refactor: scan::nanosecond to return u32

Author: sby1ce

src/format/parse.rs

@@ -208,7 +208,7 @@ pub(crate) fn parse_rfc3339<'a>(parsed: &mut Parsed, mut s: &'a str) -> ParseRes
     parsed.set_second(try_consume!(scan::number(s, 2, 2)))?;
     if s.starts_with('.') {
         let nanosecond = try_consume!(scan::nanosecond(&s[1..]));
-        parsed.set_nanosecond(nanosecond)?;
+        parsed.set_nanosecond(nanosecond as i64)?;
     }
 
     let offset = try_consume!(scan::timezone_offset(s, |s| scan::char(s, b':'), true, false, true));
@@ -420,7 +420,7 @@ where
                     &Nanosecond => {
                         if s.starts_with('.') {
                             let nano = try_consume!(scan::nanosecond(&s[1..]));
-                            parsed.set_nanosecond(nano)?;
+                            parsed.set_nanosecond(nano as i64)?;
                         }
                     }
 

src/format/scan.rs

@@ -47,14 +47,15 @@ pub(super) fn number(s: &str, min: usize, max: usize) -> ParseResult<(&str, i64)
 
 /// Tries to consume at least one digits as a fractional second.
 /// Returns the number of whole nanoseconds (0--999,999,999).
-pub(super) fn nanosecond(s: &str) -> ParseResult<(&str, i64)> {
+pub(super) fn nanosecond(s: &str) -> ParseResult<(&str, u32)> {
     // record the number of digits consumed for later scaling.
     let origlen = s.len();
     let (s, v) = number(s, 1, 9)?;
+    let v = u32::try_from(v).expect("999,999,999 should fit u32");
     let consumed = origlen - s.len();
 
     // scale the number accordingly.
-    static SCALE: [i64; 10] =
+    const SCALE: [u32; 10] =
         [0, 100_000_000, 10_000_000, 1_000_000, 100_000, 10_000, 1_000, 100, 10, 1];
     let v = v.checked_mul(SCALE[consumed]).ok_or(OUT_OF_RANGE)?;