Add support for calendars beside Gregorian

Add QCalendarBackend as a base class for calendar implementations and
QCalendar as a facade via which to access it.

QDate's implicit implementation of the Gregorian calendar becomes
QGregorianCalendar and QDate methods now support choice of calendar.

Convert QLocale's CLDR data for month names to a locale-data component
of each supported calendar and relevant QLocale methods now support
choice of calendar. Adapt Python scripts for locale data generation to
extract month name data from CLDR (keeping on version v35.1) into the
new calendar-locale files. The locale data for the Gregorian calendar
is held in a Roman calendar base, for sharing with other calendars.

Add tests for basic uses of the new API.

[ChangeLog][QtCore][QCalendar] Added QCalendar to support diverse
calendars, supported by implementing QCalendarBackend.

[ChangeLog][QtCore][QDate] Allow choice of calendar in various
operations, with Gregorian remaining the default.

Done-with: Lars Knoll <lars.knoll@qt.io>
Done-with: Edward Welbourne <edward.welbourne@qt.io>
Fixes: QTBUG-17110
Fixes: QTBUG-950
Change-Id: I9d6278f394269a183aee8156e990cec4d5198ab8
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

1 files changed, 19 insertions, 2 deletions

diff --git a/src/corelib/text/qlocale.h b/src/corelib/text/qlocale.h
index 09de830ca3..87966b266b 100644
--- a/src/corelib/text/qlocale.h
+++ b/src/corelib/text/qlocale.h
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2018 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the QtCore module of the Qt Toolkit.
@@ -47,7 +47,7 @@
 
 QT_BEGIN_NAMESPACE
 
-
+class QCalendar;
 class QDataStream;
 class QDate;
 class QDateTime;
@@ -1013,6 +1013,14 @@ public:
     QString toString(const QDate &date, FormatType format = LongFormat) const;
     QString toString(const QTime &time, FormatType format = LongFormat) const;
     QString toString(const QDateTime &dateTime, FormatType format = LongFormat) const;
+    /* Removing default value for `format' is done intentionally,
+     * after all tests we will remove non-calendar-aware version of these functions,
+     * and add a default value for both calendar instance, and format
+     */
+    QString toString(const QDate &date, QStringView formatStr, QCalendar cal) const;
+    QString toString(const QDate &date, FormatType format, QCalendar cal) const;
+    QString toString(const QDateTime &dateTime, FormatType format, QCalendar cal) const;
+    QString toString(const QDateTime &dateTime, QStringView formatStr, QCalendar cal) const;
 
     QString dateFormat(FormatType format = LongFormat) const;
     QString timeFormat(FormatType format = LongFormat) const;
@@ -1024,6 +1032,13 @@ public:
     QDate toDate(const QString &string, const QString &format) const;
     QTime toTime(const QString &string, const QString &format) const;
     QDateTime toDateTime(const QString &string, const QString &format) const;
+    // Calendar-aware API
+    QDate toDate(const QString &string, FormatType format, QCalendar cal) const;
+    QTime toTime(const QString &string, FormatType format, QCalendar cal) const;
+    QDateTime toDateTime(const QString &string, FormatType format, QCalendar cal) const;
+    QDate toDate(const QString &string, const QString &format, QCalendar cal) const;
+    QTime toTime(const QString &string, const QString &format, QCalendar cal) const;
+    QDateTime toDateTime(const QString &string, const QString &format, QCalendar cal) const;
 #endif
 
     // ### Qt 5: We need to return QString from these function since
@@ -1108,6 +1123,8 @@ private:
     QLocale(QLocalePrivate &dd);
     friend class QLocalePrivate;
     friend class QSystemLocale;
+    friend class QCalendarBackend;
+    friend class QGregorianCalendar;
     friend Q_CORE_EXPORT uint qHash(const QLocale &key, uint seed) noexcept;
 
     QSharedDataPointer<QLocalePrivate> d;