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// SPDX-License-Identifier: MPL-2.0
// (c) Hare authors <https://harelang.org>
use time::chrono;
// Calculates the [[span]] between two [[date]]s, from A to B.
//
// The returned span, provided to [[reckon]] with [[rflag]]::DEFAULT and date A,
// will produce B. The span's fields will all be the same sign.
//
// Be aware, using date of different [[locality]]s may return unexpected
// results.
export fn traverse(a: date, b: date) span = {
let s = span { ... };
if (chrono::compare(&a, &b) == 0) {
return s;
};
let reverse = chrono::compare(&a, &b) > 0;
if (reverse) {
let tmp = a;
a = b;
b = tmp;
};
s.years = _year(&b) - _year(&a);
s.months = _month(&b) - _month(&a);
if (s.months < 0) {
s.years -= 1;
s.months += 12;
};
s.days = _day(&b) - _day(&a);
let year = _year(&b);
let month = _month(&b);
let monthdays = calc_days_in_month(year, month);
for (_day(&a) > monthdays || s.days < 0) {
month -= 1;
if (month == 0) {
year -= 1;
month = 12;
};
monthdays = calc_days_in_month(year, month);
s.months -= 1;
if (s.months < 0) {
s.years -= 1;
s.months += 12;
};
s.days += monthdays;
};
s.hours = _hour(&b) - _hour(&a);
if (s.hours < 0) {
s.days -= 1;
s.hours += 24;
};
s.minutes = _minute(&b) - _minute(&a);
if (s.minutes < 0) {
s.hours -= 1;
s.minutes += 60;
};
s.seconds = _second(&b) - _second(&a);
if (s.seconds < 0) {
s.minutes -= 1;
s.seconds += 60;
};
s.nanoseconds = _nanosecond(&b) - _nanosecond(&a);
if (s.nanoseconds < 0) {
s.seconds -= 1;
s.nanoseconds += 1000000000; // 10E9
};
return if (reverse) neg(s) else s;
};
@test fn traverse() void = {
const cases = [
(
new(UTC, 0, 2021, 1, 15, 0, 0, 0, 0)!,
new(UTC, 0, 2022, 2, 16, 0, 0, 0, 0)!,
span {
years = 1,
months = 1,
days = 1,
...
},
),
(
new(UTC, 0, 2021, 1, 15, 0, 0, 0, 0)!,
new(UTC, 0, 2022, 3, 27, 0, 0, 0, 0)!,
span {
years = 1,
months = 2,
days = 12,
...
},
),
(
new(UTC, 0, 2021, 1, 15, 0, 0, 0, 0)!,
new(UTC, 0, 2022, 3, 14, 0, 0, 0, 0)!,
span {
years = 1,
months = 1,
days = 27,
...
},
),
(
new(UTC, 0, 2021, 1, 15, 0, 0, 0, 0)!,
new(UTC, 0, 2021, 1, 16, 0, 0, 0, 0)!,
span {
days = 1,
...
},
),
(
new(UTC, 0, 2021, 1, 15, 0, 0, 0, 0)!,
new(UTC, 0, 2021, 1, 16, 1, 3, 2, 4)!,
span {
days = 1,
hours = 1,
minutes = 3,
seconds = 2,
nanoseconds = 4,
...
},
),
(
new(UTC, 0, 2021, 1, 15, 2, 3, 2, 2)!,
new(UTC, 0, 2021, 1, 16, 1, 1, 2, 4)!,
span {
hours = 22,
minutes = 58,
nanoseconds = 2,
...
},
),
(
new(UTC, 0, 500, 1, 1, 0, 0, 0, 0)!,
new(UTC, 0, 3500, 1, 1, 0, 6, 0, 0)!,
span {
years = 3000,
minutes = 6,
...
},
),
(
new(UTC, 0, -500, 1, 1, 0, 0, 0, 0)!,
new(UTC, 0, 2500, 1, 1, 0, 6, 0, 0)!,
span {
years = 3000,
minutes = 6,
...
},
),
(
new(UTC, 0, 2000, 1, 1, 0, 0, 0, 0)!,
new(UTC, 0, 2000, 1, 1, 0, 6, 0, 999999999)!,
span {
minutes = 6,
nanoseconds = 999999999,
...
},
),
(
new(UTC, 0, 2000, 1, 1, 0, 6, 0, 999999999)!,
new(UTC, 0, 2000, 1, 1, 0, 6, 1, 0)!,
span {
nanoseconds = 1,
...
},
),
(
new(UTC, 0, -4000, 1, 1, 0, 6, 0, 999999999)!,
new(UTC, 0, 4000, 1, 1, 0, 6, 1, 0)!,
span {
years = 8000,
nanoseconds = 1,
...
},
),
];
for (let (da, db, expected) .. cases) {
const actual = traverse(da, db);
assert(equalspan(actual, expected), "traverse miscalculation");
};
};
|
