43 lines
1.2 KiB
Rust
43 lines
1.2 KiB
Rust
use std::cmp;
|
|
|
|
/// Calculate Levenshtein distance for two UTF-8 encoded strings.
|
|
///
|
|
/// Returns a minimum number of edits to transform from source to target string.
|
|
///
|
|
/// Levenshtein distance accepts three edit operations: insertion, deletion,
|
|
/// and substitution.
|
|
///
|
|
/// References:
|
|
///
|
|
/// - [Levenshtein distance in Cargo][1]
|
|
/// - [Ilia Schelokov: Optimizing loop heavy Rust code][2]
|
|
///
|
|
/// [1]: https://github.com/rust-lang/cargo/blob/7d7fe6797ad07f313706380d251796702272b150/src/cargo/util/lev_distance.rs
|
|
/// [2]: https://thaumant.me/optimizing-loop-heavy-rust/
|
|
pub fn distance(source: &str, target: &str) -> usize {
|
|
if source.is_empty() {
|
|
return target.len();
|
|
}
|
|
if target.is_empty() {
|
|
return source.len();
|
|
}
|
|
|
|
let mut distances = (0..=target.chars().count()).collect::<Vec<_>>();
|
|
|
|
for (i, ch1) in source.chars().enumerate() {
|
|
let mut sub = i;
|
|
distances[0] = sub + 1;
|
|
for (j, ch2) in target.chars().enumerate() {
|
|
let dist = cmp::min(
|
|
cmp::min(distances[j], distances[j + 1]) + 1,
|
|
sub + (ch1 != ch2) as usize,
|
|
);
|
|
|
|
sub = distances[j + 1];
|
|
distances[j + 1] = dist;
|
|
}
|
|
}
|
|
|
|
*distances.last().unwrap()
|
|
}
|