relative: Support parsing floating relative values with spaces

In case a string such as "now + 1.5 seconds" was parsed we were failing.

This happened because after processing now, the parser was getting
to the point in which the string contained "+ 1.5", and once the sign
was processed, the remaining " 1.5" string conained a space that was
causing sec_and_nsec to fail.

Instead of failing at this point, just strip the spaces after the sign has
been processed.

Note in fact that "0+0.0 seconds" was working fine

Closes: uutils/coreutils#8618

Author: 3v1n0

src/items/relative.rs

@@ -83,7 +83,7 @@ pub(super) fn parse(input: &mut &str) -> ModalResult<Relative> {
 fn seconds(input: &mut &str) -> ModalResult<Relative> {
     (
         opt(alt((s('+').value(1), s('-').value(-1)))),
-        sec_and_nsec,
+        s(sec_and_nsec),
         s(alpha1).verify(|s: &str| matches!(s, "seconds" | "second" | "sec" | "secs")),
         ago,
     )
@@ -138,11 +138,13 @@ mod tests {
             ("secs", Relative::Seconds(1, 0)),
             ("second ago", Relative::Seconds(-1, 0)),
             ("3 seconds", Relative::Seconds(3, 0)),
+            ("+ 3 seconds", Relative::Seconds(3, 0)),
             ("3.5 seconds", Relative::Seconds(3, 500_000_000)),
             ("-3.5 seconds", Relative::Seconds(-4, 500_000_000)),
             ("+3.5 seconds", Relative::Seconds(3, 500_000_000)),
+            ("+ 3.5 seconds", Relative::Seconds(3, 500_000_000)),
             ("3.5 seconds ago", Relative::Seconds(-4, 500_000_000)),
-            ("-3.5 seconds ago", Relative::Seconds(3, 500_000_000)),
+            ("-  3.5 seconds ago", Relative::Seconds(3, 500_000_000)),
             // Minutes
             ("minute", Relative::Minutes(1)),
             ("minutes", Relative::Minutes(1)),

src/lib.rs

@@ -307,6 +307,42 @@ mod tests {
                 assert!(parse_datetime(relative_time).is_ok());
             }
         }
+
+        #[test]
+        fn integer_seconds_offset() {
+            let dt = "0 + 0 seconds";
+            assert!(parse_datetime(dt).is_ok());
+        }
+
+        #[test]
+        fn integer_seconds_offset_spaceless() {
+            let dt = "0+0 seconds";
+            assert!(parse_datetime(dt).is_ok());
+        }
+
+        #[test]
+        fn floating_seconds_offset() {
+            let dt = "0 + 0.0 seconds";
+            assert!(parse_datetime(dt).is_ok());
+        }
+
+        #[test]
+        fn floating_seconds_offset_spaceless() {
+            let dt = "0+0.0 seconds";
+            assert!(parse_datetime(dt).is_ok());
+        }
+
+        #[test]
+        fn floating_seconds_offset_from_now() {
+            let dt = "now  +  1.5 seconds";
+            assert!(parse_datetime(dt).is_ok());
+        }
+
+        #[test]
+        fn floating_seconds_offset_from_tomorrow_spaceless() {
+            let dt = "tomorrow+1.5 seconds";
+            assert!(parse_datetime(dt).is_ok());
+        }
     }
 
     #[cfg(test)]