qstring.cpp

奇趣公司比较新的qt/emd版本

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#include "qstringlist.h"
#include "qregexp.h"
#include "qunicodetables_p.h"
#ifndef QT_NO_TEXTCODEC
#include <qtextcodec.h>
#endif
#include <qdatastream.h>
#include <qlist.h>
#include "qlocale.h"
#include "qlocale_p.h"
#include "qstringmatcher.h"
#include "qtools_p.h"
#include "qhash.h"
#include "qdebug.h"

#ifdef Q_OS_MAC
#include <private/qcore_mac_p.h>
#endif

#include <limits.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>

#ifdef truncate
#undef truncate
#endif

#include "qchar.cpp"
#include "qstringmatcher.cpp"

#ifndef LLONG_MAX
#define LLONG_MAX qint64_C(9223372036854775807)
#endif
#ifndef LLONG_MIN
#define LLONG_MIN (-LLONG_MAX - qint64_C(1))
#endif
#ifndef ULLONG_MAX
#define ULLONG_MAX quint64_C(18446744073709551615)
#endif


#ifndef QT_NO_TEXTCODEC
QTextCodec *QString::codecForCStrings;
#endif

#ifdef QT3_SUPPORT
static QHash<void *, QByteArray> *asciiCache = 0;
#endif

static int ucstricmp(const ushort *a, const ushort *ae, const ushort *b, const ushort *be)
{
    if (a == b)
        return 0;
    if (a == 0)
        return 1;
    if (b == 0)
        return -1;

    const ushort *e = ae;
    if (be - b < ae - a)
        e = a + (be - b);

    uint alast = 0;
    uint blast = 0;
    while (a != e) {
//         qDebug() << hex << alast << blast;
//         qDebug() << hex << "*a=" << *a << "alast=" << alast << "folded=" << foldCase (*a, alast);
//         qDebug() << hex << "*b=" << *b << "blast=" << blast << "folded=" << foldCase (*b, blast);
        int diff = foldCase(*a, alast) - foldCase(*b, blast);
        if ((diff))
            return diff;
        ++a;
        ++b;
    }
    if (a == ae) {
        if (b == be)
            return 0;
        return -1;
    }
    return 1;
}

static int ucstricmp(const ushort *a, const ushort *ae, const uchar *b)
{
    if (a == 0) {
        if (b == 0)
            return 0;
        return 1;
    }
    if (b == 0)
        return -1;

    while (a != ae && *b) {
        int diff = foldCase(*a) - foldCase(*b);
        if ((diff))
            return diff;
        ++a;
        ++b;
    }
    if (a == ae) {
        if (!*b)
            return 0;
        return -1;
    }
    return 1;
}


static int ucstrcmp(const QChar *a, int alen, const QChar *b, int blen)
{
    if (a == b)
        return 0;
    int l = qMin(alen, blen);
    while (l-- && *a == *b)
        a++,b++;
    if (l == -1)
        return (alen-blen);
    return a->unicode() - b->unicode();
}

inline int ucstrcmp(const QString &as, const QString &bs)
{
    return ucstrcmp(as.unicode(), as.size(), bs.unicode(), bs.size());
}

inline int ucstrcmp(const QStringRef &as, const QStringRef &bs)
{
    return ucstrcmp(as.unicode(), as.size(), bs.unicode(), bs.size());
}



static int ucstrncmp(const QChar *a, const QChar *b, int l)
{
    while (l-- && *a == *b)
        a++,b++;
    if (l==-1)
        return 0;
    return a->unicode() - b->unicode();
}


static int ucstrnicmp(const ushort *a, const ushort *b, int l)
{
    return ucstricmp(a, a + l, b, b + l);
}


inline bool qIsUpper(char ch)
{
    return ch >= 'A' && ch <= 'Z';
}

inline bool qIsDigit(char ch)
{
    return ch >= '0' && ch <= '9';
}

inline char qToLower(char ch)
{
    if (ch >= 'A' && ch <= 'Z')
        return ch - 'A' + 'a';
    else
        return ch;
}

const QString::Null QString::null = QString::Null();

/*!
  \macro QT_NO_CAST_FROM_ASCII
  \relates QString

  Disables automatic conversions from 8-bit strings (char *) to unicode QStrings

  \sa QT_NO_CAST_TO_ASCII
*/

/*!
  \macro QT_NO_CAST_TO_ASCII
  \relates QString

  disables automatic conversion from QString to ASCII 8-bit strings (char *)

  \sa QT_NO_CAST_FROM_ASCII
*/

/*!
  \macro QT_ASCII_CAST_WARNINGS
  \internal
  \relates QString

  This macro can be defined to force a warning whenever a function is
  called that automatically converts between unicode and 8-bit encodings.

  Note: This only works for compilers that support warnings for
  deprecated API.

  \sa QT_NO_CAST_TO_ASCII, QT_NO_CAST_FROM_ASCII
*/

/*!
    \class QCharRef
    \reentrant
    \brief The QCharRef class is a helper class for QString.

    \internal

    \ingroup text

    When you get an object of type QCharRef, if you can assign to it,
    the assignment will apply to the character in the string from
    which you got the reference. That is its whole purpose in life.
    The QCharRef becomes invalid once modifications are made to the
    string: if you want to keep the character, copy it into a QChar.

    Most of the QChar member functions also exist in QCharRef.
    However, they are not explicitly documented here.

    \sa QString::operator[]() QString::at() QChar
*/

/*!
    \class QString
    \reentrant

    \brief The QString class provides a Unicode character string.

    \ingroup tools
    \ingroup shared
    \ingroup text
    \mainclass
    \reentrant

    QString stores a string of 16-bit \l{QChar}s, where each QChar
    corresponds one Unicode 4.0 character. (Unicode characters
    with code values above 65535 are stored using surrogate pairs,
    i.e., two consecutive \l{QChar}s.)

    \l{Unicode} is an international standard that supports most of
    the writing systems in use today. It is a superset of ASCII and
    Latin-1 (ISO 8859-1), and all the ASCII/Latin-1 characters are
    available at the same code positions.

    Behind the scenes, QString uses \l{implicit sharing}
    (copy-on-write) to reduce memory usage and to avoid the needless
    copying of data. This also helps reduce the inherent overhead of
    storing 16-bit characters instead of 8-bit characters.

    In addition to QString, Qt also provides the QByteArray class to
    store raw bytes and traditional 8-bit '\\0'-terminated strings.
    For most purposes, QString is the class you want to use. It is
    used throughout the Qt API, and the Unicode support ensures that
    your applications will be easy to translate if you want to expand
    your application's market at some point. The two main cases where
    QByteArray is appropriate are when you need to store raw binary
    data, and when memory conservation is critical (e.g. with \l {
    Qtopia Core}).

    \tableofcontents

    \section1 Initializing a String

    One way to initialize a QString is simply to pass a \c{const char
    *} to its constructor. For example, the following code creates a
    QString of size 5 containing the data "Hello":

    \quotefromfile snippets/qstring/main.cpp
    \skipto Widget::constCharPointer()
    \skipto Hello
    \printline Hello

    QString converts the \c{const char *} data into Unicode using the
    fromAscii() function. By default, fromAscii() treats character
    above 128 as Latin-1 characters, but this can be changed by
    calling QTextCodec::setCodecForCStrings().

    In all of the QString functions that take \c{const char *}
    parameters, the \c{const char *} is interpreted as a classic
    C-style '\\0'-terminated string. It is legal for the \c{const char
    *} parameter to be 0.

    You can also provide string data as an array of \l{QChar}s:

    \skipto Widget::constCharArray()
    \skipto static const
    \printuntil str

    QString makes a deep copy of the QChar data, so you can modify it
    later without experiencing side effects. (If for performance
    reasons you don't want to take a deep copy of the character data,
    use QString::fromRawData() instead.)

    Another approach is to set the size of the string using resize()
    and to initialize the data character per character. QString uses
    0-based indexes, just like C++ arrays. To access the character at
    a particular index position, you can use \l operator[](). On
    non-const strings, \l operator[]() returns a reference to a
    character that can be used on the left side of an assignment. For
    example:

    \skipto Widget::characterReference()
    \skipto QString str
    \printuntil str[3] = QChar(0x03a3)

    For read-only access, an alternative syntax is to use the at()
    function:

    \skipto Widget::atFunction()
    \skipto QString str
    \printuntil }

    The at() function can be faster than \l operator[](), because it
    never causes a \l{deep copy} to occur. Alternatively, use the
    left(), right(), or mid() functions to extract several characters
    at a time.

    A QString can embed '\\0' characters (QChar::null). The size()
    function always returns the size of the whole string, including
    embedded '\\0' characters.

    After a call to the resize() function, newly allocated characters
    have undefined values. To set all the characters in the string to
    a particular value, use the fill() function.

    QString provides dozens of overloads designed to simplify string
    usage. For example, if you want to compare a QString with a string
    literal, you can write code like this and it will work as expected:

    \skipto Widget::stringLiteral()
    \skipto QString str
    \printuntil }

    You can also pass string literals to functions that take QStrings
    as arguments, invoking the QString(const char *)
    constructor. Similarly, you can pass a QString to a function that
    takes a \c{const char *} argument using the \l qPrintable() macro
    which returns the given QString as a \c{const char *}. This is
    equivalent to calling <QString>.toAscii().constData().

    \section1 Manipulating String Data

    QString provides the following basic functions for modifying the
    character data: append(), prepend(), insert(), replace(), and
    remove(). For example:

    \skipto Widget::modify()
    \skipto QString str
    \printuntil str.replace(5, 3, "&")

    If you are building a QString gradually and know in advance
    approximately how many characters the QString will contain, you
    can call reserve(), asking QString to preallocate a certain amount
    of memory. You can also call capacity() to find out how much
    memory QString actually allocated.

    The replace() and remove() functions' first two arguments are the
    position from which to start erasing and the number of characters
    that should be erased.  If you want to replace all occurrences of
    a particular substring with another, use one of the two-parameter
    replace() overloads.

    A frequent requirement is to remove whitespace characters from a
    string ('\\n', '\\t', ' ', etc.). If you want to remove whitespace
    from both ends of a QString, use the trimmed() function. If you
    want to remove whitespace from both ends and replace multiple
    consecutive whitespaces with a single space character within the
    string, use simplified().

    If you want to find all occurrences of a particular character or
    substring in a QString, use the indexOf() or lastIndexOf()
    functions. The former searches forward starting from a given index
    position, the latter searches backward. Both return the index
    position of the character or substring if they find it; otherwise,
    they return -1.  For example, here's a typical loop that finds all
    occurrences of a particular substring:

    \skipto Widget::index()
    \skipto QString str
    \printuntil }

    QString provides many functions for converting numbers into
    strings and strings into numbers. See the arg() functions, the
    setNum() functions, the number() static functions, and the
    toInt(), toDouble(), and similar functions.

    To get an upper- or lowercase version of a string use toUpper() or
    toLower().

    Lists of strings are handled by the QStringList class. You can
    split a string into a list of strings using the split() function,
    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 QRegExp using the QStringList::find()
    function.
:
    \section1 Querying String Data

    If you want to see if a QString starts or ends with a particular
    substring use startsWith() or endsWith(). If you simply want to
    check whether a QString contains a particular character or
    substring, use the contains() function. If you want to find out
    how many times a particular character or substring occurs in the
    string, use count().

    QStrings can be compared using overloaded operators such as \l
    operator<(), \l operator<=(), \l operator==(), \l operator>=(),
    and so on.  Note that the comparison is based exclusively on the