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Auto merge of #143540 - yotamofek:pr/library/simplify-num-fmt, r=tgross35

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Simplify num formatting helpers

Noticed `ilog10` was being open-coded when looking at this diff: 85d6768f4c..76d9775912 (diff-6be9b44b52d946ccac652ddb7c98146a01b22ea0fc5737bc10db245a24796a45)
That, and two other small cleanups 😁

(should probably go through perf just to make sure it doesn't regress formatting)
This commit is contained in:
bors 2025-07-08 10:54:22 +00:00
commit 040e2f8b9f
1 changed files with 3 additions and 22 deletions
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25
library/core/src/num/fmt.rs
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@ -22,19 +22,7 @@ impl<'a> Part<'a> {
pub fn len(&self) -> usize {
match *self {
Part::Zero(nzeroes) => nzeroes,
Part::Num(v) => {
if v < 1_000 {
if v < 10 {
1
} else if v < 100 {
2
} else {
3
}
} else {
if v < 10_000 { 4 } else { 5 }
}
}
Part::Num(v) => v.checked_ilog10().unwrap_or_default() as usize + 1,
Part::Copy(buf) => buf.len(),
}
}
@ -82,21 +70,14 @@ pub struct Formatted<'a> {
impl<'a> Formatted<'a> {
/// Returns the exact byte length of combined formatted result.
pub fn len(&self) -> usize {
let mut len = self.sign.len();
for part in self.parts {
len += part.len();
}
len
self.sign.len() + self.parts.iter().map(|part| part.len()).sum::<usize>()
}
/// Writes all formatted parts into the supplied buffer.
/// Returns the number of written bytes, or `None` if the buffer is not enough.
/// (It may still leave partially written bytes in the buffer; do not rely on that.)
pub fn write(&self, out: &mut [u8]) -> Option<usize> {
if out.len() < self.sign.len() {
return None;
}
out[..self.sign.len()].copy_from_slice(self.sign.as_bytes());
out.get_mut(..self.sign.len())?.copy_from_slice(self.sign.as_bytes());
let mut written = self.sign.len();
for part in self.parts {