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QUuid: de-duplicate uuid → string formatting

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The code was duplicated for QChar and char characters. Keep only the
char version, and use QString::fromLatin1() to convert to QString.

This does not perform more allocations. It just copies 38 bytes more
than before.

Saves 788B in text size on optimized GCC 6.1 Linux AMD64 builds.

Change-Id: I1a65c8128eb2097e11527961618d54ea362e1b80
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
This commit is contained in:
Marc Mutz 2017-04-10 15:29:59 +02:00
parent d5cecfe8fd
commit b3e66c76aa
1 changed files with 31 additions and 28 deletions
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59
src/corelib/plugin/quuid.cpp
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@ -1,6 +1,7 @@
/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Copyright (C) 2017 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Marc Mutz <marc.mutz@kdab.com>
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtCore module of the Qt Toolkit.
@ -49,16 +50,20 @@
#endif
QT_BEGIN_NAMESPACE
template <class Char, class Integral>
void _q_toHex(Char *&dst, Integral value)
// 16 bytes (a uint, two shorts and a uchar[8]), each represented by two hex
// digits; plus four dashes and a pair of enclosing brace: 16*2 + 4 + 2 = 38.
enum { MaxStringUuidLength = 38 };
template <class Integral>
void _q_toHex(char *&dst, Integral value)
{
value = qToBigEndian(value);
const char* p = reinterpret_cast<const char*>(&value);
for (uint i = 0; i < sizeof(Integral); ++i, dst += 2) {
dst[0] = Char(QtMiscUtils::toHexLower((p[i] >> 4) & 0xf));
dst[1] = Char(QtMiscUtils::toHexLower(p[i] & 0xf));
dst[0] = QtMiscUtils::toHexLower((p[i] >> 4) & 0xf);
dst[1] = QtMiscUtils::toHexLower(p[i] & 0xf);
}
}
@ -79,22 +84,22 @@ bool _q_fromHex(const Char *&src, Integral &value)
return true;
}
template <class Char>
void _q_uuidToHex(Char *&dst, const uint &d1, const ushort &d2, const ushort &d3, const uchar (&d4)[8])
static char *_q_uuidToHex(const QUuid &uuid, char *dst)
{
*dst++ = Char('{');
_q_toHex(dst, d1);
*dst++ = Char('-');
_q_toHex(dst, d2);
*dst++ = Char('-');
_q_toHex(dst, d3);
*dst++ = Char('-');
*dst++ = '{';
_q_toHex(dst, uuid.data1);
*dst++ = '-';
_q_toHex(dst, uuid.data2);
*dst++ = '-';
_q_toHex(dst, uuid.data3);
*dst++ = '-';
for (int i = 0; i < 2; i++)
_q_toHex(dst, d4[i]);
*dst++ = Char('-');
_q_toHex(dst, uuid.data4[i]);
*dst++ = '-';
for (int i = 2; i < 8; i++)
_q_toHex(dst, d4[i]);
*dst = Char('}');
_q_toHex(dst, uuid.data4[i]);
*dst++ = '}';
return dst;
}
template <class Char>
@ -548,12 +553,11 @@ QUuid QUuid::fromRfc4122(const QByteArray &bytes)
*/
QString QUuid::toString() const
{
QString result(38, Qt::Uninitialized);
ushort *data = (ushort *)result.data();
_q_uuidToHex(data, data1, data2, data3, data4);
return result;
char latin1[MaxStringUuidLength];
const auto end = _q_uuidToHex(*this, latin1);
Q_ASSERT(end - latin1 == MaxStringUuidLength);
Q_UNUSED(end);
return QString::fromLatin1(latin1, MaxStringUuidLength);
}
/*!
@ -594,11 +598,10 @@ QString QUuid::toString() const
*/
QByteArray QUuid::toByteArray() const
{
QByteArray result(38, Qt::Uninitialized);
char *data = result.data();
_q_uuidToHex(data, data1, data2, data3, data4);
QByteArray result(MaxStringUuidLength, Qt::Uninitialized);
const auto end = _q_uuidToHex(*this, const_cast<char*>(result.constData()));
Q_ASSERT(end - result.constData() == MaxStringUuidLength);
Q_UNUSED(end);
return result;
}