Code review changes

philolo1 · philolo1 · commit cbfc1cfb55f5 · 2023-08-30T20:52:35.000+09:00
diff --git a/src/parse_timestamp.rs b/src/parse_timestamp.rs
@@ -1,30 +1,40 @@
-use nom::combinator::map;
+use nom::branch::alt;
+use nom::character::complete::{char, digit1};
+use nom::combinator::all_consuming;
+use nom::multi::fold_many0;
+use nom::sequence::preceded;
+use nom::sequence::tuple;
 use nom::{self, IResult};
 
 pub(crate) fn parse_timestamp(s: &str) -> Option<i64> {
     let s = s.trim().to_lowercase();
     let s = s.as_str();
 
-    let res: IResult<&str, (&str, char, &str)> =
-        nom::combinator::all_consuming(nom::sequence::tuple((
-            nom::bytes::complete::tag("@"),
-            map(
-                nom::bytes::complete::take_while(|c: char| c == '+' || c == '-'),
-                |st: &str| st.chars().last().unwrap_or('+'),
+    let res: IResult<&str, (char, &str)> = all_consuming(preceded(
+        char('@'),
+        tuple((
+            // Note: gnu date allows multiple + and - and only considers the last one
+            fold_many0(
+                // parse either + or -
+                alt((char('+'), char('-'))),
+                // start with a +
+                || '+',
+                // whatever we get (+ or -), update the accumulator to that value
+                |_, c| c,
             ),
-            nom::character::complete::digit1,
-        )))(s);
+            digit1,
+        )),
+    ))(s);
 
-    if let Ok((_, (_, sign, number_str))) = res {
-        let number = format!("{}{}", sign, number_str).parse();
+    let (_, (sign, number_str)) = res.ok()?;
 
-        return match number {
-            Err(_) => None,
-            Ok(val) => Some(val),
-        };
+    let mut number = number_str.parse::<i64>().ok()?;
+
+    if sign == '-' {
+        number *= -1;
     }
 
-    None
+    Some(number)
 }
 
 #[cfg(test)]
@@ -41,7 +51,9 @@ mod tests {
         assert_eq!(parse_timestamp("@+4"), Some(4));
         assert_eq!(parse_timestamp("@0"), Some(0));
 
-        // gnu date accepts this
+        // gnu date acceppts numbers signs and uses the last sign
+        assert_eq!(parse_timestamp("@---+12"), Some(12));
+        assert_eq!(parse_timestamp("@+++-12"), Some(-12));
         assert_eq!(parse_timestamp("@+----+12"), Some(12));
         assert_eq!(parse_timestamp("@++++-123"), Some(-123));
     }
@@ -50,5 +62,6 @@ mod tests {
     fn test_invalid_timestamp() {
         assert_eq!(parse_timestamp("@"), None);
         assert_eq!(parse_timestamp("@+--+"), None);
+        assert_eq!(parse_timestamp("@+1ab2"), None);
     }
 }
