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Merge #280
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280: Fix matching lenghth in matching_words r=Kerollmops a=ManyTheFish

related to meilisearch/meilisearch#1441

Co-authored-by: many <maxime@meilisearch.com>
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bors[bot] and ManyTheFish authored Jul 1, 2021
2 parents f25f454 + 9f62149 commit d7bc6a6
Showing 1 changed file with 16 additions and 20 deletions.
36 changes: 16 additions & 20 deletions milli/src/search/matching_words.rs
Original file line number Diff line number Diff line change
Expand Up @@ -108,7 +108,8 @@ impl<T> IndexMut<(usize, usize)> for N2Array<T> {
/// The algorithm is a modified
/// [Damerau-Levenshtein](https://en.wikipedia.org/wiki/Damerau%E2%80%93Levenshtein_distance)
fn bytes_to_highlight(source: &str, target: &str) -> usize {
let (n, m) = (source.chars().count(), target.chars().count());
let n = source.chars().count();
let m = target.chars().count();

if n == 0 {
return 0;
Expand All @@ -125,11 +126,11 @@ fn bytes_to_highlight(source: &str, target: &str) -> usize {
let mut matrix = N2Array::new(n + 2, m + 2, 0);

matrix[(0, 0)] = inf;
for i in 0..n + 1 {
for i in 0..=n {
matrix[(i + 1, 0)] = inf;
matrix[(i + 1, 1)] = i;
}
for j in 0..m + 1 {
for j in 0..=m {
matrix[(0, j + 1)] = inf;
matrix[(1, j + 1)] = j;
}
Expand Down Expand Up @@ -163,16 +164,16 @@ fn bytes_to_highlight(source: &str, target: &str) -> usize {
last_row.insert(char_s, row);
}

let mut minimum = 2;
for x in 0..=n {
let min_dist = (0..=m).map(|y| matrix[(x + 1, y + 1)]).min().unwrap();
if min_dist <= 2 {
minimum = x;
let mut minimum = (u32::max_value(), 0);
for x in 0..=m {
let dist = matrix[(n + 1, x + 1)] as u32;
if dist < minimum.0 {
minimum = (dist, x);
}
}

// everything was done characters wise and now we want to returns a number of bytes
source.chars().take(minimum).map(|c| c.len_utf8()).sum()
source.chars().take(minimum.1).map(|c| c.len_utf8()).sum()
}

#[cfg(test)]
Expand Down Expand Up @@ -208,21 +209,16 @@ mod tests {
TestBytesToHighlight {
query: "Levenstein",
text: "Levenshte",
length: "Levenstei".len(),
length: "Levenste".len(),
},
// we get to the end of our word with only two typos at the beginning
TestBytesToHighlight {
query: "Bavenshtein",
text: "Levenshtein",
length: "Bavenshtein".len(),
},
// Since we calculate a distance char by char we are supposed to have only two mistakes
// here. That would've not be the case if we were computing the distance bytes per bytes
TestBytesToHighlight { query: "Båve", text: "Chiøt", length: "Bå".len() },
TestBytesToHighlight { query: "💪🙂🍤", text: "plouf", length: "💪🙂".len() },
TestBytesToHighlight { query: "clôu¿i", text: "bloubi", length: "clôu".len() },
TestBytesToHighlight {
query: "Альфа", text: "Альфой", length: "Альфа".len()
query: "Альфа", text: "Альфой", length: "Альф".len()
},
TestBytesToHighlight {
query: "Go💼", text: "Go💼od luck.", length: "Go💼".len()
Expand All @@ -240,7 +236,7 @@ mod tests {
];

for test in &tests {
let length = bytes_to_highlight(test.query, test.text);
let length = bytes_to_highlight(test.text, test.query);
assert_eq!(length, test.length, r#"lenght between: "{}" "{}""#, test.query, test.text);
assert!(
from_utf8(&test.query.as_bytes()[..length]).is_ok(),
Expand Down Expand Up @@ -273,12 +269,12 @@ mod tests {

let matching_words = MatchingWords::from_query_tree(&query_tree);

assert_eq!(matching_words.matching_bytes("word"), Some(4));
assert_eq!(matching_words.matching_bytes("word"), Some(3));
assert_eq!(matching_words.matching_bytes("nyc"), None);
assert_eq!(matching_words.matching_bytes("world"), Some(5));
assert_eq!(matching_words.matching_bytes("splitted"), Some(7));
assert_eq!(matching_words.matching_bytes("splitted"), Some(5));
assert_eq!(matching_words.matching_bytes("thisnew"), None);
assert_eq!(matching_words.matching_bytes("borld"), Some(5));
assert_eq!(matching_words.matching_bytes("wordsplit"), Some(5));
assert_eq!(matching_words.matching_bytes("wordsplit"), Some(4));
}
}

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