From 225ae6fd254d64ba863338f0f93c5a16ac0d20a7 Mon Sep 17 00:00:00 2001
From: many <maxime@meilisearch.com>
Date: Tue, 1 Jun 2021 11:48:56 +0200
Subject: [PATCH] Resolve PR comments

---
 milli/src/search/matching_words.rs | 12 +++++++++---
 milli/src/search/query_tree.rs     |  5 +----
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/milli/src/search/matching_words.rs b/milli/src/search/matching_words.rs
index 37a4f49c0..17649849d 100644
--- a/milli/src/search/matching_words.rs
+++ b/milli/src/search/matching_words.rs
@@ -11,24 +11,28 @@ use super::build_dfa;
 
 type IsPrefix = bool;
 
-/// The query tree builder is the interface to build a query tree.
+/// Structure created from a query tree
+/// referencing words that match the given query tree.
 #[derive(Default)]
 pub struct MatchingWords {
     dfas: Vec<(DFA, String, u8, IsPrefix)>,
 }
 
 impl MatchingWords {
-    /// Lists all words which can be considered as a match for the query tree.
     pub fn from_query_tree(tree: &Operation) -> Self {
+        // fetch matchable words from the query tree
         let mut dfas: Vec<_> = fetch_queries(tree)
             .into_iter()
+            // create DFAs for each word
             .map(|(w, t, p)| (build_dfa(w, t, p), w.to_string(), t, p))
             .collect();
+        // Sort word by len in DESC order prioritizing the longuest word,
+        // in order to highlight the longuest part of the matched word.
         dfas.sort_unstable_by_key(|(_dfa, query_word, _typo, _is_prefix)| Reverse(query_word.len()));
         Self { dfas }
     }
 
-    /// Returns the number of matching bytes if the word matches.
+    /// Returns the number of matching bytes if the word matches one of the query words.
     pub fn matching_bytes(&self, word: &str) -> Option<usize> {
         self.dfas.iter().find_map(|(dfa, query_word, typo, is_prefix)| match dfa.eval(word) {
             Distance::Exact(t) if t <= *typo => {
@@ -94,6 +98,8 @@ impl<T> IndexMut<(usize, usize)> for N2Array<T> {
     }
 }
 
+/// Returns the distance between the source word and the target word,
+/// and the number of byte matching in the target word.
 fn prefix_damerau_levenshtein(source: &[u8], target: &[u8]) -> (u32, usize) {
     let (n, m) = (source.len(), target.len());
 
diff --git a/milli/src/search/query_tree.rs b/milli/src/search/query_tree.rs
index 3125664ab..03305943b 100644
--- a/milli/src/search/query_tree.rs
+++ b/milli/src/search/query_tree.rs
@@ -1,14 +1,11 @@
-use std::collections::HashSet;
 use std::{fmt, cmp, mem};
 
 use fst::Set;
-use levenshtein_automata::{DFA, Distance};
 use meilisearch_tokenizer::{TokenKind, tokenizer::TokenStream};
 use roaring::RoaringBitmap;
 use slice_group_by::GroupBy;
 
 use crate::Index;
-use super::build_dfa;
 
 type IsOptionalWord = bool;
 type IsPrefix = bool;
@@ -519,7 +516,7 @@ pub fn maximum_proximity(operation: &Operation) -> usize {
 mod test {
     use std::collections::HashMap;
 
-    use maplit::{hashmap, hashset};
+    use maplit::hashmap;
     use meilisearch_tokenizer::{Analyzer, AnalyzerConfig};
     use rand::{Rng, SeedableRng, rngs::StdRng};