@burglekitt/gmt
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Temporal-based date and time utilities with timezone support and polyfill integration
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TypeScript
/**
* Return the overlapping span of two date intervals, or null when they do not overlap.
*
* - Uses `Temporal.PlainDate.compare` for comparison.
* - Adjacent intervals (e.g. `aEnd === bStart`) share one instant and DO overlap.
* - Returns `null` if either interval is invalid (`start > end`).
* - Returns `null` on invalid input (wrong type, malformed strings).
* - Accepts GMT calendar-annotated PlainDate strings — E5 (issue #78). Since the result is a
* date *value*, all four arguments must carry the *same* calendar tag (or all be bare ISO);
* a mismatch returns `null` (E5 decision of record D4). The output's tag is re-derived from
* the intersection span, never copied from an input.
*
* @param aStart ISO 8601 date string for the first interval start, optionally calendar-annotated
* @param aEnd ISO 8601 date string for the first interval end, optionally calendar-annotated
* @param bStart ISO 8601 date string for the second interval start, optionally calendar-annotated
* @param bEnd ISO 8601 date string for the second interval end, optionally calendar-annotated
* @returns `{ start, end }` with the overlapping span, or null on invalid input / no overlap / mismatched calendars
*
* @example intervalIntersectionDate("2024-01-01", "2024-06-30", "2024-04-01", "2024-12-31") // { start: "2024-04-01", end: "2024-06-30" }
* @example intervalIntersectionDate("2024-01-01", "2024-06-30", "2024-06-30", "2024-12-31") // { start: "2024-06-30", end: "2024-06-30" }
* @example intervalIntersectionDate("2024-01-01", "2024-06-30", "2024-07-01", "2024-12-31") // null
* @example intervalIntersectionDate("2024-01-01", "2024-06-30", "2024-02-01", "2024-03-01") // { start: "2024-02-01", end: "2024-03-01" }
* @example intervalIntersectionDate("invalid", "2024-06-30", "2024-04-01", "2024-12-31") // null
*/
export declare function intervalIntersectionDate(aStart: string, aEnd: string, bStart: string, bEnd: string): {
start: string;
end: string;
} | null;