a better regex for time parsing

src/main.rs

@@ -485,7 +485,7 @@ impl TryFrom<&str> for SubInstant {
                     f32::from_str(m).unwrap() * 60f32 +
                     f32::from_str(&s).unwrap())))
             }
-            None => Err(failure::err_msg("Error parsing time."))
+            None => Err(failure::format_err!("Error parsing time: {}", value))
         }
     }
 }
@@ -501,27 +501,23 @@ impl TryFrom<&str> for SubDuration {
 
     fn try_from(value: &str) -> Result<Self, Self::Error> {
         lazy_static! {
-            static ref TIME_RE: Regex = Regex::new(r"^(-)?(?:(\d+):)?(?:(\d+):)?(\d+(?:[,.]\d+)?)$").unwrap();
+            static ref TIME_RE: Regex = Regex::new(r"^(?P<n>-)?(?:(?:(?P<h>\d+):)?(?P<m>\d+):)?(?P<s>\d+(?:[.,]\d+)?)$").unwrap();
         }
 
         match TIME_RE.captures(value) {
             Some(caps) => {
-                let minus = if caps.get(1).is_some() { -1f32 } else { 1f32 };
-                let a = caps.get(2).map(|m| m.as_str()).unwrap_or("");
-                let b = caps.get(3).map(|m| m.as_str()).unwrap_or("");
-                let s = caps.get(4).map(|m| m.as_str()).unwrap_or("0").replace(",", ".");
-
-                let (h, m) = if b.is_empty() {
-                    ("0", if a.is_empty() { "0" } else { a })
-                } else {
-                    (a, b)
-                };
-
-                Ok(SubDuration(minus * (f32::from_str(h).unwrap() * 3600f32 +
-                    f32::from_str(m).unwrap() * 60f32 +
-                    f32::from_str(&s).unwrap())))
+                let minus = if caps.name("n").is_some() { -1f32 } else { 1f32 };
+                let h = caps.name("h").map_or(0f32, |m| f32::from_str(m.as_str()).unwrap());
+                let m = caps.name("m").map_or(0f32, |m| f32::from_str(m.as_str()).unwrap());
+                let s = caps.name("s").map_or(0f32, |m| f32::from_str(&m.as_str().replace(",", ".")).unwrap());
+
+                Ok(SubDuration(minus * (h * 3600f32 +
+                    m * 60f32 +
+                    s)))
+            }
+            None => {
+                Err(failure::format_err!("Error parsing time: {}", value))
             }
-            None => Err(failure::err_msg("Error parsing time: No match"))
         }
     }
 }