1use core::cmp::Ordering;
2
3/// Decodes the next UTF-8 encoded codepoint from the given byte slice.
4///
5/// If no valid encoding of a codepoint exists at the beginning of the given
6/// byte slice, then the first byte is returned instead.
7///
8/// This returns `None` if and only if `bytes` is empty.
9///
10/// This never panics.
11///
12/// *WARNING*: This is not designed for performance. If you're looking for a
13/// fast UTF-8 decoder, this is not it. If you feel like you need one in this
14/// crate, then please file an issue and discuss your use case.
15pub(crate) fn decode(bytes: &[u8]) -> Option<Result<char, u8>> {
16 crate::shared::util::utf8::decode(bytes)
17}
18
19/// Like std's `eq_ignore_ascii_case`, but returns a full `Ordering`.
20#[inline]
21pub(crate) fn cmp_ignore_ascii_case(s1: &str, s2: &str) -> Ordering {
22 cmp_ignore_ascii_case_bytes(s1.as_bytes(), s2.as_bytes())
23}
24
25/// Like std's `eq_ignore_ascii_case`, but returns a full `Ordering` on
26/// `&[u8]`.
27#[inline]
28pub(crate) fn cmp_ignore_ascii_case_bytes(s1: &[u8], s2: &[u8]) -> Ordering {
29 // This function used to look like this:
30 //
31 // let it1 = s1.iter().map(|&b| b.to_ascii_lowercase());
32 // let it2 = s2.iter().map(|&b| b.to_ascii_lowercase());
33 // it1.cmp(it2)
34 //
35 // But the code below seems to do better in microbenchmarks.
36 let mut i: usize = 0;
37 loop {
38 let b1: Option = s1.get(index:i).copied().map(|b: u8| b.to_ascii_lowercase());
39 let b2: Option = s2.get(index:i).copied().map(|b: u8| b.to_ascii_lowercase());
40 match (b1, b2) {
41 (None, None) => return Ordering::Equal,
42 (Some(_), None) => return Ordering::Greater,
43 (None, Some(_)) => return Ordering::Less,
44 (Some(b1: u8), Some(b2: u8)) if b1 == b2 => i += 1,
45 (Some(b1: u8), Some(b2: u8)) => return b1.cmp(&b2),
46 }
47 }
48}
49