From 5178b3d59df9c235554776b3049a339894f4731f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Renault?= <clement@meilisearch.com>
Date: Wed, 23 Sep 2020 12:01:39 +0200
Subject: [PATCH] Make the search system be aware of query words typos

---
 src/search.rs | 43 ++++++++++++++++++++++++++++++-------------
 1 file changed, 30 insertions(+), 13 deletions(-)

diff --git a/src/search.rs b/src/search.rs
index e41300cca..a4cf5ead3 100644
--- a/src/search.rs
+++ b/src/search.rs
@@ -195,22 +195,39 @@ impl<'a> Search<'a> {
             return Ok(SearchResult { found_words, documents_ids });
         }
 
+        fn words_pair_combinations<'a>(
+            w1: &'a HashMap<String, (u8, RoaringBitmap)>,
+            w2: &'a HashMap<String, (u8, RoaringBitmap)>,
+        ) -> Vec<(&'a str, &'a str)>
+        {
+            let mut pairs = Vec::new();
+            for (w1, (_typos, docids1)) in w1 {
+                for (w2, (_typos, docids2)) in w2 {
+                    if !docids1.is_disjoint(&docids2) {
+                        pairs.push((w1.as_str(), w2.as_str()));
+                    }
+                }
+            }
+            pairs
+        }
+
         let mut answer = RoaringBitmap::new();
         for (i, words) in derived_words.windows(2).enumerate() {
-            let w1: Vec<_> = words[0].0.keys().collect();
-            let w2: Vec<_> = words[1].0.keys().collect();
+            let pairs = words_pair_combinations(&words[0].0, &words[1].0);
+            eprintln!("found pairs {:?}", pairs);
 
-            let key = (w1[0].as_str(), w2[0].as_str(), 1);
-            match index.word_pair_proximity_docids.get(rtxn, &key)? {
-                Some(docids) => if i == 0 {
-                    answer = docids;
-                } else {
-                    answer.intersect_with(&docids);
-                },
-                None => {
-                    answer = RoaringBitmap::new();
-                    break;
-                },
+            let mut pairs_union = RoaringBitmap::new();
+            for (w1, w2) in pairs {
+                let key = (w1, w2, 1);
+                if let Some(docids) = index.word_pair_proximity_docids.get(rtxn, &key)? {
+                    pairs_union.union_with(&docids);
+                }
+            }
+
+            if i == 0 {
+                answer = pairs_union;
+            } else {
+                answer.intersect_with(&pairs_union);
             }
         }