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Move nick hue functions to their own module

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This commit is contained in:
Joscha 2023-01-30 15:55:39 +01:00
parent 3bc50dcf26
commit e6898cc9f7
3 changed files with 20 additions and 14 deletions
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43
src/huehash.rs
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@ -1,43 +0,0 @@
use crate::emoji::Emoji;
/// Does not remove emoji.
fn normalize(text: &str) -> String {
text.chars()
.filter(|&c| c.is_ascii_alphanumeric() || c == '_' || c == '-')
.map(|c| c.to_ascii_lowercase())
.collect()
}
/// A re-implementation of [euphoria's nick hue hashing algorithm][0].
///
/// [0]: https://github.com/euphoria-io/heim/blob/master/client/lib/hueHash.js
fn hue_hash(text: &str, offset: i64) -> u8 {
let mut val = 0_i32;
for bibyte in text.encode_utf16() {
let char_val = (bibyte as i32).wrapping_mul(439) % 256;
val = val.wrapping_mul(33).wrapping_add(char_val);
}
let val: i64 = val as i64 + 2_i64.pow(31);
((val + offset) % 255) as u8
}
const GREENIE_OFFSET: i64 = 148 - 192; // 148 - hue_hash("greenie", 0)
/// Calculate the nick hue without removing colon-delimited emoji as part of
/// normalization.
///
/// This should be slightly faster than [`nick_hue`] but produces incorrect
/// results if any colon-delimited emoji are present.
pub fn nick_hue_without_removing_emoji(nick: &str) -> u8 {
let normalized = normalize(nick);
if normalized.is_empty() {
hue_hash(nick, GREENIE_OFFSET)
} else {
hue_hash(&normalized, GREENIE_OFFSET)
}
}
pub fn nick_hue(emoji: &Emoji, nick: &str) -> u8 {
nick_hue_without_removing_emoji(&emoji.remove(nick))
}