecs;
    for (int i = 0; i < all->size(); ++i)
        codecs += all->at(i)->mibEnum();
#ifndef QT_NO_TEXTCODECPLUGIN
    QFactoryLoader *l = loader();
    QStringList keys = l->keys();
    for (int i = 0; i < keys.size(); ++i) {
        if (keys.at(i).startsWith(QLatin1String("MIB: "))) {
            int mib = keys.at(i).mid(5).toInt();
            if (!codecs.contains(mib))
                codecs += mib;
        }
    }
#endif

    return codecs;
}

/*!
    Set the codec to \a c; this will be returned by codecForLocale().
    This might be needed for some applications that want to use their
    own mechanism for setting the locale.

    Setting this codec is not supported on DOS based Windows.

    \sa codecForLocale()
*/
00896 void QTextCodec::setCodecForLocale(QTextCodec *c)
{
#ifdef Q_WS_WIN
    if (QSysInfo::WindowsVersion& QSysInfo::WV_DOS_based)
      return;
#endif
    localeMapper = c;
}

/*!
    Returns a pointer to the codec most suitable for this locale.

    On Windows, the codec will be based on a system locale. On Unix
    systems, starting with Qt 4.2, the codec will be using the \e
    iconv library. Note that in both cases the codec's name will be
    "System".
*/

00914 QTextCodec* QTextCodec::codecForLocale()
{
    if (localeMapper)
        return localeMapper;

    setup();

    return localeMapper;
}


/*!
    \fn QByteArray QTextCodec::name() const

    QTextCodec subclasses must reimplement this function. It returns
    the name of the encoding supported by the subclass.

    If the codec is registered as a character set in the
    \link http://www.iana.org/assignments/character-sets
    IANA character-sets encoding file\endlink this method should return
    the preferred mime name for the codec if defined, otherwise its name.
*/

/*!
    \fn int QTextCodec::mibEnum() const

    Subclasses of QTextCodec must reimplement this function. It
    returns the MIBenum (see \link
    http://www.iana.org/assignments/character-sets the
    IANA character-sets encoding file\endlink for more information).
    It is important that each QTextCodec subclass returns the correct
    unique value for this function.
*/

/*!
  Subclasses can return a number of aliases for the codec in question.

  Standard aliases for codecs can be found in the
  \link http://www.iana.org/assignments/character-sets
  IANA character-sets encoding file\endlink.
*/
00955 QList<QByteArray> QTextCodec::aliases() const
{
    return QList<QByteArray>();
}

/*!
    \fn QString QTextCodec::convertToUnicode(const char *chars, int len,
                                             ConverterState *state) const

    QTextCodec subclasses must reimplement this function.

    Converts the first \a len characters of \a chars from the
    encoding of the subclass to Unicode, and returns the result in a
    QString.

    \a state can be 0, in which case the conversion is stateless and
    default conversion rules should be used. If state is not 0, the
    codec should save the state after the conversion in \a state, and
    adjust the remainingChars and invalidChars members of the struct.
*/

/*!
    \fn QByteArray QTextCodec::convertFromUnicode(const QChar *input, int number,
                                                  ConverterState *state) const

    QTextCodec subclasses must reimplement this function.

    Converts the first \a number of characters from the \a input array
    from Unicode to the encoding of the subclass, and returns the result
    in a QByteArray.

    \a state can be 0 in which case the conversion is stateless and
    default conversion rules should be used. If state is not 0, the
    codec should save the state after the conversion in \a state, and
    adjust the remainingChars and invalidChars members of the struct.
*/

/*!
    Creates a QTextDecoder which stores enough state to decode chunks
    of \c{char *} data to create chunks of Unicode data.

    The caller is responsible for deleting the returned object.
*/
00998 QTextDecoder* QTextCodec::makeDecoder() const
{
    return new QTextDecoder(this);
}


/*!
    Creates a QTextEncoder which stores enough state to encode chunks
    of Unicode data as \c{char *} data.

    The caller is responsible for deleting the returned object.
*/
01010 QTextEncoder* QTextCodec::makeEncoder() const
{
    return new QTextEncoder(this);
}

/*!
    \fn QByteArray QTextCodec::fromUnicode(const QChar *input, int number,
                                           ConverterState *state) const

    Converts the first \a number of characters from the \a input array
    from Unicode to the encoding of this codec, and returns the result
    in a QByteArray.

    The \a state of the convertor used is updated.
*/

/*!
    Converts \a str from Unicode to the encoding of this codec, and
    returns the result in a QByteArray.
*/
01030 QByteArray QTextCodec::fromUnicode(const QString& str) const
{
    return convertFromUnicode(str.constData(), str.length(), 0);
}

/*!
    \fn QString QTextCodec::toUnicode(const char *input, int size,
                                      ConverterState *state) const

    Converts the first \a size characters from the \a input from the
    encoding of this codec to Unicode, and returns the result in a
    QString.

    The \a state of the convertor used is updated.
*/

/*!
    Converts \a a from the encoding of this codec to Unicode, and
    returns the result in a QString.
*/
01050 QString QTextCodec::toUnicode(const QByteArray& a) const
{
    return convertToUnicode(a.constData(), a.length(), 0);
}

/*!
    Returns true if the Unicode character \a ch can be fully encoded
    with this codec; otherwise returns false.
*/
01059 bool QTextCodec::canEncode(QChar ch) const
{
    ConverterState state;
    state.flags = ConvertInvalidToNull;
    convertFromUnicode(&ch, 1, &state);
    return (state.invalidChars == 0);
}

/*!
    \overload

    \a s contains the string being tested for encode-ability.
*/
01072 bool QTextCodec::canEncode(const QString& s) const
{
    ConverterState state;
    state.flags = ConvertInvalidToNull;
    convertFromUnicode(s.constData(), s.length(), &state);
    return (state.invalidChars == 0);
}

#ifdef QT3_SUPPORT
/*!
    Returns a string representing the current language and
    sublanguage, e.g. "pt" for Portuguese, or "pt_br" for Portuguese/Brazil.

    \sa QLocale
*/
const char *QTextCodec::locale()
{
    static char locale[6];
    QByteArray l = QLocale::system().name().toLatin1();
    int len = qMin(l.length(), 5);
    memcpy(locale, l.constData(), len);
    locale[len] = '\0';

    return locale;
}

/*!
    \overload
*/

QByteArray QTextCodec::fromUnicode(const QString& uc, int& lenInOut) const
{
    QByteArray result = convertFromUnicode(uc.constData(), lenInOut, 0);
    lenInOut = result.length();
    return result;
}

/*!
    \overload

    \a a contains the source characters; \a len contains the number of
    characters in \a a to use.
*/
QString QTextCodec::toUnicode(const QByteArray& a, int len) const
{
    len = qMin(a.size(), len);
    return convertToUnicode(a.constData(), len, 0);
}
#endif

/*!
    \overload

    \a chars contains the source characters.
*/
01127 QString QTextCodec::toUnicode(const char *chars) const
{
    int len = qstrlen(chars);
    return convertToUnicode(chars, len, 0);
}


/*!
    \class QTextEncoder
    \brief The QTextEncoder class provides a state-based encoder.
    \reentrant
    \ingroup i18n

    A text encoder converts text from Unicode into an encoded text format
    using a specific codec.

    The encoder converts Unicode into another format, remembering any
    state that is required between calls.

    \sa QTextCodec::makeEncoder(), QTextDecoder
*/

/*!
    \fn QTextEncoder::QTextEncoder(const QTextCodec *codec)

    Constructs a text encoder for the given \a codec.
*/

/*!
    Destroys the encoder.
*/
01158 QTextEncoder::~QTextEncoder()
{
}

/*!
    Converts the Unicode string \a str into an encoded QByteArray.
*/
01165 QByteArray QTextEncoder::fromUnicode(const QString& str)
{
    QByteArray result = c->fromUnicode(str.constData(), str.length(), &state);
    return result;
}

/*!
    \overload

    Converts \a len characters (not bytes) from \a uc, and returns the
    result in a QByteArray.
*/
01177 QByteArray QTextEncoder::fromUnicode(const QChar *uc, int len)
{
    QByteArray result = c->fromUnicode(uc, len, &state);
    return result;
}

#ifdef QT3_SUPPORT
/*!
  \overload

  Converts \a lenInOut characters (not bytes) from \a uc, and returns the
  result in a QByteArray. The number of characters read is returned in
  the \a lenInOut parameter.
*/
QByteArray QTextEncoder::fromUnicode(const QString& uc, int& lenInOut)
{
    QByteArray result = c->fromUnicode(uc.constData(), lenInOut, &state);
    lenInOut = result.length();
    return result;
}
#endif

/*!
    \class QTextDecoder
    \brief The QTextDecoder class provides a state-based decoder.
    \reentrant
    \ingroup i18n

    A text decoder converts text from an encoded text format into Unicode
    using a specific codec.

    The decoder converts text in this format into Unicode, remembering any
    state that is required between calls.

    \sa QTextCodec::makeDecoder(), QTextEncoder
*/

/*!
    \fn QTextDecoder::QTextDecoder(const QTextCodec *codec)

    Constructs a text decoder for the given \a codec.
*/

/*!
    Destroys the decoder.
*/
01223 QTextDecoder::~QTextDecoder()
{
}

/*!
    \fn QString QTextDecoder::toUnicode(const char *chars, int len)

    Converts the first \a len bytes in \a chars to Unicode, returning
    the result.

    If not all characters are used (e.g. if only part of a multi-byte
    encoding is at the end of the characters), the decoder remembers
    enough state to continue with the next call to this function.
*/
01237 QString QTextDecoder::toUnicode(const char *chars, int len)
{
    return c->toUnicode(chars, len, &state);
}


/*! \overload

    The converted string is returned in \a target.
 */
01247 void QTextDecoder::toUnicode(QString *target, const char *chars, int len)
{
    Q_ASSERT(target);
    switch (c->mibEnum()) {
    case 106: // utf8
        static_cast<const QUtf8Codec*>(c)->convertToUnicode(target, chars, len, &state);
        break;
    case 4: { // latin1
        target->resize(len);
        ushort *data = (ushort*)target->data();
        for (int i = len; i >=0; --i)
            data[i] = (uchar) chars[i];
    } break;
    default:
        *target = c->toUnicode(chars, len, &state);
    }
}


/*!
    \overload

    Converts the bytes in the byte array specified by \a ba to Unicode
    and returns the result.
*/
01272 QString QTextDecoder::toUnicode(const QByteArray &ba)
{
    return c->toUnicode(ba.constData(), ba.length(), &state);
}


/*!
    \fn QTextCodec* QTextCodec::codecForTr()

    Returns the codec used by QObject::tr() on its argument. If this
    function returns 0 (the default), tr() assumes Latin-1.

    \sa setCodecForTr()
*/

/*!
    \fn void QTextCodec::setCodecForTr(QTextCodec *c)
    \nonreentrant

    Sets the codec used by QObject::tr() on its argument to \a c. If
    \a c is 0 (the default), tr() assumes Latin-1.

    If the literal quoted text in the program is not in the Latin-1
    encoding, this function can be used to set the appropriate
    encoding. For example, software developed by Korean programmers
    might use eucKR for all the text in the program, in which case the
    main() function might look like this:

    \code
        int main(int argc, char *argv[])
        {
            QApplication app(argc, argv);
            QTextCodec::setCodecForTr(QTextCodec::codecForName("eucKR"));
            ...
        }
    \endcode

    Note that this is not the way to select the encoding that the \e
    user has chosen. For example, to convert an application containing
    literal English strings to Korean, all that is needed is for the
    English strings to be passed through tr() and for translation
    files to be loaded. For details of internationalization, see
    \l{Internationalization with Qt}.

    \sa codecForTr(), setCodecForCStrings()
*/


/*!
    \fn QTextCodec* QTextCodec::codecForCStrings()

    Returns the codec used by QString to convert to and from \c{const
    char *} and QByteArrays. If this function returns 0 (the default),
    QString assumes Latin-1.

    \sa setCodecForCStrings()
*/

/*!
    \fn void QTextCodec::setCodecForCStrings(QTextCodec *codec)
    \nonreentrant

    Sets the codec used by QString to convert to and from \c{const
    char *} and QByteArrays. If the \a codec is 0 (the default),
    QString assumes Latin-1.

    \warning Some codecs do not preserve the characters in the ASCII
    range (0x00 to 0x7F). For example, the Japanese Shift-JIS
    encoding maps the backslash character (0x5A) to the Yen
    character. To avoid undesirable side-effects, we recommend
    avoiding such codecs with setCodecsForCString().

    \sa codecForCStrings(), setCodecForTr()
*/

/*!
  \internal
*/
01350 QTextCodec *QTextCodec::codecForHtml(const QByteArray &ba)
{
    // determine charset
    int mib = 4; // Latin-1
    int pos;
    QTextCodec *c = 0;

    if (ba.size() > 1 && (((uchar)ba[0] == 0xfe && (uchar)ba[1] == 0xff)
                          || ((uchar)ba[0] == 0xff && (uchar)ba[1] == 0xfe))) {
        mib = 1015; // utf16
    } else if (ba.size() > 2
             && (uchar)ba[0] == 0xef
             && (uchar)ba[1] == 0xbb
             && (uchar)ba[2] == 0xbf) {
        mib = 106; // utf-8
    } else {
        QByteArray header = ba.left(512).toLower();
        if ((pos = header.indexOf("http-equiv=")) != -1) {
            pos = header.indexOf("charset=", pos) + int(strlen("charset="));
            if (pos != -1) {
                int pos2 = header.indexOf('\"', pos+1);
                QByteArray cs = header.mid(pos, pos2-pos);
                //            qDebug("found charset: %s", cs.data());
                c = QTextCodec::codecForName(cs);
            }
        }
    }
    if (!c)
        c = QTextCodec::codecForMib(mib);

    return c;
}

/*! \internal
    \since 4.3
    Determines whether the decoder encountered a failure while decoding the input. If
    an error was encountered, the produced result is undefined, and gets converted as according
    to the conversion flags.
 */
01389 bool QTextDecoder::hasFailure() const
{
    return state.invalidChars != 0;
}

/*!
    \fn QTextCodec *QTextCodec::codecForContent(const char *str, int size)

    This functionality is no longer provided by Qt. This
    compatibility function always returns a null pointer.
*/

/*!
    \fn QTextCodec *QTextCodec::codecForName(const char *hint, int accuracy)

    Use the codecForName(const QByteArray &) overload instead.
*/

/*!
    \fn QTextCodec *QTextCodec::codecForIndex(int i)

    Use availableCodecs() or availableMibs() instead and iterate
    through the resulting list.
*/


/*!
    \fn QByteArray QTextCodec::mimeName() const

    Use name() instead.
*/

#endif // QT_NO_TEXTCODEC

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