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Diffstat (limited to 'comphelper/source/misc/date.cxx')
| -rw-r--r-- | comphelper/source/misc/date.cxx | 210 |
1 files changed, 210 insertions, 0 deletions
diff --git a/comphelper/source/misc/date.cxx b/comphelper/source/misc/date.cxx new file mode 100644 index 0000000000..b95f63f75c --- /dev/null +++ b/comphelper/source/misc/date.cxx @@ -0,0 +1,210 @@ +/* -*- 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; + +constexpr sal_Int32 nNullDateDays = convertDateToDays(30, 12, 1899); +static_assert(nNullDateDays == 693594); + +sal_Int32 convertDateToDaysNormalizing(sal_uInt16 nDay, sal_uInt16 nMonth, sal_Int16 nYear) +{ + // Speed-up the common null-date 1899-12-30. + if (nYear == 1899 && nMonth == 12 && nDay == 30) + return nNullDateDays; + + 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: */ |