diff --git a/src/display.rs b/src/display.rs index 57ee1ad..09744c5 100644 --- a/src/display.rs +++ b/src/display.rs @@ -154,7 +154,6 @@ pub struct DisplayByteSlice<'a> { impl<'a> DisplayByteSlice<'a> { fn display(&self, f: &mut fmt::Formatter, case: Case) -> fmt::Result { - use fmt::Write; // There are at least two optimizations left: // // * Reusing the buffer (encoder) which may decrease the number of virtual calls @@ -166,8 +165,14 @@ impl<'a> DisplayByteSlice<'a> { let pad_right = if let Some(width) = f.width() { let string_len = match f.precision() { - Some(max) if self.bytes.len() * 2 > (max + 1) / 2 => max, - Some(_) | None => self.bytes.len() * 2, + #[rustfmt::skip] + Some(max) => { + // Odd max width which makes no sense for hex strings, honour max but use even length. + let max = if max % 2 == 1 { max - 1 } else { max }; + let hex_length = self.bytes.len() * 2; + if hex_length > max { max } else { hex_length } + } + None => self.bytes.len() * 2, }; if string_len < width { @@ -197,13 +202,10 @@ impl<'a> DisplayByteSlice<'a> { }; match f.precision() { - Some(max) if self.bytes.len() > (max + 1) / 2 => { + // Do ceil division on max so as to ignore odd length max width which makes + // no sense for hex strings i.e., honour max but use even length. + Some(max) if self.bytes.len() > max / 2 => { write!(f, "{}", self.bytes[..(max / 2)].as_hex())?; - if max % 2 == 1 && self.bytes.len() > max / 2 + 1 { - f.write_char( - case.table().byte_to_hex(self.bytes[max / 2 + 1]).as_bytes()[1].into(), - )?; - } } Some(_) | None => { let mut chunks = self.bytes.chunks_exact(512); @@ -442,6 +444,14 @@ mod tests { assert_eq!(format!("{0:.4}", v.as_hex()), "1234"); } + #[test] + fn odd_precision_truncates() { + // Precision gets the most significant bytes. + let v = vec![0x12, 0x34, 0x56, 0x78]; + // Remember the integer is number of hex chars not number of bytes. + assert_eq!(format!("{0:.5}", v.as_hex()), "1234"); + } + #[test] fn precision_with_padding_truncates() { // Precision gets the most significant bytes. @@ -449,6 +459,13 @@ mod tests { assert_eq!(format!("{0:10.4}", v.as_hex()), "1234 "); } + #[test] + fn odd_precision_with_padding_truncates() { + // Precision gets the most significant bytes. + let v = vec![0x12, 0x34, 0x56, 0x78]; + assert_eq!(format!("{0:10.5}", v.as_hex()), "1234 "); + } + #[test] fn precision_with_padding_pads_right() { let v = vec![0x12, 0x34, 0x56, 0x78];