relative: accept hence after a relative time

README.md

@@ -77,7 +77,7 @@ The `parse_datetime` and `parse_datetime_at_date` functions support absolute dat
 - "now" or "today"
 - "yesterday"
 - "tomorrow"
-- use "ago" for the past
+- use "ago" for the past or "hence" for the future
 - use "next" or "last" with `unit` (e.g., "next week", "last year")
 - unix timestamps (for example "@0" "@1344000")
 

src/items/mod.rs

@@ -159,7 +159,7 @@ pub(crate) fn parse_at_local<S: AsRef<str> + Clone>(input: S) -> Result<ParsedDa
 ///
 /// time_offset         = ( "+" | "-" ) , dec_uint , [ ":" , dec_uint ] ;
 ///
-/// relative            = [ numeric_ordinal  ] , unit , [ "ago" ] | day_shift ;
+/// relative            = [ numeric_ordinal  ] , unit , [ "ago" | "hence" ] | day_shift ;
 ///
 /// unit                = "year" | "years"
 ///                     | "month" | "months"

src/items/relative.rs

@@ -85,7 +85,7 @@ fn seconds(input: &mut &str) -> ModalResult<Relative> {
         opt(alt((s('+').value(1), s('-').value(-1)))),
         s(sec_and_nsec),
         s(alpha1).verify(|s: &str| matches!(s, "seconds" | "second" | "sec" | "secs")),
-        ago,
+        direction,
     )
         .verify_map(|(sign, (sec, nsec), _, ago)| {
             let sec = i64::try_from(sec).ok()?;
@@ -102,7 +102,7 @@ fn seconds(input: &mut &str) -> ModalResult<Relative> {
 }
 
 fn displacement(input: &mut &str) -> ModalResult<Relative> {
-    (opt(ordinal), s(alpha1), ago)
+    (opt(ordinal), s(alpha1), direction)
         .verify_map(|(n, unit, ago): (Option<i32>, &str, bool)| {
             let multiplier = n.unwrap_or(1) * if ago { -1 } else { 1 };
             Some(match unit.strip_suffix('s').unwrap_or(unit) {
@@ -120,8 +120,10 @@ fn displacement(input: &mut &str) -> ModalResult<Relative> {
         .parse_next(input)
 }
 
-fn ago(input: &mut &str) -> ModalResult<bool> {
-    opt(s("ago")).map(|o| o.is_some()).parse_next(input)
+fn direction(input: &mut &str) -> ModalResult<bool> {
+    opt(alt((s("ago").value(true), s("hence").value(false))))
+        .map(|backward| backward.unwrap_or(false))
+        .parse_next(input)
 }
 
 #[cfg(test)]

src/lib.rs

@@ -784,6 +784,30 @@ mod tests {
     mod test_relative {
         use crate::parse_datetime;
 
+        #[test]
+        fn test_hence_suffix() {
+            let now: jiff::Zoned = "2026-01-15T12:00:00Z[UTC]".parse().unwrap();
+            for relative in [
+                "2 months",
+                "year",
+                "-2 days",
+                "next week",
+                "0 hours",
+                "1.5 seconds",
+            ] {
+                let expected = crate::parse_datetime_at_date(now.clone(), relative).unwrap();
+                for suffix in ["hence", "HENCE"] {
+                    assert_eq!(
+                        crate::parse_datetime_at_date(now.clone(), format!("{relative} {suffix}"))
+                            .unwrap(),
+                        expected,
+                    );
+                }
+            }
+            assert!(crate::parse_datetime_at_date(now.clone(), "hence").is_err());
+            assert!(crate::parse_datetime_at_date(now, "2 days henceforth").is_err());
+        }
+
         #[test]
         fn test_month() {
             assert_eq!(