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qtbase/src/corelib/io/qdebug.cpp
Marc Mutz bcdd7c260b Long live \constraints! 
We have divergence in the way we document function, operator and
constructor constraints. About half use \note, while the other
doesn't. Some say "if and only if" while others say just "participates
only if".

So add a qdoc macro, \constraints, to semantically mark up these
constraints. It expands to a section titled `Constraints`, and
uses a predefined sentence (prefix) for constraints.

Documentation for constraints is moved to the end of the comment
blocks to separate them from the rest of the text.

Apply them to all the standard-ish constraint documentation blocks
(grepped for "participate"). I didn't look for other, one-off, ways
documentation authors may have documented constraints, but I'm also
not aware of any.

Re-wrap lines only if the result fits into a single line.

As a drive-by, drop additional "if"s, as in "only if X and -if- Y" to
make the texts work with the `Constraints` section.

Fixes: QTBUG-106871
Pick-to: 6.8 6.5
Change-Id: I18c2f9f734474017264e49165389f8c9c7f34030
Reviewed-by: Kai Köhne <kai.koehne@qt.io>
Reviewed-by: Paul Wicking <paul.wicking@qt.io>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
(cherry picked from commit b7a67b46e66f161def5bf879f19c66d3fcec1d8b)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
2025-03-02 07:10:48 +00:00

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// Copyright (C) 2016 The Qt Company Ltd.
// Copyright (C) 2016 Intel Corporation.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#include "qdebug.h"
#include "private/qdebug_p.h"
#include "qmetaobject.h"
#include <private/qlogging_p.h>
#include <private/qtextstream_p.h>
#include <private/qtools_p.h>
#include <array>
#include <q20chrono.h>
#include <cstdio>
QT_BEGIN_NAMESPACE
using namespace QtMiscUtils;
/*
Returns a human readable representation of the first \a maxSize
characters in \a data. The size, \a len, is a 64-bit quantity to
avoid truncation due to implicit conversions in callers.
*/
QByteArray QtDebugUtils::toPrintable(const char *data, qint64 len, qsizetype maxSize)
{
if (!data)
return "(null)";
QByteArray out;
for (qsizetype i = 0; i < qMin(len, maxSize); ++i) {
char c = data[i];
if (isAsciiPrintable(c)) {
out += c;
} else {
switch (c) {
case '\n':
out += "\\n";
break;
case '\r':
out += "\\r";
break;
case '\t':
out += "\\t";
break;
default: {
const char buf[] = {
'\\',
'x',
toHexLower(uchar(c) / 16),
toHexLower(uchar(c) % 16),
0
};
out += buf;
}
}
}
}
if (maxSize < len)
out += "...";
return out;
}
// This file is needed to force compilation of QDebug into the kernel library.
/*!
\class QDebug
\inmodule QtCore
\ingroup shared
\brief The QDebug class provides an output stream for debugging information.
QDebug is used whenever the developer needs to write out debugging or tracing
information to a device, file, string or console.
\section1 Basic Use
In the common case, it is useful to call the qDebug() function to obtain a
default QDebug object to use for writing debugging information.
\snippet qdebug/qdebugsnippet.cpp 1
This constructs a QDebug object using the constructor that accepts a QtMsgType
value of QtDebugMsg. Similarly, the qWarning(), qCritical() and qFatal()
functions also return QDebug objects for the corresponding message types.
The class also provides several constructors for other situations, including
a constructor that accepts a QFile or any other QIODevice subclass that is
used to write debugging information to files and other devices. The constructor
that accepts a QString is used to write to a string for display or serialization.
\section1 Formatting Options
QDebug formats output so that it's easily readable. It automatically adds spaces
between arguments, and adds quotes around QString, QByteArray, QChar arguments.
You can tweak these options through the space(), nospace() and quote(), noquote()
methods. Furthermore, \l{QTextStream manipulators} can be piped into a QDebug
stream.
QDebugStateSaver limits changes to the formatting to the current scope.
resetFormat() resets the options to the default ones.
\section1 Writing Custom Types to a Stream
Many standard types can be written to QDebug objects, and Qt provides support for
most Qt value types. To add support for custom types, you need to implement a
streaming operator, as in the following example:
\snippet qdebug/qdebugsnippet.cpp 0
This is described in the \l{Debugging Techniques} and
\l{Creating Custom Qt Types#Making the Type Printable}{Creating Custom Qt Types}
documents.
*/
/*!
\fn QDebug::QDebug(QIODevice *device)
Constructs a debug stream that writes to the given \a device.
*/
/*!
\fn QDebug::QDebug(QString *string)
Constructs a debug stream that writes to the given \a string.
*/
/*!
\fn QDebug::QDebug(QtMsgType t)
Constructs a debug stream that writes to the handler for the message type \a t.
*/
/*!
\fn QDebug::QDebug(const QDebug &o)
Constructs a copy of the other debug stream \a o.
*/
/*!
\fn QDebug &QDebug::operator=(const QDebug &other)
Assigns the \a other debug stream to this stream and returns a reference to
this stream.
*/
/*!
\fn QDebug::~QDebug()
Flushes any pending data to be written and destroys the debug stream.
*/
QDebug::~QDebug()
{
if (stream && !--stream->ref) {
if (stream->space && stream->buffer.endsWith(u' '))
stream->buffer.chop(1);
if (stream->message_output) {
QInternalMessageLogContext ctxt(stream->context);
qt_message_output(stream->type,
ctxt,
stream->buffer);
}
delete stream;
}
}
/*!
\internal
*/
void QDebug::putUcs4(uint ucs4)
{
maybeQuote('\'');
if (ucs4 < 0x20) {
stream->ts << "\\x" << Qt::hex << ucs4 << Qt::reset;
} else if (ucs4 < 0x80) {
stream->ts << char(ucs4);
} else {
if (ucs4 < 0x10000)
stream->ts << "\\u" << qSetFieldWidth(4);
else
stream->ts << "\\U" << qSetFieldWidth(8);
stream->ts << Qt::hex << qSetPadChar(u'0') << ucs4 << Qt::reset;
}
maybeQuote('\'');
}
// These two functions return true if the character should be printed by QDebug.
// For QByteArray, this is technically identical to US-ASCII isprint();
// for QString, we use QChar::isPrint, which requires a full UCS-4 decode.
static inline bool isPrintable(char32_t ucs4) { return QChar::isPrint(ucs4); }
static inline bool isPrintable(char16_t uc) { return QChar::isPrint(uc); }
static inline bool isPrintable(uchar c)
{ return isAsciiPrintable(c); }
template <typename Char>
static inline void putEscapedString(QTextStreamPrivate *d, const Char *begin, size_t length, bool isUnicode = true)
{
QChar quote(u'"');
d->write(&quote, 1);
bool lastWasHexEscape = false;
const Char *end = begin + length;
for (const Char *p = begin; p != end; ++p) {
// check if we need to insert "" to break an hex escape sequence
if (Q_UNLIKELY(lastWasHexEscape)) {
if (fromHex(*p) != -1) {
// yes, insert it
QChar quotes[] = { quote, quote };
d->write(quotes, 2);
}
lastWasHexEscape = false;
}
if (sizeof(Char) == sizeof(QChar)) {
// Surrogate characters are category Cs (Other_Surrogate), so isPrintable = false for them
qsizetype runLength = 0;
while (p + runLength != end &&
isPrintable(p[runLength]) && p[runLength] != '\\' && p[runLength] != '"')
++runLength;
if (runLength) {
d->write(reinterpret_cast<const QChar *>(p), runLength);
p += runLength - 1;
continue;
}
} else if (isPrintable(*p) && *p != '\\' && *p != '"') {
QChar c = QLatin1Char(*p);
d->write(&c, 1);
continue;
}
// print as an escape sequence (maybe, see below for surrogate pairs)
qsizetype buflen = 2;
char16_t buf[std::char_traits<char>::length("\\U12345678")];
buf[0] = '\\';
switch (*p) {
case '"':
case '\\':
buf[1] = *p;
break;
case '\b':
buf[1] = 'b';
break;
case '\f':
buf[1] = 'f';
break;
case '\n':
buf[1] = 'n';
break;
case '\r':
buf[1] = 'r';
break;
case '\t':
buf[1] = 't';
break;
default:
if (!isUnicode) {
// print as hex escape
buf[1] = 'x';
buf[2] = toHexUpper(uchar(*p) >> 4);
buf[3] = toHexUpper(uchar(*p));
buflen = 4;
lastWasHexEscape = true;
break;
}
if (QChar::isHighSurrogate(*p)) {
if ((p + 1) != end && QChar::isLowSurrogate(p[1])) {
// properly-paired surrogates
char32_t ucs4 = QChar::surrogateToUcs4(*p, p[1]);
if (isPrintable(ucs4)) {
buf[0] = *p;
buf[1] = p[1];
buflen = 2;
} else {
buf[1] = 'U';
buf[2] = '0'; // toHexUpper(ucs4 >> 32);
buf[3] = '0'; // toHexUpper(ucs4 >> 28);
buf[4] = toHexUpper(ucs4 >> 20);
buf[5] = toHexUpper(ucs4 >> 16);
buf[6] = toHexUpper(ucs4 >> 12);
buf[7] = toHexUpper(ucs4 >> 8);
buf[8] = toHexUpper(ucs4 >> 4);
buf[9] = toHexUpper(ucs4);
buflen = 10;
}
++p;
break;
}
// improperly-paired surrogates, fall through
}
buf[1] = 'u';
buf[2] = toHexUpper(char16_t(*p) >> 12);
buf[3] = toHexUpper(char16_t(*p) >> 8);
buf[4] = toHexUpper(*p >> 4);
buf[5] = toHexUpper(*p);
buflen = 6;
}
d->write(reinterpret_cast<QChar *>(buf), buflen);
}
d->write(&quote, 1);
}
/*!
\internal
Duplicated from QtTest::toPrettyUnicode().
*/
void QDebug::putString(const QChar *begin, size_t length)
{
if (stream->noQuotes) {
// no quotes, write the string directly too (no pretty-printing)
// this respects the QTextStream state, though
stream->ts.d_ptr->putString(begin, qsizetype(length));
} else {
// we'll reset the QTextStream formatting mechanisms, so save the state
QDebugStateSaver saver(*this);
stream->ts.d_ptr->params.reset();
putEscapedString(stream->ts.d_ptr.get(), reinterpret_cast<const char16_t *>(begin), length);
}
}
/*!
\internal
Duplicated from QtTest::toPrettyCString().
*/
void QDebug::putByteArray(const char *begin, size_t length, Latin1Content content)
{
if (stream->noQuotes) {
// no quotes, write the string directly too (no pretty-printing)
// this respects the QTextStream state, though
QString string = content == ContainsLatin1 ? QString::fromLatin1(begin, qsizetype(length))
: QString::fromUtf8(begin, qsizetype(length));
stream->ts.d_ptr->putString(string);
} else {
// we'll reset the QTextStream formatting mechanisms, so save the state
QDebugStateSaver saver(*this);
stream->ts.d_ptr->params.reset();
putEscapedString(stream->ts.d_ptr.get(), reinterpret_cast<const uchar *>(begin),
length, content == ContainsLatin1);
}
}
static QByteArray timeUnit(qint64 num, qint64 den)
{
using namespace std::chrono;
using namespace q20::chrono;
if (num == 1 && den > 1) {
// sub-multiple of seconds
char prefix = '\0';
auto tryprefix = [&](auto d, char c) {
static_assert(decltype(d)::num == 1, "not an SI prefix");
if (den == decltype(d)::den)
prefix = c;
};
// "u" should be "µ", but debugging output is not always UTF-8-safe
tryprefix(std::milli{}, 'm');
tryprefix(std::micro{}, 'u');
tryprefix(std::nano{}, 'n');
tryprefix(std::pico{}, 'p');
tryprefix(std::femto{}, 'f');
tryprefix(std::atto{}, 'a');
// uncommon ones later
tryprefix(std::centi{}, 'c');
tryprefix(std::deci{}, 'd');
if (prefix) {
char unit[3] = { prefix, 's' };
return QByteArray(unit, sizeof(unit) - 1);
}
}
const char *unit = nullptr;
if (num > 1 && den == 1) {
// multiple of seconds - but we don't use SI prefixes
auto tryunit = [&](auto d, const char *name) {
static_assert(decltype(d)::period::den == 1, "not a multiple of a second");
if (unit || num % decltype(d)::period::num)
return;
unit = name;
num /= decltype(d)::period::num;
};
tryunit(years{}, "yr");
tryunit(weeks{}, "wk");
tryunit(days{}, "d");
tryunit(hours{}, "h");
tryunit(minutes{}, "min");
}
if (!unit)
unit = "s";
if (num == 1 && den == 1)
return unit;
if (Q_UNLIKELY(num < 1 || den < 1))
return QString::asprintf("<invalid time unit %lld/%lld>", num, den).toLatin1();
// uncommon units: will return something like "[2/3]s"
// strlen("[/]min") = 6
char buf[2 * (std::numeric_limits<qint64>::digits10 + 2) + 10];
size_t len = 0;
auto appendChar = [&](char c) {
Q_ASSERT(len < sizeof(buf));
buf[len++] = c;
};
auto appendNumber = [&](qint64 value) {
if (value >= 10'000 && (value % 1000) == 0)
len += std::snprintf(buf + len, sizeof(buf) - len, "%.6g", double(value)); // "1e+06"
else
len += std::snprintf(buf + len, sizeof(buf) - len, "%lld", value);
};
appendChar('[');
appendNumber(num);
if (den != 1) {
appendChar('/');
appendNumber(den);
}
appendChar(']');
memcpy(buf + len, unit, strlen(unit));
return QByteArray(buf, len + strlen(unit));
}
/*!
\since 6.6
\internal
Helper to the std::chrono::duration debug streaming output.
*/
void QDebug::putTimeUnit(qint64 num, qint64 den)
{
stream->ts << timeUnit(num, den); // ### optimize
}
namespace {
#ifdef QT_SUPPORTS_INT128
constexpr char Q_INT128_MIN_STR[] = "-170141183460469231731687303715884105728";
constexpr int Int128BufferSize = sizeof(Q_INT128_MIN_STR);
using Int128Buffer = std::array<char, Int128BufferSize>;
// numeric_limits<qint128>::digits10 may not exist
static char *i128ToStringHelper(Int128Buffer &buffer, quint128 n)
{
auto dst = buffer.data() + buffer.size();
*--dst = '\0'; // NUL-terminate
if (n == 0) {
*--dst = '0'; // and done
} else {
while (n != 0) {
*--dst = "0123456789"[n % 10];
n /= 10;
}
}
return dst;
}
#endif // QT_SUPPORTS_INT128
[[maybe_unused]]
static const char *int128Warning()
{
const char *msg = "Qt was not compiled with int128 support.";
qWarning("%s", msg);
return msg;
}
} // unnamed namespace
/*!
\since 6.7
\internal
Helper to the qint128 debug streaming output.
*/
void QDebug::putInt128([[maybe_unused]] const void *p)
{
#ifdef QT_SUPPORTS_INT128
Q_ASSERT(p);
qint128 i;
memcpy(&i, p, sizeof(i)); // alignment paranoia
if (i == Q_INT128_MIN) {
// -i is not representable, hardcode the result:
stream->ts << Q_INT128_MIN_STR;
} else {
Int128Buffer buffer;
auto dst = i128ToStringHelper(buffer, i < 0 ? -i : i);
if (i < 0)
*--dst = '-';
stream->ts << dst;
}
return;
#endif // QT_SUPPORTS_INT128
stream->ts << int128Warning();
}
/*!
\since 6.7
\internal
Helper to the quint128 debug streaming output.
*/
void QDebug::putUInt128([[maybe_unused]] const void *p)
{
#ifdef QT_SUPPORTS_INT128
Q_ASSERT(p);
quint128 i;
memcpy(&i, p, sizeof(i)); // alignment paranoia
Int128Buffer buffer;
stream->ts << i128ToStringHelper(buffer, i);
return;
#endif // QT_SUPPORTS_INT128
stream->ts << int128Warning();
}
/*!
\since 6.9
\internal
Helper to the <Std/Qt>::<>_ordering debug output.
It generates the string in following format:
<Qt/Std>::<weak/partial/strong>_ordering::<less/equal/greater/unordered>
*/
void QDebug::putQtOrdering(QtOrderingPrivate::QtOrderingTypeFlag flags, Qt::partial_ordering order)
{
using QtOrderingPrivate::QtOrderingType;
std::string result;
if ((flags & QtOrderingType::StdOrder) == QtOrderingType::StdOrder)
result += "std";
else if ((flags & QtOrderingType::QtOrder) == QtOrderingType::QtOrder)
result += "Qt";
result += "::";
const bool isStrong = ((flags & QtOrderingType::Strong) == QtOrderingType::Strong);
if (isStrong)
result += "strong";
else if ((flags & QtOrderingType::Weak) == QtOrderingType::Weak)
result += "weak";
else if ((flags & QtOrderingType::Partial) == QtOrderingType::Partial)
result += "partial";
result += "_ordering::";
if (order == Qt::partial_ordering::equivalent) {
if (isStrong)
result += "equal";
else
result += "equivalent";
} else if (order == Qt::partial_ordering::greater) {
result += "greater";
} else if (order == Qt::partial_ordering::less) {
result += "less";
} else {
result += "unordered";
}
stream->ts << result.data();
}
/*!
\fn QDebug::swap(QDebug &other)
\since 5.0
\memberswap{debug stream instance}
*/
/*!
Resets the stream formatting options, bringing it back to its original constructed state.
\sa space(), quote()
\since 5.4
*/
QDebug &QDebug::resetFormat()
{
stream->ts.reset();
stream->space = true;
stream->noQuotes = false;
stream->verbosity = DefaultVerbosity;
return *this;
}
/*!
\fn QDebug &QDebug::space()
Writes a space character to the debug stream and returns a reference to
the stream.
The stream remembers that automatic insertion of spaces is
enabled for future writes.
\sa nospace(), maybeSpace()
*/
/*!
\fn QDebug &QDebug::nospace()
Disables automatic insertion of spaces and returns a reference to the stream.
\sa space(), maybeSpace()
*/
/*!
\fn QDebug &QDebug::maybeSpace()
Writes a space character to the debug stream, depending on the current
setting for automatic insertion of spaces, and returns a reference to the stream.
\sa space(), nospace()
*/
/*!
\fn bool QDebug::autoInsertSpaces() const
Returns \c true if this QDebug instance will automatically insert spaces
between writes.
\since 5.0
\sa QDebugStateSaver
*/
/*!
\fn void QDebug::setAutoInsertSpaces(bool b)
Enables automatic insertion of spaces between writes if \a b is true; otherwise
automatic insertion of spaces is disabled.
\since 5.0
\sa QDebugStateSaver
*/
/*!
\fn bool QDebug::quoteStrings() const
\since 6.7
Returns \c true if this QDebug instance will quote strings streamed into
it (which is the default).
\sa QDebugStateSaver, quote(), noquote(), setQuoteStrings()
*/
/*!
\fn void QDebug::setQuoteStrings(bool b)
\since 6.7
Enables quoting of strings streamed into this QDebug instance if \a b is
\c true; otherwise quoting is disabled.
The default is to quote strings.
\sa QDebugStateSaver, quote(), noquote(), quoteStrings()
*/
/*!
\fn QDebug &QDebug::quote()
\since 5.4
Enables automatic insertion of quotation characters around QChar, QString and QByteArray
contents and returns a reference to the stream.
Quoting is enabled by default.
\sa noquote(), maybeQuote()
*/
/*!
\fn QDebug &QDebug::noquote()
\since 5.4
Disables automatic insertion of quotation characters around QChar, QString and QByteArray
contents and returns a reference to the stream.
When quoting is disabled, these types are printed without quotation
characters and without escaping of non-printable characters.
\sa quote(), maybeQuote()
*/
/*!
\fn QDebug &QDebug::maybeQuote(char c)
\since 5.4
Writes a character \a c to the debug stream, depending on the
current setting for automatic insertion of quotes, and returns a reference to the stream.
The default character is a double quote \c{"}.
\sa quote(), noquote()
*/
/*!
\fn int QDebug::verbosity() const
\since 5.6
Returns the verbosity of the debug stream.
Streaming operators can check the value to decide whether
verbose output is desired and print more information depending on the
level. Higher values indicate that more information is desired.
The allowed range is from 0 to 7. The default value is 2.
\sa setVerbosity(), VerbosityLevel
*/
/*!
\fn void QDebug::setVerbosity(int verbosityLevel)
\since 5.6
Sets the verbosity of the stream to \a verbosityLevel.
The allowed range is from 0 to 7. The default value is 2.
\sa verbosity(), VerbosityLevel
*/
/*!
\fn QDebug &QDebug::verbosity(int verbosityLevel)
\since 5.13
Sets the verbosity of the stream to \a verbosityLevel and returns a reference to the stream.
The allowed range is from 0 to 7. The default value is 2.
\sa verbosity(), setVerbosity(), VerbosityLevel
*/
/*!
\enum QDebug::VerbosityLevel
\since 5.13
This enum describes the range of verbosity levels.
\value MinimumVerbosity
\value DefaultVerbosity
\value MaximumVerbosity
\sa verbosity(), setVerbosity()
*/
/*!
\fn QDebug &QDebug::operator<<(QChar t)
Writes the character, \a t, to the stream and returns a reference to the
stream. Normally, QDebug prints control characters and non-US-ASCII
characters as their C escape sequences or their Unicode value (\\u1234). To
print non-printable characters without transformation, enable the noquote()
functionality, but note that some QDebug backends may not be 8-bit clean
and may not be able to represent \c t.
*/
/*!
\fn QDebug &QDebug::operator<<(bool t)
Writes the boolean value, \a t, to the stream and returns a reference to the
stream.
*/
/*!
\fn QDebug &QDebug::operator<<(char t)
Writes the character, \a t, to the stream and returns a reference to the
stream.
*/
/*!
\fn QDebug &QDebug::operator<<(signed short t)
Writes the signed short integer, \a t, to the stream and returns a reference
to the stream.
*/
/*!
\fn QDebug &QDebug::operator<<(unsigned short t)
Writes then unsigned short integer, \a t, to the stream and returns a
reference to the stream.
*/
/*!
\fn QDebug &QDebug::operator<<(signed int t)
Writes the signed integer, \a t, to the stream and returns a reference
to the stream.
*/
/*!
\fn QDebug &QDebug::operator<<(unsigned int t)
Writes then unsigned integer, \a t, to the stream and returns a reference to
the stream.
*/
/*!
\fn QDebug &QDebug::operator<<(signed long t)
Writes the signed long integer, \a t, to the stream and returns a reference
to the stream.
*/
/*!
\fn QDebug &QDebug::operator<<(unsigned long t)
Writes then unsigned long integer, \a t, to the stream and returns a reference
to the stream.
*/
/*!
\fn QDebug &QDebug::operator<<(qint64 t)
Writes the signed 64-bit integer, \a t, to the stream and returns a reference
to the stream.
*/
/*!
\fn QDebug &QDebug::operator<<(quint64 t)
Writes then unsigned 64-bit integer, \a t, to the stream and returns a
reference to the stream.
*/
/*!
\fn QDebug &QDebug::operator<<(float t)
Writes the 32-bit floating point number, \a t, to the stream and returns a
reference to the stream.
*/
/*!
\fn QDebug &QDebug::operator<<(double t)
Writes the 64-bit floating point number, \a t, to the stream and returns a
reference to the stream.
*/
/*!
\fn QDebug &QDebug::operator<<(const char *t)
Writes the '\\0'-terminated UTF-8 string, \a t, to the stream and returns a
reference to the stream. The string is never quoted or escaped for the
output. Note that QDebug buffers internally as UTF-16 and may need to
transform to 8-bit using the locale's codec in order to use some backends,
which may cause garbled output (mojibake). Restricting to US-ASCII strings
is recommended.
*/
/*!
\fn QDebug &QDebug::operator<<(const char16_t *t)
\since 6.0
Writes the u'\\0'-terminated UTF-16 string, \a t, to the stream and returns
a reference to the stream. The string is never quoted or escaped for the
output. Note that QDebug buffers internally as UTF-16 and may need to
transform to 8-bit using the locale's codec in order to use some backends,
which may cause garbled output (mojibake). Restricting to US-ASCII strings
is recommended.
*/
/*!
\fn QDebug &QDebug::operator<<(char16_t t)
\since 5.5
Writes the UTF-16 character, \a t, to the stream and returns a reference
to the stream.
*/
/*!
\fn QDebug &QDebug::operator<<(char32_t t)
\since 5.5
Writes the UTF-32 character, \a t, to the stream and returns a reference
to the stream.
*/
/*!
\fn QDebug &QDebug::operator<<(const QString &t)
Writes the string, \a t, to the stream and returns a reference to the
stream. Normally, QDebug prints the string inside quotes and transforms
non-printable characters to their Unicode values (\\u1234).
To print non-printable characters without transformation, enable the
noquote() functionality. Note that some QDebug backends might not be 8-bit
clean.
Output examples:
\snippet code/src_corelib_io_qdebug.cpp 0
*/
/*!
\since 5.10
\fn QDebug &QDebug::operator<<(QStringView s)
Writes the string view, \a s, to the stream and returns a reference to the
stream. Normally, QDebug prints the string inside quotes and transforms
non-printable characters to their Unicode values (\\u1234).
To print non-printable characters without transformation, enable the
noquote() functionality. Note that some QDebug backends might not be 8-bit
clean.
See the QString overload for examples.
*/
/*!
\since 6.0
\fn QDebug &QDebug::operator<<(QUtf8StringView s)
Writes the string view, \a s, to the stream and returns a reference to the
stream.
Normally, QDebug prints the data inside quotes and transforms control or
non-US-ASCII characters to their C escape sequences (\\xAB). This way, the
output is always 7-bit clean and the string can be copied from the output
and pasted back into C++ sources, if necessary.
To print non-printable characters without transformation, enable the
noquote() functionality. Note that some QDebug backends might not be 8-bit
clean.
*/
/*!
\fn QDebug &QDebug::operator<<(QLatin1StringView t)
Writes the string, \a t, to the stream and returns a reference to the
stream. Normally, QDebug prints the string inside quotes and transforms
non-printable characters to their Unicode values (\\u1234).
To print non-printable characters without transformation, enable the
noquote() functionality. Note that some QDebug backends might not be 8-bit
clean.
See the QString overload for examples.
*/
/*!
\fn QDebug &QDebug::operator<<(const QByteArray &t)
Writes the byte array, \a t, to the stream and returns a reference to the
stream. Normally, QDebug prints the array inside quotes and transforms
control or non-US-ASCII characters to their C escape sequences (\\xAB). This
way, the output is always 7-bit clean and the string can be copied from the
output and pasted back into C++ sources, if necessary.
To print non-printable characters without transformation, enable the
noquote() functionality. Note that some QDebug backends might not be 8-bit
clean.
Output examples:
\snippet code/src_corelib_io_qdebug.cpp 1
Note how QDebug needed to close and reopen the string in the way C and C++
languages concatenate string literals so that the letter 'b' is not
interpreted as part of the previous hexadecimal escape sequence.
*/
/*!
\since 6.0
\fn QDebug &QDebug::operator<<(QByteArrayView t)
Writes the data of the observed byte array, \a t, to the stream and returns
a reference to the stream.
Normally, QDebug prints the data inside quotes and transforms control or
non-US-ASCII characters to their C escape sequences (\\xAB). This way, the
output is always 7-bit clean and the string can be copied from the output
and pasted back into C++ sources, if necessary.
To print non-printable characters without transformation, enable the
noquote() functionality. Note that some QDebug backends might not be 8-bit
clean.
See the QByteArray overload for examples.
*/
/*!
\fn QDebug &QDebug::operator<<(const void *t)
Writes a pointer, \a t, to the stream and returns a reference to the stream.
*/
/*!
\fn QDebug &QDebug::operator<<(QTextStreamFunction f)
\internal
*/
/*!
\fn QDebug &QDebug::operator<<(QTextStreamManipulator m)
\internal
*/
/*!
\fn template <typename T, QDebug::if_ordering_type<T>> QDebug::operator<<(QDebug debug, T t)
\since 6.9
Prints the Qt or std ordering value \a t to the \a debug object.
\constraints \c T is one of <Qt/Std>::<weak/partial/strong>_ordering.
*/
/*!
\since 6.5
\fn template <typename Char, typename...Args> QDebug &QDebug::operator<<(const std::basic_string<Char, Args...> &s)
\fn template <typename Char, typename...Args> QDebug &QDebug::operator<<(std::basic_string_view<Char, Args...> s)
Writes the string or string-view \a s to the stream and returns a reference
to the stream.
These operators only participate in overload resolution if \c Char is one of
\list
\li char
\li char8_t (C++20 only)
\li char16_t
\li char32_t
\li wchar_t
\endlist
*/
/*!
\since 6.6
\fn template <typename Rep, typename Period> QDebug &QDebug::operator<<(std::chrono::duration<Rep, Period> duration)
Prints the time duration \a duration to the stream and returns a reference
to the stream. The printed string is the numeric representation of the
period followed by the time unit, similar to what the C++ Standard Library
would produce with \c{std::ostream}.
The unit is not localized.
*/
/*!
\fn template <typename T, QDebug::if_qint128<T>> QDebug::operator<<(T i)
\fn template <typename T, QDebug::if_quint128<T>> QDebug::operator<<(T i)
\since 6.7
Prints the textual representation of the 128-bit integer \a i.
\note This operator is only available if Qt supports 128-bit integer types.
If 128-bit integer types are available in your build, but the Qt libraries
were compiled without, the operator will print a warning instead.
\note Because the operator is a function template, no implicit conversions
are performed on its argument. It must be exactly qint128/quint128.
\sa QT_SUPPORTS_INT128
*/
/*!
\fn template <class T> QString QDebug::toString(const T &object)
\since 6.0
\include qdebug-toString.qdocinc
\sa toBytes()
*/
/*! \internal */
QString QDebug::toStringImpl(StreamTypeErased s, const void *obj)
{
QString result;
{
QDebug d(&result);
s(d.nospace(), obj);
}
return result;
}
/*!
\fn template <class T> QByteArray QDebug::toBytes(const T &object)
\since 6.9
This is equivalent to passing \a object to
\c{QDebug::toString(object).toUtf8()}, but more efficient.
\sa toString()
*/
/*! \internal */
QByteArray QDebug::toBytesImpl(StreamTypeErased s, const void *obj)
{
QByteArray result;
{
QDebug d(&result);
s(d.nospace(), obj);
}
return result;
}
/*!
\internal
\since 6.9
Outputs a heterogeneous product type (pair, tuple, or anything that
implements the Tuple Protocol). The class name is described by "\a ns
\c{::} \a what", while the addresses of the \a n elements are stored in the
array \a data. The formatters are stored in the array \a ops.
If \a ns is empty, only \a what is used.
*/
QDebug &QDebug::putTupleLikeImplImpl(const char *ns, const char *what,
size_t n, StreamTypeErased *ops, const void **data)
{
const QDebugStateSaver saver(*this);
nospace();
if (ns && *ns)
*this << ns << "::";
*this << what << '(';
while (n--) {
(*ops++)(*this, *data++);
if (n)
*this << ", ";
}
return *this << ')';
}
/*!
\fn template <class T> QDebug operator<<(QDebug debug, const QList<T> &list)
\relates QDebug
Writes the contents of \a list to \a debug. \c T needs to
support streaming into QDebug.
*/
/*!
\fn template <class T, qsizetype P> QDebug operator<<(QDebug debug, const QVarLengthArray<T,P> &array)
\relates QDebug
\since 6.3
Writes the contents of \a array to \a debug. \c T needs to
support streaming into QDebug.
*/
/*!
\fn template <typename T, typename Alloc> QDebug operator<<(QDebug debug, const std::list<T, Alloc> &vec)
\relates QDebug
\since 5.7
Writes the contents of list \a vec to \a debug. \c T needs to
support streaming into QDebug.
*/
/*!
\fn template <typename T, typename Alloc> QDebug operator<<(QDebug debug, const std::vector<T, Alloc> &vec)
\relates QDebug
\since 5.7
Writes the contents of vector \a vec to \a debug. \c T needs to
support streaming into QDebug.
*/
/*!
\fn template <typename T, std::size_t N> QDebug operator<<(QDebug debug, const std::array<T, N> &array)
\relates QDebug
\since 6.9
Writes the contents of \a array to \a debug. \c T needs to
support streaming into QDebug.
*/
/*!
\fn template <typename T> QDebug operator<<(QDebug debug, const QSet<T> &set)
\relates QDebug
Writes the contents of \a set to \a debug. \c T needs to
support streaming into QDebug.
*/
/*!
\fn template <class Key, class T> QDebug operator<<(QDebug debug, const QMap<Key, T> &map)
\relates QDebug
Writes the contents of \a map to \a debug. Both \c Key and
\c T need to support streaming into QDebug.
*/
/*!
\fn template <class Key, class T> QDebug operator<<(QDebug debug, const QMultiMap<Key, T> &map)
\relates QDebug
Writes the contents of \a map to \a debug. Both \c Key and
\c T need to support streaming into QDebug.
*/
/*!
\fn template <typename Key, typename T, typename Compare, typename Alloc> QDebug operator<<(QDebug debug, const std::map<Key, T, Compare, Alloc> &map)
\relates QDebug
\since 5.7
Writes the contents of \a map to \a debug. Both \c Key and
\c T need to support streaming into QDebug.
*/
/*!
\fn template <typename Key, typename T, typename Compare, typename Alloc> QDebug operator<<(QDebug debug, const std::multimap<Key, T, Compare, Alloc> &map)
\relates QDebug
\since 5.7
Writes the contents of \a map to \a debug. Both \c Key and
\c T need to support streaming into QDebug.
*/
/*!
\fn template <typename Key, typename Compare, typename Alloc> QDebug operator<<(QDebug debug, const std::multiset<Key, Compare, Alloc> &multiset)
\relates QDebug
\since 6.9
Writes the contents of \a multiset to \a debug. The \c Key type
needs to support streaming into QDebug.
*/
/*!
\fn template <typename Key, typename Compare, typename Alloc> QDebug operator<<(QDebug debug, const std::set<Key, Compare, Alloc> &set)
\relates QDebug
\since 6.9
Writes the contents of \a set to \a debug. The \c Key type
needs to support streaming into QDebug.
*/
/*!
\fn template <typename Key, typename T, typename Hash, typename KeyEqual, typename Alloc> QDebug operator<<(QDebug debug, const std::unordered_map<Key, T, Hash, KeyEqual, Alloc> &map)
\relates QDebug
\since 6.9
Writes the contents of \a map to \a debug. Both \c Key and
\c T need to support streaming into QDebug.
*/
/*!
\fn template <typename Key, typename Hash, typename KeyEqual, typename Alloc> QDebug operator<<(QDebug debug, const std::unordered_set<Key, Hash, KeyEqual, Alloc> &unordered_set)
\relates QDebug
\since 6.9
Writes the contents of \a unordered_set to \a debug. The \c Key type
needs to support streaming into QDebug.
*/
/*!
\fn template <class Key, class T> QDebug operator<<(QDebug debug, const QHash<Key, T> &hash)
\relates QDebug
Writes the contents of \a hash to \a debug. Both \c Key and
\c T need to support streaming into QDebug.
*/
/*!
\fn template <class Key, class T> QDebug operator<<(QDebug debug, const QMultiHash<Key, T> &hash)
\relates QDebug
Writes the contents of \a hash to \a debug. Both \c Key and
\c T need to support streaming into QDebug.
*/
/*!
\fn template <class...Ts, QDebug::if_streamable<Ts...>> QDebug &QDebug::operator<<(const std::tuple<Ts...> &tuple)
\since 6.9
Writes the contents of \a tuple to the stream. All \c Ts... need to support
streaming into QDebug.
*/
/*!
\fn template <class T1, class T2> QDebug operator<<(QDebug debug, const std::pair<T1, T2> &pair)
\relates QDebug
Writes the contents of \a pair to \a debug. Both \c T1 and
\c T2 need to support streaming into QDebug.
*/
/*!
\since 6.7
\fn template <class T, QDebug::if_streamable<T>> QDebug::operator<<(const std::optional<T> &opt)
Writes the contents of \a opt (or \c nullopt if not set) to this stream.
\c T needs to support streaming into QDebug.
*/
/*!
\fn template <typename T> QDebug operator<<(QDebug debug, const QContiguousCache<T> &cache)
\relates QDebug
Writes the contents of \a cache to \a debug. \c T needs to
support streaming into QDebug.
*/
/*!
\fn template<typename T> QDebug operator<<(QDebug debug, const QFlags<T> &flags)
\relates QDebug
\since 4.7
Writes \a flags to \a debug.
*/
/*!
\fn template<typename T> QDebug operator<<(QDebug debug, const QSharedPointer<T> &ptr)
\relates QSharedPointer
\since 5.7
Writes the pointer tracked by \a ptr into the debug object \a debug for
debugging purposes.
\sa {Debugging Techniques}
*/
/*!
\fn QDebug &QDebug::operator<<(std::nullptr_t)
\internal
*/
/*!
\since 6.7
\fn QDebug &QDebug::operator<<(std::nullopt_t)
Writes nullopt to the stream.
*/
/*!
\class QDebugStateSaver
\inmodule QtCore
\brief Convenience class for custom QDebug operators.
Saves the settings used by QDebug, and restores them upon destruction,
then calls \l {QDebug::maybeSpace()}{maybeSpace()}, to separate arguments with a space if
\l {QDebug::autoInsertSpaces()}{autoInsertSpaces()} was true at the time of constructing the QDebugStateSaver.
The automatic insertion of spaces between writes is one of the settings
that QDebugStateSaver stores for the duration of the current block.
The settings of the internal QTextStream are also saved and restored,
so that using << Qt::hex in a QDebug operator doesn't affect other QDebug
operators.
QDebugStateSaver is typically used in the implementation of an operator<<() for debugging:
\snippet customtype/customtypeexample.cpp custom type streaming operator
\since 5.1
*/
class QDebugStateSaverPrivate
{
public:
QDebugStateSaverPrivate(QDebug::Stream *stream)
: m_stream(stream),
m_spaces(stream->space),
m_noQuotes(stream->noQuotes),
m_verbosity(stream->verbosity),
m_streamParams(stream->ts.d_ptr->params)
{
}
void restoreState()
{
const bool currentSpaces = m_stream->space;
if (currentSpaces && !m_spaces)
if (m_stream->buffer.endsWith(u' '))
m_stream->buffer.chop(1);
m_stream->space = m_spaces;
m_stream->noQuotes = m_noQuotes;
m_stream->ts.d_ptr->params = m_streamParams;
m_stream->verbosity = m_verbosity;
if (!currentSpaces && m_spaces)
m_stream->ts << ' ';
}
QDebug::Stream *m_stream;
// QDebug state
const bool m_spaces;
const bool m_noQuotes;
const int m_verbosity;
// QTextStream state
const QTextStreamPrivate::Params m_streamParams;
};
/*!
Creates a QDebugStateSaver instance, which saves the settings
currently used by \a dbg.
\sa QDebug::setAutoInsertSpaces(), QDebug::autoInsertSpaces()
*/
QDebugStateSaver::QDebugStateSaver(QDebug &dbg)
: d(new QDebugStateSaverPrivate(dbg.stream))
{
}
/*!
Destroys a QDebugStateSaver instance, which restores the settings
used when the QDebugStateSaver instance was created.
\sa QDebug::setAutoInsertSpaces(), QDebug::autoInsertSpaces()
*/
QDebugStateSaver::~QDebugStateSaver()
{
d->restoreState();
}
/*!
\internal
Specialization of the primary template in qdebug.h to out-of-line
the common case of QFlags<T>::Int being 32-bit.
Just call the generic version so the two don't get out of sync.
*/
void qt_QMetaEnum_flagDebugOperator(QDebug &debug, size_t sizeofT, uint value)
{
qt_QMetaEnum_flagDebugOperator(debug, sizeofT, quint64(value));
}
/*!
\internal
Ditto, for 64-bit.
*/
void qt_QMetaEnum_flagDebugOperator(QDebug &debug, size_t sizeofT, quint64 value)
{
qt_QMetaEnum_flagDebugOperator<quint64>(debug, sizeofT, value);
}
#ifndef QT_NO_QOBJECT
/*!
\internal
Formats the given enum \a value for debug output.
The supported verbosity are:
0: Just the key, or value with enum name if no key is found:
MyEnum2
MyEnum(123)
MyScopedEnum::Enum3
MyScopedEnum(456)
1: Same as 0, but treating all enums as scoped:
MyEnum::MyEnum2
MyEnum(123)
MyScopedEnum::Enum3
MyScopedEnum(456)
2: The QDebug default. Same as 0, and includes class/namespace scope:
MyNamespace::MyClass::MyEnum2
MyNamespace::MyClass::MyEnum(123)
MyNamespace::MyClass::MyScopedEnum::Enum3
MyNamespace::MyClass::MyScopedEnum(456)
3: Same as 2, but treating all enums as scoped:
MyNamespace::MyClass::MyEnum::MyEnum2
MyNamespace::MyClass::MyEnum(123)
MyNamespace::MyClass::MyScopedEnum::Enum3
MyNamespace::MyClass::MyScopedEnum(456)
*/
QDebug qt_QMetaEnum_debugOperator(QDebug &dbg, qint64 value, const QMetaObject *meta, const char *name)
{
QDebugStateSaver saver(dbg);
dbg.nospace();
QMetaEnum me = meta->enumerator(meta->indexOfEnumerator(name));
const int verbosity = dbg.verbosity();
if (verbosity >= QDebug::DefaultVerbosity) {
if (const char *scope = me.scope())
dbg << scope << u"::";
}
const char *key = me.valueToKey(static_cast<int>(value));
const bool scoped = me.isScoped() || verbosity & 1;
if (scoped || !key)
dbg << me.enumName() << (!key ? u"(" : u"::");
if (key)
dbg << key;
else
dbg << value << ')';
return dbg;
}
/*!
\fn QDebug qt_QMetaEnum_flagDebugOperator(QDebug &, quint64 value, const QMetaObject *, const char *name)
\internal
Formats the given flag \a value for debug output.
The supported verbosity are:
0: Just the key(s):
MyFlag1
MyFlag2|MyFlag3
MyScopedFlag(MyFlag2)
MyScopedFlag(MyFlag2|MyFlag3)
1: Same as 0, but treating all flags as scoped:
MyFlag(MyFlag1)
MyFlag(MyFlag2|MyFlag3)
MyScopedFlag(MyFlag2)
MyScopedFlag(MyFlag2|MyFlag3)
2: The QDebug default. Same as 1, and includes class/namespace scope:
QFlags<MyNamespace::MyClass::MyFlag>(MyFlag1)
QFlags<MyNamespace::MyClass::MyFlag>(MyFlag2|MyFlag3)
QFlags<MyNamespace::MyClass::MyScopedFlag>(MyFlag2)
QFlags<MyNamespace::MyClass::MyScopedFlag>(MyFlag2|MyFlag3)
*/
QDebug qt_QMetaEnum_flagDebugOperator(QDebug &debug, quint64 value, const QMetaObject *meta, const char *name)
{
const int verbosity = debug.verbosity();
QDebugStateSaver saver(debug);
debug.resetFormat();
debug.noquote();
debug.nospace();
const QMetaEnum me = meta->enumerator(meta->indexOfEnumerator(name));
const bool classScope = verbosity >= QDebug::DefaultVerbosity;
if (classScope) {
debug << u"QFlags<";
if (const char *scope = me.scope())
debug << scope << u"::";
}
const bool enumScope = me.isScoped() || verbosity > QDebug::MinimumVerbosity;
if (enumScope) {
debug << me.enumName();
if (classScope)
debug << '>';
debug << '(';
}
debug << me.valueToKeys(value);
if (enumScope)
debug << ')';
return debug;
}
#endif // !QT_NO_QOBJECT
QT_END_NAMESPACE
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