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use std::cmp;
use crate::symbol::Symbol;
pub fn lev_distance(a: &str, b: &str) -> usize {
if a.is_empty() {
return b.chars().count();
} else if b.is_empty() {
return a.chars().count();
}
let mut dcol: Vec<_> = (0..=b.len()).collect();
let mut t_last = 0;
for (i, sc) in a.chars().enumerate() {
let mut current = i;
dcol[0] = current + 1;
for (j, tc) in b.chars().enumerate() {
let next = dcol[j + 1];
if sc == tc {
dcol[j + 1] = current;
} else {
dcol[j + 1] = cmp::min(current, next);
dcol[j + 1] = cmp::min(dcol[j + 1], dcol[j]) + 1;
}
current = next;
t_last = j;
}
}
dcol[t_last + 1]
}
pub fn find_best_match_for_name<'a, T>(iter_names: T,
lookup: &str,
dist: Option<usize>) -> Option<Symbol>
where T: Iterator<Item = &'a Symbol> {
let max_dist = dist.map_or_else(|| cmp::max(lookup.len(), 3) / 3, |d| d);
let (case_insensitive_match, levenstein_match) = iter_names
.filter_map(|&name| {
let dist = lev_distance(lookup, &name.as_str());
if dist <= max_dist {
Some((name, dist))
} else {
None
}
})
.fold((None, None), |result, (candidate, dist)| {
(
if candidate.as_str().to_uppercase() == lookup.to_uppercase() {
Some(candidate)
} else {
result.0
},
match result.1 {
None => Some((candidate, dist)),
Some((c, d)) => Some(if dist < d { (candidate, dist) } else { (c, d) })
}
)
});
if let Some(candidate) = case_insensitive_match {
Some(candidate)
} else {
if let Some((candidate, _)) = levenstein_match { Some(candidate) } else { None }
}
}
#[test]
fn test_lev_distance() {
use std::char::{from_u32, MAX};
for c in (0..MAX as u32)
.filter_map(|i| from_u32(i))
.map(|i| i.to_string()) {
assert_eq!(lev_distance(&c[..], &c[..]), 0);
}
let a = "\nMäry häd ä little lämb\n\nLittle lämb\n";
let b = "\nMary häd ä little lämb\n\nLittle lämb\n";
let c = "Mary häd ä little lämb\n\nLittle lämb\n";
assert_eq!(lev_distance(a, b), 1);
assert_eq!(lev_distance(b, a), 1);
assert_eq!(lev_distance(a, c), 2);
assert_eq!(lev_distance(c, a), 2);
assert_eq!(lev_distance(b, c), 1);
assert_eq!(lev_distance(c, b), 1);
}
#[test]
fn test_find_best_match_for_name() {
use crate::with_globals;
with_globals(|| {
let input = vec![Symbol::intern("aaab"), Symbol::intern("aaabc")];
assert_eq!(
find_best_match_for_name(input.iter(), "aaaa", None),
Some(Symbol::intern("aaab"))
);
assert_eq!(
find_best_match_for_name(input.iter(), "1111111111", None),
None
);
let input = vec![Symbol::intern("aAAA")];
assert_eq!(
find_best_match_for_name(input.iter(), "AAAA", None),
Some(Symbol::intern("aAAA"))
);
let input = vec![Symbol::intern("AAAA")];
assert_eq!(
find_best_match_for_name(input.iter(), "aaaa", None),
None
);
let input = vec![Symbol::intern("AAAA")];
assert_eq!(
find_best_match_for_name(input.iter(), "aaaa", Some(4)),
Some(Symbol::intern("AAAA"))
);
})
}