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Long live qCompareStrings()!

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These free functions are designed to solve the problem that we
currently have QString::compare(QString, QString), but we have no
QString::compare(QStringRef, QString), even though we have
QString::compare(QStringRef). A compare(QString, QStringRef) only
exists in QStringRef.

This makes writing generic code tedious and error prone.

Notably absent are comparisons involving char* and QByteArray. These
will be added when we add QUtf8String, the UTF-8 counterpart to
QLatin1String.

Change-Id: I2dd7c4b1a1e0883ef0091396ee8c190012f4efba
Reviewed-by: Anton Kudryavtsev <antkudr@mail.ru>
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
This commit is contained in:
Marc Mutz 2017-03-10 11:06:01 +01:00
parent 8c779f9760
commit 9349ec2921
3 changed files with 127 additions and 10 deletions
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6
src/corelib/doc/snippets/qstring/main.cpp
View File

@ -321,6 +321,12 @@ void Widget::compareSensitiveFunction()
int y = QString::compare("auto", "Car", Qt::CaseSensitive); // y > 0
int z = QString::compare("auto", "Car", Qt::CaseInsensitive); // z < 0
//! [16]
//! [qCompareStrings-QSV-QSV]
int x = qCompareStrings(u"aUtO", u"AuTo", Qt::CaseInsensitive); // x == 0
int y = qCompareStrings(u"auto", u"Car", Qt::CaseSensitive); // y > 0
int z = qCompareStrings(u"auto", u"Car", Qt::CaseInsensitive); // z < 0
//! [qCompareStrings-QSV-QSV]
}
void Widget::containsFunction()

125
src/corelib/tools/qstring.cpp
View File

@ -693,6 +693,93 @@ static int qt_compare_strings(QStringView lhs, QLatin1String rhs, Qt::CaseSensit
return ucstricmp(lhs.begin(), lhs.end(), rhs.begin(), rhs.end());
}
static int qt_compare_strings(QLatin1String lhs, QLatin1String rhs, Qt::CaseSensitivity cs) Q_DECL_NOTHROW
{
const auto l = std::min(lhs.size(), rhs.size());
int r;
if (cs == Qt::CaseSensitive)
r = qstrncmp(lhs.data(), rhs.data(), l);
else
r = qstrnicmp(lhs.data(), rhs.data(), l);
return r ? r : lencmp(lhs.size(), rhs.size());
}
/*!
\relates QStringView
\since 5.10
Returns an integer that compares to 0 as \a lhs compares to \a rhs.
If \a cs is Qt::CaseSensitive (the default), the comparison is case-sensitive;
otherwise the comparison is case-insensitive.
Case-sensitive comparison is based exclusively on the numeric Unicode values
of the characters and is very fast, but is not what a human would expect.
Consider sorting user-visible strings with QString::localeAwareCompare().
\snippet qstring/main.cpp qCompareStrings-QSV-QSV
*/
int qCompareStrings(QStringView lhs, QStringView rhs, Qt::CaseSensitivity cs) Q_DECL_NOTHROW
{
return qt_compare_strings(lhs, rhs, cs);
}
/*!
\relates QStringView
\since 5.10
\overload
Returns an integer that compares to 0 as \a lhs compares to \a rhs.
If \a cs is Qt::CaseSensitive (the default), the comparison is case-sensitive;
otherwise the comparison is case-insensitive.
Case-sensitive comparison is based exclusively on the numeric Unicode values
of the characters and is very fast, but is not what a human would expect.
Consider sorting user-visible strings with QString::localeAwareCompare().
*/
int qCompareStrings(QStringView lhs, QLatin1String rhs, Qt::CaseSensitivity cs) Q_DECL_NOTHROW
{
return qt_compare_strings(lhs, rhs, cs);
}
/*!
\relates QStringView
\since 5.10
\overload
Returns an integer that compares to 0 as \a lhs compares to \a rhs.
If \a cs is Qt::CaseSensitive (the default), the comparison is case-sensitive;
otherwise the comparison is case-insensitive.
Case-sensitive comparison is based exclusively on the numeric Unicode values
of the characters and is very fast, but is not what a human would expect.
Consider sorting user-visible strings with QString::localeAwareCompare().
*/
int qCompareStrings(QLatin1String lhs, QStringView rhs, Qt::CaseSensitivity cs) Q_DECL_NOTHROW
{
return -qt_compare_strings(rhs, lhs, cs);
}
/*!
\relates QStringView
\since 5.10
\overload
Returns an integer that compares to 0 as \a lhs compares to \a rhs.
If \a cs is Qt::CaseSensitive (the default), the comparison is case-sensitive;
otherwise the comparison is case-insensitive.
Case-sensitive comparison is based exclusively on the numeric Latin-1 values
of the characters and is very fast, but is not what a human would expect.
Consider sorting user-visible strings with QString::localeAwareCompare().
*/
int qCompareStrings(QLatin1String lhs, QLatin1String rhs, Qt::CaseSensitivity cs) Q_DECL_NOTHROW
{
return qt_compare_strings(lhs, rhs, cs);
}
/*!
\internal
@ -5279,7 +5366,7 @@ QString& QString::fill(QChar ch, int size)
Equivalent to \c {s1 != 0 && compare(s1, s2) == 0}.
\sa QString::compare()
\sa qCompareStrings()
*/
/*!
@ -5292,7 +5379,7 @@ QString& QString::fill(QChar ch, int size)
For \a s1 != 0, this is equivalent to \c {compare(} \a s1, \a s2
\c {) != 0}. Note that no string is equal to \a s1 being 0.
\sa QString::compare()
\sa qCompareStrings()
*/
/*!
@ -5308,7 +5395,7 @@ QString& QString::fill(QChar ch, int size)
expect. Consider sorting user-interface strings using the
QString::localeAwareCompare() function.
\sa QString::compare()
\sa qCompareStrings()
*/
/*!
@ -5324,7 +5411,7 @@ QString& QString::fill(QChar ch, int size)
expect. Consider sorting user-interface strings with
QString::localeAwareCompare().
\sa QString::compare()
\sa qCompareStrings()
*/
/*!
@ -5339,7 +5426,7 @@ QString& QString::fill(QChar ch, int size)
expect. Consider sorting user-interface strings using the
QString::localeAwareCompare() function.
\sa QString::compare()
\sa qCompareStrings()
*/
/*!
@ -5420,7 +5507,7 @@ QString& QString::fill(QChar ch, int size)
\snippet qstring/main.cpp 16
\sa operator==(), operator<(), operator>()
\sa qCompareStrings(), operator==(), operator<(), operator>()
*/
/*!
@ -5430,6 +5517,8 @@ QString& QString::fill(QChar ch, int size)
Performs a comparison of \a s1 and \a s2, using the case
sensitivity setting \a cs.
\sa qCompareStrings()
*/
/*!
@ -5440,6 +5529,8 @@ QString& QString::fill(QChar ch, int size)
Performs a comparison of \a s1 and \a s2, using the case
sensitivity setting \a cs.
\sa qCompareStrings()
*/
@ -5453,6 +5544,8 @@ QString& QString::fill(QChar ch, int size)
string.
Same as compare(*this, \a other, \a cs).
\sa qCompareStrings()
*/
int QString::compare(const QString &other, Qt::CaseSensitivity cs) const Q_DECL_NOTHROW
{
@ -5478,6 +5571,8 @@ int QString::compare_helper(const QChar *data1, int length1, const QChar *data2,
\since 4.2
Same as compare(*this, \a other, \a cs).
\sa qCompareStrings()
*/
int QString::compare(QLatin1String other, Qt::CaseSensitivity cs) const Q_DECL_NOTHROW
{
@ -5491,6 +5586,8 @@ int QString::compare(QLatin1String other, Qt::CaseSensitivity cs) const Q_DECL_N
Compares the string reference, \a ref, with the string and returns
an integer less than, equal to, or greater than zero if the string
is less than, equal to, or greater than \a ref.
\sa qCompareStrings()
*/
/*!
@ -5516,6 +5613,8 @@ int QString::compare_helper(const QChar *data1, int length1, const char *data2,
/*!
\fn int QString::compare(const QString &s1, const QStringRef &s2, Qt::CaseSensitivity cs = Qt::CaseSensitive)
\overload compare()
\sa qCompareStrings()
*/
/*!
@ -9588,6 +9687,8 @@ QStringRef QStringRef::appendTo(QString *string) const
If \a cs is Qt::CaseSensitive, the comparison is case sensitive;
otherwise the comparison is case insensitive.
\sa qCompareStrings()
*/
/*!
@ -9601,6 +9702,8 @@ QStringRef QStringRef::appendTo(QString *string) const
If \a cs is Qt::CaseSensitive, the comparison is case sensitive;
otherwise the comparison is case insensitive.
\sa qCompareStrings()
*/
/*!
@ -9614,6 +9717,8 @@ QStringRef QStringRef::appendTo(QString *string) const
If \a cs is Qt::CaseSensitive, the comparison is case sensitive;
otherwise the comparison is case insensitive.
\sa qCompareStrings()
*/
/*!
@ -9630,7 +9735,7 @@ QStringRef QStringRef::appendTo(QString *string) const
Equivalent to \c {compare(*this, other, cs)}.
\sa QString::compare()
\sa qCompareStrings()
*/
/*!
@ -9647,7 +9752,7 @@ QStringRef QStringRef::appendTo(QString *string) const
Equivalent to \c {compare(*this, other, cs)}.
\sa QString::compare()
\sa qCompareStrings()
*/
/*!
@ -9664,7 +9769,7 @@ QStringRef QStringRef::appendTo(QString *string) const
Equivalent to \c {compare(*this, other, cs)}.
\sa QString::compare()
\sa qCompareStrings()
*/
/*!
@ -9682,7 +9787,7 @@ QStringRef QStringRef::appendTo(QString *string) const
Equivalent to \c {compare(*this, other, cs)}.
\sa QString::compare()
\sa qCompareStrings()
*/
/*!

6
src/corelib/tools/qstring.h
View File

@ -88,8 +88,14 @@ class QStringList;
class QTextCodec;
class QStringRef;
class QStringView;
class QLatin1String;
template <typename T> class QVector;
Q_CORE_EXPORT int qCompareStrings(QStringView lhs, QStringView rhs, Qt::CaseSensitivity cs = Qt::CaseSensitive) Q_DECL_NOTHROW Q_REQUIRED_RESULT;
Q_CORE_EXPORT int qCompareStrings(QStringView lhs, QLatin1String rhs, Qt::CaseSensitivity cs = Qt::CaseSensitive) Q_DECL_NOTHROW Q_REQUIRED_RESULT;
Q_CORE_EXPORT int qCompareStrings(QLatin1String lhs, QStringView rhs, Qt::CaseSensitivity cs = Qt::CaseSensitive) Q_DECL_NOTHROW Q_REQUIRED_RESULT;
Q_CORE_EXPORT int qCompareStrings(QLatin1String lhs, QLatin1String rhs, Qt::CaseSensitivity cs = Qt::CaseSensitive) Q_DECL_NOTHROW Q_REQUIRED_RESULT;
class QLatin1String
{
public: