Related: tdf#152114 Move some tools' Date class algorithms to comphelper::date

So they can be reused, specifically in
connectivity/source/commontools/dbconversion.cxx

Change-Id: I8b2b59e3cb078a73d5f670f0756404471009cf9b
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/143114
Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Jenkins

4 files changed, 375 insertions, 211 deletions

diff --git a/comphelper/Library_comphelper.mk b/comphelper/Library_comphelper.mk
index 6d0536058882..0bad46866d54 100644
--- a/comphelper/Library_comphelper.mk
+++ b/comphelper/Library_comphelper.mk
@@ -97,6 +97,7 @@ $(eval $(call gb_Library_add_exception_objects,comphelper,\
     comphelper/source/misc/componentbase \
     comphelper/source/misc/configuration \
     comphelper/source/misc/configurationhelper \
+    comphelper/source/misc/date \
     comphelper/source/misc/debuggerinfo \
     comphelper/source/misc/diagnose_ex \
     comphelper/source/misc/DirectoryHelper \
diff --git a/comphelper/source/misc/date.cxx b/comphelper/source/misc/date.cxx
new file mode 100644
index 000000000000..ea8a588dbabd
--- /dev/null
+++ b/comphelper/source/misc/date.cxx
@@ -0,0 +1,262 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * This file incorporates work covered by the following license notice:
+ *
+ *   Licensed to the Apache Software Foundation (ASF) under one or more
+ *   contributor license agreements. See the NOTICE file distributed
+ *   with this work for additional information regarding copyright
+ *   ownership. The ASF licenses this file to you under the Apache
+ *   License, Version 2.0 (the "License"); you may not use this file
+ *   except in compliance with the License. You may obtain a copy of
+ *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
+ */
+
+#include <comphelper/date.hxx>
+
+#include <cassert>
+
+namespace comphelper::date
+{
+// Once upon a time the number of days we internally handled in tools' class
+// Date was limited to MAX_DAYS 3636532. That changed with a full 16-bit year.
+// Assuming the first valid positive date in a proleptic Gregorian calendar is
+// 0001-01-01, this resulted in an end date of 9957-06-26.
+// Hence we documented that years up to and including 9956 are handled.
+/* XXX: it is unclear history why this value was chosen, the representable
+ * 9999-12-31 would be 3652060 days from 0001-01-01. Even 9998-12-31 to
+ * distinguish from a maximum possible date would be 3651695.
+ * There is connectivity/source/commontools/dbconversion.cxx that still has the
+ * same value to calculate with css::util::Date */
+/* XXX can that dbconversion cope with years > 9999 or negative years at all?
+ * Database fields may be limited to positive 4 digits. */
+
+constexpr sal_Int32 MIN_DAYS = -11968265; // -32768-01-01
+constexpr sal_Int32 MAX_DAYS = 11967900; //  32767-12-31
+
+constexpr sal_Int16 kYearMax = SAL_MAX_INT16;
+constexpr sal_Int16 kYearMin = SAL_MIN_INT16;
+
+sal_Int32 YearToDays(sal_Int16 nYear)
+{
+    assert(nYear != 0);
+    sal_Int32 nOffset;
+    sal_Int32 nYr;
+    if (nYear < 0)
+    {
+        nOffset = -366;
+        nYr = nYear + 1;
+    }
+    else
+    {
+        nOffset = 0;
+        nYr = nYear - 1;
+    }
+    return nOffset + nYr * 365 + nYr / 4 - nYr / 100 + nYr / 400;
+}
+
+bool isLeapYear(sal_Int16 nYear)
+{
+    assert(nYear != 0);
+    if (nYear < 0)
+        nYear = -nYear - 1;
+    return (((nYear % 4) == 0) && ((nYear % 100) != 0)) || ((nYear % 400) == 0);
+}
+
+sal_uInt16 getDaysInMonth(sal_uInt16 nMonth, sal_Int16 nYear)
+{
+    assert(1 <= nMonth && nMonth <= 12);
+    if (nMonth < 1 || 12 < nMonth)
+        return 0;
+
+    constexpr sal_uInt16 aDaysInMonth[12] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
+    if (nMonth != 2)
+        return aDaysInMonth[nMonth - 1];
+    else
+    {
+        if (isLeapYear(nYear))
+            return aDaysInMonth[nMonth - 1] + 1;
+        else
+            return aDaysInMonth[nMonth - 1];
+    }
+}
+
+sal_Int32 convertDateToDays(sal_uInt16 nDay, sal_uInt16 nMonth, sal_Int16 nYear)
+{
+    sal_Int32 nDays = YearToDays(nYear);
+    for (sal_uInt16 i = 1; i < nMonth; ++i)
+        nDays += getDaysInMonth(i, nYear);
+    nDays += nDay;
+    return nDays;
+}
+
+sal_Int32 convertDateToDaysNormalizing(sal_uInt16 nDay, sal_uInt16 nMonth, sal_Int16 nYear)
+{
+    // Speed-up the common null-date 1899-12-30.
+    if (nYear == 1899 && nDay == 30 && nMonth == 12)
+    {
+        assert(convertDateToDays(nDay, nMonth, nYear) == 693594);
+        return 693594;
+    }
+    normalize(nDay, nMonth, nYear);
+    return convertDateToDays(nDay, nMonth, nYear);
+}
+
+bool isValidDate(sal_uInt16 nDay, sal_uInt16 nMonth, sal_Int16 nYear)
+{
+    if (nYear == 0)
+        return false;
+    if (nMonth < 1 || 12 < nMonth)
+        return false;
+    if (nDay < 1 || (nDay > comphelper::date::getDaysInMonth(nMonth, nYear)))
+        return false;
+    return true;
+}
+
+void convertDaysToDate(sal_Int32 nDays, sal_uInt16& rDay, sal_uInt16& rMonth, sal_Int16& rYear)
+{
+    if (nDays <= MIN_DAYS)
+    {
+        rDay = 1;
+        rMonth = 1;
+        rYear = kYearMin;
+        return;
+    }
+    if (nDays >= MAX_DAYS)
+    {
+        rDay = 31;
+        rMonth = 12;
+        rYear = kYearMax;
+        return;
+    }
+
+    // Day 0 is -0001-12-31, day 1 is 0001-01-01
+    const sal_Int16 nSign = (nDays <= 0 ? -1 : 1);
+    sal_Int32 nTempDays;
+    sal_Int32 i = 0;
+    bool bCalc;
+
+    do
+    {
+        rYear = static_cast<sal_Int16>((nDays / 365) - (i * nSign));
+        if (rYear == 0)
+            rYear = nSign;
+        nTempDays = nDays - YearToDays(rYear);
+        bCalc = false;
+        if (nTempDays < 1)
+        {
+            i += nSign;
+            bCalc = true;
+        }
+        else
+        {
+            if (nTempDays > 365)
+            {
+                if ((nTempDays != 366) || !isLeapYear(rYear))
+                {
+                    i -= nSign;
+                    bCalc = true;
+                }
+            }
+        }
+    } while (bCalc);
+
+    rMonth = 1;
+    while (nTempDays > getDaysInMonth(rMonth, rYear))
+    {
+        nTempDays -= getDaysInMonth(rMonth, rYear);
+        ++rMonth;
+    }
+
+    rDay = static_cast<sal_uInt16>(nTempDays);
+}
+
+bool normalize(sal_uInt16& rDay, sal_uInt16& rMonth, sal_Int16& rYear)
+{
+    if (isValidDate(rDay, rMonth, rYear))
+        return false;
+
+    if (rDay == 0 && rMonth == 0 && rYear == 0)
+        return false; // empty date
+
+    if (rDay == 0)
+    {
+        if (rMonth == 0)
+            ; // nothing, handled below
+        else
+            --rMonth;
+        // Last day of month is determined at the end.
+    }
+
+    if (rMonth > 12)
+    {
+        rYear += rMonth / 12;
+        rMonth = rMonth % 12;
+        if (rYear == 0)
+            rYear = 1;
+    }
+    if (rMonth == 0)
+    {
+        --rYear;
+        if (rYear == 0)
+            rYear = -1;
+        rMonth = 12;
+    }
+
+    if (rYear < 0)
+    {
+        sal_uInt16 nDays;
+        while (rDay > (nDays = getDaysInMonth(rMonth, rYear)))
+        {
+            rDay -= nDays;
+            if (rMonth > 1)
+                --rMonth;
+            else
+            {
+                if (rYear == kYearMin)
+                {
+                    rDay = 1;
+                    rMonth = 1;
+                    return true;
+                }
+                --rYear;
+                rMonth = 12;
+            }
+        }
+    }
+    else
+    {
+        sal_uInt16 nDays;
+        while (rDay > (nDays = getDaysInMonth(rMonth, rYear)))
+        {
+            rDay -= nDays;
+            if (rMonth < 12)
+                ++rMonth;
+            else
+            {
+                if (rYear == kYearMax)
+                {
+                    rDay = 31;
+                    rMonth = 12;
+                    return true;
+                }
+                ++rYear;
+                rMonth = 1;
+            }
+        }
+    }
+
+    if (rDay == 0)
+        rDay = getDaysInMonth(rMonth, rYear);
+
+    return true;
+}
+
+} // namespace comphelper::date
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */
diff --git a/include/comphelper/date.hxx b/include/comphelper/date.hxx
new file mode 100644
index 000000000000..7dbe9589690e
--- /dev/null
+++ b/include/comphelper/date.hxx
@@ -0,0 +1,95 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * This file incorporates work covered by the following license notice:
+ *
+ *   Licensed to the Apache Software Foundation (ASF) under one or more
+ *   contributor license agreements. See the NOTICE file distributed
+ *   with this work for additional information regarding copyright
+ *   ownership. The ASF licenses this file to you under the Apache
+ *   License, Version 2.0 (the "License"); you may not use this file
+ *   except in compliance with the License. You may obtain a copy of
+ *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
+ */
+#pragma once
+
+#include <sal/config.h>
+#include <sal/types.h>
+#include <comphelper/comphelperdllapi.h>
+
+namespace comphelper::date
+{
+/** Days until start of year from zero, so month and day of month can be added.
+
+    year 1 => 0 days, year 2 => 365 days, ...
+    year -1 => -366 days, year -2 => -731 days, ...
+
+    @param  nYear
+            MUST be != 0.
+ */
+COMPHELPER_DLLPUBLIC sal_Int32 YearToDays(sal_Int16 nYear);
+
+/** Whether year is a leap year.
+
+    Leap years BCE are -1, -5, -9, ...
+    See
+    https://en.wikipedia.org/wiki/Proleptic_Gregorian_calendar#Usage
+    https://en.wikipedia.org/wiki/0_(year)#History_of_astronomical_usage
+
+    @param  nYear
+            MUST be != 0.
+ */
+COMPHELPER_DLLPUBLIC bool isLeapYear(sal_Int16 nYear);
+
+/** Get number of days in month of year.
+
+    @param  nYear
+            MUST be != 0.
+ */
+COMPHELPER_DLLPUBLIC sal_uInt16 getDaysInMonth(sal_uInt16 nMonth, sal_Int16 nYear);
+
+/** Obtain days from zero for a given date, without normalizing.
+
+    nDay, nMonth, nYear MUST form a valid proleptic Gregorian calendar date.
+ */
+COMPHELPER_DLLPUBLIC sal_Int32 convertDateToDays(sal_uInt16 nDay, sal_uInt16 nMonth,
+                                                 sal_Int16 nYear);
+
+/** Obtain days from zero for a given date, with normalizing.
+
+    nDay, nMonth, nYear may be out-of-bounds and are adjusted/normalized.
+
+    @param  nYear
+            Must be != 0, unless nMonth > 12.
+ */
+COMPHELPER_DLLPUBLIC sal_Int32 convertDateToDaysNormalizing(sal_uInt16 nDay, sal_uInt16 nMonth,
+                                                            sal_Int16 nYear);
+
+/** Whether date is a valid date.
+ */
+COMPHELPER_DLLPUBLIC bool isValidDate(sal_uInt16 nDay, sal_uInt16 nMonth, sal_Int16 nYear);
+
+/** Obtain date for a days from zero value.
+ */
+COMPHELPER_DLLPUBLIC void convertDaysToDate(sal_Int32 nDays, sal_uInt16& rDay, sal_uInt16& rMonth,
+                                            sal_Int16& rYear);
+
+/** Normalize date, i.e. add days or months to form a proper proleptic
+    Gregorian calendar date, unless all values are 0.
+
+    @param  rYear
+            Must be != 0, unless rMonth > 12.
+
+    @return <TRUE/> if date was normalized, <FALSE/> if it was valid already
+    or empty (all values 0).
+ */
+COMPHELPER_DLLPUBLIC bool normalize(sal_uInt16& rDay, sal_uInt16& rMonth, sal_Int16& rYear);
+
+} // namespace comphelper::date
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */
diff --git a/tools/source/datetime/tdate.cxx b/tools/source/datetime/tdate.cxx
index 979611333813..6c33dca13558 100644
--- a/tools/source/datetime/tdate.cxx
+++ b/tools/source/datetime/tdate.cxx
@@ -21,25 +21,7 @@
 #include <com/sun/star/util/DateTime.hpp>
 
 #include <systemdatetime.hxx>
-
-const sal_uInt16 aDaysInMonth[12] = { 31, 28, 31, 30, 31, 30,
-                                             31, 31, 30, 31, 30, 31 };
-
-// Once upon a time the number of days we internally handled was limited to
-// MAX_DAYS 3636532. That changed with a full 16-bit year.
-// Assuming the first valid positive date in a proleptic Gregorian calendar is
-// 0001-01-01, this resulted in an end date of 9957-06-26.
-// Hence we documented that years up to and including 9956 are handled.
-/* XXX: it is unclear history why this value was chosen, the representable
- * 9999-12-31 would be 3652060 days from 0001-01-01. Even 9998-12-31 to
- * distinguish from a maximum possible date would be 3651695.
- * There is connectivity/source/commontools/dbconversion.cxx that still has the
- * same value to calculate with css::util::Date */
-/* XXX can that dbconversion cope with years > 9999 or negative years at all?
- * Database fields may be limited to positive 4 digits. */
-
-const sal_Int32 MIN_DAYS = -11968265;     // -32768-01-01
-const sal_Int32 MAX_DAYS =  11967900;     //  32767-12-31
+#include <comphelper/date.hxx>
 
 namespace
 {
@@ -47,54 +29,6 @@ namespace
 const sal_Int16 kYearMax = SAL_MAX_INT16;
 const sal_Int16 kYearMin = SAL_MIN_INT16;
 
-// Days until start of year from zero, so month and day of month can be added.
-// year 1 => 0 days, year 2 => 365 days, ...
-// year -1 => -366 days, year -2 => -731 days, ...
-sal_Int32 ImpYearToDays( sal_Int16 nYear )
-{
-    assert( nYear != 0 );
-    sal_Int32 nOffset;
-    sal_Int32 nYr;
-    if (nYear < 0)
-    {
-        nOffset = -366;
-        nYr = nYear + 1;
-    }
-    else
-    {
-        nOffset = 0;
-        nYr = nYear - 1;
-    }
-    return nOffset + nYr*365 + nYr/4 - nYr/100 + nYr/400;
-}
-
-bool ImpIsLeapYear( sal_Int16 nYear )
-{
-    // Leap years BCE are -1, -5, -9, ...
-    // See
-    // https://en.wikipedia.org/wiki/Proleptic_Gregorian_calendar#Usage
-    // https://en.wikipedia.org/wiki/0_(year)#History_of_astronomical_usage
-    assert( nYear != 0 );
-    if (nYear < 0)
-        nYear = -nYear - 1;
-    return ( ( ((nYear % 4) == 0) && ((nYear % 100) != 0) ) ||
-             ( (nYear % 400) == 0 ) );
-}
-
-// All callers must have sanitized or normalized month and year values!
-sal_uInt16 ImplDaysInMonth( sal_uInt16 nMonth, sal_Int16 nYear )
-{
-    if ( nMonth != 2 )
-        return aDaysInMonth[nMonth-1];
-    else
-    {
-        if (ImpIsLeapYear(nYear))
-            return aDaysInMonth[nMonth-1] + 1;
-        else
-            return aDaysInMonth[nMonth-1];
-    }
-}
-
 }
 
 void Date::setDateFromDMY( sal_uInt16 nDay, sal_uInt16 nMonth, sal_Int16 nYear )
@@ -130,7 +64,7 @@ sal_uInt16 Date::GetDaysInMonth( sal_uInt16 nMonth, sal_Int16 nYear )
         nMonth = 1;
     else if (12 < nMonth)
         nMonth = 12;
-    return ImplDaysInMonth( nMonth, nYear);
+    return comphelper::date::getDaysInMonth( nMonth, nYear);
 }
 
 sal_Int32 Date::GetAsNormalizedDays() const
@@ -146,63 +80,16 @@ sal_Int32 Date::GetAsNormalizedDays() const
 
 sal_Int32 Date::DateToDays( sal_uInt16 nDay, sal_uInt16 nMonth, sal_Int16 nYear )
 {
-    Normalize( nDay, nMonth, nYear);
-
-    sal_Int32 nDays = ImpYearToDays(nYear);
-    for( sal_uInt16 i = 1; i < nMonth; i++ )
-        nDays += ImplDaysInMonth(i,nYear);
-    nDays += nDay;
-    return nDays;
+    return comphelper::date::convertDateToDaysNormalizing( nDay, nMonth, nYear);
 }
 
 static Date lcl_DaysToDate( sal_Int32 nDays )
 {
-    if ( nDays <= MIN_DAYS )
-        return Date( 1, 1, kYearMin );
-    if ( nDays >= MAX_DAYS )
-        return Date( 31, 12, kYearMax );
-
-    // Day 0 is -0001-12-31, day 1 is 0001-01-01
-    const sal_Int16 nSign = (nDays <= 0 ? -1 : 1);
-    sal_Int32 nTempDays;
-    sal_Int32 i = 0;
-    bool bCalc;
-
+    sal_uInt16 nDay;
+    sal_uInt16 nMonth;
     sal_Int16 nYear;
-    do
-    {
-        nYear = static_cast<sal_Int16>((nDays / 365) - (i * nSign));
-        if (nYear == 0)
-            nYear = nSign;
-        nTempDays = nDays - ImpYearToDays(nYear);
-        bCalc = false;
-        if ( nTempDays < 1 )
-        {
-            i += nSign;
-            bCalc = true;
-        }
-        else
-        {
-            if ( nTempDays > 365 )
-            {
-                if ( (nTempDays != 366) || !ImpIsLeapYear( nYear ) )
-                {
-                    i -= nSign;
-                    bCalc = true;
-                }
-            }
-        }
-    }
-    while ( bCalc );
-
-    sal_uInt16 nMonth = 1;
-    while ( nTempDays > ImplDaysInMonth( nMonth, nYear ) )
-    {
-        nTempDays -= ImplDaysInMonth( nMonth, nYear );
-        ++nMonth;
-    }
-
-    return Date( static_cast<sal_uInt16>(nTempDays), nMonth, nYear );
+    comphelper::date::convertDaysToDate( nDays, nDay, nMonth, nYear);
+    return Date( nDay, nMonth, nYear);
 }
 
 Date::Date( DateInitSystem )
@@ -269,7 +156,7 @@ void Date::AddYears( sal_Int16 nAddYears )
     }
 
     SetYear( nYear );
-    if (GetMonth() == 2 && GetDay() == 29 && !ImpIsLeapYear( nYear))
+    if (GetMonth() == 2 && GetDay() == 29 && !comphelper::date::isLeapYear( nYear))
         SetDay(28);
 }
 
@@ -306,7 +193,7 @@ sal_uInt16 Date::GetDayOfYear() const
     Normalize( nDay, nMonth, nYear);
 
     for( sal_uInt16 i = 1; i < nMonth; i++ )
-         nDay += ::ImplDaysInMonth( i, nYear );
+         nDay += comphelper::date::getDaysInMonth( i, nYear );
     return nDay;
 }
 
@@ -403,13 +290,13 @@ sal_uInt16 Date::GetDaysInMonth() const
     sal_Int16  nYear  = GetYear();
     Normalize( nDay, nMonth, nYear);
 
-    return ImplDaysInMonth( nMonth, nYear );
+    return comphelper::date::getDaysInMonth( nMonth, nYear );
 }
 
 bool Date::IsLeapYear() const
 {
     sal_Int16 nYear = GetYear();
-    return ImpIsLeapYear( nYear );
+    return comphelper::date::isLeapYear( nYear );
 }
 
 bool Date::IsValidAndGregorian() const
@@ -420,7 +307,7 @@ bool Date::IsValidAndGregorian() const
 
     if ( !nMonth || (nMonth > 12) )
         return false;
-    if ( !nDay || (nDay > ImplDaysInMonth( nMonth, nYear )) )
+    if ( !nDay || (nDay > comphelper::date::getDaysInMonth( nMonth, nYear )) )
         return false;
     else if ( nYear <= 1582 )
     {
@@ -437,19 +324,13 @@ bool Date::IsValidAndGregorian() const
 
 bool Date::IsValidDate() const
 {
-    return IsValidDate( GetDay(), GetMonth(), GetYear());
+    return comphelper::date::isValidDate( GetDay(), GetMonth(), GetYear());
 }
 
 //static
 bool Date::IsValidDate( sal_uInt16 nDay, sal_uInt16 nMonth, sal_Int16 nYear )
 {
-    if (nYear == 0)
-        return false;
-    if ( !nMonth || (nMonth > 12) )
-        return false;
-    if ( !nDay || (nDay > ImplDaysInMonth( nMonth, nYear )) )
-        return false;
-    return true;
+    return comphelper::date::isValidDate( nDay, nMonth, nYear);
 }
 
 bool Date::IsEndOfMonth() const
@@ -460,7 +341,8 @@ bool Date::IsEndOfMonth() const
 //static
 bool Date::IsEndOfMonth(sal_uInt16 nDay, sal_uInt16 nMonth, sal_Int16 nYear)
 {
-    return IsValidDate(nDay, nMonth, nYear) && ImplDaysInMonth(nMonth, nYear) == nDay;
+    return comphelper::date::isValidDate(nDay, nMonth, nYear)
+        && comphelper::date::getDaysInMonth(nMonth, nYear) == nDay;
 }
 
 void Date::Normalize()
@@ -478,83 +360,7 @@ void Date::Normalize()
 //static
 bool Date::Normalize( sal_uInt16 & rDay, sal_uInt16 & rMonth, sal_Int16 & rYear )
 {
-    if (IsValidDate( rDay, rMonth, rYear))
-        return false;
-
-    if (rDay == 0 && rMonth == 0 && rYear == 0)
-        return false;   // empty date
-
-    if (rDay == 0)
-    {
-        if (rMonth == 0)
-            ;   // nothing, handled below
-        else
-            --rMonth;
-        // Last day of month is determined at the end.
-    }
-
-    if (rMonth > 12)
-    {
-        rYear += rMonth / 12;
-        rMonth = rMonth % 12;
-        if (rYear == 0)
-            rYear = 1;
-    }
-    if (rMonth == 0)
-    {
-        --rYear;
-        if (rYear == 0)
-            rYear = -1;
-        rMonth = 12;
-    }
-
-    if (rYear < 0)
-    {
-        sal_uInt16 nDays;
-        while (rDay > (nDays = ImplDaysInMonth( rMonth, rYear)))
-        {
-            rDay -= nDays;
-            if (rMonth > 1)
-                --rMonth;
-            else
-            {
-                if (rYear == kYearMin)
-                {
-                    rDay = 1;
-                    rMonth = 1;
-                    return true;
-                }
-                --rYear;
-                rMonth = 12;
-            }
-        }
-    }
-    else
-    {
-        sal_uInt16 nDays;
-        while (rDay > (nDays = ImplDaysInMonth( rMonth, rYear)))
-        {
-            rDay -= nDays;
-            if (rMonth < 12)
-                ++rMonth;
-            else
-            {
-                if (rYear == kYearMax)
-                {
-                    rDay = 31;
-                    rMonth = 12;
-                    return true;
-                }
-                ++rYear;
-                rMonth = 1;
-            }
-        }
-    }
-
-    if (rDay == 0)
-        rDay = ImplDaysInMonth( rMonth, rYear);
-
-    return true;
+    return comphelper::date::normalize( rDay, rMonth, rYear);
 }
 
 void Date::AddDays( sal_Int32 nDays )