Implement Alphabetic with a branchless jump

This still barely got a faster benchmark despite being one of the quickest solutions on theory

Author: 1Git2Clone

src/distr/other.rs

@@ -155,10 +155,11 @@ impl Distribution<u8> for Alphanumeric {
 impl Distribution<u8> for Alphabetic {
  fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> u8 {
  const RANGE: u8 = 26 + 26;
- const GEN_ASCII_STR_CHARSET: &[u8] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZ\
- abcdefghijklmnopqrstuvwxyz";
 
- GEN_ASCII_STR_CHARSET[rng.random_range(0..RANGE) as usize]
+ let offset = rng.random_range(0..RANGE) + b'A';
+
+ // Account for upper-cases
+ offset + (offset > b'Z') as u8 * (b'a' - b'Z' - 1)
  }
 }
 
@@ -300,6 +301,8 @@ where
 
 #[cfg(test)]
 mod tests {
+ use std::dbg;
+
  use super::*;
  use crate::RngCore;
 
@@ -350,6 +353,7 @@ mod tests {
  for _ in 0..100 {
  let c: char = rng.sample(Alphabetic).into();
  incorrect |= !c.is_ascii_alphabetic();
+ dbg!(c);
  }
  assert!(!incorrect);
  }