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Prevent 2 unnecessary QString allocations for QString::number(0u) 

QLocaleData::unsLongLongToString uses qulltoa, which will allocate a
zero-length QArrayData. Then with padding a single 0 was put in a
QString, which gets prepended to the result. By taking care of this
special case, we can now also fast-path the common case where base=10
and no flags nor precision was provided.

Change-Id: Ia893b0ea4c77634c24e7cef5aafb06d0ef44c507
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
bb10
Erik Verbruggen 2017-04-20 15:43:01 +02:00
parent dbd55cdaf3
commit 3727474421
1 changed files with 6 additions and 3 deletions
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9
src/corelib/tools/qlocale.cpp
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@ -3005,14 +3005,18 @@ QString QLocaleData::unsLongLongToString(const QChar zero, const QChar group,
int base, int width,
unsigned flags)
{
const QChar resultZero = base == 10 ? zero : QChar(QLatin1Char('0'));
QString num_str = l ? qulltoa(l, base, zero) : QString(resultZero);
bool precision_not_specified = false;
if (precision == -1) {
if (flags == NoFlags)
return num_str; // fast-path: nothing below applies, so we're done.
precision_not_specified = true;
precision = 1;
}
QString num_str = qulltoa(l, base, zero);
uint cnt_thousand_sep = 0;
if (flags & ThousandsGroup && base == 10) {
for (int i = num_str.length() - 3; i > 0; i -=3) {
@ -3021,7 +3025,6 @@ QString QLocaleData::unsLongLongToString(const QChar zero, const QChar group,
}
}
const QChar resultZero = base == 10 ? zero : QChar(QLatin1Char('0'));
const int zeroPadding = precision - num_str.length()/* + cnt_thousand_sep*/;
if (zeroPadding > 0)
num_str.prepend(QString(zeroPadding, resultZero));