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Add Date/Time/DateTime utility helpers (draft – interface discussion) #285

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118 changes: 118 additions & 0 deletions src/eckit/types/Date.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -271,6 +271,124 @@ long Date::dateToJulian(long ddate) {
return (j1);
}

bool Date::isLeapYear(long year) {
return ((year % 4) == 0) && (((year % 100) != 0) || ((year % 400) == 0));
}

bool Date::isLeap() const {
return isLeapYear(year());
}

long Date::numberOfDaysInMonth(long year, long month) {
ASSERT(month >= 1 && month <= 12);

static const long days[] = {
31, 28, 31, 30, 31, 30,
31, 31, 30, 31, 30, 31
};

if (month == 2 && isLeapYear(year)) {
return 29;
}

return days[month - 1];
}

long Date::numberOfDaysInMonth() const {
return numberOfDaysInMonth(year(), month());
}

Date& Date::shiftMonths(long n) {
long y = year();
long m = month();
long d = day();

long total = (m - 1) + n;
long newYear = y + total / 12;
long newMonth = total % 12;

if (newMonth < 0) {
newMonth += 12;
--newYear;
}

newMonth += 1;

long maxDay = numberOfDaysInMonth(newYear, newMonth);
if (d > maxDay) {
d = maxDay;
}

julian_ = dateToJulian(newYear * 10000 + newMonth * 100 + d);
return *this;
}

Date& Date::shiftYears(long n) {
return shiftMonths(12 * n);
}

Date& Date::beginOfMonth() {
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@simondsmart simondsmart Mar 23, 2026

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begin is a verb, not a noun.

You want 'startOfMonth', (and equivalently for other places you have used 'begin' in this file).

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@MircoValentiniECMWF MircoValentiniECMWF Mar 23, 2026

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Thanks, I fully agree; I am usually really bad in choosing names

long y = year();
long m = month();
julian_ = dateToJulian(y * 10000 + m * 100 + 1);
return *this;
}

Date& Date::endOfMonth() {
long y = year();
long m = month();
long d = numberOfDaysInMonth(y, m);
julian_ = dateToJulian(y * 10000 + m * 100 + d);
return *this;
}

Date& Date::beginOfYear() {
long y = year();
julian_ = dateToJulian(y * 10000 + 101);
return *this;
}

Date& Date::endOfYear() {
long y = year();
julian_ = dateToJulian(y * 10000 + 1231);
return *this;
}

Date Date::withShiftMonths(long n) const {
Date out(*this);
out.shiftMonths(n);
return out;
}

Date Date::withShiftYears(long n) const {
Date out(*this);
out.shiftYears(n);
return out;
}

Date Date::withBeginOfMonth() const {
Date out(*this);
out.beginOfMonth();
return out;
}

Date Date::withEndOfMonth() const {
Date out(*this);
out.endOfMonth();
return out;
}

Date Date::withBeginOfYear() const {
Date out(*this);
out.beginOfYear();
return out;
}

Date Date::withEndOfYear() const {
Date out(*this);
out.endOfYear();
return out;
}

void Date::print(std::ostream& s) const {
long ddate = julianToDate(julian_);
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24 changes: 24 additions & 0 deletions src/eckit/types/Date.h
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Expand Up @@ -111,6 +111,27 @@ class Date {
std::string monthName() const;
long dayOfWeek() const { return julian_ % 7; }

bool isLeap() const;
long numberOfDaysInMonth() const;

Date& shiftMonths(long n = 1);
Date& shiftYears(long n = 1);

Date& beginOfMonth();
Date& endOfMonth();

Date& beginOfYear();
Date& endOfYear();
Comment on lines +114 to +124
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Copilot AI Mar 23, 2026

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Date gains non-trivial calendar logic (leap-year, days-in-month, month/year shifting with day clamping, begin/end of month/year). There doesn’t seem to be direct unit test coverage for Date behavior in the test suite; please add tests for edge cases like shifting from Jan 31 to Feb, leap years (Feb 29), and negative month shifts.

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Date withShiftMonths(long n = 1) const;
Date withShiftYears(long n = 1) const;

Date withBeginOfMonth() const;
Date withEndOfMonth() const;

Date withBeginOfYear() const;
Date withEndOfYear() const;

void dump(DumpLoad&) const;
void load(DumpLoad&);

Expand Down Expand Up @@ -147,6 +168,9 @@ class Date {
static long dateToJulian(long);
static long today();

static bool isLeapYear(long year);
static long numberOfDaysInMonth(long year, long month);

// -- Friends

friend long operator-(const Date& d1, const Date& d2) { return (d1.julian_ - d2.julian_); }
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180 changes: 180 additions & 0 deletions src/eckit/types/DateTime.cc
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Expand Up @@ -149,6 +149,186 @@ DateTime DateTime::round(const Second& rnd) const {
return DateTime(Date(d, true), Time(t));
}

bool DateTime::isLeap() const {
return date_.isLeap();
}

long DateTime::numberOfDaysInMonth() const {
return date_.numberOfDaysInMonth();
}

DateTime& DateTime::shiftSeconds(long n) {
long dummy;
return shiftSeconds(n, dummy);
}

DateTime& DateTime::shiftSeconds(long n, long& dayCarry) {
time_.shiftSeconds(n, dayCarry);
date_ += dayCarry;
return *this;
}

DateTime& DateTime::shiftMinutes(long n) {
long dummy;
return shiftMinutes(n, dummy);
}

DateTime& DateTime::shiftMinutes(long n, long& dayCarry) {
time_.shiftMinutes(n, dayCarry);
date_ += dayCarry;
return *this;
}

DateTime& DateTime::shiftHours(long n) {
long dummy;
return shiftHours(n, dummy);
}

DateTime& DateTime::shiftHours(long n, long& dayCarry) {
time_.shiftHours(n, dayCarry);
date_ += dayCarry;
return *this;
}

DateTime& DateTime::shiftDays(long n) {
date_ += n;
return *this;
}

DateTime& DateTime::shiftMonths(long n) {
date_.shiftMonths(n);
return *this;
}

DateTime& DateTime::shiftYears(long n) {
date_.shiftYears(n);
return *this;
}

DateTime& DateTime::beginOfDay() {
time_ = Time(0, 0, 0);
return *this;
}

DateTime& DateTime::endOfDay() {
time_ = Time(23, 59, 59);
return *this;
}

DateTime& DateTime::beginOfMonth() {
date_.beginOfMonth();
time_ = Time(0, 0, 0);
return *this;
}

DateTime& DateTime::endOfMonth() {
date_.endOfMonth();
time_ = Time(23, 59, 59);
return *this;
}

DateTime& DateTime::beginOfYear() {
date_.beginOfYear();
time_ = Time(0, 0, 0);
return *this;
}

DateTime& DateTime::endOfYear() {
date_.endOfYear();
time_ = Time(23, 59, 59);
return *this;
}

DateTime DateTime::withShiftSeconds(long n) const {
DateTime out(*this);
out.shiftSeconds(n);
return out;
}

DateTime DateTime::withShiftSeconds(long n, long& dayCarry) const {
DateTime out(*this);
out.shiftSeconds(n, dayCarry);
return out;
}

DateTime DateTime::withShiftMinutes(long n) const {
DateTime out(*this);
out.shiftMinutes(n);
return out;
}

DateTime DateTime::withShiftMinutes(long n, long& dayCarry) const {
DateTime out(*this);
out.shiftMinutes(n, dayCarry);
return out;
}

DateTime DateTime::withShiftHours(long n) const {
DateTime out(*this);
out.shiftHours(n);
return out;
}

DateTime DateTime::withShiftHours(long n, long& dayCarry) const {
DateTime out(*this);
out.shiftHours(n, dayCarry);
return out;
}

DateTime DateTime::withShiftDays(long n) const {
DateTime out(*this);
out.shiftDays(n);
return out;
}

DateTime DateTime::withShiftMonths(long n) const {
DateTime out(*this);
out.shiftMonths(n);
return out;
}

DateTime DateTime::withShiftYears(long n) const {
DateTime out(*this);
out.shiftYears(n);
return out;
}

DateTime DateTime::withBeginOfDay() const {
DateTime out(*this);
out.beginOfDay();
return out;
}

DateTime DateTime::withEndOfDay() const {
DateTime out(*this);
out.endOfDay();
return out;
}

DateTime DateTime::withBeginOfMonth() const {
DateTime out(*this);
out.beginOfMonth();
return out;
}

DateTime DateTime::withEndOfMonth() const {
DateTime out(*this);
out.endOfMonth();
return out;
}

DateTime DateTime::withBeginOfYear() const {
DateTime out(*this);
out.beginOfYear();
return out;
}

DateTime DateTime::withEndOfYear() const {
DateTime out(*this);
out.endOfYear();
return out;
}

void DateTime::dump(DumpLoad& a) const {
date_.dump(a);
time_.dump(a);
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