qstring.cpp

Trolltech公司发布的图形界面操作系统。可在qt-embedded-2.3.10平台上编译为嵌入式图形界面操作系统。

		}
	    }
	    ligature.next();
	}
	cindex++;
	index++;
    }
    *this = composed;
#endif
}


// These macros are used for efficient allocation of QChar strings.
// IMPORTANT! If you change these, make sure you also change the
// "delete unicode" statement in ~QStringData() in qstring.h correspondingly!

#define QT_ALLOC_QCHAR_VEC( N ) (QChar*) new char[ sizeof(QChar)*( N ) ]
#define QT_DELETE_QCHAR_VEC( P ) delete[] ((char*)( P ))


/*!
    This utility function converts the 8-bit string \a ba to Unicode,
    returning the result.

    The caller is responsible for deleting the return value with
    delete[].
*/

QChar* QString::latin1ToUnicode( const QByteArray& ba, uint* len )
{
    if ( ba.isNull() ) {
	*len = 0;
	return 0;
    }
    int l = 0;
    while ( l < (int)ba.size() && ba[l] )
	l++;
    char* str = ba.data();
    QChar *uc = new QChar[ l ];   // Can't use macro, since function is public
    QChar *result = uc;
    if ( len )
	*len = l;
    while (l--)
	*uc++ = *str++;
    return result;
}

static QChar* internalLatin1ToUnicode( const QByteArray& ba, uint* len )
{
    if ( ba.isNull() ) {
	*len = 0;
	return 0;
    }
    int l = 0;
    while ( l < (int)ba.size() && ba[l] )
	l++;
    char* str = ba.data();
    QChar *uc = QT_ALLOC_QCHAR_VEC( l );
    QChar *result = uc;
    if ( len )
	*len = l;
    while (l--)
	*uc++ = *str++;
    return result;
}

/*!
    \overload

    This utility function converts the '\0'-terminated 8-bit string \a
    str to Unicode, returning the result and setting \a *len to the
    length of the Unicode string.

    The caller is responsible for deleting the return value with
    delete[].
*/

QChar* QString::latin1ToUnicode( const char *str, uint* len, uint maxlen )
{
    QChar* result = 0;
    uint l = 0;
    if ( str ) {
	if ( maxlen != (uint)-1 ) {
	    while ( l < maxlen && str[l] )
		l++;
	} else {
	    // Faster?
	    l = strlen( str );
	}
	QChar *uc = new QChar[ l ]; // Can't use macro since function is public
	result = uc;
	uint i = l;
	while ( i-- )
	    *uc++ = *str++;
    }
    if ( len )
	*len = l;
    return result;
}

static QChar* internalLatin1ToUnicode( const char *str, uint* len,
				      uint maxlen = (uint)-1 )
{
    QChar* result = 0;
    uint l = 0;
    if ( str ) {
	if ( maxlen != (uint)-1 ) {
	    while ( l < maxlen && str[l] )
		l++;
	} else {
	    // Faster?
	    l = strlen( str );
	}
	QChar *uc = QT_ALLOC_QCHAR_VEC( l );
	result = uc;
	uint i = l;
	while ( i-- )
	    *uc++ = *str++;
    }
    if ( len )
	*len = l;
    return result;
}

/*!
    This utility function converts \a l 16-bit characters from \a uc
    to ASCII, returning a '\0'-terminated string.

    The caller is responsible for deleting the resultant string with
    delete[].
*/
char* QString::unicodeToLatin1(const QChar *uc, uint l)
{
    if (!uc) {
	return 0;
    }
    char *a = new char[l+1];
    char *result = a;
    while (l--) {
	*a++ = (uc->unicode() > 0xff) ? '?' : (char)uc->unicode();
	uc++;
    }
    *a = '\0';
    return result;
}

/*****************************************************************************
  QString member functions
 *****************************************************************************/

/*!
    \class QString qstring.h
    \reentrant

    \brief The QString class provides an abstraction of Unicode text
    and the classic C '\0'-terminated char array.

    \ingroup tools
    \ingroup shared
    \ingroup text
    \mainclass

    QString uses \link shclass.html implicit sharing\endlink, which
    makes it very efficient and easy to use.

    In all of the QString methods that take \c {const char *}
    parameters, the \c {const char *} is interpreted as a classic
    C-style '\0'-terminated ASCII string. It is legal for the \c
    {const char *} parameter to be 0. If the \c {const char *} is not
    '\0'-terminated, the results are undefined. Functions that copy
    classic C strings into a QString will not copy the terminating
    '\0' character. The QChar array of the QString (as returned by
    unicode()) is generally not terminated by a '\0'. If you need to
    pass a QString to a function that requires a C '\0'-terminated
    string use latin1().

    \keyword QString::null
    A QString that has not been assigned to anything is \e null, i.e.
    both the length and data pointer is 0. A QString that references
    the empty string ("", a single '\0' char) is \e empty. Both null
    and empty QStrings are legal parameters to the methods. Assigning
    \c{(const char *) 0} to QString gives a null QString. For
    convenience, \c QString::null is a null QString. When sorting,
    empty strings come first, followed by non-empty strings, followed
    by null strings. We recommend using \c{if ( !str.isNull() )} to
    check for a non-null string rather than \c{if ( !str )}; see \l
    operator!() for an explanation.

    Note that if you find that you are mixing usage of \l QCString,
    QString, and \l QByteArray, this causes lots of unnecessary
    copying and might indicate that the true nature of the data you
    are dealing with is uncertain. If the data is '\0'-terminated 8-bit
    data, use \l QCString; if it is unterminated (i.e. contains '\0's)
    8-bit data, use \l QByteArray; if it is text, use QString.

    Lists of strings are handled by the QStringList class. You can
    split a string into a list of strings using QStringList::split(),
    and join a list of strings into a single string with an optional
    separator using QStringList::join(). You can obtain a list of
    strings from a string list that contain a particular substring or
    that match a particular \link qregexp.html regex\endlink using
    QStringList::grep().

    <b>Note for C programmers</b>

    Due to C++'s type system and the fact that QString is implicitly
    shared, QStrings may be treated like ints or other simple base
    types. For example:

    \code
    QString boolToString( bool b )
    {
	QString result;
	if ( b )
	    result = "True";
	else
	    result = "False";
	return result;
    }
    \endcode

    The variable, result, is an auto variable allocated on the stack.
    When return is called, because we're returning by value, The copy
    constructor is called and a copy of the string is returned. (No
    actual copying takes place thanks to the implicit sharing, see
    below.)

    Throughout Qt's source code you will encounter QString usages like
    this:
    \code
    QString func( const QString& input )
    {
	QString output = input;
	// process output
	return output;
    }
    \endcode

    The 'copying' of input to output is almost as fast as copying a
    pointer because behind the scenes copying is achieved by
    incrementing a reference count. QString (like all Qt's implicitly
    shared classes) operates on a copy-on-write basis, only copying if
    an instance is actually changed.

    If you wish to create a deep copy of a QString without losing any
    Unicode information then you should use QDeepCopy.

    \sa QChar QCString QByteArray QConstString
*/

/*! \enum Qt::ComparisonFlags
\internal
*/
/*!
    \enum Qt::StringComparisonMode

    This enum type is used to set the string comparison mode when
    searching for an item. It is used by QListBox, QListView and
    QIconView, for example. We'll refer to the string being searched
    as the 'target' string.

    \value CaseSensitive The strings must match case sensitively.
    \value ExactMatch The target and search strings must match exactly.
    \value BeginsWith The target string begins with the search string.
    \value EndsWith The target string ends with the search string.
    \value Contains The target string contains the search string.

    If you OR these flags together (excluding \c CaseSensitive), the
    search criteria be applied in the following order: \c ExactMatch,
    \c BeginsWith, \c EndsWith, \c Contains.

    Matching is case-insensitive unless \c CaseSensitive is set. \c
    CaseSensitive may be OR-ed with any combination of the other
    flags.

*/
Q_EXPORT QStringData *QString::shared_null = 0;
QT_STATIC_CONST_IMPL QString QString::null;
QT_STATIC_CONST_IMPL QChar QChar::null;
QT_STATIC_CONST_IMPL QChar QChar::replacement((ushort)0xfffd);
QT_STATIC_CONST_IMPL QChar QChar::byteOrderMark((ushort)0xfeff);
QT_STATIC_CONST_IMPL QChar QChar::byteOrderSwapped((ushort)0xfffe);
QT_STATIC_CONST_IMPL QChar QChar::nbsp((ushort)0x00a0);

QStringData* QString::makeSharedNull()
{
    QString::shared_null = new QStringData;
#if defined( Q_OS_MAC )
    QString *that = const_cast<QString *>(&QString::null);
    that->d = QString::shared_null;
#endif
    return QString::shared_null;
}

/*!
    \fn QString::QString()

    Constructs a null string, i.e. both the length and data pointer
    are 0.

    \sa isNull()
*/

/*!
    Constructs a string of length one, containing the character \a ch.
*/
QString::QString( QChar ch )
{
    d = new QStringData( QT_ALLOC_QCHAR_VEC( 1 ), 1, 1 );
    d->unicode[0] = ch;
}

/*!
    Constructs an implicitly shared copy of \a s. This is very fast
    since it only involves incrementing a reference count.
*/
QString::QString( const QString &s ) :
    d(s.d)
{
    d->ref();
}

/*!
  \internal

  Private function.

  Constructs a string with preallocated space for \a size characters.

  The string is empty.

  \sa isNull()
*/

QString::QString( int size, bool /*dummy*/ )
{
    if ( size ) {
	int l = size;
	QChar* uc = QT_ALLOC_QCHAR_VEC( l );
	d = new QStringData( uc, 0, l );
    } else {
	d = shared_null ? shared_null : (shared_null=new QStringData);
	d->ref();
    }
}

/*!
    Constructs a string that is a deep copy of \a ba interpreted as a
    classic C string.
*/

QString::QString( const QByteArray& ba )
{
#ifndef QT_NO_TEXTCODEC
    if ( QTextCodec::codecForCStrings() ) {
	d = 0;
	*this = fromAscii( ba.data(), ba.size() );
	return;
    }
#endif
    uint l;
    QChar *uc = internalLatin1ToUnicode(ba,&l);
    d = new QStringData(uc,l,l);
}

/*!
    Constructs a string that is a deep copy of the first \a length
    characters in the QChar array.

    If \a unicode and \a length are 0, then a null string is created.

    If only \a unicode is 0, the string is empty but has \a length
    characters of space preallocated: QString expands automatically
    anyway, but this may speed up some cases a little. We recommend
    using the plain constructor and setLength() for this purpose since
    it will result in more readable code.

    \sa isNull() setLength()
*/

QString::QString( const QChar* unicode, uint length )
{
    if ( !unicode && !length ) {
	d = shared_null ? shared_null : makeSharedNull();
	d->ref();
    } else {
	QChar* uc = QT_ALLOC_QCHAR_VEC( length );
	if ( unicode )
	    memcpy(uc, unicode, length*sizeof(QChar));
	d = new QStringData(uc,unicode ? length : 0,length);
    }
}

/*!
    Constructs a string that is a deep copy of \a str, interpreted as
    a classic C string.

    If \a str is 0, then a null string is created.

    This is a cast constructor, but it is perfectly safe: converting a
    Latin-1 \c{const char *} to QString preserves all the information. You
    can disable this constructor by defining \c QT_NO_CAST_ASCII when
    you compile your applications. You can also make QString objects
    by using setLatin1(), fromLatin1(), fromLocal8Bit(), and
    fromUtf8(). Or whatever encoding is appropriate for the 8-bit data
    you have.

    \sa isNull()
*/

QString::QString( const char *str )
{
#ifndef QT_NO_TEXTCODEC
    if ( QTextCodec::codecForCStrings() ) {
	d = 0;
	*this = fromAscii( str );
	return;
    }
#endif
    uint l;
    QChar *uc = internalLatin1ToUnicode(str,&l);
    d = new QStringData(uc,l,l);
}

#ifndef QT_NO_STL
/*!
    Constructs a string that is a deep copy of \a str.

    This is the same as fromAscii(\a str).
*/

QString::QString( const std::string &str )
{
#ifndef QT_NO_TEXTCODEC
    if ( QTextCodec::codecForCStrings() ) {
	d = 0;
	*this = fromAscii( str.c_str() );
	return;
    }
#endif
    uint l;
    QChar *uc = internalLatin1ToUnicode(str.c_str(),&l);
    d = new QStringData(uc,l,l);
}
#endif

/*!
    \fn QString::~QString()

    Destroys the string and frees the string's data if this is the
    last reference to the string.
*/


/*!
    Deallocates any space reserved solely by this QString.

    If the string does not share its data with another QString
    instance, nothing happens; otherwise the function creates a new,
    unique copy of this string. This function is called whenever the
    string is modified.
*/

void QString::real_detach()
{
    setLength( length() );
}

void QString::deref()
{
    if ( d && d->deref() ) {
	if ( d != shared_null )
	    delete d;
	d = 0;
    }
}

void QStringData::deleteSelf()
{
    delete this;
}

/*!
    \fn QString& QString::operator=( QChar c )

    Sets the string to contain just the single character \a c.
*/

/*!
    \fn QString& QString::operator=( const std::string& s )

    \overload

    Makes a deep copy of \a s and returns a reference to the deep
    copy.
*/

/*!
    \fn QString& QString::operator=( char c )

    \overload

    Sets the string to contain just the single character \a c.
*/

/*!
    \overload

    Assigns a shallow copy of \a s to this string and returns a
    reference to this string. This is very fast because the string
    isn't actually copied.
*/
QString &QString::operator=( const QString &s )
{
    s.d->ref();
    deref();
    d = s.d;
    return *this;
}

/*!
    \overload

    Assigns a deep copy of \a cstr, interpreted as a classic C
    string, to this string. Returns a reference to this string.