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QString: introduce ucstreq() to optimize equalStrings()

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If the lengths aren't equal, the strings can't be equal either, so we
can skip the entire comparison. Some of the front-end functions that
call these entry points already check for this, actually.

Change-Id: Ib42b3adc93bf4d43bd55fffd16c8ceb9594512f2
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
This commit is contained in:
Thiago Macieira 2022-01-09 20:35:59 -08:00
parent b386346468
commit 2932c3f942
1 changed files with 15 additions and 2 deletions
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17
src/corelib/text/qstring.cpp
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@ -1314,6 +1314,19 @@ constexpr int lencmp(qsizetype lhs, qsizetype rhs) noexcept
/* else */ -1 ;
}
// Unicode case-sensitive equality
template <typename Char2>
static bool ucstreq(const QChar *a, size_t alen, const Char2 *b, size_t blen)
{
if (alen != blen)
return false;
if constexpr (std::is_same_v<decltype(a), decltype(b)>) {
if (a == b)
return true;
}
return ucstrncmp(a, b, alen) == 0;
}
// Unicode case-sensitive comparison
static int ucstrcmp(const QChar *a, size_t alen, const QChar *b, size_t blen)
{
@ -1371,12 +1384,12 @@ static int latin1nicmp(const char *lhsChar, qsizetype lSize, const char *rhsChar
}
bool QtPrivate::equalStrings(QStringView lhs, QStringView rhs) noexcept
{
return ucstrcmp(lhs.begin(), lhs.size(), rhs.begin(), rhs.size()) == 0;
return ucstreq(lhs.begin(), lhs.size(), rhs.begin(), rhs.size());
}
bool QtPrivate::equalStrings(QStringView lhs, QLatin1String rhs) noexcept
{
return ucstrcmp(lhs.begin(), lhs.size(), rhs.begin(), rhs.size()) == 0;
return ucstreq(lhs.begin(), lhs.size(), rhs.begin(), rhs.size());
}
bool QtPrivate::equalStrings(QLatin1String lhs, QStringView rhs) noexcept