qtextstream.cpp

奇趣公司比较新的qt/emd版本

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//#define QTEXTSTREAM_DEBUG
static const int QTEXTSTREAM_BUFFERSIZE = 16384;

/*!
    \class QTextStream

    \brief The QTextStream class provides a convenient interface for
    reading and writing text.

    \ingroup io
    \ingroup text
    \reentrant

    QTextStream can operate on a QIODevice, a QByteArray or a
    QString. Using QTextStream's streaming operators, you can
    conveniently read and write words, lines and numbers. For
    generating text, QTextStream supports formatting options for field
    padding and alignment, and formatting of numbers. Example:

    \code
        QFile data("output.txt");
        if (data.open(QFile::WriteOnly | QFile::Truncate)) {
            QTextStream out(&data);
            out << "Result: " << qSetFieldWidth(10) << left << 3.14 << 2.7 << endl;
            // writes "Result: 3.14      2.7       \n"
        }
    \endcode

    It's also common to use QTextStream to read console input and write
    console output. QTextStream is locale aware, and will automatically decode
    standard input using the correct codec. Example:

    \code
        QTextStream stream(stdin);
        QString line;
        do {
            line = stream.readLine();
        } while (!line.isNull());
    \endcode

    Note that you cannot use QTextStream::atEnd(), which returns true when you
    have reached the end of the data stream, with stdin.

    Besides using QTextStream's constructors, you can also set the
    device or string QTextStream operates on by calling setDevice() or
    setString(). You can seek to a position by calling seek(), and
    atEnd() will return true when there is no data left to be read. If
    you call flush(), QTextStream will empty all data from its write
    buffer into the device and call flush() on the device.

    Internally, QTextStream uses a Unicode based buffer, and
    QTextCodec is used by QTextStream to automatically support
    different character sets. By default, QTextCodec::codecForLocale()
    is used for reading and writing, but you can also set the codec by
    calling setCodec(). Automatic Unicode detection is also
    supported. When this feature is enabled (the default behavior),
    QTextStream will detect the UTF-16 BOM (Byte Order Mark) and
    switch to the appropriate UTF-16 codec when reading. QTextStream
    does not write a BOM by default, but you can enable this by calling
    setGenerateByteOrderMark(true). When QTextStream operates on a QString
    directly, the codec is disabled.

    There are three general ways to use QTextStream when reading text
    files:

    \list

    \o Chunk by chunk, by calling readLine() or readAll().

    \o Word by word. QTextStream supports streaming into QStrings,
    QByteArrays and char* buffers. Words are delimited by space, and
    leading white space is automatically skipped.

    \o Character by character, by streaming into QChar or char types.
    This method is often used for convenient input handling when
    parsing files, independent of character encoding and end-of-line
    semantics. To skip white space, call skipWhiteSpace().

    \endlist

    Since the text stream uses a buffer, you should not read from
    the stream using the implementation of a superclass. For instance,
    if you have a QFile and read from it directly using
    QFile::readLine() instead of using the stream, the text stream's
    internal position will be out of sync with the file's position.

    By default, when reading numbers from a stream of text,
    QTextStream will automatically detect the number's base
    representation. For example, if the number starts with "0x", it is
    assumed to be in hexadecimal form. If it starts with the digits
    1-9, it is assumed to be in decimal form, and so on. You can set
    the integer base, thereby disabling the automatic detection, by
    calling setIntegerBase(). Example:

    \code
        QTextStream in("0x50 0x20");
        int firstNumber, secondNumber;

        in >> firstNumber;             // firstNumber == 80
        in >> dec >> secondNumber;     // secondNumber == 0

        char ch;
        in >> ch;                      // ch == 'x'
    \endcode

    QTextStream supports many formatting options for generating text.
    You can set the field width and pad character by calling
    setFieldWidth() and setPadChar(). Use setFieldAlignment() to set
    the alignment within each field. For real numbers, call
    setRealNumberNotation() and setRealNumberPrecision() to set the
    notation (SmartNotation, ScientificNotation, FixedNotation) and precision in
    digits of the generated number. Some extra number formatting
    options are also available through setNumberFlags().

    \keyword QTextStream manipulators

    Like \c <iostream> in the standard C++ library, QTextStream also
    defines several global manipulator functions:

    \table
    \header \o Manipulator        \o Description
    \row    \o \c bin             \o Same as setIntegerBase(2).
    \row    \o \c oct             \o Same as setIntegerBase(8).
    \row    \o \c dec             \o Same as setIntegerBase(10).
    \row    \o \c hex             \o Same as setIntegerBase(16).
    \row    \o \c showbase        \o Same as setNumberFlags(numberFlags() | ShowBase).
    \row    \o \c forcesign       \o Same as setNumberFlags(numberFlags() | ForceSign).
    \row    \o \c forcepoint      \o Same as setNumberFlags(numberFlags() | ForcePoint).
    \row    \o \c noshowbase      \o Same as setNumberFlags(numberFlags() & ~ShowBase).
    \row    \o \c noforcesign     \o Same as setNumberFlags(numberFlags() & ~ForceSign).
    \row    \o \c noforcepoint    \o Same as setNumberFlags(numberFlags() & ~ForcePoint).
    \row    \o \c uppercasebase   \o Same as setNumberFlags(numberFlags() | UppercaseBase).
    \row    \o \c uppercasedigits \o Same as setNumberFlags(numberFlags() | UppercaseDigits).
    \row    \o \c lowercasebase   \o Same as setNumberFlags(numberFlags() & ~UppercaseBase).
    \row    \o \c lowercasedigits \o Same as setNumberFlags(numberFlags() & ~UppercaseDigits).
    \row    \o \c fixed           \o Same as setRealNumberNotation(FixedNotation).
    \row    \o \c scientific      \o Same as setRealNumberNotation(ScientificNotation).
    \row    \o \c left            \o Same as setFieldAlignment(AlignLeft).
    \row    \o \c right           \o Same as setFieldAlignment(AlignRight).
    \row    \o \c center          \o Same as setFieldAlignment(AlignCenter).
    \row    \o \c endl            \o Same as operator<<('\n') and flush().
    \row    \o \c flush           \o Same as flush().
    \row    \o \c reset           \o Same as reset().
    \row    \o \c ws              \o Same as skipWhiteSpace().
    \row    \o \c bom             \o Same as setGenerateByteOrderMark(true).
    \endtable

    In addition, Qt provides three global manipulators that take a
    parameter: qSetFieldWidth(), qSetPadChar(), and
    qSetRealNumberPrecision().

    \sa QDataStream, QIODevice, QFile, QBuffer, QTcpSocket, {Codecs Example}
*/

/*! \enum QTextStream::RealNumberNotation

    This enum specifies which notations to use for expressing \c
    float and \c double as strings.

    \value ScientificNotation Scientific notation (\c{printf()}'s \c %e flag).
    \value FixedNotation Fixed-point notation (\c{printf()}'s \c %f flag).
    \value SmartNotation Scientific or fixed-point notation, depending on which makes most sense (\c{printf()}'s \c %g flag).

    \sa setRealNumberNotation()
*/

/*! \enum QTextStream::FieldAlignment

    This enum specifies how to align text in fields when the field is
    wider than the text that occupies it.

    \value AlignLeft  Pad on the right side of fields.
    \value AlignRight  Pad on the left side of fields.
    \value AlignCenter  Pad on both sides of field.
    \value AlignAccountingStyle  Same as AlignRight, except that the
                                 sign of a number is flush left.

    \sa setFieldAlignment()
*/

/*! \enum QTextStream::NumberFlag

    This enum specifies various flags that can be set to affect the
    output of integers, \c{float}s, and \c{double}s.

    \value ShowBase  Show the base as a prefix if the base
                     is 16 ("0x"), 8 ("0"), or 2 ("0b").
    \value ForcePoint  Always put the decimal separator in numbers, even if
                       there are no decimals.
    \value ForceSign  Always put the sign in numbers, even for positive numbers.
    \value UppercaseBase  Use uppercase versions of base prefixes ("0X", "0B").
    \value UppercaseDigits  Use uppercase letters for expressing
                            digits 10 to 35 instead of lowercase.

    \sa setNumberFlags()
*/

/*! \enum QTextStream::Status

    This enum describes the current status of the text stream.

    \value Ok               The text stream is operating normally.
    \value ReadPastEnd      The text stream has read past the end of the
                            data in the underlying device.
    \value ReadCorruptData  The text stream has read corrupt data.

    \sa status()
*/

#include "qtextstream.h"
#include "qbuffer.h"
#include "qfile.h"
#include "qnumeric.h"
#ifndef QT_NO_TEXTCODEC
#include "qtextcodec.h"
#endif
#ifndef Q_OS_TEMP
#include <locale.h>
#endif

#include <stdlib.h>

#if defined QTEXTSTREAM_DEBUG
#include <ctype.h>

// Returns a human readable representation of the first \a len
// characters in \a data.
static QByteArray qt_prettyDebug(const char *data, int len, int maxSize)
{
    if (!data) return "(null)";
    QByteArray out;
    for (int i = 0; i < len; ++i) {
        char c = data[i];
        if (isprint(int(uchar(c)))) {
            out += c;
        } else switch (c) {
        case '\n': out += "\\n"; break;
        case '\r': out += "\\r"; break;
        case '\t': out += "\\t"; break;
        default:
            QString tmp;
            tmp.sprintf("\\x%x", (unsigned int)(unsigned char)c);
            out += tmp.toLatin1();
        }
    }

    if (len < maxSize)
        out += "...";

    return out;
}
#endif

// A precondition macro
#define Q_VOID
#define CHECK_VALID_STREAM(x) do { \
    if (!d->string && !d->device) { \
        qWarning("QTextStream: No device"); \
        return x; \
    } } while (0)

// Base implementations of operator>> for ints and reals
#define IMPLEMENT_STREAM_RIGHT_INT_OPERATOR(type) do { \
    Q_D(QTextStream); \
    CHECK_VALID_STREAM(*this); \
    qulonglong tmp; \
    switch (d->getNumber(&tmp)) { \
    case QTextStreamPrivate::npsOk: \
        i = (type)tmp; \
        break; \
    case QTextStreamPrivate::npsMissingDigit: \
    case QTextStreamPrivate::npsInvalidPrefix: \
        i = (type)0; \
        setStatus(atEnd() ? QTextStream::ReadPastEnd : QTextStream::ReadCorruptData); \
        break; \
    } \
    return *this; } while (0)

#define IMPLEMENT_STREAM_RIGHT_REAL_OPERATOR(type) do { \
    Q_D(QTextStream); \
    CHECK_VALID_STREAM(*this); \
    double tmp; \
    if (d->getReal(&tmp)) { \
        f = (type)tmp; \
    } else { \
        f = (type)0; \
        setStatus(atEnd() ? QTextStream::ReadPastEnd : QTextStream::ReadCorruptData); \
    } \
    return *this; } while (0)

#ifndef QT_NO_QOBJECT
class QDeviceClosedNotifier : public QObject
{
    Q_OBJECT
public:
    inline QDeviceClosedNotifier()
    { }

    inline void setupDevice(QTextStream *stream, QIODevice *device)
    {
        disconnect();
        if (device)
            connect(device, SIGNAL(aboutToClose()), this, SLOT(flushStream()));
        this->stream = stream;
    }

public slots:
    inline void flushStream() { stream->flush(); }

private:
    QTextStream *stream;
};
#endif

//-------------------------------------------------------------------
class QTextStreamPrivate
{
    Q_DECLARE_PUBLIC(QTextStream)
public:
    QTextStreamPrivate(QTextStream *q_ptr);
    ~QTextStreamPrivate();
    void reset();

    // device
    QIODevice *device;
#ifndef QT_NO_QOBJECT
    QDeviceClosedNotifier deviceClosedNotifier;
#endif
    bool deleteDevice;

    // string
    QString *string;
    int stringOffset;
    QIODevice::OpenMode stringOpenMode;

#ifndef QT_NO_TEXTCODEC
    // codec
    QTextCodec *codec;
    QTextCodec::ConverterState readConverterState;
    QTextCodec::ConverterState writeConverterState;
    bool autoDetectUnicode;
#endif

    // i/o
    enum TokenDelimiter {
        Space,
        NotSpace,
        EndOfLine,
        EndOfFile
    };

    bool scan(const QChar **ptr, int *tokenLength,
              int maxlen, TokenDelimiter delimiter);
    inline const QChar *readPtr() const;
    inline void consumeLastToken();
    inline void consume(int nchars);
    int lastTokenSize;

    // Return value type for getNumber()
    enum NumberParsingStatus {
        npsOk,
        npsMissingDigit,
        npsInvalidPrefix
    };

    inline bool write(const QString &data);
    inline bool getChar(QChar *ch);
    inline void ungetChar(const QChar &ch);
    NumberParsingStatus getNumber(qulonglong *l);
    bool getReal(double *f);

    bool putNumber(qulonglong number, bool negative);
    inline bool putString(const QString &ch);

    // buffers
    bool fillReadBuffer(qint64 maxBytes = -1);
    bool flushWriteBuffer();
    QString writeBuffer;
    QString readBuffer;
    int readBufferOffset;
    qint64 readBufferStartDevicePos;
#ifndef QT_NO_TEXTCODEC
    QTextCodec::ConverterState readBufferStartReadConverterState;
#endif

    // streaming parameters
    int realNumberPrecision;
    int integerBase;
    int fieldWidth;
    QChar padChar;
    QTextStream::FieldAlignment fieldAlignment;
    QTextStream::RealNumberNotation realNumberNotation;
    QTextStream::NumberFlags numberFlags;

    // status
    QTextStream::Status status;

    QTextStream *q_ptr;
};

/*! \internal
*/
QTextStreamPrivate::QTextStreamPrivate(QTextStream *q_ptr)
{
    this->q_ptr = q_ptr;
    reset();
}

/*! \internal
*/
QTextStreamPrivate::~QTextStreamPrivate()
{
    if (deleteDevice)
        delete device;
}

#ifndef QT_NO_TEXTCODEC
static void resetCodecConverterState(QTextCodec::ConverterState *state) {
    state->flags = QTextCodec::DefaultConversion;
    state->remainingChars = state->invalidChars =
           state->state_data[0] = state->state_data[1] = state->state_data[2] = 0;
    if (state->d) qFree(state->d);