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Duration: support negative durations by prefixing a '-' before the P in ISO format #111

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Duration: support negative durations by prefixing a '-' before the P in ISO format #111

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5df98cb
Duration: support negative durations by prefixing a '-' before the P …
apoelstra Dec 27, 2025
b76e66e
Duration: update other format methods to support negative dates
apoelstra Dec 27, 2025
a6da52e
Add curly braces, apply coding style
lauft Apr 1, 2026
720aa50
Add test coverage
lauft Apr 1, 2026
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90 changes: 74 additions & 16 deletions src/Duration.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -217,55 +217,84 @@ bool Duration::parse_designated (Pig& pig)
{
auto checkpoint = pig.cursor ();

// sign = -1 if a '-' is present, else 1
int sign = !pig.skip ('-') * 2 - 1;

if (pig.skip ('P') &&
! pig.eos ())
{
long long value;
pig.save ();
if (pig.getDigits (value) && pig.skip ('Y'))
_year = value;
{
_year = sign * value;
}
else
{
pig.restore ();
}

pig.save ();
if (pig.getDigits (value) && pig.skip ('M'))
_month = value;
{
_month = sign * value;
}
else
{
pig.restore ();
}

pig.save ();
if (pig.getDigits (value) && pig.skip ('D'))
_day = value;
{
_day = sign * value;
}
else
{
pig.restore ();
}

if (pig.skip ('T') &&
! pig.eos ())
{
pig.save ();
if (pig.getDigits (value) && pig.skip ('H'))
_hours = value;
{
_hours = sign * value;
}
else
{
pig.restore ();
}

pig.save ();
if (pig.getDigits (value) && pig.skip ('M'))
_minutes = value;
{
_minutes = sign * value;
}
else
{
pig.restore ();
}

pig.save ();
if (pig.getDigits (value) && pig.skip ('S'))
_seconds = value;
{
_seconds = sign * value;
}
else
{
pig.restore ();
}
}

auto following = pig.peek ();
if (pig.cursor () - checkpoint >= 3 &&
! unicodeLatinAlpha (following) &&
! unicodeLatinDigit (following))
{
return true;
}
}

pig.restoreTo (checkpoint);
Expand Down Expand Up @@ -400,12 +429,19 @@ std::string Duration::format () const
if (_period)
{
time_t t = _period;

std::stringstream s;
if (t < 0)
{
s << '-';
t *= -1;
}

int seconds = t % 60; t /= 60;
int minutes = t % 60; t /= 60;
int hours = t % 24; t /= 24;
int days = t;

std::stringstream s;
if (days)
s << days << "d ";

Expand All @@ -429,11 +465,18 @@ std::string Duration::formatHours () const
if (_period)
{
time_t t = _period;

std::stringstream s;
if (t < 0)
{
s << '-';
t *= -1;
}

int seconds = t % 60; t /= 60;
int minutes = t % 60; t /= 60;
int hours = t;

std::stringstream s;
s << hours
<< ':'
<< std::setw (2) << std::setfill ('0') << minutes
Expand All @@ -454,12 +497,19 @@ std::string Duration::formatISO () const
if (_period)
{
time_t t = _period;

std::stringstream s;
if (t < 0)
{
s << '-';
t *= -1;
}

int seconds = t % 60; t /= 60;
int minutes = t % 60; t /= 60;
int hours = t % 24; t /= 24;
int days = t;

std::stringstream s;
s << 'P';
if (days) s << days << 'D';

Expand Down Expand Up @@ -492,16 +542,24 @@ std::string Duration::formatISO () const
//
std::string Duration::formatVague (bool padding) const
{
time_t t = _period;
float days = (float) _period / 86400.0;

std::stringstream formatted;
if (_period >= 86400 * 365) formatted << std::fixed << std::setprecision (1) << (days / 365) << (padding ? "y " : "y");
else if (_period >= 86400 * 90) formatted << static_cast <int> (days / 30) << (padding ? "mo " : "mo");
else if (_period >= 86400 * 14) formatted << static_cast <int> (days / 7) << (padding ? "w " : "w");
else if (_period >= 86400) formatted << static_cast <int> (days) << (padding ? "d " : "d");
else if (_period >= 3600) formatted << static_cast <int> (_period / 3600) << (padding ? "h " : "h");
else if (_period >= 60) formatted << static_cast <int> (_period / 60) << "min"; // Longest suffix - no padding
else if (_period >= 1) formatted << static_cast <int> (_period) << (padding ? "s " : "s");
if (t < 0)
{
formatted << '-';
t *= -1;
days *= -1.0;
}

if (t >= 86400 * 365) formatted << std::fixed << std::setprecision (1) << (days / 365) << (padding ? "y " : "y");
else if (t >= 86400 * 90) formatted << static_cast <int> (days / 30) << (padding ? "mo " : "mo");
else if (t >= 86400 * 14) formatted << static_cast <int> (days / 7) << (padding ? "w " : "w");
else if (t >= 86400) formatted << static_cast <int> (days) << (padding ? "d " : "d");
else if (t >= 3600) formatted << static_cast <int> (t / 3600) << (padding ? "h " : "h");
else if (t >= 60) formatted << static_cast <int> (t / 60) << "min"; // Longest suffix - no padding
else if (t >= 1) formatted << static_cast <int> (t) << (padding ? "s " : "s");

return formatted.str ();
}
Expand Down
80 changes: 79 additions & 1 deletion test/duration.t.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -93,7 +93,7 @@ void testParseError (
////////////////////////////////////////////////////////////////////////////////
int main (int, char**)
{
UnitTest t (1921);
UnitTest t (2229);

// Simple negative tests.
testParseError (t, "foo");
Expand Down Expand Up @@ -133,6 +133,28 @@ int main (int, char**)

// input i Year Mo We Da Ho Mi Se time_t format hours iso vague
testParse (t, "0seconds", 8, 0, 0, 0, 0, 0, 0, 0, 0, "0:00:00", "0:00:00", "PT0S", "");

// Negative ISO format tests
// input i Year Mo We Da Ho Mi Se time_t format hours iso vague
testParse (t, "-P1Y", 4, -1, 0, 0, 0, 0, 0, 0, -year, "-365d 0:00:00", "-8760:00:00", "-P365D", "-1.0y");
testParse (t, "-P1M", 4, 0, -1, 0, 0, 0, 0, 0, -month, "-30d 0:00:00", "-720:00:00", "-P30D", "-4w");
testParse (t, "-P1D", 4, 0, 0, 0, -1, 0, 0, 0, -day, "-1d 0:00:00", "-24:00:00", "-P1D", "-1d");
testParse (t, "-P1Y1M", 6, -1, -1, 0, 0, 0, 0, 0, -(year + month), "-395d 0:00:00", "-9480:00:00", "-P395D", "-1.1y");
testParse (t, "-P1Y1D", 6, -1, 0, 0, -1, 0, 0, 0, -(year + day), "-366d 0:00:00", "-8784:00:00", "-P366D", "-1.0y");
testParse (t, "-P1M1D", 6, 0, -1, 0, -1, 0, 0, 0, -(month + day), "-31d 0:00:00", "-744:00:00", "-P31D", "-4w");
testParse (t, "-P1Y1M1D", 8, -1, -1, 0, -1, 0, 0, 0, -(year + month + day), "-396d 0:00:00", "-9504:00:00", "-P396D", "-1.1y");
testParse (t, "-PT1H", 5, 0, 0, 0, 0, -1, 0, 0, -h, "-1:00:00", "-1:00:00", "-PT1H", "-1h");
testParse (t, "-PT1M", 5, 0, 0, 0, 0, 0, -1, 0, -m, "-0:01:00", "-0:01:00", "-PT1M", "-1min");
testParse (t, "-PT1S", 5, 0, 0, 0, 0, 0, 0, -1, -1, "-0:00:01", "-0:00:01", "-PT1S", "-1s");
testParse (t, "-PT1H1M", 7, 0, 0, 0, 0, -1, -1, 0, -(h + m), "-1:01:00", "-1:01:00", "-PT1H1M", "-1h");
testParse (t, "-PT1H1S", 7, 0, 0, 0, 0, -1, 0, -1, -(h + 1), "-1:00:01", "-1:00:01", "-PT1H1S", "-1h");
testParse (t, "-PT1M1S", 7, 0, 0, 0, 0, 0, -1, -1, -(m + 1), "-0:01:01", "-0:01:01", "-PT1M1S", "-1min");
testParse (t, "-PT1H1M1S", 9, 0, 0, 0, 0, -1, -1, -1, -(h + m + 1), "-1:01:01", "-1:01:01", "-PT1H1M1S", "-1h");
testParse (t, "-P1Y1M1DT1H1M1S",15, -1, -1, 0, -1, -1, -1, -1, -(year + month + day + h + m + 1), "-396d 1:01:01", "-9505:01:01", "-P396DT1H1M1S", "-1.1y");
testParse (t, "-PT24H", 6, 0, 0, 0, 0, -24, 0, 0, -day, "-1d 0:00:00", "-24:00:00", "-P1D", "-1d");
testParse (t, "-PT40000000S", 12, 0, 0, 0, 0, 0, 0, -40000000, -40000000, "-462d 23:06:40", "-11111:06:40", "-P462DT23H6M40S", "-1.3y");
testParse (t, "-PT3600S", 8, 0, 0, 0, 0, 0, 0, -3600, -h, "-1:00:00", "-1:00:00", "-PT1H", "-1h");
testParse (t, "-PT60M", 6, 0, 0, 0, 0, 0, -60, 0, -h, "-1:00:00", "-1:00:00", "-PT1H", "-1h");
testParse (t, "2 seconds", 9, 0, 0, 0, 0, 0, 0, 0, 2, "0:00:02", "0:00:02", "PT2S", "2s");
testParse (t, "10seconds", 9, 0, 0, 0, 0, 0, 0, 0, 10, "0:00:10", "0:00:10", "PT10S", "10s");
testParse (t, "1.5seconds", 10, 0, 0, 0, 0, 0, 0, 0, 1, "0:00:01", "0:00:01", "PT1S", "1s");
Expand Down Expand Up @@ -399,6 +421,62 @@ int main (int, char**)

t.diag ("--------------------------------------------");

// Test negative duration formatting
// Verify that negative durations are formatted with a leading '-'
t.is (Duration ("-1s").format (), "-0:00:01", "format: -1s -> '-0:00:01'");
t.is (Duration ("-60s").format (), "-0:01:00", "format: -60s -> '-0:01:00'");
t.is (Duration ("-3600s").format (), "-1:00:00", "format: -3600s -> '-1:00:00'");
t.is (Duration ("-86400s").format (), "-1d 0:00:00", "format: -86400s -> '-1d 0:00:00'");
t.is (Duration ("-90061s").format (), "-1d 1:01:01", "format: -90061s -> '-1d 1:01:01'");

t.is (Duration ("-1s").formatHours (), "-0:00:01", "formatHours: -1s -> '-0:00:01'");
t.is (Duration ("-60s").formatHours (), "-0:01:00", "formatHours: -60s -> '-0:01:00'");
t.is (Duration ("-3600s").formatHours (), "-1:00:00", "formatHours: -3600s -> '-1:00:00'");
t.is (Duration ("-90061s").formatHours (), "-25:01:01", "formatHours: -90061s -> '-25:01:01'");

t.is (Duration ("-1s").formatISO (), "-PT1S", "formatISO: -1s -> '-PT1S'");
t.is (Duration ("-60s").formatISO (), "-PT1M", "formatISO: -60s -> '-PT1M'");
t.is (Duration ("-3600s").formatISO (), "-PT1H", "formatISO: -3600s -> '-PT1H'");
t.is (Duration ("-86400s").formatISO (), "-P1D", "formatISO: -86400s -> '-P1D'");
t.is (Duration ("-90061s").formatISO (), "-P1DT1H1M1S", "formatISO: -90061s -> '-P1DT1H1M1S'");

t.is (Duration ("-1s").formatVague (), "-1s", "formatVague: -1s -> '-1s'");
t.is (Duration ("-60s").formatVague (), "-1min", "formatVague: -60s -> '-1min'");
t.is (Duration ("-3600s").formatVague (), "-1h", "formatVague: -3600s -> '-1h'");
t.is (Duration ("-86400s").formatVague (), "-1d", "formatVague: -86400s -> '-1d'");
t.is (Duration ("-604800s").formatVague (), "-7d", "formatVague: -604800s -> '-7d'");
t.is (Duration ("-2592000s").formatVague (), "-4w", "formatVague: -2592000 -> '-4w'");
t.is (Duration ("-7776000s").formatVague (), "-3mo", "formatVague: -7776000 -> '-3mo'");
t.is (Duration ("-31536000s").formatVague (), "-1.0y", "formatVague: -31536000 -> '-1.0y'");

// Test round-trip: parse negative ISO format, then format back
t.is (Duration ("-PT1S").formatISO (), "-PT1S", "round-trip: -PT1S -> parse -> formatISO -> -PT1S");
t.is (Duration ("-PT1M").formatISO (), "-PT1M", "round-trip: -PT1M -> parse -> formatISO -> -PT1M");
t.is (Duration ("-PT1H").formatISO (), "-PT1H", "round-trip: -PT1H -> parse -> formatISO -> -PT1H");
t.is (Duration ("-P1D").formatISO (), "-P1D", "round-trip: -P1D -> parse -> formatISO -> -P1D");
t.is (Duration ("-P1DT1H1M1S").formatISO (), "-P1DT1H1M1S", "round-trip: -P1DT1H1M1S -> parse -> formatISO -> -P1DT1H1M1S");
t.is (Duration ("-PT1H1M1S").formatISO (), "-PT1H1M1S", "round-trip: -PT1H1M1S -> parse -> formatISO -> -PT1H1M1S");
t.is (Duration ("-P1Y").formatISO (), "-P365D", "round-trip: -P1Y -> parse -> formatISO -> -P365D");
t.is (Duration ("-P1M").formatISO (), "-P30D", "round-trip: -P1M -> parse -> formatISO -> -P30D");

// Test formatVague with padding
t.is (Duration ("-1s").formatVague (true), "-1s ", "formatVague (true): -1s -> '-1s '");
t.is (Duration ("-3600s").formatVague (true), "-1h ", "formatVague (true): -3600s -> '-1h '");
t.is (Duration ("-86400s").formatVague (true), "-1d ", "formatVague (true): -86400s -> '-1d '");
t.is (Duration ("-604800s").formatVague (true), "-7d ", "formatVague (true): -604800s -> '-7d '");

// Test that positive durations don't get a leading '-'
t.is (Duration ("1s").format (), "0:00:01", "format: 1s -> '0:00:01' (no leading '-')");
t.is (Duration ("1s").formatHours (), "0:00:01", "formatHours: 1s -> '0:00:01' (no leading '-')");
t.is (Duration ("1s").formatISO (), "PT1S", "formatISO: 1s -> 'PT1S' (no leading '-')");
t.is (Duration ("1s").formatVague (), "1s", "formatVague: 1s -> '1s' (no leading '-')");

// Test zero duration
t.is (Duration ("0s").format (), "0:00:00", "format: 0s -> '0:00:00'");
t.is (Duration ("0s").formatHours (), "0:00:00", "formatHours: 0s -> '0:00:00'");
t.is (Duration ("0s").formatISO (), "PT0S", "formatISO: 0s -> 'PT0S'");
t.is (Duration ("0s").formatVague (), "", "formatVague: 0s -> ''");

return 0;
}

Expand Down