Performance is more important in this case than the theoretical benefit
of constexpr. This commit implements the SSE2 search for 16-bit null and
it might be possible to implement the equivalent for AArch64
(investigation required). It also adds a fallback to wcslen() for
systems where wchar_t is short (non-x86 Windows or 32-bit x86 build with
-no-sse2).
We can re-add the constexpr loop once the C++ language has a way of
overloading constexpr and non-constexpr. GCC has a non-standard way to
do that with __builtin_constant_p, which is also implemented in this
commit, but note that the inline function is still not constexpr.
Change-Id: I6e9274c1e7444ad48c81fffd14dcaacafda5ebdc
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This is often more natural than (ptr, len), and I need it in the
implementation of QStringView::trimmed().
Change-Id: I1d99b5ddaf76eee0582150b0233ef6ce9c37d25d
Reviewed-by: Anton Kudryavtsev <antkudr@mail.ru>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
[ChangeLog][QtTest][QCOMPARE] Now supports printing QStringViews in
case of test failures.
Change-Id: I4dc2542cd1013fd63c094c249e721d7102387bde
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
... instead of the combination with Q_OS_WIN we used so far.
This patch adapts ocurrences that are new in 5.10.
Change-Id: If392df481713e56c776c2326e0e02324a3a80c89
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Nothing changes, we've just given 'QIntegerForSizeof<size_t>::Signed'
a better name in qglobal.h and now use it in QStringView API and
users.
Change-Id: Ibea1ae26e95b3a96708400fd4b0cd120459d57b6
Reviewed-by: Anton Kudryavtsev <antkudr@mail.ru>
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
With sufficient enable_if magic, the array ctor can overload the
pointer ctor and statically determine the size of the array passed.
Consequently, remove the sizeof in QStringViewLiteral again.
Change-Id: I486baa3cafefde60ccc5f2b47eb94ee53cefe63c
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Remove most of the std::equal() tests that were used to determine
equality in pre-relational-operator-times again.
Amends a1421e4787.
Change-Id: Iff64808f5ac60861caee899d594b512b58046636
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Anton Kudryavtsev <antkudr@mail.ru>
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
We want to prevent
QStringView(QChar|QLatin1String|QByteArray|const char*)
from compiling as QStringView(QString(...)), so I added = delete'ed
ctors for these types to QStringView. However, that makes QStringView
participate in overload resolution for these types. Even if the
QStringView ctor will always fail to compile, the presence of these
ctors alone makes calls to functions overloaded on QString and
QStringView ambiguous:
f(QStringView);
f(QString);
f(foo); // ambiguous
f(QChar('f')) // ambiguous
f(QLatin1String(foo)); // ambiguous
f(QByteArray(foo)); // ambiguous
Fix by making the QString and QStringRef constructors templates
constrained to accept only these two types. This should also help to
move the QStringView definition to before the QString one (as soon as
we get rid of or start to ignore QString::Null), simplifying a lot of
code in qstring.h down the line.
This should also fix MSVC's accepting of two user-defined conversions
which caused static non-compile-tests to fail in the initial
QStringView patch, and which were therefore removed. This patch brings
them back.
Change-Id: I95ac38c0d31cd8c726f7e952017569d32e484413
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
QStringView is a simple container for (const QChar*, int) and (const
char16_t*, size_t). It acts as a replacement interface type for const
QString and const QStringRef, and enables passing all kinds of
string-like types to functions otherwise expecting const QString& -
without the need to convert to QString first.
The use of this new class is guarded by a macro that enables three
levels of QStringView support:
1. offer QStringView, overload some functions taking QString with
QStringView
2. like 1, but remove all overloads of functions taking QStringRef,
leaving only the function taking QStringView. Do this only where
QStringRef overloads tradionally existed.
3. like 2, but replace functions taking QString, too.
This is done in order to measure the impact of QStringView on code
size and execution speed, and to help guide the decision of which
level to choose for Qt 6.
This first patch adds QStringView with most of its planned
constructors, but not much more than iterators and isNull()/isEmpty().
Further patches will add support for QStringView to QStringBuilder,
add QStringView overloads of functions taking QString, and add the
complete API of const QString to QStringView.
[ChangeLog][QtCore][QStringView] New class, superseding const QString
and QStringRef as function parameters, accepting a wide variety of
UTF-16 string data sources, e.g. u"string", std::u16string{,_view},
and, on Windows, L"string", std::wstring{,_view} without converting to
QString first.
Change-Id: Iac273e46b2c61ec2c31b3dacebb29500599d6898
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
