QCollator: add public, static functions to do comparisons

Collation with the default QCollator object (no numeric, punctuation or
case sensitivity changes) is a common-place occurrence, so add two
functions to do this work.

It's also what QString::localeAwareCompare() calls.

The test ends up testing that default, static collator updates after the
default QLocale changes too.

Task-number: QTBUG-95050
Change-Id: I7e0b82c2d2fe464082d8fffd1696ac77f32840b2
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

src/corelib/text/qcollator.cpp

@@ -43,9 +43,33 @@
 #include "qstring.h"
 
 #include "qdebug.h"
+#include "qlocale_p.h"
+#include "qthreadstorage.h"
 
 QT_BEGIN_NAMESPACE
 
+namespace {
+struct GenerationalCollator
+{
+    QCollator theCollator;
+    int generation = QLocalePrivate::s_generation.loadRelaxed();
+public:
+    GenerationalCollator() = default;
+    GenerationalCollator(const QCollator &copy) : theCollator(copy) {}
+    QCollator &collator()
+    {
+        int currentGeneration = QLocalePrivate::s_generation.loadRelaxed();
+        if (Q_UNLIKELY(generation != currentGeneration)) {
+            // reinitialize the collator
+            generation = currentGeneration;
+            theCollator = QCollator();
+        }
+        return theCollator;
+    }
+};
+}
+Q_GLOBAL_STATIC(QThreadStorage<GenerationalCollator>, defaultCollator)
+
 /*!
     \class QCollator
     \inmodule QtCore
@@ -344,6 +368,33 @@ bool QCollator::ignorePunctuation() const
 */
 #endif // QT_STRINGVIEW_LEVEL < 2
 
+/*!
+    \since 6.3
+
+    Compares the strings \a s1 and \a s2, returning their sorting order. This
+    function performs the same operation as compare() on a default-constructed
+    QCollator object.
+
+    \sa compare(), defaultSortKey()
+*/
+int QCollator::defaultCompare(QStringView s1, QStringView s2)
+{
+    return defaultCollator->localData().collator().compare(s1, s2);
+}
+
+/*!
+    \since 6.3
+
+    Returns the sort key for the string \a key. This function performs the same
+    operation as sortKey() on a default-constructed QCollator object.
+
+    \sa sortKey(), defaultCompare()
+*/
+QCollatorSortKey QCollator::defaultSortKey(QStringView key)
+{
+    return defaultCollator->localData().collator().sortKey(key.toString());
+}
+
 /*!
     \fn QCollatorSortKey QCollator::sortKey(const QString &string) const
 

src/corelib/text/qcollator.h

@@ -117,6 +117,9 @@ public:
 
     QCollatorSortKey sortKey(const QString &string) const;
 
+    static int defaultCompare(QStringView s1, QStringView s2);
+    static QCollatorSortKey defaultSortKey(QStringView key);
+
 private:
     QCollatorPrivate *d;
 

src/corelib/text/qstring.cpp

@@ -6214,28 +6214,6 @@ int QString::localeAwareCompare(const QString &other) const
     return localeAwareCompare_helper(constData(), length(), other.constData(), other.length());
 }
 
-#if QT_CONFIG(icu)
-namespace {
-class GenerationalCollator
-{
-    QCollator theCollator;
-    int generation = QLocalePrivate::s_generation.loadRelaxed();
-public:
-    QCollator &collator()
-    {
-        int currentGeneration = QLocalePrivate::s_generation.loadRelaxed();
-        if (Q_UNLIKELY(generation != currentGeneration)) {
-            // reinitialize the collator
-            generation = currentGeneration;
-            theCollator = QCollator();
-        }
-        return theCollator;
-    }
-};
-}
-Q_GLOBAL_STATIC(QThreadStorage<GenerationalCollator>, defaultCollator)
-#endif
-
 /*!
     \internal
     \since 4.5
@@ -6254,9 +6232,7 @@ int QString::localeAwareCompare_helper(const QChar *data1, qsizetype length1,
                                Qt::CaseSensitive);
 
 #if QT_CONFIG(icu)
-    if (!defaultCollator()->hasLocalData())
-        defaultCollator()->setLocalData(GenerationalCollator());
-    return defaultCollator()->localData().collator().compare(data1, length1, data2, length2);
+    return QCollator::defaultCompare(QStringView(data1, length1), QStringView(data2, length2));
 #else
     const QString lhs = QString::fromRawData(data1, length1).normalized(QString::NormalizationForm_C);
     const QString rhs = QString::fromRawData(data2, length2).normalized(QString::NormalizationForm_C);

tests/auto/corelib/text/qcollator/tst_qcollator.cpp

@@ -31,6 +31,7 @@
 #include <qlocale.h>
 #include <qcollator.h>
 #include <private/qglobal_p.h>
+#include <QScopeGuard>
 
 #include <cstring>
 
@@ -276,6 +277,13 @@ void tst_QCollator::compare()
     QFETCH(int, punctuationResult);
 
     QCollator collator((QLocale(locale)));
+
+    // AFTER the QCollator initialization
+    auto localechanger = qScopeGuard([original = QLocale()] {
+        QLocale::setDefault(original);  // reset back to what it was
+    });
+    QLocale::setDefault(QLocale(locale));
+
     // Need to canonicalize sign to -1, 0 or 1, as .compare() can produce any -ve for <, any +ve for >.
     auto asSign = [](int compared) {
         return compared < 0 ? -1 : compared > 0 ? 1 : 0;
@@ -310,10 +318,17 @@ void tst_QCollator::compare()
     // NOTE: currently QCollatorSortKey::compare is not working
     // properly without icu: see QTBUG-88704 for details
     QCOMPARE(asSign(collator.compare(s1, s2)), result);
+    if (!numericMode)
+        QCOMPARE(asSign(QCollator::defaultCompare(s1, s2)), result);
 #if QT_CONFIG(icu)
     auto key1 = collator.sortKey(s1);
     auto key2 = collator.sortKey(s2);
     QCOMPARE(asSign(key1.compare(key2)), keyCompareResult);
+
+    key1 = QCollator::defaultSortKey(s1);
+    key2 = QCollator::defaultSortKey(s2);
+    if (!numericMode)
+        QCOMPARE(asSign(key1.compare(key2)), keyCompareResult);
 #endif
     collator.setCaseSensitivity(Qt::CaseInsensitive);
     QCOMPARE(asSign(collator.compare(s1, s2)), caseInsensitiveResult);