qstring.cpp

QT 开发环境里面一个很重要的文件

    \overload

    The \a other byte array is converted to a QString using the
    fromAscii() function.

    You can disable this operator by defining \c
    QT_NO_CAST_FROM_ASCII when you compile your applications. This
    can be useful if you want to ensure that all user-visible strings
    go through QObject::tr(), for example.
*/

/*! \fn bool QString::operator<=(const char *other) const

    \overload

    The \a other const char pointer is converted to a QString using
    the fromAscii() function.

    You can disable this operator by defining \c
    QT_NO_CAST_FROM_ASCII when you compile your applications. This
    can be useful if you want to ensure that all user-visible strings
    go through QObject::tr(), for example.
*/

/*! \fn bool QString::operator>(const QString &other) const

    Returns true if this string is lexically greater than string \a
    other; otherwise returns false.

    The comparison is based exclusively on the numeric Unicode values
    of the characters and is very fast, but is not what a human would
    expect. Consider sorting user-interface strings with
    localeAwareCompare().
*/

/*!
    \overload
*/
bool QString::operator>(const QLatin1String &other) const
{
    const ushort *uc = d->data;;
    const ushort *e = uc + d->size;
    const uchar *c = (uchar *) other.latin1();

    if (!c || *c == '\0')
        return !isEmpty();

    while (*c) {
        if (uc == e || *uc != *c)
            break;
        ++uc;
        ++c;
    }
    return (uc == e ? false : *uc > *c);
}

/*! \fn bool QString::operator>(const QByteArray &other) const

    \overload

    The \a other byte array is converted to a QString using the
    fromAscii() function.

    You can disable this operator by defining \c
    QT_NO_CAST_FROM_ASCII when you compile your applications. This
    can be useful if you want to ensure that all user-visible strings
    go through QObject::tr(), for example.
*/

/*! \fn bool QString::operator>(const char *other) const

    \overload

    The \a other const char pointer is converted to a QString using
    the fromAscii() function.

    You can disable this operator by defining \c QT_NO_CAST_FROM_ASCII
    when you compile your applications. This can be useful if you want
    to ensure that all user-visible strings go through QObject::tr(),
    for example.
*/

/*! \fn bool QString::operator>=(const QString &other) const

    Returns true if this string is lexically greater than or equal to
    string \a other; otherwise returns false.

    The comparison is based exclusively on the numeric Unicode values
    of the characters and is very fast, but is not what a human would
    expect. Consider sorting user-interface strings with
    localeAwareCompare().
*/

/*! \fn bool QString::operator>=(const QLatin1String &other) const

    \overload
*/

/*! \fn bool QString::operator>=(const QByteArray &other) const

    \overload

    The \a other byte array is converted to a QString using the
    fromAscii() function.

    You can disable this operator by defining \c QT_NO_CAST_FROM_ASCII
    when you compile your applications. This can be useful if you want
    to ensure that all user-visible strings go through QObject::tr(),
    for example.
*/

/*! \fn bool QString::operator>=(const char *other) const

    \overload

    The \a other const char pointer is converted to a QString using
    the fromAscii() function.

    You can disable this operator by defining \c
    QT_NO_CAST_FROM_ASCII when you compile your applications. This
    can be useful if you want to ensure that all user-visible strings
    go through QObject::tr(), for example.
*/

/*! \fn bool QString::operator!=(const QString &other) const

    Returns true if this string is not equal to string \a other;
    otherwise returns false.

    The comparison is based exclusively on the numeric Unicode values
    of the characters and is very fast, but is not what a human would
    expect. Consider sorting user-interface strings with
    localeAwareCompare().
*/

/*! \fn bool QString::operator!=(const QLatin1String &other) const

    \overload
*/

/*! \fn bool QString::operator!=(const QByteArray &other) const

    \overload

    The \a other byte array is converted to a QString using the
    fromAscii() function.

    You can disable this operator by defining \c QT_NO_CAST_FROM_ASCII
    when you compile your applications. This can be useful if you want
    to ensure that all user-visible strings go through QObject::tr(),
    for example.
*/

/*! \fn bool QString::operator!=(const char *other) const

    \overload

    The \a other const char pointer is converted to a QString using
    the fromAscii() function.

    You can disable this operator by defining \c
    QT_NO_CAST_FROM_ASCII when you compile your applications. This
    can be useful if you want to ensure that all user-visible strings
    go through QObject::tr(), for example.
*/

#define REHASH(a) \
    if (sl_minus_1 < (int)sizeof(int) * CHAR_BIT)       \
        hashHaystack -= (a) << sl_minus_1; \
    hashHaystack <<= 1

/*!
    Returns the index position of the first occurrence of the string
    \a str in this string, searching forward from index position \a
    from. Returns -1 if \a str is not found.

    If \a cs is Qt::CaseSensitive (the default), the search is
    case sensitive; otherwise the search is case insensitive.

    Example:

    \quotefromfile snippets/qstring/main.cpp
    \skipto Widget::indexOfFunction()
    \skipto QString x
    \printuntil  x.indexOf(y, 11)

    If \a from is -1, the search starts at the last character; if it
    is -2, at the next to last character and so on.

    \sa lastIndexOf(), contains(), count()
*/
int QString::indexOf(const QString &str, int from, Qt::CaseSensitivity cs) const
{
    const int l = d->size;
    const int sl = str.d->size;
    if (from < 0)
        from += l;
    if (uint(sl + from) > (uint)l)
        return -1;
    if (!sl)
        return from;
    if (!l)
        return -1;

    if (sl == 1)
        return indexOf(*(const QChar *)str.d->data, from, cs);

    /*
        We use the Boyer-Moore algorithm in cases where the overhead
        for the skip table should pay off, otherwise we use a simple
        hash function.
    */
    if (l > 500 && sl > 5)
        return QStringMatcher(str, cs).indexIn(*this, from);

    /*
        We use some hashing for efficiency's sake. Instead of
        comparing strings, we compare the hash value of str with that
        of a part of this QString. Only if that matches, we call
        ucstrncmp() or ucstrnicmp().
    */
    const QChar *needle = (const QChar*) str.d->data;
    const QChar *haystack = (const QChar*) d->data + from;
    const QChar *end = (const QChar*) d->data + (l-sl);
    const int sl_minus_1 = sl-1;
    int hashNeedle = 0, hashHaystack = 0, idx;

    if (cs == Qt::CaseSensitive) {
        for (idx = 0; idx < sl; ++idx) {
            hashNeedle = ((hashNeedle<<1) + needle[idx].unicode());
            hashHaystack = ((hashHaystack<<1) + haystack[idx].unicode());
        }
        hashHaystack -= (haystack+sl_minus_1)->unicode();

        while (haystack <= end) {
            hashHaystack += (haystack+sl_minus_1)->unicode();
            if (hashHaystack == hashNeedle
                 && ucstrncmp(needle, haystack, sl) == 0)
                return haystack-unicode();

            REHASH(haystack->unicode());
            ++haystack;
        }
    } else {
        for (idx = 0; idx < sl; ++idx) {
            hashNeedle = ((hashNeedle<<1) +
                          QUnicodeTables::lower(needle[idx].unicode()));
            hashHaystack = ((hashHaystack<<1) +
                            QUnicodeTables::lower(haystack[idx].unicode()));
        }

        hashHaystack -= QUnicodeTables::lower(*(haystack+sl_minus_1)).unicode();
        while (haystack <= end) {
            hashHaystack += QUnicodeTables::lower(*(haystack+sl_minus_1)).unicode();
            if (hashHaystack == hashNeedle
                 && ucstrnicmp(needle, haystack, sl) == 0)
                return haystack-unicode();

            REHASH(QUnicodeTables::lower(*haystack).unicode());
            ++haystack;
        }
    }
    return -1;
}

/*!
    \overload

    Returns the index position of the first occurrence of the
    character \a ch in the string, searching forward from index
    position \a from. Returns -1 if \a ch could not be found.
*/
int QString::indexOf(QChar ch, int from, Qt::CaseSensitivity cs) const
{
    if (from < 0)
        from = qMax(from + d->size, 0);
    if (from  < d->size) {
        const QChar *n = (const QChar*)d->data + from - 1;
        const QChar *e = (const QChar*)d->data + d->size;
        if (cs == Qt::CaseSensitive) {
            while (++n != e)
                if (*n == ch)
                    return  n - (const QChar*)d->data;
        } else {
            ch = QUnicodeTables::lower(ch);
            while (++n != e)
                if (QUnicodeTables::lower(*n) == ch)
                    return  n - (const QChar*)d->data;
        }
    }
    return -1;
}

/*!
    Returns the index position of the last occurrence of the string
    \a str in this string, searching backward from index position \a
    from. If \a from is -1 (the default), the search starts at the
    last character; if \a from is -2, at the next to last character
    and so on. Returns -1 if \a str is not found.

    If \a cs is Qt::CaseSensitive (the default), the search is
    case sensitive; otherwise the search is case insensitive.

    Example:

    \quotefromfile snippets/qstring/main.cpp
    \skipto Widget::lastIndexOfFunction()
    \skipto QString x
    \printuntil x.lastIndexOf(y, 1)

    \sa indexOf(), contains(), count()
*/
int QString::lastIndexOf(const QString &str, int from, Qt::CaseSensitivity cs) const
{
    /*
        See indexOf() for explanations.
    */
    const int l = d->size;
    if (from < 0)
        from += l;
    const int sl = str.d->size;
    int delta = l-sl;
    if (from == l && sl == 0)
        return from;
    if (from < 0 || from >= l || delta < 0)
        return -1;
    if (from > delta)
        from = delta;

    if (sl == 1)
        return lastIndexOf(*(const QChar*) str.d->data, from, cs);

    const QChar *needle = (const QChar*) str.d->data;
    const QChar *haystack = (const QChar*) d->data + from;
    const QChar *end = (const QChar*) d->data;
    const int sl_minus_1 = sl-1;
    const QChar *n = needle+sl_minus_1;
    const QChar *h = haystack+sl_minus_1;
    int hashNeedle = 0, hashHaystack = 0, idx;

    if (cs == Qt::CaseSensitive) {
        for (idx = 0; idx < sl; ++idx) {
            hashNeedle = ((hashNeedle<<1) + (n-idx)->unicode());
            hashHaystack = ((hashHaystack<<1) + (h-idx)->unicode());
        }
        hashHaystack -= haystack->unicode();

        while (haystack >= end) {
            hashHaystack += haystack->unicode();
            if (hashHaystack == hashNeedle
                 && ucstrncmp(needle, haystack, sl) == 0)
                return haystack-unicode();
            --haystack;
            REHASH((haystack+sl)->unicode());
        }
    } else {
        for (idx = 0; idx < sl; ++idx) {
            hashNeedle = ((hashNeedle<<1)
                          + QUnicodeTables::lower((n-idx)->unicode()));
            hashHaystack = ((hashHaystack<<1)
                            + QUnicodeTables::lower((h-idx)->unicode()));
        }
        hashHaystack -= QUnicodeTables::lower(*haystack).unicode();

        while (haystack >= end) {
            hashHaystack += QUnicodeTables::lower(*haystack).unicode();
            if (hashHaystack == hashNeedle
                 && ucstrnicmp(needle, haystack, sl) == 0)
                return haystack-unicode();
            --haystack;
            REHASH(QUnicodeTables::lower(*(haystack+sl)).unicode());
        }
    }
    return -1;
}

/*! \overload

    Returns the index position of the last occurrence of the
    character \a ch, searching backward from position \a from.
*/
int QString::lastIndexOf(QChar ch, int from, Qt::CaseSensitivity cs) const
{
    if (from < 0)
        from += d->size;
    if (from < 0 || from >= d->size)
        return -1;
    if (from >= 0) {
        const QChar *n =  (const QChar*)d->data + from;
        const QChar *b = (const QChar*)d->data;
        if (cs == Qt::CaseSensitive) {
            for (; n >= b; --n)
                if (*n == ch)
                    return  n - b;
        } else {
            ch = QUnicodeTables::lower(ch);
            for (; n >= b; --n)
                if (QUnicodeTables::lower(*n) == ch)
                    return  n - b;
        }
    }
    return -1;
}

#ifndef QT_NO_REGEXP
/*! \overload

    Replaces every occurrence of the regular expression \a rx in the
    string with \a after. Returns a reference to the string. For
    example:

    \quotefromfile snippets/qstring/main.cpp
    \skipto Widget::replaceFunction()
    \skipto QString s =
    \printuntil // s == "Boxoxa"

    For regular expressions containing \l{capturing parentheses},
    occurrences of \bold{\\1}, \bold{\\2}, ..., in \a after are
    replaced with \a{rx}.cap(1), cap(2), ...

    \quotefromfile snippets/qstring/main.cpp
    \skipto Widget::replaceFunction()
    \skipto QString t
    \printuntil // t == "A \\emph{bon mot}."

    \sa indexOf(), lastIndexOf(), remove(), QRegExp::cap()
*/
QString& QString::replace(const QRegExp &rx, const QString &after)
{
    QRegExp rx2(rx);

    if (isEmpty() && rx2.indexIn(*this) == -1)
        return *this;

    realloc();

    int index = 0;
    int numCaptur