From 5a91b734f2ac42df694c8052eaaf39c03c7cfab0 Mon Sep 17 00:00:00 2001
From: Edward Welbourne <edward.welbourne@qt.io>
Date: Mon, 23 Jan 2023 19:57:01 +0100
Subject: [PATCH] Shuffle QGregorianCalendar's parts
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Before I embark on some cleanup in the calendrical calculations, move
julianFromParts() to alongside partsFromJulian() - they're the static
methods used to bypass virtuals internally - and pull out a duplicated
comment from them to put before both.

Move julianDayToDate() to sit with its fellow virtual shim, each
calling one of the above, dateToJulianDay().

Change-Id: I581c08bae4c921c4a5cd48eebb66d46035d7d046
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
---
 src/corelib/time/qgregoriancalendar.cpp | 48 ++++++++++++-------------
 1 file changed, 22 insertions(+), 26 deletions(-)

diff --git a/src/corelib/time/qgregoriancalendar.cpp b/src/corelib/time/qgregoriancalendar.cpp
index db0bdb2e45..846a115446 100644
--- a/src/corelib/time/qgregoriancalendar.cpp
+++ b/src/corelib/time/qgregoriancalendar.cpp
@@ -100,26 +100,9 @@ bool QGregorianCalendar::dateToJulianDay(int year, int month, int day, qint64 *j
     return julianFromParts(year, month, day, jd);
 }
 
-bool QGregorianCalendar::julianFromParts(int year, int month, int day, qint64 *jd)
+QCalendar::YearMonthDay QGregorianCalendar::julianDayToDate(qint64 jd) const
 {
-    Q_ASSERT(jd);
-    if (!validParts(year, month, day))
-        return false;
-
-    if (year < 0)
-        ++year;
-
-    /*
-     * Math from The Calendar FAQ at http://www.tondering.dk/claus/cal/julperiod.php
-     * This formula is correct for all julian days, when using mathematical integer
-     * division (round to negative infinity), not c++11 integer division (round to zero)
-     */
-    int    a = month < 3 ? 1 : 0;
-    qint64 y = qint64(year) + 4800 - a;
-    int    m = month + 12 * a - 3;
-    *jd = day + qDiv<5>(153 * m + 2) - 32045
-        + 365 * y + qDiv<4>(y) - qDiv<100>(y) + qDiv<400>(y);
-    return true;
+    return partsFromJulian(jd);
 }
 
 int QGregorianCalendar::yearStartWeekDay(int year)
@@ -175,18 +158,31 @@ int QGregorianCalendar::yearSharingWeekDays(QDate date)
     return res;
 }
 
-QCalendar::YearMonthDay QGregorianCalendar::julianDayToDate(qint64 jd) const
+/*
+ * Math from The Calendar FAQ at http://www.tondering.dk/claus/cal/julperiod.php
+ * This formula is correct for all julian days, when using mathematical integer
+ * division (round to negative infinity), not c++11 integer division (round to zero).
+ */
+
+bool QGregorianCalendar::julianFromParts(int year, int month, int day, qint64 *jd)
 {
-    return partsFromJulian(jd);
+    Q_ASSERT(jd);
+    if (!validParts(year, month, day))
+        return false;
+
+    if (year < 0)
+        ++year;
+
+    int    a = month < 3 ? 1 : 0;
+    qint64 y = qint64(year) + 4800 - a;
+    int    m = month + 12 * a - 3;
+    *jd = day + qDiv<5>(153 * m + 2) - 32045
+        + 365 * y + qDiv<4>(y) - qDiv<100>(y) + qDiv<400>(y);
+    return true;
 }
 
 QCalendar::YearMonthDay QGregorianCalendar::partsFromJulian(qint64 jd)
 {
-    /*
-     * Math from The Calendar FAQ at http://www.tondering.dk/claus/cal/julperiod.php
-     * This formula is correct for all julian days, when using mathematical integer
-     * division (round to negative infinity), not c++11 integer division (round to zero)
-     */
     qint64 a = jd + 32044;
     qint64 b = qDiv<146097>(4 * a + 3);
     int    c = a - qDiv<4>(146097 * b);