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node_modules/date-fns/differenceInISOWeekYears.mjs

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+import { compareAsc } from "./compareAsc.mjs";
+import { differenceInCalendarISOWeekYears } from "./differenceInCalendarISOWeekYears.mjs";
+import { subISOWeekYears } from "./subISOWeekYears.mjs";
+import { toDate } from "./toDate.mjs";
+
+/**
+ * @name differenceInISOWeekYears
+ * @category ISO Week-Numbering Year Helpers
+ * @summary Get the number of full ISO week-numbering years between the given dates.
+ *
+ * @description
+ * Get the number of full ISO week-numbering years between the given dates.
+ *
+ * ISO week-numbering year: http://en.wikipedia.org/wiki/ISO_week_date
+ *
+ * @typeParam DateType - The `Date` type, the function operates on. Gets inferred from passed arguments. Allows to use extensions like [`UTCDate`](https://github.com/date-fns/utc).
+ *
+ * @param dateLeft - The later date
+ * @param dateRight - The earlier date
+ *
+ * @returns The number of full ISO week-numbering years
+ *
+ * @example
+ * // How many full ISO week-numbering years are between 1 January 2010 and 1 January 2012?
+ * const result = differenceInISOWeekYears(
+ *   new Date(2012, 0, 1),
+ *   new Date(2010, 0, 1)
+ * )
+ * //=> 1
+ */
+export function differenceInISOWeekYears(dateLeft, dateRight) {
+  let _dateLeft = toDate(dateLeft);
+  const _dateRight = toDate(dateRight);
+
+  const sign = compareAsc(_dateLeft, _dateRight);
+  const difference = Math.abs(
+    differenceInCalendarISOWeekYears(_dateLeft, _dateRight),
+  );
+  _dateLeft = subISOWeekYears(_dateLeft, sign * difference);
+
+  // Math.abs(diff in full ISO years - diff in calendar ISO years) === 1
+  // if last calendar ISO year is not full
+  // If so, result must be decreased by 1 in absolute value
+  const isLastISOWeekYearNotFull = Number(
+    compareAsc(_dateLeft, _dateRight) === -sign,
+  );
+  const result = sign * (difference - isLastISOWeekYearNotFull);
+  // Prevent negative zero
+  return result === 0 ? 0 : result;
+}
+
+// Fallback for modularized imports:
+export default differenceInISOWeekYears;