Merge remote-tracking branch 'origin/search-refactor-tests-doc' into search-refactor

milli/src/search/new/bucket_sort.rs

@@ -0,0 +1,195 @@
+use roaring::RoaringBitmap;
+
+use super::logger::SearchLogger;
+use super::ranking_rules::{BoxRankingRule, RankingRuleQueryTrait};
+use super::SearchContext;
+use crate::search::new::distinct::{apply_distinct_rule, distinct_single_docid, DistinctOutput};
+use crate::Result;
+
+pub fn bucket_sort<'ctx, Q: RankingRuleQueryTrait>(
+    ctx: &mut SearchContext<'ctx>,
+    mut ranking_rules: Vec<BoxRankingRule<'ctx, Q>>,
+    query: &Q,
+    universe: &RoaringBitmap,
+    from: usize,
+    length: usize,
+    logger: &mut dyn SearchLogger<Q>,
+) -> Result<Vec<u32>> {
+    logger.initial_query(query);
+    logger.ranking_rules(&ranking_rules);
+    logger.initial_universe(universe);
+
+    let distinct_fid = if let Some(field) = ctx.index.distinct_field(ctx.txn)? {
+        ctx.index.fields_ids_map(ctx.txn)?.id(field)
+    } else {
+        None
+    };
+
+    if universe.len() < from as u64 {
+        return Ok(vec![]);
+    }
+    if ranking_rules.is_empty() {
+        if let Some(distinct_fid) = distinct_fid {
+            let mut excluded = RoaringBitmap::new();
+            let mut results = vec![];
+            for docid in universe.iter() {
+                if results.len() >= from + length {
+                    break;
+                }
+                if excluded.contains(docid) {
+                    continue;
+                }
+                distinct_single_docid(ctx.index, ctx.txn, distinct_fid, docid, &mut excluded)?;
+                results.push(docid);
+            }
+            return Ok(results);
+        } else {
+            return Ok(universe.iter().skip(from).take(length).collect());
+        };
+    }
+
+    let ranking_rules_len = ranking_rules.len();
+
+    logger.start_iteration_ranking_rule(0, ranking_rules[0].as_ref(), query, universe);
+    ranking_rules[0].start_iteration(ctx, logger, universe, query)?;
+
+    let mut ranking_rule_universes: Vec<RoaringBitmap> =
+        vec![RoaringBitmap::default(); ranking_rules_len];
+    ranking_rule_universes[0] = universe.clone();
+
+    let mut cur_ranking_rule_index = 0;
+
+    /// Finish iterating over the current ranking rule, yielding
+    /// control to the parent (or finishing the search if not possible).
+    /// Update the candidates accordingly and inform the logger.
+    macro_rules! back {
+        () => {
+            assert!(ranking_rule_universes[cur_ranking_rule_index].is_empty());
+            logger.end_iteration_ranking_rule(
+                cur_ranking_rule_index,
+                ranking_rules[cur_ranking_rule_index].as_ref(),
+                &ranking_rule_universes[cur_ranking_rule_index],
+            );
+            ranking_rule_universes[cur_ranking_rule_index].clear();
+            ranking_rules[cur_ranking_rule_index].end_iteration(ctx, logger);
+            if cur_ranking_rule_index == 0 {
+                break;
+            } else {
+                cur_ranking_rule_index -= 1;
+            }
+        };
+    }
+
+    let mut results = vec![];
+    let mut cur_offset = 0usize;
+
+    /// Add the candidates to the results. Take `distinct`, `from`, `length`, and `cur_offset`
+    /// into account and inform the logger.
+    macro_rules! maybe_add_to_results {
+        ($candidates:expr) => {
+            // First apply the distinct rule on the candidates, reducing the universes if necessary
+            let candidates = if let Some(distinct_fid) = distinct_fid {
+                let DistinctOutput { remaining, excluded } = apply_distinct_rule(ctx, distinct_fid, $candidates)?;
+                for universe in ranking_rule_universes.iter_mut() {
+                    *universe -= &excluded;
+                }
+                remaining
+            } else {
+                $candidates.clone()
+            };
+            let len = candidates.len();
+            // if the candidates are empty, there is nothing to do;
+            if !candidates.is_empty() {
+                // if we still haven't reached the first document to return
+                if cur_offset < from {
+                    // and if no document from this bucket can be returned
+                    if cur_offset + (candidates.len() as usize) < from {
+                        // then just skip the bucket
+                        logger.skip_bucket_ranking_rule(
+                            cur_ranking_rule_index,
+                            ranking_rules[cur_ranking_rule_index].as_ref(),
+                            &candidates,
+                        );
+                    } else {
+                        // otherwise, skip some of the documents and add some of the rest, in order of ids
+                        let all_candidates = candidates.iter().collect::<Vec<_>>();
+                        let (skipped_candidates, candidates) =
+                            all_candidates.split_at(from - cur_offset);
+                        logger.skip_bucket_ranking_rule(
+                            cur_ranking_rule_index,
+                            ranking_rules[cur_ranking_rule_index].as_ref(),
+                            &skipped_candidates.into_iter().collect(),
+                        );
+                        let candidates = candidates
+                            .iter()
+                            .take(length - results.len())
+                            .copied()
+                            .collect::<Vec<_>>();
+                        logger.add_to_results(&candidates);
+                        results.extend(&candidates);
+                    }
+                } else {
+                    // if we have passed the offset already, add some of the documents (up to the limit)
+                    let candidates =
+                        candidates.iter().take(length - results.len()).collect::<Vec<u32>>();
+                    logger.add_to_results(&candidates);
+                    results.extend(&candidates);
+                }
+            }
+            cur_offset += len as usize;
+        };
+    }
+
+    while results.len() < length {
+        // The universe for this bucket is zero or one element, so we don't need to sort
+        // anything, just extend the results and go back to the parent ranking rule.
+        if ranking_rule_universes[cur_ranking_rule_index].len() <= 1 {
+            maybe_add_to_results!(&ranking_rule_universes[cur_ranking_rule_index]);
+            ranking_rule_universes[cur_ranking_rule_index].clear();
+            back!();
+            continue;
+        }
+
+        let Some(next_bucket) = ranking_rules[cur_ranking_rule_index].next_bucket(ctx, logger, &ranking_rule_universes[cur_ranking_rule_index])? else {
+            back!();
+            continue;
+        };
+
+        logger.next_bucket_ranking_rule(
+            cur_ranking_rule_index,
+            ranking_rules[cur_ranking_rule_index].as_ref(),
+            &ranking_rule_universes[cur_ranking_rule_index],
+            &next_bucket.candidates,
+        );
+
+        debug_assert!(
+            ranking_rule_universes[cur_ranking_rule_index].is_superset(&next_bucket.candidates)
+        );
+        ranking_rule_universes[cur_ranking_rule_index] -= &next_bucket.candidates;
+
+        if cur_ranking_rule_index == ranking_rules_len - 1
+            || next_bucket.candidates.len() <= 1
+            || cur_offset + (next_bucket.candidates.len() as usize) < from
+        {
+            maybe_add_to_results!(&next_bucket.candidates);
+            continue;
+        }
+
+        cur_ranking_rule_index += 1;
+        ranking_rule_universes[cur_ranking_rule_index] = next_bucket.candidates.clone();
+        logger.start_iteration_ranking_rule(
+            cur_ranking_rule_index,
+            ranking_rules[cur_ranking_rule_index].as_ref(),
+            &next_bucket.query,
+            &ranking_rule_universes[cur_ranking_rule_index],
+        );
+        ranking_rules[cur_ranking_rule_index].start_iteration(
+            ctx,
+            logger,
+            &next_bucket.candidates,
+            &next_bucket.query,
+        )?;
+    }
+
+    Ok(results)
+}

milli/src/search/new/db_cache.rs

@@ -1,3 +1,4 @@
+use std::borrow::Cow;
 use std::collections::hash_map::Entry;
 use std::hash::Hash;
 
@@ -24,6 +25,8 @@ pub struct DatabaseCache<'ctx> {
     pub word_docids: FxHashMap<Interned<String>, Option<&'ctx [u8]>>,
     pub exact_word_docids: FxHashMap<Interned<String>, Option<&'ctx [u8]>>,
     pub word_prefix_docids: FxHashMap<Interned<String>, Option<&'ctx [u8]>>,
+
+    pub words_fst: Option<fst::Set<Cow<'ctx, [u8]>>>,
     pub word_position_docids: FxHashMap<(Interned<String>, u16), Option<&'ctx [u8]>>,
     pub word_fid_docids: FxHashMap<(Interned<String>, u16), Option<&'ctx [u8]>>,
 }
@@ -51,6 +54,16 @@ impl<'ctx> DatabaseCache<'ctx> {
     }
 }
 impl<'ctx> SearchContext<'ctx> {
+    pub fn get_words_fst(&mut self) -> Result<fst::Set<Cow<'ctx, [u8]>>> {
+        if let Some(fst) = self.db_cache.words_fst.clone() {
+            Ok(fst)
+        } else {
+            let fst = self.index.words_fst(self.txn)?;
+            self.db_cache.words_fst = Some(fst.clone());
+            Ok(fst)
+        }
+    }
+
     /// Retrieve or insert the given value in the `word_docids` database.
     pub fn get_db_word_docids(&mut self, word: Interned<String>) -> Result<Option<&'ctx [u8]>> {
         DatabaseCache::get_value(

milli/src/search/new/distinct.rs

@@ -41,7 +41,7 @@ pub fn apply_distinct_rule(
 }
 
 /// Apply the distinct rule defined by [`apply_distinct_rule`] for a single document id.
-fn distinct_single_docid(
+pub fn distinct_single_docid(
     index: &Index,
     txn: &RoTxn,
     field_id: u16,

milli/src/search/new/interner.rs

@@ -176,6 +176,9 @@ impl<T> Interner<T> {
     pub fn iter_mut(&mut self) -> impl Iterator<Item = (Interned<T>, &mut T)> {
         self.stable_store.iter_mut().enumerate().map(|(i, x)| (Interned::from_raw(i as u16), x))
     }
+    pub fn freeze(self) -> FixedSizeInterner<T> {
+        FixedSizeInterner { stable_store: self.stable_store }
+    }
 }
 
 /// A store of values of type `T`, each linked to a value of type `From`

milli/src/search/new/logger/detailed.rs

@@ -8,9 +8,7 @@ use roaring::RoaringBitmap;
 
 use crate::search::new::interner::{Interned, MappedInterner};
 use crate::search::new::query_graph::QueryNodeData;
-use crate::search::new::query_term::{
-    Lazy, LocatedQueryTermSubset, OneTypoTerm, QueryTerm, TwoTypoTerm, ZeroTypoTerm,
-};
+use crate::search::new::query_term::LocatedQueryTermSubset;
 use crate::search::new::ranking_rule_graph::{
     DeadEndsCache, Edge, ProximityCondition, ProximityGraph, RankingRuleGraph,
     RankingRuleGraphTrait, TypoCondition, TypoGraph,
@@ -439,87 +437,26 @@ results.{cur_ranking_rule}{cur_activated_id} {{
                 positions: _,
                 term_ids: _,
             }) => {
-                let QueryTerm {
-                    original,
-                    is_ngram: _,
-                    is_prefix: _,
-                    max_nbr_typos,
-                    zero_typo,
-                    one_typo,
-                    two_typo,
-                } = ctx.term_interner.get(term_subset.original);
-
-                let original = ctx.word_interner.get(*original);
                 writeln!(
                     file,
-                    "{node_idx} : \"{original}\" {{
+                    "{node_idx} : \"{}\" {{
                 shape: class
-                max_nbr_typo: {max_nbr_typos}"
+                max_nbr_typo: {}",
+                    term_subset.description(ctx),
+                    term_subset.max_nbr_typos(ctx)
                 )
                 .unwrap();
 
-                let ZeroTypoTerm { phrase, exact: zero_typo, prefix_of, synonyms, use_prefix_db } =
-                    zero_typo;
-
-                for w in zero_typo.iter().copied() {
-                    if term_subset.zero_typo_subset.contains_word(w) {
+                for w in term_subset.all_single_words_except_prefix_db(ctx).unwrap() {
                     let w = ctx.word_interner.get(w);
-                        writeln!(file, "\"{w}\" : 0").unwrap();
+                    writeln!(file, "{w}: word").unwrap();
                 }
+                for p in term_subset.all_phrases(ctx).unwrap() {
+                    writeln!(file, "{}: phrase", p.description(ctx)).unwrap();
                 }
-                for w in prefix_of.iter().copied() {
-                    if term_subset.zero_typo_subset.contains_word(w) {
+                if let Some(w) = term_subset.use_prefix_db(ctx) {
                     let w = ctx.word_interner.get(w);
-                        writeln!(file, "\"{w}\" : 0P").unwrap();
-                    }
-                }
-
-                if let Some(phrase) = phrase {
-                    if term_subset.zero_typo_subset.contains_phrase(*phrase) {
-                        let phrase = ctx.phrase_interner.get(*phrase);
-                        let phrase_str = phrase.description(&ctx.word_interner);
-                        writeln!(file, "\"{phrase_str}\" : phrase").unwrap();
-                    }
-                }
-
-                for synonym in synonyms.iter().copied() {
-                    if term_subset.zero_typo_subset.contains_phrase(synonym) {
-                        let phrase = ctx.phrase_interner.get(synonym);
-                        let phrase_str = phrase.description(&ctx.word_interner);
-                        writeln!(file, "\"{phrase_str}\" : synonym").unwrap();
-                    }
-                }
-                if let Some(use_prefix_db) = use_prefix_db {
-                    if term_subset.zero_typo_subset.contains_word(*use_prefix_db) {
-                        let p = ctx.word_interner.get(*use_prefix_db);
-                        writeln!(file, "use prefix DB : {p}").unwrap();
-                    }
-                }
-                if let Lazy::Init(one_typo) = one_typo {
-                    let OneTypoTerm { split_words, one_typo } = one_typo;
-
-                    for w in one_typo.iter().copied() {
-                        if term_subset.one_typo_subset.contains_word(w) {
-                            let w = ctx.word_interner.get(w);
-                            writeln!(file, "\"{w}\" : 1").unwrap();
-                        }
-                    }
-                    if let Some(split_words) = split_words {
-                        if term_subset.one_typo_subset.contains_phrase(*split_words) {
-                            let phrase = ctx.phrase_interner.get(*split_words);
-                            let phrase_str = phrase.description(&ctx.word_interner);
-                            writeln!(file, "\"{phrase_str}\" : split_words").unwrap();
-                        }
-                    }
-                }
-                if let Lazy::Init(two_typo) = two_typo {
-                    let TwoTypoTerm { two_typos } = two_typo;
-                    for w in two_typos.iter().copied() {
-                        if term_subset.two_typo_subset.contains_word(w) {
-                            let w = ctx.word_interner.get(w);
-                            writeln!(file, "\"{w}\" : 2").unwrap();
-                        }
-                    }
+                    writeln!(file, "{w}: prefix db").unwrap();
                 }
 
                 writeln!(file, "}}").unwrap();

milli/src/search/new/logger/mod.rs

@@ -1,6 +1,8 @@
 // #[cfg(test)]
 pub mod detailed;
 
+pub mod test_logger;
+
 use roaring::RoaringBitmap;
 
 use super::interner::{Interned, MappedInterner};

milli/src/search/new/mod.rs

@@ -1,3 +1,4 @@
+mod bucket_sort;
 mod db_cache;
 mod distinct;
 mod graph_based_ranking_rule;
@@ -18,6 +19,9 @@ mod sort;
 // TODO: documentation + comments
 mod words;
 
+#[cfg(test)]
+mod tests;
+
 use std::collections::HashSet;
 
 use charabia::TokenizerBuilder;
@@ -29,7 +33,8 @@ pub use logger::detailed::DetailedSearchLogger;
 pub use logger::{DefaultSearchLogger, SearchLogger};
 use query_graph::{QueryGraph, QueryNode};
 use query_term::{located_query_terms_from_string, Phrase, QueryTerm};
-use ranking_rules::{bucket_sort, PlaceholderQuery, RankingRuleOutput, RankingRuleQueryTrait};
+use ranking_rules::{PlaceholderQuery, RankingRuleOutput, RankingRuleQueryTrait};
+use bucket_sort::bucket_sort;
 use resolve_query_graph::PhraseDocIdsCache;
 use roaring::RoaringBitmap;
 use words::Words;

milli/src/search/new/query_graph.rs

@@ -1,11 +1,10 @@
 use super::interner::{FixedSizeInterner, Interned};
 use super::query_term::{
-    self, number_of_typos_allowed, LocatedQueryTerm, LocatedQueryTermSubset, NTypoTermSubset,
-    QueryTermSubset,
+    self, number_of_typos_allowed, LocatedQueryTerm, LocatedQueryTermSubset, QueryTermSubset,
 };
 use super::small_bitmap::SmallBitmap;
 use super::SearchContext;
-use crate::search::new::interner::DedupInterner;
+use crate::search::new::interner::Interner;
 use crate::Result;
 use std::cmp::Ordering;
 use std::collections::BTreeMap;
@@ -107,12 +106,7 @@ impl QueryGraph {
             let new_node_idx = add_node(
                 &mut nodes_data,
                 QueryNodeData::Term(LocatedQueryTermSubset {
-                    term_subset: QueryTermSubset {
-                        original: Interned::from_raw(term_idx as u16),
-                        zero_typo_subset: NTypoTermSubset::All,
-                        one_typo_subset: NTypoTermSubset::All,
-                        two_typo_subset: NTypoTermSubset::All,
-                    },
+                    term_subset: QueryTermSubset::full(Interned::from_raw(term_idx as u16)),
                     positions: terms[term_idx].positions.clone(),
                     term_ids: term_idx as u8..=term_idx as u8,
                 }),
@@ -126,12 +120,7 @@ impl QueryGraph {
                     let ngram_idx = add_node(
                         &mut nodes_data,
                         QueryNodeData::Term(LocatedQueryTermSubset {
-                            term_subset: QueryTermSubset {
-                                original: ngram.value,
-                                zero_typo_subset: NTypoTermSubset::All,
-                                one_typo_subset: NTypoTermSubset::All,
-                                two_typo_subset: NTypoTermSubset::All,
-                            },
+                            term_subset: QueryTermSubset::full(ngram.value),
                             positions: ngram.positions,
                             term_ids: term_idx as u8 - 1..=term_idx as u8,
                         }),
@@ -146,12 +135,7 @@ impl QueryGraph {
                     let ngram_idx = add_node(
                         &mut nodes_data,
                         QueryNodeData::Term(LocatedQueryTermSubset {
-                            term_subset: QueryTermSubset {
-                                original: ngram.value,
-                                zero_typo_subset: NTypoTermSubset::All,
-                                one_typo_subset: NTypoTermSubset::All,
-                                two_typo_subset: NTypoTermSubset::All,
-                            },
+                            term_subset: QueryTermSubset::full(ngram.value),
                             positions: ngram.positions,
                             term_ids: term_idx as u8 - 2..=term_idx as u8,
                         }),
@@ -329,7 +313,7 @@ impl QueryGraph {
         let mut at_least_one_phrase = false;
         for (node_id, node) in self.nodes.iter() {
             let QueryNodeData::Term(t) = &node.data else { continue };
-            if ctx.term_interner.get(t.term_subset.original).zero_typo.phrase.is_some() {
+            if t.term_subset.original_phrase(ctx).is_some() {
                 at_least_one_phrase = true;
                 continue;
             }
@@ -361,29 +345,13 @@ impl QueryGraph {
     Build a query graph from a list of paths
 
     The paths are composed of source and dest terms.
-    If the source term is `None`, then the last dest term is used
-    as the predecessor of the dest term. If the source is Some(_),
-    then an edge is built between the last dest term and the source,
-    and between the source and new dest term.
 
-    Note that the resulting graph will not correspond to a perfect
-    representation of the set of paths.
     For example, consider the following paths:
     ```txt
     PATH 1 :  a -> b1 -> c1 -> d -> e1
     PATH 2 :  a -> b2 -> c2 -> d -> e2
     ```
     Then the resulting graph will be:
-    ```txt
-              ┌────┐  ┌────┐             ┌────┐
-           ┌──│ b1 │──│ c1 │─┐        ┌──│ e1 │
-    ┌────┐ │  └────┘  └────┘ │ ┌────┐ │  └────┘
-    │ a  │─┤                 ├─│ d  │─┤
-    └────┘ │  ┌────┐  ┌────┐ │ └────┘ │  ┌────┐
-           └──│ b2 │──│ c2 │─┘        └──│ e2 │
-              └────┘  └────┘             └────┘
-    ```
-    which is different from the fully correct representation:
     ```txt
               ┌────┐  ┌────┐   ┌────┐   ┌────┐
            ┌──│ b1 │──│ c1 │───│ d  │───│ e1 │
@@ -399,21 +367,51 @@ impl QueryGraph {
     pub fn build_from_paths(
         paths: Vec<Vec<(Option<LocatedQueryTermSubset>, LocatedQueryTermSubset)>>,
     ) -> Self {
-        let mut node_data = DedupInterner::default();
-        let root_node = node_data.insert(QueryNodeData::Start);
-        let end_node = node_data.insert(QueryNodeData::End);
+        let mut node_data = Interner::default();
+        let root_node = node_data.push(QueryNodeData::Start);
+        let end_node = node_data.push(QueryNodeData::End);
+
+        let mut paths_with_single_terms = vec![];
+
+        for path in paths {
+            let mut processed_path = vec![];
+            let mut prev_dest_term: Option<LocatedQueryTermSubset> = None;
+            for (start_term, dest_term) in path {
+                if let Some(prev_dest_term) = prev_dest_term.take() {
+                    if let Some(mut start_term) = start_term {
+                        if start_term.term_ids == prev_dest_term.term_ids {
+                            start_term.term_subset.intersect(&prev_dest_term.term_subset);
+                            processed_path.push(start_term);
+                        } else {
+                            processed_path.push(prev_dest_term);
+                            processed_path.push(start_term);
+                        }
+                    } else {
+                        processed_path.push(prev_dest_term);
+                    }
+                } else if let Some(start_term) = start_term {
+                    processed_path.push(start_term);
+                }
+                prev_dest_term = Some(dest_term);
+            }
+            if let Some(prev_dest_term) = prev_dest_term {
+                processed_path.push(prev_dest_term);
+            }
+            paths_with_single_terms.push(processed_path);
+        }
+
+        // TODO: make a prefix tree of the processed paths to avoid uselessly duplicating nodes
 
         let mut paths_with_ids = vec![];
-        for path in paths {
+        for path in paths_with_single_terms {
             let mut path_with_ids = vec![];
-            for node in path {
-                let (start_term, end_term) = node;
-                let src_node_id = start_term.map(|x| node_data.insert(QueryNodeData::Term(x)));
-                let dest_node_id = node_data.insert(QueryNodeData::Term(end_term));
-                path_with_ids.push((src_node_id, dest_node_id));
+            for term in path {
+                let id = node_data.push(QueryNodeData::Term(term));
+                path_with_ids.push(Interned::from_raw(id.into_raw()));
             }
             paths_with_ids.push(path_with_ids);
         }
+
         let nodes_data = node_data.freeze();
         let nodes_data_len = nodes_data.len();
         let mut nodes = nodes_data.map_move(|n| QueryNode {
@@ -422,28 +420,22 @@ impl QueryGraph {
             successors: SmallBitmap::new(nodes_data_len),
         });
 
-        let root_node = Interned::from_raw(root_node.into_raw());
-        let end_node = Interned::from_raw(end_node.into_raw());
+        let root_node = Interned::<QueryNode>::from_raw(root_node.into_raw());
+        let end_node = Interned::<QueryNode>::from_raw(end_node.into_raw());
 
         for path in paths_with_ids {
-            let mut prev_node = root_node;
-            for node in path {
-                let (start_term, dest_term) = node;
-                let end_term = Interned::from_raw(dest_term.into_raw());
-                let src = if let Some(start_term) = start_term {
-                    let start_term = Interned::from_raw(start_term.into_raw());
-                    nodes.get_mut(prev_node).successors.insert(start_term);
-                    nodes.get_mut(start_term).predecessors.insert(prev_node);
-                    start_term
-                } else {
-                    prev_node
-                };
-                nodes.get_mut(src).successors.insert(end_term);
-                nodes.get_mut(end_term).predecessors.insert(src);
-                prev_node = end_term;
+            let mut prev_node_id = root_node;
+            for node_id in path {
+                let prev_node = nodes.get_mut(prev_node_id);
+                prev_node.successors.insert(node_id);
+                let node = nodes.get_mut(node_id);
+                node.predecessors.insert(prev_node_id);
+                prev_node_id = node_id;
             }
-            nodes.get_mut(prev_node).successors.insert(end_node);
-            nodes.get_mut(end_node).predecessors.insert(prev_node);
+            let prev_node = nodes.get_mut(prev_node_id);
+            prev_node.successors.insert(end_node);
+            let node = nodes.get_mut(end_node);
+            node.predecessors.insert(prev_node_id);
         }
 
         QueryGraph { root_node, end_node, nodes }

milli/src/search/new/query_term/compute_derivations.rs

@@ -0,0 +1,381 @@
+use fst::automaton::Str;
+use fst::{Automaton, IntoStreamer, Streamer};
+use heed::types::DecodeIgnore;
+use heed::BytesDecode;
+use std::borrow::Cow;
+use std::collections::BTreeSet;
+use std::ops::ControlFlow;
+
+use super::*;
+use crate::search::fst_utils::{Complement, Intersection, StartsWith, Union};
+use crate::search::new::query_term::TwoTypoTerm;
+use crate::search::new::{limits, SearchContext};
+use crate::search::{build_dfa, get_first};
+use crate::{CboRoaringBitmapLenCodec, Result, MAX_WORD_LENGTH};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum NumberOfTypos {
+    Zero,
+    One,
+    Two,
+}
+
+pub enum ZeroOrOneTypo {
+    Zero,
+    One,
+}
+
+impl Interned<QueryTerm> {
+    pub fn compute_fully_if_needed(self, ctx: &mut SearchContext) -> Result<()> {
+        let s = ctx.term_interner.get_mut(self);
+        if s.max_nbr_typos == 0 {
+            s.one_typo = Lazy::Init(OneTypoTerm::default());
+            s.two_typo = Lazy::Init(TwoTypoTerm::default());
+        } else if s.max_nbr_typos == 1 && s.one_typo.is_uninit() {
+            assert!(s.two_typo.is_uninit());
+            self.initialize_one_typo_subterm(ctx)?;
+            let s = ctx.term_interner.get_mut(self);
+            assert!(s.one_typo.is_init());
+            s.two_typo = Lazy::Init(TwoTypoTerm::default());
+        } else if s.max_nbr_typos > 1 && s.two_typo.is_uninit() {
+            assert!(s.two_typo.is_uninit());
+            self.initialize_one_and_two_typo_subterm(ctx)?;
+            let s = ctx.term_interner.get_mut(self);
+            assert!(s.one_typo.is_init() && s.two_typo.is_init());
+        }
+        Ok(())
+    }
+}
+
+fn find_zero_typo_prefix_derivations(
+    word_interned: Interned<String>,
+    fst: fst::Set<Cow<[u8]>>,
+    word_interner: &mut DedupInterner<String>,
+    mut visit: impl FnMut(Interned<String>) -> Result<ControlFlow<()>>,
+) -> Result<()> {
+    let word = word_interner.get(word_interned).to_owned();
+    let word = word.as_str();
+    let prefix = Str::new(word).starts_with();
+    let mut stream = fst.search(prefix).into_stream();
+
+    while let Some(derived_word) = stream.next() {
+        let derived_word = std::str::from_utf8(derived_word)?.to_owned();
+        let derived_word_interned = word_interner.insert(derived_word);
+        if derived_word_interned != word_interned {
+            let cf = visit(derived_word_interned)?;
+            if cf.is_break() {
+                break;
+            }
+        }
+    }
+    Ok(())
+}
+
+fn find_zero_one_typo_derivations(
+    ctx: &mut SearchContext,
+    word_interned: Interned<String>,
+    is_prefix: bool,
+    mut visit: impl FnMut(Interned<String>, ZeroOrOneTypo) -> Result<ControlFlow<()>>,
+) -> Result<()> {
+    let fst = ctx.get_words_fst()?;
+    let word = ctx.word_interner.get(word_interned).to_owned();
+    let word = word.as_str();
+
+    let dfa = build_dfa(word, 1, is_prefix);
+    let starts = StartsWith(Str::new(get_first(word)));
+    let mut stream = fst.search_with_state(Intersection(starts, &dfa)).into_stream();
+
+    while let Some((derived_word, state)) = stream.next() {
+        let derived_word = std::str::from_utf8(derived_word)?;
+        let derived_word = ctx.word_interner.insert(derived_word.to_owned());
+        let d = dfa.distance(state.1);
+        match d.to_u8() {
+            0 => {
+                if derived_word != word_interned {
+                    let cf = visit(derived_word, ZeroOrOneTypo::Zero)?;
+                    if cf.is_break() {
+                        break;
+                    }
+                }
+            }
+            1 => {
+                let cf = visit(derived_word, ZeroOrOneTypo::One)?;
+                if cf.is_break() {
+                    break;
+                }
+            }
+            _ => {
+                unreachable!("One typo dfa produced multiple typos")
+            }
+        }
+    }
+    Ok(())
+}
+
+fn find_zero_one_two_typo_derivations(
+    word_interned: Interned<String>,
+    is_prefix: bool,
+    fst: fst::Set<Cow<[u8]>>,
+    word_interner: &mut DedupInterner<String>,
+    mut visit: impl FnMut(Interned<String>, NumberOfTypos) -> Result<ControlFlow<()>>,
+) -> Result<()> {
+    let word = word_interner.get(word_interned).to_owned();
+    let word = word.as_str();
+
+    let starts = StartsWith(Str::new(get_first(word)));
+    let first = Intersection(build_dfa(word, 1, is_prefix), Complement(&starts));
+    let second_dfa = build_dfa(word, 2, is_prefix);
+    let second = Intersection(&second_dfa, &starts);
+    let automaton = Union(first, &second);
+
+    let mut stream = fst.search_with_state(automaton).into_stream();
+
+    while let Some((derived_word, state)) = stream.next() {
+        let derived_word = std::str::from_utf8(derived_word)?;
+        let derived_word_interned = word_interner.insert(derived_word.to_owned());
+        // in the case the typo is on the first letter, we know the number of typo
+        // is two
+        if get_first(derived_word) != get_first(word) {
+            let cf = visit(derived_word_interned, NumberOfTypos::Two)?;
+            if cf.is_break() {
+                break;
+            }
+        } else {
+            // Else, we know that it is the second dfa that matched and compute the
+            // correct distance
+            let d = second_dfa.distance((state.1).0);
+            match d.to_u8() {
+                0 => {
+                    if derived_word_interned != word_interned {
+                        let cf = visit(derived_word_interned, NumberOfTypos::Zero)?;
+                        if cf.is_break() {
+                            break;
+                        }
+                    }
+                }
+                1 => {
+                    let cf = visit(derived_word_interned, NumberOfTypos::One)?;
+                    if cf.is_break() {
+                        break;
+                    }
+                }
+                2 => {
+                    let cf = visit(derived_word_interned, NumberOfTypos::Two)?;
+                    if cf.is_break() {
+                        break;
+                    }
+                }
+                _ => unreachable!("2 typos DFA produced a distance greater than 2"),
+            }
+        }
+    }
+    Ok(())
+}
+
+pub fn partially_initialized_term_from_word(
+    ctx: &mut SearchContext,
+    word: &str,
+    max_typo: u8,
+    is_prefix: bool,
+) -> Result<QueryTerm> {
+    let word_interned = ctx.word_interner.insert(word.to_owned());
+
+    if word.len() > MAX_WORD_LENGTH {
+        return Ok({
+            QueryTerm {
+                original: ctx.word_interner.insert(word.to_owned()),
+                ngram_words: None,
+                is_prefix: false,
+                max_nbr_typos: 0,
+                zero_typo: <_>::default(),
+                one_typo: Lazy::Init(<_>::default()),
+                two_typo: Lazy::Init(<_>::default()),
+            }
+        });
+    }
+
+    let fst = ctx.index.words_fst(ctx.txn)?;
+
+    let use_prefix_db = is_prefix
+        && ctx
+            .index
+            .word_prefix_docids
+            .remap_data_type::<DecodeIgnore>()
+            .get(ctx.txn, word)?
+            .is_some();
+    let use_prefix_db = if use_prefix_db { Some(word_interned) } else { None };
+
+    let mut zero_typo = None;
+    let mut prefix_of = BTreeSet::new();
+
+    if fst.contains(word) {
+        zero_typo = Some(word_interned);
+    }
+
+    if is_prefix && use_prefix_db.is_none() {
+        find_zero_typo_prefix_derivations(
+            word_interned,
+            fst,
+            &mut ctx.word_interner,
+            |derived_word| {
+                if prefix_of.len() < limits::MAX_PREFIX_COUNT {
+                    prefix_of.insert(derived_word);
+                    Ok(ControlFlow::Continue(()))
+                } else {
+                    Ok(ControlFlow::Break(()))
+                }
+            },
+        )?;
+    }
+    let synonyms = ctx.index.synonyms(ctx.txn)?;
+    let mut synonym_word_count = 0;
+    let synonyms = synonyms
+        .get(&vec![word.to_owned()])
+        .cloned()
+        .unwrap_or_default()
+        .into_iter()
+        .take(limits::MAX_SYNONYM_PHRASE_COUNT)
+        .filter_map(|words| {
+            if synonym_word_count + words.len() > limits::MAX_SYNONYM_WORD_COUNT {
+                return None;
+            }
+            synonym_word_count += words.len();
+            let words = words.into_iter().map(|w| Some(ctx.word_interner.insert(w))).collect();
+            Some(ctx.phrase_interner.insert(Phrase { words }))
+        })
+        .collect();
+    let zero_typo =
+        ZeroTypoTerm { phrase: None, exact: zero_typo, prefix_of, synonyms, use_prefix_db };
+
+    Ok(QueryTerm {
+        original: word_interned,
+        ngram_words: None,
+        max_nbr_typos: max_typo,
+        is_prefix,
+        zero_typo,
+        one_typo: Lazy::Uninit,
+        two_typo: Lazy::Uninit,
+    })
+}
+
+fn find_split_words(ctx: &mut SearchContext, word: &str) -> Result<Option<Interned<Phrase>>> {
+    if let Some((l, r)) = split_best_frequency(ctx, word)? {
+        Ok(Some(ctx.phrase_interner.insert(Phrase { words: vec![Some(l), Some(r)] })))
+    } else {
+        Ok(None)
+    }
+}
+
+impl Interned<QueryTerm> {
+    fn initialize_one_typo_subterm(self, ctx: &mut SearchContext) -> Result<()> {
+        let self_mut = ctx.term_interner.get_mut(self);
+        let QueryTerm { original, is_prefix, one_typo, .. } = self_mut;
+        let original = *original;
+        let is_prefix = *is_prefix;
+        // let original_str = ctx.word_interner.get(*original).to_owned();
+        if one_typo.is_init() {
+            return Ok(());
+        }
+        let mut one_typo_words = BTreeSet::new();
+
+        find_zero_one_typo_derivations(ctx, original, is_prefix, |derived_word, nbr_typos| {
+            match nbr_typos {
+                ZeroOrOneTypo::Zero => {}
+                ZeroOrOneTypo::One => {
+                    if one_typo_words.len() < limits::MAX_ONE_TYPO_COUNT {
+                        one_typo_words.insert(derived_word);
+                    } else {
+                        return Ok(ControlFlow::Break(()));
+                    }
+                }
+            }
+            Ok(ControlFlow::Continue(()))
+        })?;
+        let original_str = ctx.word_interner.get(original).to_owned();
+        let split_words = find_split_words(ctx, original_str.as_str())?;
+        let one_typo = OneTypoTerm { split_words, one_typo: one_typo_words };
+
+        let self_mut = ctx.term_interner.get_mut(self);
+        self_mut.one_typo = Lazy::Init(one_typo);
+
+        Ok(())
+    }
+    fn initialize_one_and_two_typo_subterm(self, ctx: &mut SearchContext) -> Result<()> {
+        let self_mut = ctx.term_interner.get_mut(self);
+        let QueryTerm { original, is_prefix, two_typo, .. } = self_mut;
+        let original_str = ctx.word_interner.get(*original).to_owned();
+        if two_typo.is_init() {
+            return Ok(());
+        }
+        let mut one_typo_words = BTreeSet::new();
+        let mut two_typo_words = BTreeSet::new();
+
+        find_zero_one_two_typo_derivations(
+            *original,
+            *is_prefix,
+            ctx.index.words_fst(ctx.txn)?,
+            &mut ctx.word_interner,
+            |derived_word, nbr_typos| {
+                if one_typo_words.len() >= limits::MAX_ONE_TYPO_COUNT
+                    && two_typo_words.len() >= limits::MAX_TWO_TYPOS_COUNT
+                {
+                    // No chance we will add either one- or two-typo derivations anymore, stop iterating.
+                    return Ok(ControlFlow::Break(()));
+                }
+                match nbr_typos {
+                    NumberOfTypos::Zero => {}
+                    NumberOfTypos::One => {
+                        if one_typo_words.len() < limits::MAX_ONE_TYPO_COUNT {
+                            one_typo_words.insert(derived_word);
+                        }
+                    }
+                    NumberOfTypos::Two => {
+                        if two_typo_words.len() < limits::MAX_TWO_TYPOS_COUNT {
+                            two_typo_words.insert(derived_word);
+                        }
+                    }
+                }
+                Ok(ControlFlow::Continue(()))
+            },
+        )?;
+        let split_words = find_split_words(ctx, original_str.as_str())?;
+        let self_mut = ctx.term_interner.get_mut(self);
+
+        let one_typo = OneTypoTerm { one_typo: one_typo_words, split_words };
+
+        let two_typo = TwoTypoTerm { two_typos: two_typo_words };
+
+        self_mut.one_typo = Lazy::Init(one_typo);
+        self_mut.two_typo = Lazy::Init(two_typo);
+
+        Ok(())
+    }
+}
+
+/// Split the original word into the two words that appear the
+/// most next to each other in the index.
+///
+/// Return `None` if the original word cannot be split.
+fn split_best_frequency(
+    ctx: &mut SearchContext,
+    original: &str,
+) -> Result<Option<(Interned<String>, Interned<String>)>> {
+    let chars = original.char_indices().skip(1);
+    let mut best = None;
+
+    for (i, _) in chars {
+        let (left, right) = original.split_at(i);
+        let left = ctx.word_interner.insert(left.to_owned());
+        let right = ctx.word_interner.insert(right.to_owned());
+
+        if let Some(docid_bytes) = ctx.get_db_word_pair_proximity_docids(left, right, 1)? {
+            let frequency =
+                CboRoaringBitmapLenCodec::bytes_decode(docid_bytes).ok_or(heed::Error::Decoding)?;
+            if best.map_or(true, |(old, _, _)| frequency > old) {
+                best = Some((frequency, left, right));
+            }
+        }
+    }
+
+    Ok(best.map(|(_, left, right)| (left, right)))
+}

milli/src/search/new/query_term/mod.rs

@@ -0,0 +1,370 @@
+mod compute_derivations;
+mod ntypo_subset;
+mod parse_query;
+mod phrase;
+
+use super::interner::{DedupInterner, Interned};
+use super::{limits, SearchContext};
+use crate::Result;
+use std::collections::BTreeSet;
+use std::ops::RangeInclusive;
+
+use either::Either;
+pub use ntypo_subset::NTypoTermSubset;
+pub use parse_query::{located_query_terms_from_string, make_ngram, number_of_typos_allowed};
+pub use phrase::Phrase;
+
+use compute_derivations::partially_initialized_term_from_word;
+
+/// A set of word derivations attached to a location in the search query.
+#[derive(Clone, PartialEq, Eq, Hash)]
+pub struct LocatedQueryTermSubset {
+    pub term_subset: QueryTermSubset,
+    pub positions: RangeInclusive<u16>,
+    pub term_ids: RangeInclusive<u8>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct QueryTermSubset {
+    original: Interned<QueryTerm>,
+    zero_typo_subset: NTypoTermSubset,
+    one_typo_subset: NTypoTermSubset,
+    two_typo_subset: NTypoTermSubset,
+}
+
+#[derive(Clone, PartialEq, Eq, Hash)]
+pub struct QueryTerm {
+    original: Interned<String>,
+    ngram_words: Option<Vec<Interned<String>>>,
+    max_nbr_typos: u8,
+    is_prefix: bool,
+    zero_typo: ZeroTypoTerm,
+    // May not be computed yet
+    one_typo: Lazy<OneTypoTerm>,
+    // May not be computed yet
+    two_typo: Lazy<TwoTypoTerm>,
+}
+
+// SubTerms will be in a dedup interner
+#[derive(Default, Clone, PartialEq, Eq, Hash)]
+struct ZeroTypoTerm {
+    /// The original phrase, if any
+    phrase: Option<Interned<Phrase>>,
+    /// A single word equivalent to the original term, with zero typos
+    exact: Option<Interned<String>>,
+    /// All the words that contain the original word as prefix
+    prefix_of: BTreeSet<Interned<String>>,
+    /// All the synonyms of the original word or phrase
+    synonyms: BTreeSet<Interned<Phrase>>,
+    /// A prefix in the prefix databases matching the original word
+    use_prefix_db: Option<Interned<String>>,
+}
+#[derive(Default, Clone, PartialEq, Eq, Hash)]
+struct OneTypoTerm {
+    /// The original word split into multiple consecutive words
+    split_words: Option<Interned<Phrase>>,
+    /// Words that are 1 typo away from the original word
+    one_typo: BTreeSet<Interned<String>>,
+}
+#[derive(Default, Clone, PartialEq, Eq, Hash)]
+struct TwoTypoTerm {
+    /// Words that are 2 typos away from the original word
+    two_typos: BTreeSet<Interned<String>>,
+}
+
+#[derive(Clone, PartialEq, Eq, Hash)]
+pub enum Lazy<T> {
+    Uninit,
+    Init(T),
+}
+impl<T> Lazy<T> {
+    pub fn is_init(&self) -> bool {
+        match self {
+            Lazy::Uninit => false,
+            Lazy::Init(_) => true,
+        }
+    }
+    pub fn is_uninit(&self) -> bool {
+        match self {
+            Lazy::Uninit => true,
+            Lazy::Init(_) => false,
+        }
+    }
+}
+
+#[derive(Clone, Copy)]
+pub enum ExactTerm {
+    Phrase(Interned<Phrase>),
+    Word(Interned<String>),
+}
+
+impl ExactTerm {
+    pub fn interned_words<'ctx>(
+        &self,
+        ctx: &'ctx SearchContext<'ctx>,
+    ) -> impl Iterator<Item = Option<Interned<String>>> + 'ctx {
+        match *self {
+            ExactTerm::Phrase(phrase) => {
+                let phrase = ctx.phrase_interner.get(phrase);
+                Either::Left(phrase.words.iter().copied())
+            }
+            ExactTerm::Word(word) => Either::Right(std::iter::once(Some(word))),
+        }
+    }
+}
+
+impl QueryTermSubset {
+    pub fn exact_term(&self, ctx: &SearchContext) -> Option<ExactTerm> {
+        let full_query_term = ctx.term_interner.get(self.original);
+        if full_query_term.ngram_words.is_some() {
+            return None;
+        }
+        // TODO: included in subset
+        if let Some(phrase) = full_query_term.zero_typo.phrase {
+            self.zero_typo_subset.contains_phrase(phrase).then_some(ExactTerm::Phrase(phrase))
+        } else if let Some(word) = full_query_term.zero_typo.exact {
+            self.zero_typo_subset.contains_word(word).then_some(ExactTerm::Word(word))
+        } else {
+            None
+        }
+    }
+
+    pub fn empty(for_term: Interned<QueryTerm>) -> Self {
+        Self {
+            original: for_term,
+            zero_typo_subset: NTypoTermSubset::Nothing,
+            one_typo_subset: NTypoTermSubset::Nothing,
+            two_typo_subset: NTypoTermSubset::Nothing,
+        }
+    }
+    pub fn full(for_term: Interned<QueryTerm>) -> Self {
+        Self {
+            original: for_term,
+            zero_typo_subset: NTypoTermSubset::All,
+            one_typo_subset: NTypoTermSubset::All,
+            two_typo_subset: NTypoTermSubset::All,
+        }
+    }
+
+    pub fn union(&mut self, other: &Self) {
+        assert!(self.original == other.original);
+        self.zero_typo_subset.union(&other.zero_typo_subset);
+        self.one_typo_subset.union(&other.one_typo_subset);
+        self.two_typo_subset.union(&other.two_typo_subset);
+    }
+    pub fn intersect(&mut self, other: &Self) {
+        assert!(self.original == other.original);
+        self.zero_typo_subset.intersect(&other.zero_typo_subset);
+        self.one_typo_subset.intersect(&other.one_typo_subset);
+        self.two_typo_subset.intersect(&other.two_typo_subset);
+    }
+
+    pub fn use_prefix_db(&self, ctx: &SearchContext) -> Option<Interned<String>> {
+        let original = ctx.term_interner.get(self.original);
+        let Some(use_prefix_db) = original.zero_typo.use_prefix_db else {
+            return None
+        };
+        match &self.zero_typo_subset {
+            NTypoTermSubset::All => Some(use_prefix_db),
+            NTypoTermSubset::Subset { words, phrases: _ } => {
+                // TODO: use a subset of prefix words instead
+                if words.contains(&use_prefix_db) {
+                    Some(use_prefix_db)
+                } else {
+                    None
+                }
+            }
+            NTypoTermSubset::Nothing => None,
+        }
+    }
+    pub fn all_single_words_except_prefix_db(
+        &self,
+        ctx: &mut SearchContext,
+    ) -> Result<BTreeSet<Interned<String>>> {
+        let mut result = BTreeSet::default();
+        // TODO: a compute_partially funtion
+        if !self.one_typo_subset.is_empty() || !self.two_typo_subset.is_empty() {
+            self.original.compute_fully_if_needed(ctx)?;
+        }
+
+        let original = ctx.term_interner.get_mut(self.original);
+        if !self.zero_typo_subset.is_empty() {
+            let ZeroTypoTerm {
+                phrase: _,
+                exact: zero_typo,
+                prefix_of,
+                synonyms: _,
+                use_prefix_db: _,
+            } = &original.zero_typo;
+            result.extend(zero_typo.iter().copied());
+            result.extend(prefix_of.iter().copied());
+        };
+
+        match &self.one_typo_subset {
+            NTypoTermSubset::All => {
+                let Lazy::Init(OneTypoTerm { split_words: _, one_typo }) = &original.one_typo else {
+                    panic!()
+                };
+                result.extend(one_typo.iter().copied())
+            }
+            NTypoTermSubset::Subset { words, phrases: _ } => {
+                let Lazy::Init(OneTypoTerm { split_words: _, one_typo }) = &original.one_typo else {
+                    panic!()
+                };
+                result.extend(one_typo.intersection(words));
+            }
+            NTypoTermSubset::Nothing => {}
+        };
+
+        match &self.two_typo_subset {
+            NTypoTermSubset::All => {
+                let Lazy::Init(TwoTypoTerm { two_typos }) = &original.two_typo else {
+                    panic!()
+                };
+                result.extend(two_typos.iter().copied());
+            }
+            NTypoTermSubset::Subset { words, phrases: _ } => {
+                let Lazy::Init(TwoTypoTerm { two_typos }) = &original.two_typo else {
+                    panic!()
+                };
+                result.extend(two_typos.intersection(words));
+            }
+            NTypoTermSubset::Nothing => {}
+        };
+
+        Ok(result)
+    }
+    pub fn all_phrases(&self, ctx: &mut SearchContext) -> Result<BTreeSet<Interned<Phrase>>> {
+        let mut result = BTreeSet::default();
+
+        if !self.one_typo_subset.is_empty() {
+            // TODO: compute less than fully if possible
+            self.original.compute_fully_if_needed(ctx)?;
+        }
+        let original = ctx.term_interner.get_mut(self.original);
+
+        let ZeroTypoTerm { phrase, exact: _, prefix_of: _, synonyms, use_prefix_db: _ } =
+            &original.zero_typo;
+        result.extend(phrase.iter().copied());
+        result.extend(synonyms.iter().copied());
+
+        if !self.one_typo_subset.is_empty() {
+            let Lazy::Init(OneTypoTerm { split_words, one_typo: _ }) = &original.one_typo else {
+                panic!();
+            };
+            result.extend(split_words.iter().copied());
+        }
+
+        Ok(result)
+    }
+
+    pub fn original_phrase(&self, ctx: &SearchContext) -> Option<Interned<Phrase>> {
+        let t = ctx.term_interner.get(self.original);
+        if let Some(p) = t.zero_typo.phrase {
+            if self.zero_typo_subset.contains_phrase(p) {
+                return Some(p);
+            }
+        }
+        None
+    }
+    pub fn max_nbr_typos(&self, ctx: &SearchContext) -> u8 {
+        let t = ctx.term_interner.get(self.original);
+        match t.max_nbr_typos {
+            0 => 0,
+            1 => {
+                if self.one_typo_subset.is_empty() {
+                    0
+                } else {
+                    1
+                }
+            }
+            2 => {
+                if self.two_typo_subset.is_empty() {
+                    if self.one_typo_subset.is_empty() {
+                        0
+                    } else {
+                        1
+                    }
+                } else {
+                    2
+                }
+            }
+            _ => panic!(),
+        }
+    }
+    pub fn clear_zero_typo_subset(&mut self) {
+        self.zero_typo_subset = NTypoTermSubset::Nothing;
+    }
+    pub fn clear_one_typo_subset(&mut self) {
+        self.one_typo_subset = NTypoTermSubset::Nothing;
+    }
+    pub fn clear_two_typo_subset(&mut self) {
+        self.two_typo_subset = NTypoTermSubset::Nothing;
+    }
+    pub fn description(&self, ctx: &SearchContext) -> String {
+        let t = ctx.term_interner.get(self.original);
+        ctx.word_interner.get(t.original).to_owned()
+    }
+}
+
+impl ZeroTypoTerm {
+    fn is_empty(&self) -> bool {
+        let ZeroTypoTerm { phrase, exact: zero_typo, prefix_of, synonyms, use_prefix_db } = self;
+        phrase.is_none()
+            && zero_typo.is_none()
+            && prefix_of.is_empty()
+            && synonyms.is_empty()
+            && use_prefix_db.is_none()
+    }
+}
+impl OneTypoTerm {
+    fn is_empty(&self) -> bool {
+        let OneTypoTerm { split_words, one_typo } = self;
+        one_typo.is_empty() && split_words.is_none()
+    }
+}
+impl TwoTypoTerm {
+    fn is_empty(&self) -> bool {
+        let TwoTypoTerm { two_typos } = self;
+        two_typos.is_empty()
+    }
+}
+
+impl QueryTerm {
+    fn is_empty(&self) -> bool {
+        let Lazy::Init(one_typo) = &self.one_typo else {
+            return false;
+        };
+        let Lazy::Init(two_typo) = &self.two_typo else {
+            return false;
+        };
+
+        self.zero_typo.is_empty() && one_typo.is_empty() && two_typo.is_empty()
+    }
+}
+
+impl Interned<QueryTerm> {
+    /// Return the original word from the given query term
+    fn original_single_word(self, ctx: &SearchContext) -> Option<Interned<String>> {
+        let self_ = ctx.term_interner.get(self);
+        if self_.ngram_words.is_some() {
+            None
+        } else {
+            Some(self_.original)
+        }
+    }
+}
+
+/// A query term coupled with its position in the user's search query.
+#[derive(Clone)]
+pub struct LocatedQueryTerm {
+    pub value: Interned<QueryTerm>,
+    pub positions: RangeInclusive<u16>,
+}
+
+impl LocatedQueryTerm {
+    /// Return `true` iff the term is empty
+    pub fn is_empty(&self, interner: &DedupInterner<QueryTerm>) -> bool {
+        interner.get(self.value).is_empty()
+    }
+}

milli/src/search/new/query_term/ntypo_subset.rs

@@ -0,0 +1,80 @@
+use std::collections::BTreeSet;
+
+use crate::search::new::interner::Interned;
+
+use super::Phrase;
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub enum NTypoTermSubset {
+    All,
+    Subset {
+        words: BTreeSet<Interned<String>>,
+        phrases: BTreeSet<Interned<Phrase>>,
+        // TODO: prefixes: BTreeSet<Interned<String>>,
+    },
+    Nothing,
+}
+
+impl NTypoTermSubset {
+    pub fn contains_word(&self, word: Interned<String>) -> bool {
+        match self {
+            NTypoTermSubset::All => true,
+            NTypoTermSubset::Subset { words, phrases: _ } => words.contains(&word),
+            NTypoTermSubset::Nothing => false,
+        }
+    }
+    pub fn contains_phrase(&self, phrase: Interned<Phrase>) -> bool {
+        match self {
+            NTypoTermSubset::All => true,
+            NTypoTermSubset::Subset { words: _, phrases } => phrases.contains(&phrase),
+            NTypoTermSubset::Nothing => false,
+        }
+    }
+    pub fn is_empty(&self) -> bool {
+        match self {
+            NTypoTermSubset::All => false,
+            NTypoTermSubset::Subset { words, phrases } => words.is_empty() && phrases.is_empty(),
+            NTypoTermSubset::Nothing => true,
+        }
+    }
+    pub fn union(&mut self, other: &Self) {
+        match self {
+            Self::All => {}
+            Self::Subset { words, phrases } => match other {
+                Self::All => {
+                    *self = Self::All;
+                }
+                Self::Subset { words: w2, phrases: p2 } => {
+                    words.extend(w2);
+                    phrases.extend(p2);
+                }
+                Self::Nothing => {}
+            },
+            Self::Nothing => {
+                *self = other.clone();
+            }
+        }
+    }
+    pub fn intersect(&mut self, other: &Self) {
+        match self {
+            Self::All => *self = other.clone(),
+            Self::Subset { words, phrases } => match other {
+                Self::All => {}
+                Self::Subset { words: w2, phrases: p2 } => {
+                    let mut ws = BTreeSet::new();
+                    for w in words.intersection(w2) {
+                        ws.insert(*w);
+                    }
+                    let mut ps = BTreeSet::new();
+                    for p in phrases.intersection(p2) {
+                        ps.insert(*p);
+                    }
+                    *words = ws;
+                    *phrases = ps;
+                }
+                Self::Nothing => *self = Self::Nothing,
+            },
+            Self::Nothing => {}
+        }
+    }
+}

milli/src/search/new/query_term/parse_query.rs

@@ -0,0 +1,281 @@
+use charabia::{normalizer::NormalizedTokenIter, SeparatorKind, TokenKind};
+
+use crate::{Result, SearchContext, MAX_WORD_LENGTH};
+
+use super::*;
+
+/// Convert the tokenised search query into a list of located query terms.
+// TODO: checking if the positions are correct for phrases, separators, ngrams
+pub fn located_query_terms_from_string(
+    ctx: &mut SearchContext,
+    query: NormalizedTokenIter<&[u8]>,
+    words_limit: Option<usize>,
+) -> Result<Vec<LocatedQueryTerm>> {
+    let nbr_typos = number_of_typos_allowed(ctx)?;
+
+    let mut located_terms = Vec::new();
+
+    let mut phrase: Option<PhraseBuilder> = None;
+
+    let parts_limit = words_limit.unwrap_or(usize::MAX);
+
+    // start with the last position as we will wrap around to position 0 at the beginning of the loop below.
+    let mut position = u16::MAX;
+
+    let mut peekable = query.take(super::limits::MAX_TOKEN_COUNT).peekable();
+    while let Some(token) = peekable.next() {
+        // early return if word limit is exceeded
+        if located_terms.len() >= parts_limit {
+            return Ok(located_terms);
+        }
+
+        match token.kind {
+            TokenKind::Word | TokenKind::StopWord => {
+                // On first loop, goes from u16::MAX to 0, then normal increment.
+                position = position.wrapping_add(1);
+
+                // 1. if the word is quoted we push it in a phrase-buffer waiting for the ending quote,
+                // 2. if the word is not the last token of the query and is not a stop_word we push it as a non-prefix word,
+                // 3. if the word is the last token of the query we push it as a prefix word.
+                if let Some(phrase) = &mut phrase {
+                    phrase.push_word(ctx, &token, position)
+                } else if peekable.peek().is_some() {
+                    match token.kind {
+                        TokenKind::Word => {
+                            let word = token.lemma();
+                            let term = partially_initialized_term_from_word(
+                                ctx,
+                                word,
+                                nbr_typos(word),
+                                false,
+                            )?;
+                            let located_term = LocatedQueryTerm {
+                                value: ctx.term_interner.push(term),
+                                positions: position..=position,
+                            };
+                            located_terms.push(located_term);
+                        }
+                        TokenKind::StopWord | TokenKind::Separator(_) | TokenKind::Unknown => {}
+                    }
+                } else {
+                    let word = token.lemma();
+                    let term =
+                        partially_initialized_term_from_word(ctx, word, nbr_typos(word), true)?;
+                    let located_term = LocatedQueryTerm {
+                        value: ctx.term_interner.push(term),
+                        positions: position..=position,
+                    };
+                    located_terms.push(located_term);
+                }
+            }
+            TokenKind::Separator(separator_kind) => {
+                match separator_kind {
+                    SeparatorKind::Hard => {
+                        position += 1;
+                    }
+                    SeparatorKind::Soft => {
+                        position += 0;
+                    }
+                }
+
+                phrase = 'phrase: {
+                    let phrase = phrase.take();
+
+                    // If we have a hard separator inside a phrase, we immediately start a new phrase
+                    let phrase = if separator_kind == SeparatorKind::Hard {
+                        if let Some(phrase) = phrase {
+                            if let Some(located_query_term) = phrase.build(ctx) {
+                                located_terms.push(located_query_term)
+                            }
+                            Some(PhraseBuilder::empty())
+                        } else {
+                            None
+                        }
+                    } else {
+                        phrase
+                    };
+
+                    // We close and start a new phrase depending on the number of double quotes
+                    let mut quote_count = token.lemma().chars().filter(|&s| s == '"').count();
+                    if quote_count == 0 {
+                        break 'phrase phrase;
+                    }
+
+                    // Consume the closing quote and the phrase
+                    if let Some(phrase) = phrase {
+                        // Per the check above, quote_count > 0
+                        quote_count -= 1;
+                        if let Some(located_query_term) = phrase.build(ctx) {
+                            located_terms.push(located_query_term)
+                        }
+                    }
+
+                    // Start new phrase if the token ends with an opening quote
+                    (quote_count % 2 == 1).then_some(PhraseBuilder::empty())
+                };
+            }
+            _ => (),
+        }
+    }
+
+    // If a quote is never closed, we consider all of the end of the query as a phrase.
+    if let Some(phrase) = phrase.take() {
+        if let Some(located_query_term) = phrase.build(ctx) {
+            located_terms.push(located_query_term);
+        }
+    }
+
+    Ok(located_terms)
+}
+
+pub fn number_of_typos_allowed<'ctx>(
+    ctx: &SearchContext<'ctx>,
+) -> Result<impl Fn(&str) -> u8 + 'ctx> {
+    let authorize_typos = ctx.index.authorize_typos(ctx.txn)?;
+    let min_len_one_typo = ctx.index.min_word_len_one_typo(ctx.txn)?;
+    let min_len_two_typos = ctx.index.min_word_len_two_typos(ctx.txn)?;
+
+    // TODO: should `exact_words` also disable prefix search, ngrams, split words, or synonyms?
+    let exact_words = ctx.index.exact_words(ctx.txn)?;
+
+    Ok(Box::new(move |word: &str| {
+        if !authorize_typos
+            || word.len() < min_len_one_typo as usize
+            || exact_words.as_ref().map_or(false, |fst| fst.contains(word))
+        {
+            0
+        } else if word.len() < min_len_two_typos as usize {
+            1
+        } else {
+            2
+        }
+    }))
+}
+
+pub fn make_ngram(
+    ctx: &mut SearchContext,
+    terms: &[LocatedQueryTerm],
+    number_of_typos_allowed: &impl Fn(&str) -> u8,
+) -> Result<Option<LocatedQueryTerm>> {
+    assert!(!terms.is_empty());
+    for t in terms {
+        if ctx.term_interner.get(t.value).zero_typo.phrase.is_some() {
+            return Ok(None);
+        }
+    }
+    for ts in terms.windows(2) {
+        let [t1, t2] = ts else { panic!() };
+        if *t1.positions.end() != t2.positions.start() - 1 {
+            return Ok(None);
+        }
+    }
+    let mut words_interned = vec![];
+    for term in terms {
+        if let Some(original_term_word) = term.value.original_single_word(ctx) {
+            words_interned.push(original_term_word);
+        } else {
+            return Ok(None);
+        }
+    }
+    let words =
+        words_interned.iter().map(|&i| ctx.word_interner.get(i).to_owned()).collect::<Vec<_>>();
+
+    let start = *terms.first().as_ref().unwrap().positions.start();
+    let end = *terms.last().as_ref().unwrap().positions.end();
+    let is_prefix = ctx.term_interner.get(terms.last().as_ref().unwrap().value).is_prefix;
+    let ngram_str = words.join("");
+    if ngram_str.len() > MAX_WORD_LENGTH {
+        return Ok(None);
+    }
+    let ngram_str_interned = ctx.word_interner.insert(ngram_str.clone());
+
+    let max_nbr_typos =
+        number_of_typos_allowed(ngram_str.as_str()).saturating_sub(terms.len() as u8 - 1);
+
+    let mut term = partially_initialized_term_from_word(ctx, &ngram_str, max_nbr_typos, is_prefix)?;
+
+    // Now add the synonyms
+    let index_synonyms = ctx.index.synonyms(ctx.txn)?;
+
+    term.zero_typo.synonyms.extend(
+        index_synonyms.get(&words).cloned().unwrap_or_default().into_iter().map(|words| {
+            let words = words.into_iter().map(|w| Some(ctx.word_interner.insert(w))).collect();
+            ctx.phrase_interner.insert(Phrase { words })
+        }),
+    );
+
+    let term = QueryTerm {
+        original: ngram_str_interned,
+        ngram_words: Some(words_interned),
+        is_prefix,
+        max_nbr_typos,
+        zero_typo: term.zero_typo,
+        one_typo: Lazy::Uninit,
+        two_typo: Lazy::Uninit,
+    };
+
+    let term = LocatedQueryTerm { value: ctx.term_interner.push(term), positions: start..=end };
+
+    Ok(Some(term))
+}
+
+struct PhraseBuilder {
+    words: Vec<Option<Interned<String>>>,
+    start: u16,
+    end: u16,
+}
+
+impl PhraseBuilder {
+    fn empty() -> Self {
+        Self { words: Default::default(), start: u16::MAX, end: u16::MAX }
+    }
+
+    fn is_empty(&self) -> bool {
+        self.words.is_empty()
+    }
+
+    // precondition: token has kind Word or StopWord
+    fn push_word(&mut self, ctx: &mut SearchContext, token: &charabia::Token, position: u16) {
+        if self.is_empty() {
+            self.start = position;
+        }
+        self.end = position;
+        if let TokenKind::StopWord = token.kind {
+            self.words.push(None);
+        } else {
+            // token has kind Word
+            let word = ctx.word_interner.insert(token.lemma().to_string());
+            // TODO: in a phrase, check that every word exists
+            // otherwise return an empty term
+            self.words.push(Some(word));
+        }
+    }
+
+    fn build(self, ctx: &mut SearchContext) -> Option<LocatedQueryTerm> {
+        if self.is_empty() {
+            return None;
+        }
+        Some(LocatedQueryTerm {
+            value: ctx.term_interner.push({
+                let phrase = ctx.phrase_interner.insert(Phrase { words: self.words });
+                let phrase_desc = phrase.description(ctx);
+                QueryTerm {
+                    original: ctx.word_interner.insert(phrase_desc),
+                    ngram_words: None,
+                    max_nbr_typos: 0,
+                    is_prefix: false,
+                    zero_typo: ZeroTypoTerm {
+                        phrase: Some(phrase),
+                        exact: None,
+                        prefix_of: BTreeSet::default(),
+                        synonyms: BTreeSet::default(),
+                        use_prefix_db: None,
+                    },
+                    one_typo: Lazy::Uninit,
+                    two_typo: Lazy::Uninit,
+                }
+            }),
+            positions: self.start..=self.end,
+        })
+    }
+}

milli/src/search/new/query_term/phrase.rs

@@ -0,0 +1,16 @@
+use itertools::Itertools;
+
+use crate::{search::new::interner::Interned, SearchContext};
+
+/// A phrase in the user's search query, consisting of several words
+/// that must appear side-by-side in the search results.
+#[derive(Default, Clone, PartialEq, Eq, Hash)]
+pub struct Phrase {
+    pub words: Vec<Option<Interned<String>>>,
+}
+impl Interned<Phrase> {
+    pub fn description(self, ctx: &SearchContext) -> String {
+        let p = ctx.phrase_interner.get(self);
+        p.words.iter().flatten().map(|w| ctx.word_interner.get(*w)).join(" ")
+    }
+}

milli/src/search/new/ranking_rule_graph/proximity/mod.rs

@@ -57,9 +57,7 @@ impl RankingRuleGraphTrait for ProximityGraph {
                 Ok(format!("{cost}: cost"))
             }
             ProximityCondition::Term { term } => {
-                let original_term = ctx.term_interner.get(term.term_subset.original);
-                let original_word = ctx.word_interner.get(original_term.original);
-                Ok(format!("{original_word} : exists"))
+                Ok(format!("{} : exists", term.term_subset.description(ctx)))
             }
         }
     }

milli/src/search/new/ranking_rule_graph/typo/mod.rs

@@ -3,7 +3,7 @@ use roaring::RoaringBitmap;
 use super::{ComputedCondition, DeadEndsCache, RankingRuleGraph, RankingRuleGraphTrait};
 use crate::search::new::interner::{DedupInterner, Interned, MappedInterner};
 use crate::search::new::logger::SearchLogger;
-use crate::search::new::query_term::{LocatedQueryTermSubset, NTypoTermSubset};
+use crate::search::new::query_term::LocatedQueryTermSubset;
 use crate::search::new::resolve_query_graph::compute_query_term_subset_docids;
 use crate::search::new::{QueryGraph, QueryNode, SearchContext};
 use crate::Result;
@@ -43,8 +43,7 @@ impl RankingRuleGraphTrait for TypoGraph {
         _from: Option<&LocatedQueryTermSubset>,
         to_term: &LocatedQueryTermSubset,
     ) -> Result<Vec<(u32, Interned<Self::Condition>)>> {
-        let term = to_term; // LocatedQueryTermSubset { term_subset, positions: _, term_ids } = to_term;
-        let original_full_term = ctx.term_interner.get(term.term_subset.original);
+        let term = to_term;
 
         let mut edges = vec![];
         // Ngrams have a base typo cost
@@ -52,20 +51,20 @@ impl RankingRuleGraphTrait for TypoGraph {
         // 3-gram -> equivalent to 2 typos
         let base_cost = if term.term_ids.len() == 1 { 0 } else { term.term_ids.len() as u32 };
 
-        for nbr_typos in 0..=original_full_term.max_nbr_typos {
+        for nbr_typos in 0..=term.term_subset.max_nbr_typos(ctx) {
             let mut term = term.clone();
             match nbr_typos {
                 0 => {
-                    term.term_subset.one_typo_subset = NTypoTermSubset::Nothing;
-                    term.term_subset.two_typo_subset = NTypoTermSubset::Nothing;
+                    term.term_subset.clear_one_typo_subset();
+                    term.term_subset.clear_two_typo_subset();
                 }
                 1 => {
-                    term.term_subset.zero_typo_subset = NTypoTermSubset::Nothing;
-                    term.term_subset.two_typo_subset = NTypoTermSubset::Nothing;
+                    term.term_subset.clear_zero_typo_subset();
+                    term.term_subset.clear_two_typo_subset();
                 }
                 2 => {
-                    term.term_subset.zero_typo_subset = NTypoTermSubset::Nothing;
-                    term.term_subset.one_typo_subset = NTypoTermSubset::Nothing;
+                    term.term_subset.clear_zero_typo_subset();
+                    term.term_subset.clear_one_typo_subset();
                 }
                 _ => panic!(),
             };
@@ -92,9 +91,6 @@ impl RankingRuleGraphTrait for TypoGraph {
 
     fn label_for_condition(ctx: &mut SearchContext, condition: &Self::Condition) -> Result<String> {
         let TypoCondition { term, nbr_typos } = condition;
-        let original_term = ctx.term_interner.get(term.term_subset.original);
-        let original = ctx.word_interner.get(original_term.original);
-
-        Ok(format!("{original}: {nbr_typos}"))
+        Ok(format!("{}: {nbr_typos}", term.term_subset.description(ctx)))
     }
 }

milli/src/search/new/ranking_rules.rs

@@ -2,8 +2,6 @@ use roaring::RoaringBitmap;
 
 use super::logger::SearchLogger;
 use super::{QueryGraph, SearchContext};
-// use crate::search::new::sort::Sort;
-use crate::search::new::distinct::{apply_distinct_rule, DistinctOutput};
 use crate::Result;
 
 /// An internal trait implemented by only [`PlaceholderQuery`] and [`QueryGraph`]
@@ -69,171 +67,3 @@ pub struct RankingRuleOutput<Q> {
     /// The allowed candidates for the child ranking rule
     pub candidates: RoaringBitmap,
 }
-
-pub fn bucket_sort<'ctx, Q: RankingRuleQueryTrait>(
-    ctx: &mut SearchContext<'ctx>,
-    mut ranking_rules: Vec<BoxRankingRule<'ctx, Q>>,
-    query: &Q,
-    universe: &RoaringBitmap,
-    from: usize,
-    length: usize,
-    logger: &mut dyn SearchLogger<Q>,
-) -> Result<Vec<u32>> {
-    logger.initial_query(query);
-    logger.ranking_rules(&ranking_rules);
-    logger.initial_universe(universe);
-
-    let distinct_fid = if let Some(field) = ctx.index.distinct_field(ctx.txn)? {
-        ctx.index.fields_ids_map(ctx.txn)?.id(field)
-    } else {
-        None
-    };
-
-    if universe.len() < from as u64 {
-        return Ok(vec![]);
-    }
-
-    let ranking_rules_len = ranking_rules.len();
-    logger.start_iteration_ranking_rule(0, ranking_rules[0].as_ref(), query, universe);
-    ranking_rules[0].start_iteration(ctx, logger, universe, query)?;
-
-    let mut ranking_rule_universes: Vec<RoaringBitmap> =
-        vec![RoaringBitmap::default(); ranking_rules_len];
-    ranking_rule_universes[0] = universe.clone();
-
-    let mut cur_ranking_rule_index = 0;
-
-    /// Finish iterating over the current ranking rule, yielding
-    /// control to the parent (or finishing the search if not possible).
-    /// Update the candidates accordingly and inform the logger.
-    macro_rules! back {
-        () => {
-            assert!(ranking_rule_universes[cur_ranking_rule_index].is_empty());
-            logger.end_iteration_ranking_rule(
-                cur_ranking_rule_index,
-                ranking_rules[cur_ranking_rule_index].as_ref(),
-                &ranking_rule_universes[cur_ranking_rule_index],
-            );
-            ranking_rule_universes[cur_ranking_rule_index].clear();
-            ranking_rules[cur_ranking_rule_index].end_iteration(ctx, logger);
-            if cur_ranking_rule_index == 0 {
-                break;
-            } else {
-                cur_ranking_rule_index -= 1;
-            }
-        };
-    }
-
-    let mut results = vec![];
-    let mut cur_offset = 0usize;
-
-    /// Add the candidates to the results. Take `distinct`, `from`, `length`, and `cur_offset`
-    /// into account and inform the logger.
-    macro_rules! maybe_add_to_results {
-        ($candidates:expr) => {
-            // First apply the distinct rule on the candidates, reducing the universes if necessary
-            let candidates = if let Some(distinct_fid) = distinct_fid {
-                let DistinctOutput { remaining, excluded } = apply_distinct_rule(ctx, distinct_fid, $candidates)?;
-                for universe in ranking_rule_universes.iter_mut() {
-                    *universe -= &excluded;
-                }
-                remaining
-            } else {
-                $candidates.clone()
-            };
-            let len = candidates.len();
-            // if the candidates are empty, there is nothing to do;
-            if !candidates.is_empty() {
-                // if we still haven't reached the first document to return
-                if cur_offset < from {
-                    // and if no document from this bucket can be returned
-                    if cur_offset + (candidates.len() as usize) < from {
-                        // then just skip the bucket
-                        logger.skip_bucket_ranking_rule(
-                            cur_ranking_rule_index,
-                            ranking_rules[cur_ranking_rule_index].as_ref(),
-                            &candidates,
-                        );
-                    } else {
-                        // otherwise, skip some of the documents and add some of the rest, in order of ids
-                        let all_candidates = candidates.iter().collect::<Vec<_>>();
-                        let (skipped_candidates, candidates) =
-                            all_candidates.split_at(from - cur_offset);
-                        logger.skip_bucket_ranking_rule(
-                            cur_ranking_rule_index,
-                            ranking_rules[cur_ranking_rule_index].as_ref(),
-                            &skipped_candidates.into_iter().collect(),
-                        );
-                        let candidates = candidates
-                            .iter()
-                            .take(length - results.len())
-                            .copied()
-                            .collect::<Vec<_>>();
-                        logger.add_to_results(&candidates);
-                        results.extend(&candidates);
-                    }
-                } else {
-                    // if we have passed the offset already, add some of the documents (up to the limit)
-                    let candidates =
-                        candidates.iter().take(length - results.len()).collect::<Vec<u32>>();
-                    logger.add_to_results(&candidates);
-                    results.extend(&candidates);
-                }
-            }
-            cur_offset += len as usize;
-        };
-    }
-
-    while results.len() < length {
-        // The universe for this bucket is zero or one element, so we don't need to sort
-        // anything, just extend the results and go back to the parent ranking rule.
-        if ranking_rule_universes[cur_ranking_rule_index].len() <= 1 {
-            maybe_add_to_results!(&ranking_rule_universes[cur_ranking_rule_index]);
-            ranking_rule_universes[cur_ranking_rule_index].clear();
-            back!();
-            continue;
-        }
-
-        let Some(next_bucket) = ranking_rules[cur_ranking_rule_index].next_bucket(ctx, logger, &ranking_rule_universes[cur_ranking_rule_index])? else {
-            back!();
-            continue;
-        };
-
-        logger.next_bucket_ranking_rule(
-            cur_ranking_rule_index,
-            ranking_rules[cur_ranking_rule_index].as_ref(),
-            &ranking_rule_universes[cur_ranking_rule_index],
-            &next_bucket.candidates,
-        );
-
-        debug_assert!(
-            ranking_rule_universes[cur_ranking_rule_index].is_superset(&next_bucket.candidates)
-        );
-        ranking_rule_universes[cur_ranking_rule_index] -= &next_bucket.candidates;
-
-        if cur_ranking_rule_index == ranking_rules_len - 1
-            || next_bucket.candidates.len() <= 1
-            || cur_offset + (next_bucket.candidates.len() as usize) < from
-        {
-            maybe_add_to_results!(&next_bucket.candidates);
-            continue;
-        }
-
-        cur_ranking_rule_index += 1;
-        ranking_rule_universes[cur_ranking_rule_index] = next_bucket.candidates.clone();
-        logger.start_iteration_ranking_rule(
-            cur_ranking_rule_index,
-            ranking_rules[cur_ranking_rule_index].as_ref(),
-            &next_bucket.query,
-            &ranking_rule_universes[cur_ranking_rule_index],
-        );
-        ranking_rules[cur_ranking_rule_index].start_iteration(
-            ctx,
-            logger,
-            &next_bucket.candidates,
-            &next_bucket.query,
-        )?;
-    }
-
-    Ok(results)
-}

milli/src/search/new/tests/distinct.rs

@@ -0,0 +1,590 @@
+/*!
+This module tests the "distinct attribute" feature, and its
+interaction with other ranking rules.
+
+1. no duplicate distinct attributes are ever returned
+2. only the best document (according to the search rules) for each distinct value appears in the result
+3. if a document does not have a distinct attribute, then the distinct rule does not apply to it
+
+It doesn't test properly:
+- combination of distinct + exhaustive_nbr_hits (because we know it's incorrect)
+- distinct attributes with arrays (because we know it's incorrect as well)
+*/
+
+use std::collections::HashSet;
+
+use big_s::S;
+use heed::RoTxn;
+use maplit::hashset;
+
+use crate::{
+    index::tests::TempIndex, AscDesc, Criterion, Index, Member, Search, SearchResult,
+    TermsMatchingStrategy,
+};
+
+use super::collect_field_values;
+
+fn create_index() -> TempIndex {
+    let index = TempIndex::new();
+
+    index
+        .update_settings(|s| {
+            s.set_primary_key("id".to_owned());
+            s.set_searchable_fields(vec!["text".to_owned()]);
+            s.set_sortable_fields(hashset! { S("rank1"), S("letter") });
+            s.set_distinct_field("letter".to_owned());
+            s.set_criteria(vec![Criterion::Words]);
+        })
+        .unwrap();
+
+    index
+        .add_documents(documents!([
+            {
+                "id": 0,
+                "letter": "A",
+                "rank1": 0,
+                "text": "the quick brown fox jamps over the lazy dog",
+            },
+            {
+                "id": 1,
+                "letter": "A",
+                "rank1": 1,
+                "text": "the quick brown fox jumpes over the lazy dog",
+            },
+            {
+                "id": 2,
+                "letter": "B",
+                "rank1": 0,
+                "text": "the quick brown foxjumps over the lazy dog",
+            },
+            {
+                "id": 3,
+                "letter": "B",
+                "rank1": 1,
+                "text": "the quick brown fox jumps over the lazy dog",
+            },
+            {
+                "id": 4,
+                "letter": "B",
+                "rank1": 2,
+                "text": "the quick brown fox jumps over the lazy",
+            },
+            {
+                "id": 5,
+                "letter": "C",
+                "rank1": 0,
+                "text": "the quickbrownfox jumps over the lazy",
+            },
+            {
+                "id": 6,
+                "letter": "C",
+                "rank1": 1,
+                "text": "the quick brown fox jumpss over the lazy",
+            },
+            {
+                "id": 7,
+                "letter": "C",
+                "rank1": 2,
+                "text": "the quick brown fox jumps over the lazy",
+            },
+            {
+                "id": 8,
+                "letter": "D",
+                "rank1": 0,
+                "text": "the quick brown fox jumps over the lazy",
+            },
+            {
+                "id": 9,
+                "letter": "E",
+                "rank1": 0,
+                "text": "the quick brown fox jumps over the lazy",
+            },
+            {
+                "id": 10,
+                "letter": "E",
+                "rank1": 1,
+                "text": "the quackbrown foxjunps over",
+            },
+            {
+                "id": 11,
+                "letter": "E",
+                "rank1": 2,
+                "text": "the quicko browno fox junps over",
+            },
+            {
+                "id": 12,
+                "letter": "E",
+                "rank1": 3,
+                "text": "the quicko browno fox jumps over",
+            },
+            {
+                "id": 13,
+                "letter": "E",
+                "rank1": 4,
+                "text": "the quick brewn fox jumps over",
+            },
+            {
+                "id": 14,
+                "letter": "E",
+                "rank1": 5,
+                "text": "the quick brown fox jumps over",
+            },
+            {
+                "id": 15,
+                "letter": "F",
+                "rank1": 0,
+                "text": "the quick brownf fox jumps over",
+            },
+            {
+                "id": 16,
+                "letter": "F",
+                "rank1": 1,
+                "text": "the quic brown fox jamps over",
+            },
+            {
+                "id": 17,
+                "letter": "F",
+                "rank1": 2,
+                "text": "thequick browns fox jimps",
+            },
+            {
+                "id": 18,
+                "letter": "G",
+                "rank1": 0,
+                "text": "the qick brown fox jumps",
+            },
+            {
+                "id": 19,
+                "letter": "G",
+                "rank1": 1,
+                "text": "the quick brownfoxjumps",
+            },
+            {
+                "id": 20,
+                "letter": "H",
+                "rank1": 0,
+                "text": "the quick brow fox jumps",
+            },
+            {
+                "id": 21,
+                "letter": "I",
+                "rank1": 0,
+                "text": "the quick brown fox jpmps",
+            },
+            {
+                "id": 22,
+                "letter": "I",
+                "rank1": 1,
+                "text": "the quick brown fox jumps",
+            },
+            {
+                "id": 23,
+                "letter": "I",
+                "rank1": 2,
+                "text": "the quick",
+            },
+            {
+                "id": 24,
+                "rank1": 0,
+                "text": "the quick",
+            },
+            {
+                "id": 25,
+                "rank1": 1,
+                "text": "the quick brown",
+            },
+            {
+                "id": 26,
+                "rank1": 2,
+                "text": "the quick brown fox",
+            },
+            {
+                "id": 26,
+                "rank1": 3,
+                "text": "the quick brown fox jumps over the lazy dog",
+            },
+        ]))
+        .unwrap();
+    index
+}
+
+fn verify_distinct(index: &Index, txn: &RoTxn, docids: &[u32]) -> Vec<String> {
+    let vs = collect_field_values(index, txn, index.distinct_field(txn).unwrap().unwrap(), docids);
+
+    let mut unique = HashSet::new();
+    for v in vs.iter() {
+        if v == "__does_not_exist__" {
+            continue;
+        }
+        assert!(unique.insert(v.clone()));
+    }
+
+    vs
+}
+
+#[test]
+fn test_distinct_placeholder_no_ranking_rules() {
+    let index = create_index();
+
+    let txn = index.read_txn().unwrap();
+
+    let s = Search::new(&txn, &index);
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[0, 2, 5, 8, 9, 15, 18, 20, 21, 24, 25, 26]");
+    let distinct_values = verify_distinct(&index, &txn, &documents_ids);
+    insta::assert_debug_snapshot!(distinct_values, @r###"
+    [
+        "\"A\"",
+        "\"B\"",
+        "\"C\"",
+        "\"D\"",
+        "\"E\"",
+        "\"F\"",
+        "\"G\"",
+        "\"H\"",
+        "\"I\"",
+        "__does_not_exist__",
+        "__does_not_exist__",
+        "__does_not_exist__",
+    ]
+    "###);
+}
+
+#[test]
+fn test_distinct_placeholder_sort() {
+    let index = create_index();
+    index
+        .update_settings(|s| {
+            s.set_criteria(vec![Criterion::Sort]);
+        })
+        .unwrap();
+
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.sort_criteria(vec![AscDesc::Desc(Member::Field(S("rank1")))]);
+
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[14, 26, 4, 7, 17, 23, 1, 19, 25, 8, 20, 24]");
+    let distinct_values = verify_distinct(&index, &txn, &documents_ids);
+    insta::assert_debug_snapshot!(distinct_values, @r###"
+    [
+        "\"E\"",
+        "__does_not_exist__",
+        "\"B\"",
+        "\"C\"",
+        "\"F\"",
+        "\"I\"",
+        "\"A\"",
+        "\"G\"",
+        "__does_not_exist__",
+        "\"D\"",
+        "\"H\"",
+        "__does_not_exist__",
+    ]
+    "###);
+    let rank_values = collect_field_values(&index, &txn, "rank1", &documents_ids);
+    insta::assert_debug_snapshot!(rank_values, @r###"
+    [
+        "5",
+        "3",
+        "2",
+        "2",
+        "2",
+        "2",
+        "1",
+        "1",
+        "1",
+        "0",
+        "0",
+        "0",
+    ]
+    "###);
+
+    let mut s = Search::new(&txn, &index);
+    s.sort_criteria(vec![AscDesc::Desc(Member::Field(S("letter")))]);
+
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[21, 20, 18, 15, 9, 8, 5, 2, 0, 24, 25, 26]");
+    let distinct_values = verify_distinct(&index, &txn, &documents_ids);
+    insta::assert_debug_snapshot!(distinct_values, @r###"
+    [
+        "\"I\"",
+        "\"H\"",
+        "\"G\"",
+        "\"F\"",
+        "\"E\"",
+        "\"D\"",
+        "\"C\"",
+        "\"B\"",
+        "\"A\"",
+        "__does_not_exist__",
+        "__does_not_exist__",
+        "__does_not_exist__",
+    ]
+    "###);
+    let rank_values = collect_field_values(&index, &txn, "rank1", &documents_ids);
+    insta::assert_debug_snapshot!(rank_values, @r###"
+    [
+        "0",
+        "0",
+        "0",
+        "0",
+        "0",
+        "0",
+        "0",
+        "0",
+        "0",
+        "0",
+        "1",
+        "3",
+    ]
+    "###);
+
+    let mut s = Search::new(&txn, &index);
+    s.sort_criteria(vec![
+        AscDesc::Desc(Member::Field(S("letter"))),
+        AscDesc::Desc(Member::Field(S("rank1"))),
+    ]);
+
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[23, 20, 19, 17, 14, 8, 7, 4, 1, 26, 25, 24]");
+    let distinct_values = verify_distinct(&index, &txn, &documents_ids);
+    insta::assert_debug_snapshot!(distinct_values, @r###"
+    [
+        "\"I\"",
+        "\"H\"",
+        "\"G\"",
+        "\"F\"",
+        "\"E\"",
+        "\"D\"",
+        "\"C\"",
+        "\"B\"",
+        "\"A\"",
+        "__does_not_exist__",
+        "__does_not_exist__",
+        "__does_not_exist__",
+    ]
+    "###);
+    let rank_values = collect_field_values(&index, &txn, "rank1", &documents_ids);
+    insta::assert_debug_snapshot!(rank_values, @r###"
+    [
+        "2",
+        "0",
+        "1",
+        "2",
+        "5",
+        "0",
+        "2",
+        "2",
+        "1",
+        "3",
+        "1",
+        "0",
+    ]
+    "###);
+}
+
+#[test]
+fn test_distinct_words() {
+    let index = create_index();
+    index
+        .update_settings(|s| {
+            s.set_criteria(vec![Criterion::Words]);
+        })
+        .unwrap();
+
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::Last);
+    s.query("the quick brown fox jumps over the lazy dog");
+
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[0, 2, 26, 5, 8, 9, 15, 18, 20, 21, 25, 24]");
+    let distinct_values = verify_distinct(&index, &txn, &documents_ids);
+    insta::assert_debug_snapshot!(distinct_values, @r###"
+    [
+        "\"A\"",
+        "\"B\"",
+        "__does_not_exist__",
+        "\"C\"",
+        "\"D\"",
+        "\"E\"",
+        "\"F\"",
+        "\"G\"",
+        "\"H\"",
+        "\"I\"",
+        "__does_not_exist__",
+        "__does_not_exist__",
+    ]
+    "###);
+    let text_values = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(text_values, @r###"
+    [
+        "\"the quick brown fox jamps over the lazy dog\"",
+        "\"the quick brown foxjumps over the lazy dog\"",
+        "\"the quick brown fox jumps over the lazy dog\"",
+        "\"the quickbrownfox jumps over the lazy\"",
+        "\"the quick brown fox jumps over the lazy\"",
+        "\"the quick brown fox jumps over the lazy\"",
+        "\"the quick brownf fox jumps over\"",
+        "\"the qick brown fox jumps\"",
+        "\"the quick brow fox jumps\"",
+        "\"the quick brown fox jpmps\"",
+        "\"the quick brown\"",
+        "\"the quick\"",
+    ]
+    "###);
+}
+
+#[test]
+fn test_distinct_sort_words() {
+    let index = create_index();
+    index
+        .update_settings(|s| {
+            s.set_criteria(vec![Criterion::Sort, Criterion::Words, Criterion::Desc(S("rank1"))]);
+        })
+        .unwrap();
+
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::Last);
+    s.query("the quick brown fox jumps over the lazy dog");
+    s.sort_criteria(vec![AscDesc::Desc(Member::Field(S("letter")))]);
+
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[22, 20, 19, 16, 9, 8, 7, 3, 1, 26, 25, 24]");
+    let distinct_values = verify_distinct(&index, &txn, &documents_ids);
+    insta::assert_debug_snapshot!(distinct_values, @r###"
+    [
+        "\"I\"",
+        "\"H\"",
+        "\"G\"",
+        "\"F\"",
+        "\"E\"",
+        "\"D\"",
+        "\"C\"",
+        "\"B\"",
+        "\"A\"",
+        "__does_not_exist__",
+        "__does_not_exist__",
+        "__does_not_exist__",
+    ]
+    "###);
+
+    let rank_values = collect_field_values(&index, &txn, "rank1", &documents_ids);
+    insta::assert_debug_snapshot!(rank_values, @r###"
+    [
+        "1",
+        "0",
+        "1",
+        "1",
+        "0",
+        "0",
+        "2",
+        "1",
+        "1",
+        "3",
+        "1",
+        "0",
+    ]
+    "###);
+
+    let text_values = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(text_values, @r###"
+    [
+        "\"the quick brown fox jumps\"",
+        "\"the quick brow fox jumps\"",
+        "\"the quick brownfoxjumps\"",
+        "\"the quic brown fox jamps over\"",
+        "\"the quick brown fox jumps over the lazy\"",
+        "\"the quick brown fox jumps over the lazy\"",
+        "\"the quick brown fox jumps over the lazy\"",
+        "\"the quick brown fox jumps over the lazy dog\"",
+        "\"the quick brown fox jumpes over the lazy dog\"",
+        "\"the quick brown fox jumps over the lazy dog\"",
+        "\"the quick brown\"",
+        "\"the quick\"",
+    ]
+    "###);
+}
+
+#[test]
+fn test_distinct_all_candidates() {
+    let index = create_index();
+    index
+        .update_settings(|s| {
+            s.set_criteria(vec![Criterion::Sort]);
+        })
+        .unwrap();
+
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::Last);
+    s.sort_criteria(vec![AscDesc::Desc(Member::Field(S("rank1")))]);
+    s.exhaustive_number_hits(true);
+
+    let SearchResult { documents_ids, candidates, .. } = s.execute().unwrap();
+    let candidates = candidates.iter().collect::<Vec<_>>();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[14, 26, 4, 7, 17, 23, 1, 19, 25, 8, 20, 24]");
+    // TODO: this is incorrect!
+    insta::assert_snapshot!(format!("{candidates:?}"), @"[0, 2, 5, 8, 9, 15, 18, 20, 21, 24, 25, 26]");
+}
+
+#[test]
+fn test_distinct_typo() {
+    let index = create_index();
+    index
+        .update_settings(|s| {
+            s.set_criteria(vec![Criterion::Words, Criterion::Typo]);
+        })
+        .unwrap();
+
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.query("the quick brown fox jumps over the lazy dog");
+    s.terms_matching_strategy(TermsMatchingStrategy::Last);
+
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[3, 26, 0, 7, 8, 9, 15, 22, 18, 20, 25, 24]");
+
+    let distinct_values = verify_distinct(&index, &txn, &documents_ids);
+    insta::assert_debug_snapshot!(distinct_values, @r###"
+    [
+        "\"B\"",
+        "__does_not_exist__",
+        "\"A\"",
+        "\"C\"",
+        "\"D\"",
+        "\"E\"",
+        "\"F\"",
+        "\"I\"",
+        "\"G\"",
+        "\"H\"",
+        "__does_not_exist__",
+        "__does_not_exist__",
+    ]
+    "###);
+
+    let text_values = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(text_values, @r###"
+    [
+        "\"the quick brown fox jumps over the lazy dog\"",
+        "\"the quick brown fox jumps over the lazy dog\"",
+        "\"the quick brown fox jamps over the lazy dog\"",
+        "\"the quick brown fox jumps over the lazy\"",
+        "\"the quick brown fox jumps over the lazy\"",
+        "\"the quick brown fox jumps over the lazy\"",
+        "\"the quick brownf fox jumps over\"",
+        "\"the quick brown fox jumps\"",
+        "\"the qick brown fox jumps\"",
+        "\"the quick brow fox jumps\"",
+        "\"the quick brown\"",
+        "\"the quick\"",
+    ]
+    "###);
+}

milli/src/search/new/tests/language.rs

@@ -0,0 +1,22 @@
+use crate::{index::tests::TempIndex, Search, SearchResult};
+
+#[test]
+fn test_kanji_language_detection() {
+    let index = TempIndex::new();
+
+    index
+        .add_documents(documents!([
+            { "id": 0, "title": "The quick (\"brown\") fox can't jump 32.3 feet, right? Brr, it's 29.3°F!" },
+            { "id": 1, "title": "東京のお寿司。" },
+            { "id": 2, "title": "הַשּׁוּעָל הַמָּהִיר (״הַחוּם״) לֹא יָכוֹל לִקְפֹּץ 9.94 מֶטְרִים, נָכוֹן? ברר, 1.5°C- בַּחוּץ!" }
+        ]))
+        .unwrap();
+
+    let txn = index.write_txn().unwrap();
+    let mut search = Search::new(&txn, &index);
+
+    search.query("東京");
+    let SearchResult { documents_ids, .. } = search.execute().unwrap();
+
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[1]");
+}

milli/src/search/new/tests/mod.rs

@@ -0,0 +1,30 @@
+pub mod distinct;
+#[cfg(feature = "default")]
+pub mod language;
+pub mod ngram_split_words;
+pub mod proximity;
+pub mod proximity_typo;
+pub mod sort;
+pub mod typo;
+pub mod typo_proximity;
+pub mod words_tms;
+
+fn collect_field_values(
+    index: &crate::Index,
+    txn: &heed::RoTxn,
+    fid: &str,
+    docids: &[u32],
+) -> Vec<String> {
+    let mut values = vec![];
+    let fid = index.fields_ids_map(txn).unwrap().id(fid).unwrap();
+    for doc in index.documents(txn, docids.iter().copied()).unwrap() {
+        if let Some(v) = doc.1.get(fid) {
+            let v: serde_json::Value = serde_json::from_slice(v).unwrap();
+            let v = v.to_string();
+            values.push(v);
+        } else {
+            values.push("__does_not_exist__".to_owned());
+        }
+    }
+    values
+}

milli/src/search/new/tests/ngram_split_words.rs

@@ -0,0 +1,372 @@
+/*!
+This module tests the following properties:
+
+1. Two consecutive words from a query can be combined into a "2gram"
+2. Three consecutive words from a query can be combined into a "3gram"
+3. A word from the query can be split into two consecutive words (split words)
+4. A 2gram can be split into two words
+5. A 3gram cannot be split into two words
+6. 2grams can contain up to 1 typo
+7. 3grams cannot have typos
+8. 2grams and 3grams can be prefix tolerant
+9. Disabling typo tolerance also disable the split words feature
+10. Disabling typo tolerance does not disable prefix tolerance
+11. Disabling typo tolerance does not disable ngram tolerance
+12. Prefix tolerance is disabled for the last word if a space follows it
+13. Ngrams cannot be formed by combining a phrase and a word or two phrases
+*/
+
+use crate::{
+    index::tests::TempIndex, search::new::tests::collect_field_values, Criterion, Search,
+    SearchResult, TermsMatchingStrategy,
+};
+
+fn create_index() -> TempIndex {
+    let index = TempIndex::new();
+
+    index
+        .update_settings(|s| {
+            s.set_primary_key("id".to_owned());
+            s.set_searchable_fields(vec!["text".to_owned()]);
+            s.set_criteria(vec![Criterion::Words]);
+        })
+        .unwrap();
+
+    index
+        .add_documents(documents!([
+            {
+                "id": 0,
+                "text": "the sun flowers are pretty"
+            },
+            {
+                "id": 1,
+                "text": "the sun flower is tall"
+            },
+            {
+                "id": 2,
+                "text": "the sunflowers are pretty"
+            },
+            {
+                "id": 3,
+                "text": "the sunflower is tall"
+            },
+            {
+                "id": 4,
+                "text": "the sunflawer is tall"
+            },
+            {
+                "id": 5,
+                "text": "sunflowering is not a verb"
+            }
+        ]))
+        .unwrap();
+    index
+}
+
+#[test]
+fn test_2gram_simple() {
+    let index = create_index();
+    index
+        .update_settings(|s| {
+            s.set_autorize_typos(false);
+        })
+        .unwrap();
+
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("sun flower");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    // will also match documents with "sunflower" + prefix tolerance
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[0, 1, 2, 3, 5]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the sun flowers are pretty\"",
+        "\"the sun flower is tall\"",
+        "\"the sunflowers are pretty\"",
+        "\"the sunflower is tall\"",
+        "\"sunflowering is not a verb\"",
+    ]
+    "###);
+}
+#[test]
+fn test_3gram_simple() {
+    let index = create_index();
+    index
+        .update_settings(|s| {
+            s.set_autorize_typos(false);
+        })
+        .unwrap();
+
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("sun flower s are");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[0, 2]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the sun flowers are pretty\"",
+        "\"the sunflowers are pretty\"",
+    ]
+    "###);
+}
+
+#[test]
+fn test_2gram_typo() {
+    let index = create_index();
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("sun flawer");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[0, 1, 2, 3, 4, 5]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the sun flowers are pretty\"",
+        "\"the sun flower is tall\"",
+        "\"the sunflowers are pretty\"",
+        "\"the sunflower is tall\"",
+        "\"the sunflawer is tall\"",
+        "\"sunflowering is not a verb\"",
+    ]
+    "###);
+}
+
+#[test]
+fn test_no_disable_ngrams() {
+    let index = create_index();
+    index
+        .update_settings(|s| {
+            s.set_autorize_typos(false);
+        })
+        .unwrap();
+
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("sun flower ");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    // documents containing `sunflower`
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[1, 3]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the sun flower is tall\"",
+        "\"the sunflower is tall\"",
+    ]
+    "###);
+}
+
+#[test]
+fn test_2gram_prefix() {
+    let index = create_index();
+    index
+        .update_settings(|s| {
+            s.set_autorize_typos(false);
+        })
+        .unwrap();
+
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("sun flow");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    // documents containing words beginning with `sunflow`
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[0, 1, 2, 3, 5]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the sun flowers are pretty\"",
+        "\"the sun flower is tall\"",
+        "\"the sunflowers are pretty\"",
+        "\"the sunflower is tall\"",
+        "\"sunflowering is not a verb\"",
+    ]
+    "###);
+}
+
+#[test]
+fn test_3gram_prefix() {
+    let index = create_index();
+    index
+        .update_settings(|s| {
+            s.set_autorize_typos(false);
+        })
+        .unwrap();
+
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("su nf l");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+
+    // documents containing a word beginning with sunfl
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[2, 3, 4, 5]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the sunflowers are pretty\"",
+        "\"the sunflower is tall\"",
+        "\"the sunflawer is tall\"",
+        "\"sunflowering is not a verb\"",
+    ]
+    "###);
+}
+
+#[test]
+fn test_split_words() {
+    let index = create_index();
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("sunflower ");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+
+    // all the documents with either `sunflower` or `sun flower` + eventual typo
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[1, 2, 3, 4]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the sun flower is tall\"",
+        "\"the sunflowers are pretty\"",
+        "\"the sunflower is tall\"",
+        "\"the sunflawer is tall\"",
+    ]
+    "###);
+}
+
+#[test]
+fn test_disable_split_words() {
+    let index = create_index();
+    index
+        .update_settings(|s| {
+            s.set_autorize_typos(false);
+        })
+        .unwrap();
+
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("sunflower ");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    // no document containing `sun flower`
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[3]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the sunflower is tall\"",
+    ]
+    "###);
+}
+
+#[test]
+fn test_2gram_split_words() {
+    let index = create_index();
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("sunf lower");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+
+    // all the documents with "sunflower", "sun flower", (sunflower + 1 typo), or (sunflower as prefix)
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[1, 2, 3, 4, 5]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the sun flower is tall\"",
+        "\"the sunflowers are pretty\"",
+        "\"the sunflower is tall\"",
+        "\"the sunflawer is tall\"",
+        "\"sunflowering is not a verb\"",
+    ]
+    "###);
+}
+
+#[test]
+fn test_3gram_no_split_words() {
+    let index = create_index();
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("sunf lo wer");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+
+    // no document with `sun flower`
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[2, 3, 5]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the sunflowers are pretty\"",
+        "\"the sunflower is tall\"",
+        "\"sunflowering is not a verb\"",
+    ]
+    "###);
+}
+
+#[test]
+fn test_3gram_no_typos() {
+    let index = create_index();
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("sunf la wer");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[4]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the sunflawer is tall\"",
+    ]
+    "###);
+}
+
+#[test]
+fn test_no_ngram_phrases() {
+    let index = create_index();
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("\"sun\" flower");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[0, 1]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the sun flowers are pretty\"",
+        "\"the sun flower is tall\"",
+    ]
+    "###);
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("\"sun\" \"flower\"");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[1]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the sun flower is tall\"",
+    ]
+    "###);
+}

milli/src/search/new/tests/proximity.rs

@@ -0,0 +1,471 @@
+/*!
+This module tests the Proximity ranking rule:
+
+1. A proximity of >7 always has the same cost.
+
+2. Phrase terms can be in sprximity to other terms via their start and end words,
+but we need to make sure that the phrase exists in the document that meets this
+proximity condition. This is especially relevant with split words and synonyms.
+
+3. An ngram has the same sprximity cost as its component words being consecutive.
+e.g. `sunflower` equivalent to `sun flower`.
+
+4. The prefix databases can be used to find the sprximity between two words, but
+they store fewer sprximities than the regular word sprximity DB.
+
+*/
+
+use std::collections::HashMap;
+
+use crate::{
+    index::tests::TempIndex, search::new::tests::collect_field_values, Criterion, Search,
+    SearchResult, TermsMatchingStrategy,
+};
+
+fn create_simple_index() -> TempIndex {
+    let index = TempIndex::new();
+
+    index
+        .update_settings(|s| {
+            s.set_primary_key("id".to_owned());
+            s.set_searchable_fields(vec!["text".to_owned()]);
+            s.set_criteria(vec![Criterion::Words, Criterion::Proximity]);
+        })
+        .unwrap();
+
+    index
+        .add_documents(documents!([
+            {
+                "id": 0,
+                "text": "the very quick dark brown and smart fox did jump over the terribly lazy and small dog"
+            },
+            {
+                "id": 1,
+                "text": "the. quick brown fox jumps over the lazy. dog"
+            },
+            {
+                "id": 2,
+                "text": "the quick brown fox jumps over the lazy. dog"
+            },
+            {
+                "id": 3,
+                "text": "dog the quick brown fox jumps over the lazy"
+            },
+            {
+                "id": 4,
+                "text": "the quickbrown fox jumps over the lazy dog"
+            },
+            {
+                "id": 5,
+                "text": "brown quick fox jumps over the lazy dog"
+            },
+            {
+                "id": 6,
+                "text": "the really quick brown fox jumps over the very lazy dog"
+            },
+            {
+                "id": 7,
+                "text": "the really quick brown fox jumps over the lazy dog"
+            },
+            {
+                "id": 8,
+                "text": "the quick brown fox jumps over the lazy"
+            },
+            {
+                "id": 9,
+                "text": "the quack brown fox jumps over the lazy"
+            },
+            {
+                "id": 9,
+                "text": "the quack brown fox jumps over the lazy dog"
+            },
+            {
+                "id": 10,
+                "text": "the quick brown fox jumps over the lazy dog"
+            }
+        ]))
+        .unwrap();
+    index
+}
+
+fn create_edge_cases_index() -> TempIndex {
+    let index = TempIndex::new();
+
+    index
+        .update_settings(|s| {
+            s.set_primary_key("id".to_owned());
+            s.set_searchable_fields(vec!["text".to_owned()]);
+            s.set_criteria(vec![Criterion::Words, Criterion::Proximity]);
+        })
+        .unwrap();
+
+    index.add_documents(documents!([
+        {
+            // This document will insert "s" in the prefix database
+            "id": 0,
+            "text": "
+            saa sab sac sae saf sag sah sai saj sak sal sam san sao sap saq sar sasa sat sau sav saw sax say saz
+            sba sbb sbc sbe sbf sbg sbh sbi sbj sbk sbl sbm sbn sbo sbp sbq sbr sbsb sbt sbu sbv sbw sbx sby sbz
+            sca scb scc sce scf scg sch sci scj sck scl scm scn sco scp scq scr scsc sct scu scv scw scx scy scz
+            sda sdb sdc sde sdf sdg sdh sdi sdj sdk sdl sdm sdn sdo sdp sdq sdr sdsd sdt sdu sdv sdw sdx sdy sdz
+            sea seb sec see sef seg seh sei sej sek sel sem sen seo sep seq ser sese set seu sev sew sex sey sez
+            sfa sfb sfc sfe sff sfg sfh sfi sfj sfk sfl sfm sfn sfo sfp sfq sfr sfsf sft sfu sfv sfw sfx sfy sfz
+            sga sgb sgc sge sgf sgg sgh sgi sgj sgk sgl sgm sgn sgo sgp sgq sgr sgsg sgt sgu sgv sgw sgx sgy sgz
+            ska skb skc ske skf skg skh ski skj skk skl skm skn sko skp skq skr sksk skt sku skv skw skx sky skz
+            sla slb slc sle slf slg slh sli slj slk sll slm sln slo slp slq slr slsl slt slu slv slw slx sly slz
+            sma smb smc sme smf smg smh smi smj smk sml smm smn smo smp smq smr smsm smt smu smv smw smx smy smz
+            sna snb snc sne snf sng snh sni snj snk snl snm snn sno snp snq snr snsn snt snu snv snw snx sny snz
+            soa sob soc soe sof sog soh soi soj sok sol som son soo sop soq sor soso sot sou sov sow sox soy soz
+            spa spb spc spe spf spg sph spi spj spk spl spm spn spo spp spq spr spsp spt spu spv spw spx spy spz
+            sqa sqb sqc sqe sqf sqg sqh sqi sqj sqk sql sqm sqn sqo sqp sqq sqr sqsq sqt squ sqv sqw sqx sqy sqz
+            sra srb src sre srf srg srh sri srj srk srl srm srn sro srp srq srr srsr srt sru srv srw srx sry srz
+            ssa ssb ssc sse ssf ssg ssh ssi ssj ssk ssl ssm ssn sso ssp ssq ssr ssss sst ssu ssv ssw ssx ssy ssz
+            sta stb stc ste stf stg sth sti stj stk stl stm stn sto stp stq str stst stt stu stv stw stx sty stz
+            "
+        },
+        // The next 5 documents lay out a trap with the split word, phrase search, or synonym `sun flower`. 
+        // If the search query is "sunflower", the split word "Sun Flower" will match some documents. 
+        // If the query is `sunflower wilting`, then we should make sure that
+        // the sprximity condition `flower wilting: sprx N` also comes with the condition
+        // `sun wilting: sprx N+1`. TODO: this is not the exact condition we use for now. 
+        // We only check that the phrase `sun flower` exists and `flower wilting: sprx N`, which
+        // is better than nothing but not the best.
+        {
+            "id": 1,
+            "text": "Sun Flower sounds like the title of a painting, maybe about a plant wilting under the heat."
+        },
+        {
+            "id": 2,
+            "text": "Sun Flower sounds like the title of a painting, maybe about a flower wilting under the heat."
+        },
+        {
+            "id": 3,
+            // This document matches the query `sunflower wilting`, but the sprximity condition 
+            // between `sunflower` and `wilting` cannot be through the split-word `Sun Flower`
+            // which would reduce to only `flower` and `wilting` being in sprximity.
+            "text": "A flower wilting under the sun, unlike a sunflower"
+        },
+        {
+            // This should be the best document for `sunflower wilting`
+            "id": 4,
+            "text": "sun flower wilting under the heat"
+        },
+        {
+            // This is also the best document for `sunflower wilting`
+            "id": 5,
+            "text": "sunflower wilting under the heat"
+        },
+        {
+            // Prox MAX between `best` and `s` prefix
+            "id": 6,
+            "text": "this is the best meal I have ever had in such a beautiful summer day"
+        },
+        {
+            // Prox 5 between `best` and `s` prefix
+            "id": 7,
+            "text": "this is the best cooked meal of the summer"
+        },
+        {
+            // Prox 4 between `best` and `s` prefix
+            "id": 8,
+            "text": "this is the best meal of the summer"
+        },
+        {
+            // Prox 3 between `best` and `s` prefix
+            "id": 9,
+            "text": "this is the best meal of summer"
+        },
+        {
+            // Prox 1 between `best` and `s` prefix
+            "id": 10,
+            "text": "this is the best summer meal"
+        },
+        {
+            // Reverse Prox 3 between `best` and `s` prefix
+            "id": 11,
+            "text": "summer x y best"
+        },
+        {
+            // Reverse Prox 2 between `best` and `s` prefix
+            "id": 12,
+            "text": "summer x best"
+        },
+        {
+            // Reverse Prox 1 between `best` and `s` prefix
+            "id": 13,
+            "text": "summer best"
+        },
+        {
+            // This document will insert "win" in the prefix database
+            "id": 14,
+            "text": "
+            winaa winab winac winae winaf winag winah winai winaj winak winal winam winan winao winap winaq winar winasa winat winau winav winaw winax winay winaz
+            winba winbb winbc winbe winbf winbg winbh winbi winbj winbk winbl winbm winbn winbo winbp winbq winbr winbsb winbt winbu winbv winbw winbx winby winbz
+            winca wincb wincc wince wincf wincg winch winci wincj winck wincl wincm wincn winco wincp wincq wincr wincsc winct wincu wincv wincw wincx wincy wincz
+            winda windb windc winde windf windg windh windi windj windk windl windm windn windo windp windq windr windsd windt windu windv windw windx windy windz
+            winea wineb winec winee winef wineg wineh winei winej winek winel winem winen wineo winep wineq winer winese winet wineu winev winew winex winey winez
+            winfa winfb winfc winfe winff winfg winfh winfi winfj winfk winfl winfm winfn winfo winfp winfq winfr winfsf winft winfu winfv winfw winfx winfy winfz
+            winga wingb wingc winge wingf wingg wingh wingi wingj wingk wingl wingm wingn wingo wingp wingq wingr wingsg wingt wingu wingv wingw wingx wingy wingz
+            winka winkb winkc winke winkf winkg winkh winki winkj winkk winkl winkm winkn winko winkp winkq winkr winksk winkt winku winkv winkw winkx winky winkz
+            winla winlb winlc winle winlf winlg winlh winli winlj winlk winll winlm winln winlo winlp winlq winlr winlsl winlt winlu winlv winlw winlx winly winlz
+            winma winmb winmc winme winmf winmg winmh winmi winmj winmk winml winmm winmn winmo winmp winmq winmr winmsm winmt winmu winmv winmw winmx winmy winmz
+            winna winnb winnc winne winnf winng winnh winni winnj winnk winnl winnm winnn winno winnp winnq winnr winnsn winnt winnu winnv winnw winnx winny winnz
+            winoa winob winoc winoe winof winog winoh winoi winoj winok winol winom winon winoo winop winoq winor winoso winot winou winov winow winox winoy winoz
+            winpa winpb winpc winpe winpf winpg winph winpi winpj winpk winpl winpm winpn winpo winpp winpq winpr winpsp winpt winpu winpv winpw winpx winpy winpz
+            winqa winqb winqc winqe winqf winqg winqh winqi winqj winqk winql winqm winqn winqo winqp winqq winqr winqsq winqt winqu winqv winqw winqx winqy winqz
+            winra winrb winrc winre winrf winrg winrh winri winrj winrk winrl winrm winrn winro winrp winrq winrr winrsr winrt winru winrv winrw winrx winry winrz
+            winsa winsb winsc winse winsf winsg winsh winsi winsj winsk winsl winsm winsn winso winsp winsq winsr winsss winst winsu winsv winsw winsx winsy winsz
+            winta wintb wintc winte wintf wintg winth winti wintj wintk wintl wintm wintn winto wintp wintq wintr wintst wintt wintu wintv wintw wintx winty wintz
+            "
+        },
+        {
+            // Prox MAX between `best` and `win` prefix
+            "id": 15,
+            "text": "this is the best meal I have ever had in such a beautiful winter day"
+        },
+        {
+            // Prox 5 between `best` and `win` prefix
+            "id": 16,
+            "text": "this is the best cooked meal of the winter"
+        },
+        {
+            // Prox 4 between `best` and `win` prefix
+            "id": 17,
+            "text": "this is the best meal of the winter"
+        },
+        {
+            // Prox 3 between `best` and `win` prefix
+            "id": 18,
+            "text": "this is the best meal of winter"
+        },
+        {
+            // Prox 1 between `best` and `win` prefix
+            "id": 19,
+            "text": "this is the best winter meal"
+        },
+        {
+            // Reverse Prox 3 between `best` and `win` prefix
+            "id": 20,
+            "text": "winter x y best"
+        },
+        {
+            // Reverse Prox 2 between `best` and `win` prefix
+            "id": 21,
+            "text": "winter x best"
+        },
+        {
+            // Reverse Prox 1 between `best` and `win` prefix
+            "id": 22,
+            "text": "winter best"
+        },
+    ])).unwrap();
+    index
+}
+
+#[test]
+fn test_proximity_simple() {
+    let index = create_simple_index();
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("the quick brown fox jumps over the lazy dog");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[4, 9, 10, 7, 6, 5, 2, 3, 0, 1]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the quickbrown fox jumps over the lazy dog\"",
+        "\"the quack brown fox jumps over the lazy dog\"",
+        "\"the quick brown fox jumps over the lazy dog\"",
+        "\"the really quick brown fox jumps over the lazy dog\"",
+        "\"the really quick brown fox jumps over the very lazy dog\"",
+        "\"brown quick fox jumps over the lazy dog\"",
+        "\"the quick brown fox jumps over the lazy. dog\"",
+        "\"dog the quick brown fox jumps over the lazy\"",
+        "\"the very quick dark brown and smart fox did jump over the terribly lazy and small dog\"",
+        "\"the. quick brown fox jumps over the lazy. dog\"",
+    ]
+    "###);
+}
+
+#[test]
+fn test_proximity_split_word() {
+    let index = create_edge_cases_index();
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("sunflower wilting");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[2, 4, 5, 1, 3]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    // TODO: "2" and "4" should be swapped ideally
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"Sun Flower sounds like the title of a painting, maybe about a flower wilting under the heat.\"",
+        "\"sun flower wilting under the heat\"",
+        "\"sunflower wilting under the heat\"",
+        "\"Sun Flower sounds like the title of a painting, maybe about a plant wilting under the heat.\"",
+        "\"A flower wilting under the sun, unlike a sunflower\"",
+    ]
+    "###);
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("\"sun flower\" wilting");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[2, 4, 1]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    // TODO: "2" and "4" should be swapped ideally
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"Sun Flower sounds like the title of a painting, maybe about a flower wilting under the heat.\"",
+        "\"sun flower wilting under the heat\"",
+        "\"Sun Flower sounds like the title of a painting, maybe about a plant wilting under the heat.\"",
+    ]
+    "###);
+    drop(txn);
+
+    index
+        .update_settings(|s| {
+            let mut syns = HashMap::new();
+            syns.insert("xyz".to_owned(), vec!["sun flower".to_owned()]);
+            s.set_synonyms(syns);
+        })
+        .unwrap();
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("xyz wilting");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[2, 4, 1]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    // TODO: "2" and "4" should be swapped ideally
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"Sun Flower sounds like the title of a painting, maybe about a flower wilting under the heat.\"",
+        "\"sun flower wilting under the heat\"",
+        "\"Sun Flower sounds like the title of a painting, maybe about a plant wilting under the heat.\"",
+    ]
+    "###);
+}
+
+#[test]
+fn test_proximity_prefix_db() {
+    let index = create_edge_cases_index();
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("best s");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[10, 13, 9, 12, 8, 6, 7, 11, 15]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+
+    // This test illustrates the loss of precision from using the prefix DB
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"this is the best summer meal\"",
+        "\"summer best\"",
+        "\"this is the best meal of summer\"",
+        "\"summer x best\"",
+        "\"this is the best meal of the summer\"",
+        "\"this is the best meal I have ever had in such a beautiful summer day\"",
+        "\"this is the best cooked meal of the summer\"",
+        "\"summer x y best\"",
+        "\"this is the best meal I have ever had in such a beautiful winter day\"",
+    ]
+    "###);
+
+    // Difference when using the `su` prefix, which is not in the prefix DB
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("best su");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[10, 13, 9, 12, 8, 11, 7, 6, 15]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"this is the best summer meal\"",
+        "\"summer best\"",
+        "\"this is the best meal of summer\"",
+        "\"summer x best\"",
+        "\"this is the best meal of the summer\"",
+        "\"summer x y best\"",
+        "\"this is the best cooked meal of the summer\"",
+        "\"this is the best meal I have ever had in such a beautiful summer day\"",
+        "\"this is the best meal I have ever had in such a beautiful winter day\"",
+    ]
+    "###);
+
+    // Note that there is a case where a prefix is in the prefix DB but not in the
+    // **proximity** prefix DB. In that case, its sprximity score will always be
+    // the maximum. This happens for prefixes that are larger than 2 bytes.
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("best win");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[15, 16, 17, 18, 19, 20, 21, 22]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"this is the best meal I have ever had in such a beautiful winter day\"",
+        "\"this is the best cooked meal of the winter\"",
+        "\"this is the best meal of the winter\"",
+        "\"this is the best meal of winter\"",
+        "\"this is the best winter meal\"",
+        "\"winter x y best\"",
+        "\"winter x best\"",
+        "\"winter best\"",
+    ]
+    "###);
+
+    // Now using `wint`, which is not in the prefix DB:
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("best wint");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[19, 22, 18, 21, 17, 20, 16, 15]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"this is the best winter meal\"",
+        "\"winter best\"",
+        "\"this is the best meal of winter\"",
+        "\"winter x best\"",
+        "\"this is the best meal of the winter\"",
+        "\"winter x y best\"",
+        "\"this is the best cooked meal of the winter\"",
+        "\"this is the best meal I have ever had in such a beautiful winter day\"",
+    ]
+    "###);
+
+    // and using `wi` which is in the prefix DB and proximity prefix DB
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("best wi");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[19, 22, 18, 21, 17, 15, 16, 20]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"this is the best winter meal\"",
+        "\"winter best\"",
+        "\"this is the best meal of winter\"",
+        "\"winter x best\"",
+        "\"this is the best meal of the winter\"",
+        "\"this is the best meal I have ever had in such a beautiful winter day\"",
+        "\"this is the best cooked meal of the winter\"",
+        "\"winter x y best\"",
+    ]
+    "###);
+}

milli/src/search/new/tests/proximity_typo.rs

@@ -0,0 +1,75 @@
+/*!
+This module tests the interactions between the proximity and typo ranking rules.
+
+The proximity ranking rule should transform the query graph such that it
+only contains the word pairs that it used to compute its bucket.
+
+TODO: This is not currently implemented.
+*/
+
+use crate::{
+    index::tests::TempIndex, search::new::tests::collect_field_values, Criterion, Search,
+    SearchResult, TermsMatchingStrategy,
+};
+
+fn create_index() -> TempIndex {
+    let index = TempIndex::new();
+
+    index
+        .update_settings(|s| {
+            s.set_primary_key("id".to_owned());
+            s.set_searchable_fields(vec!["text".to_owned()]);
+            s.set_criteria(vec![Criterion::Words, Criterion::Proximity, Criterion::Typo]);
+        })
+        .unwrap();
+
+    index
+        .add_documents(documents!([
+            // Basic trap.
+            //
+            // We have one document with the perfect word pair: `sommer - holiday`
+            // and another with the perfect word pair: `sommer holidty`.
+            //
+            // The proximity ranking rule will put them both in the same bucket, and it
+            // should minify the query graph to make it represent:
+            // EITHER:
+            //    sommer + holiday
+            // OR:
+            //    sommer + holidty
+            //
+            // Such that the child typo ranking rule does not find any match
+            // for its zero-typo bucket `summer + holiday`, even though both documents
+            // contain these two exact words.
+            {
+                "id": 0,
+                "text": "summer. holiday. sommer holidty"
+            },
+            {
+                "id": 1,
+                "text": "summer. holiday. sommer holiday"
+            },
+
+        ]))
+        .unwrap();
+    index
+}
+
+#[test]
+fn test_trap_basic() {
+    let index = create_index();
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("summer holiday");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[0, 1]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    // TODO: this is incorrect, 1 should come before 0
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"summer. holiday. sommer holidty\"",
+        "\"summer. holiday. sommer holiday\"",
+    ]
+    "###);
+}

milli/src/search/new/tests/sort.rs

@@ -0,0 +1,316 @@
+/*!
+This module tests the `sort` ranking rule:
+
+1. an error is returned if the sort ranking rule exists but no fields-to-sort were given at search time
+2. an error is returned if the fields-to-sort are not sortable
+3. it is possible to add multiple fields-to-sort at search time
+4. custom sort ranking rules can be added to the settings, they interact with the generic `sort` ranking rule as expected
+5. numbers appear before strings
+6. documents with either: (1) no value, (2) null, or (3) an object for the field-to-sort appear at the end of the bucket
+7. boolean values are translated to strings
+8. if a field contains an array, it is sorted by the best value in the array according to the sort rule
+*/
+
+use big_s::S;
+use maplit::hashset;
+
+use crate::{
+    index::tests::TempIndex, search::new::tests::collect_field_values, AscDesc, Criterion, Member,
+    Search, SearchResult, TermsMatchingStrategy,
+};
+
+fn create_index() -> TempIndex {
+    let index = TempIndex::new();
+
+    index
+        .update_settings(|s| {
+            s.set_primary_key("id".to_owned());
+            s.set_searchable_fields(vec!["text".to_owned()]);
+            s.set_sortable_fields(hashset! { S("rank"), S("vague"), S("letter") });
+            s.set_criteria(vec![Criterion::Sort]);
+        })
+        .unwrap();
+
+    index
+        .add_documents(documents!([
+            {
+                "id": 0,
+                "letter": "A",
+                "rank": 0,
+                "vague": 0,
+            },
+            {
+                "id": 1,
+                "letter": "A",
+                "rank": 1,
+                "vague": "0",
+            },
+            {
+                "id": 2,
+                "letter": "B",
+                "rank": 0,
+                "vague": 1,
+            },
+            {
+                "id": 3,
+                "letter": "B",
+                "rank": 1,
+                "vague": "1",
+            },
+            {
+                "id": 4,
+                "letter": "B",
+                "rank": 2,
+                "vague": [1, 2],
+            },
+            {
+                "id": 5,
+                "letter": "C",
+                "rank": 0,
+                "vague": [1, "2"],
+            },
+            {
+                "id": 6,
+                "letter": "C",
+                "rank": 1,
+            },
+            {
+                "id": 7,
+                "letter": "C",
+                "rank": 2,
+                "vague": null,
+            },
+            {
+                "id": 8,
+                "letter": "D",
+                "rank": 0,
+                "vague": [null, null, ""]
+            },
+            {
+                "id": 9,
+                "letter": "E",
+                "rank": 0,
+                "vague": ""
+            },
+            {
+                "id": 10,
+                "letter": "E",
+                "rank": 1,
+                "vague": {
+                    "sub": 0,
+                }
+            },
+            {
+                "id": 11,
+                "letter": "E",
+                "rank": 2,
+                "vague": true,
+            },
+            {
+                "id": 12,
+                "letter": "E",
+                "rank": 3,
+                "vague": false,
+            },
+            {
+                "id": 13,
+                "letter": "E",
+                "rank": 4,
+                "vague": 1.5673,
+            },
+            {
+                "id": 14,
+                "letter": "E",
+                "rank": 5,
+            },
+            {
+                "id": 15,
+                "letter": "F",
+                "rank": 0,
+            },
+            {
+                "id": 16,
+                "letter": "F",
+                "rank": 1,
+            },
+            {
+                "id": 17,
+                "letter": "F",
+                "rank": 2,
+            },
+            {
+                "id": 18,
+                "letter": "G",
+                "rank": 0,
+            },
+            {
+                "id": 19,
+                "letter": "G",
+                "rank": 1,
+            },
+            {
+                "id": 20,
+                "letter": "H",
+                "rank": 0,
+                "vague": true,
+            },
+            {
+                "id": 21,
+                "letter": "I",
+                "rank": 0,
+                "vague": false,
+            },
+            {
+                "id": 22,
+                "letter": "I",
+                "rank": 1,
+                "vague": [1.1367, "help", null]
+            },
+            {
+                "id": 23,
+                "letter": "I",
+                "rank": 2,
+                "vague": [1.2367, "hello"]
+            },
+        ]))
+        .unwrap();
+    index
+}
+
+#[test]
+fn test_sort() {
+    let index = create_index();
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::Last);
+    s.sort_criteria(vec![AscDesc::Desc(Member::Field(S("letter")))]);
+
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[21, 22, 23, 20, 18, 19, 15, 16, 17, 9, 10, 11, 12, 13, 14, 8, 5, 6, 7, 2]");
+
+    let letter_values = collect_field_values(&index, &txn, "letter", &documents_ids);
+    insta::assert_debug_snapshot!(letter_values, @r###"
+    [
+        "\"I\"",
+        "\"I\"",
+        "\"I\"",
+        "\"H\"",
+        "\"G\"",
+        "\"G\"",
+        "\"F\"",
+        "\"F\"",
+        "\"F\"",
+        "\"E\"",
+        "\"E\"",
+        "\"E\"",
+        "\"E\"",
+        "\"E\"",
+        "\"E\"",
+        "\"D\"",
+        "\"C\"",
+        "\"C\"",
+        "\"C\"",
+        "\"B\"",
+    ]
+    "###);
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::Last);
+    s.sort_criteria(vec![AscDesc::Desc(Member::Field(S("rank")))]);
+
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[14, 13, 12, 4, 7, 11, 17, 23, 1, 3, 6, 10, 16, 19, 22, 0, 2, 5, 8, 9]");
+
+    let rank_values = collect_field_values(&index, &txn, "rank", &documents_ids);
+    insta::assert_debug_snapshot!(rank_values, @r###"
+    [
+        "5",
+        "4",
+        "3",
+        "2",
+        "2",
+        "2",
+        "2",
+        "2",
+        "1",
+        "1",
+        "1",
+        "1",
+        "1",
+        "1",
+        "1",
+        "0",
+        "0",
+        "0",
+        "0",
+        "0",
+    ]
+    "###);
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::Last);
+    s.sort_criteria(vec![AscDesc::Asc(Member::Field(S("vague")))]);
+
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[0, 2, 4, 5, 22, 23, 13, 1, 3, 12, 21, 11, 20, 6, 7, 8, 9, 10, 14, 15]");
+
+    let vague_values = collect_field_values(&index, &txn, "vague", &documents_ids);
+    insta::assert_debug_snapshot!(vague_values, @r###"
+    [
+        "0",
+        "1",
+        "[1,2]",
+        "[1,\"2\"]",
+        "[1.1367,\"help\",null]",
+        "[1.2367,\"hello\"]",
+        "1.5673",
+        "\"0\"",
+        "\"1\"",
+        "false",
+        "false",
+        "true",
+        "true",
+        "__does_not_exist__",
+        "null",
+        "[null,null,\"\"]",
+        "\"\"",
+        "{\"sub\":0}",
+        "__does_not_exist__",
+        "__does_not_exist__",
+    ]
+    "###);
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::Last);
+    s.sort_criteria(vec![AscDesc::Desc(Member::Field(S("vague")))]);
+
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[4, 13, 23, 22, 2, 5, 0, 11, 20, 12, 21, 3, 1, 6, 7, 8, 9, 10, 14, 15]");
+
+    let vague_values = collect_field_values(&index, &txn, "vague", &documents_ids);
+    insta::assert_debug_snapshot!(vague_values, @r###"
+    [
+        "[1,2]",
+        "1.5673",
+        "[1.2367,\"hello\"]",
+        "[1.1367,\"help\",null]",
+        "1",
+        "[1,\"2\"]",
+        "0",
+        "true",
+        "true",
+        "false",
+        "false",
+        "\"1\"",
+        "\"0\"",
+        "__does_not_exist__",
+        "null",
+        "[null,null,\"\"]",
+        "\"\"",
+        "{\"sub\":0}",
+        "__does_not_exist__",
+        "__does_not_exist__",
+    ]
+    "###);
+}

milli/src/search/new/tests/typo.rs

@@ -0,0 +1,497 @@
+/*!
+This module tests the following properties:
+
+1. The `words` ranking rule is typo-tolerant
+2. Typo-tolerance handles missing letters, extra letters, replaced letters, and swapped letters (at least)
+3. Words which are < `min_word_len_one_typo` are not typo tolerant
+4. Words which are >= `min_word_len_one_typo` but < `min_word_len_two_typos` can have one typo
+5. Words which are >= `min_word_len_two_typos` can have two typos
+6. A typo on the first letter of a word counts as two typos
+7. Phrases are not typo tolerant
+8. 2grams can have 1 typo if they are larger than `min_word_len_two_typos`
+9. 3grams are not typo tolerant
+10. The `typo` ranking rule assumes the role of the `words` ranking rule implicitly
+if `words` doesn't exist before it.
+11. The `typo` ranking rule places documents with the same number of typos in the same bucket
+12. Prefix tolerance costs nothing according to the typo ranking rule
+13. Split words cost 1 typo according to the typo ranking rule
+14. Synonyms cost nothing according to the typo ranking rule
+*/
+
+use std::collections::HashMap;
+
+use crate::{
+    index::tests::TempIndex, search::new::tests::collect_field_values, Criterion, Search,
+    SearchResult, TermsMatchingStrategy,
+};
+
+fn create_index() -> TempIndex {
+    let index = TempIndex::new();
+
+    index
+        .update_settings(|s| {
+            s.set_primary_key("id".to_owned());
+            s.set_searchable_fields(vec!["text".to_owned()]);
+            s.set_criteria(vec![Criterion::Words]);
+        })
+        .unwrap();
+
+    index
+        .add_documents(documents!([
+            {
+                "id": 0,
+                "text": "the quick brown fox jumps over the lazy dog"
+            },
+            {
+                "id": 1,
+                "text": "the quick brown foxes jump over the lazy dog"
+            },
+            {
+                "id": 2,
+                "text": "the quick brown fax sends a letter to the dog"
+            },
+            {
+                "id": 3,
+                "text": "the quickest brownest fox jumps over the laziest dog"
+            },
+            {
+                "id": 4,
+                "text": "a fox doesn't quack, that crown goes to the duck."
+            },
+            {
+                "id": 5,
+                "text": "the quicker browner fox jumped over the lazier dog"
+            },
+            {
+                "id": 6,
+                "text": "the extravagant fox skyrocketed over the languorous dog" // thanks thesaurus
+            },
+            {
+                "id": 7,
+                "text": "the quick brown fox jumps over the lazy"
+            },
+            {
+                "id": 8,
+                "text": "the quick brown fox jumps over the"
+            },
+            {
+                "id": 9,
+                "text": "the quick brown fox jumps over"
+            },
+            {
+                "id": 10,
+                "text": "the quick brown fox jumps"
+            },
+            {
+                "id": 11,
+                "text": "the quick brown fox"
+            },
+            {
+                "id": 12,
+                "text": "the quick brown"
+            },
+            {
+                "id": 13,
+                "text": "the quick"
+            },
+            {
+                "id": 14,
+                "text": "netwolk interconections sunflawar"
+            },
+            {
+                "id": 15,
+                "text": "network interconnections sunflawer"
+            },
+            {
+                "id": 16,
+                "text": "network interconnection sunflower"
+            },
+            {
+                "id": 17,
+                "text": "network interconnection sun flower"
+            },
+            {
+                "id": 18,
+                "text": "network interconnection sunflowering"
+            },
+            {
+                "id": 19,
+                "text": "network interconnection sun flowering"
+            },
+            {
+                "id": 20,
+                "text": "network interconnection sunflowar"
+            },
+            {
+                "id": 21,
+                "text": "the fast brownish fox jumps over the lackadaisical dog"
+            },
+            {
+                "id": 22,
+                "text": "the quick brown fox jumps over the lackadaisical dog"
+            },
+            {
+                "id": 23,
+                "text": "the quivk brown fox jumps over the lazy dog"
+            },
+        ]))
+        .unwrap();
+    index
+}
+
+#[test]
+fn test_no_typo() {
+    let index = create_index();
+    index
+        .update_settings(|s| {
+            s.set_autorize_typos(false);
+        })
+        .unwrap();
+
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("the quick brown fox jumps over the lazy dog");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[0]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the quick brown fox jumps over the lazy dog\"",
+    ]
+    "###);
+}
+
+#[test]
+fn test_default_typo() {
+    let index = create_index();
+    let txn = index.read_txn().unwrap();
+
+    let ot = index.min_word_len_one_typo(&txn).unwrap();
+    let tt = index.min_word_len_two_typos(&txn).unwrap();
+    insta::assert_debug_snapshot!(ot, @"5");
+    insta::assert_debug_snapshot!(tt, @"9");
+
+    // 0 typo
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("the quick brown fox jumps over the lazy dog");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[0, 23]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the quick brown fox jumps over the lazy dog\"",
+        "\"the quivk brown fox jumps over the lazy dog\"",
+    ]
+    "###);
+
+    // 1 typo on one word, replaced letter
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("the quack brown fox jumps over the lazy dog");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[0]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the quick brown fox jumps over the lazy dog\"",
+    ]
+    "###);
+
+    // 1 typo on one word, missing letter, extra letter
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("the quicest brownest fox jummps over the laziest dog");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[3]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the quickest brownest fox jumps over the laziest dog\"",
+    ]
+    "###);
+
+    // 1 typo on one word, swapped letters
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("the quikc borwn fox jupms over the lazy dog");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[0]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the quick brown fox jumps over the lazy dog\"",
+    ]
+    "###);
+
+    // 1 first letter typo on a word <5 bytes, replaced letter
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("the nuick brown fox jumps over the lazy dog");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[]");
+
+    // 1 first letter typo on a word <5 bytes, missing letter
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("the uick brown fox jumps over the lazy dog");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[]");
+
+    // 1 typo on all words >=5 bytes, replaced letters
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("the quack brawn fox junps over the lazy dog");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[0]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the quick brown fox jumps over the lazy dog\"",
+    ]
+    "###);
+
+    // 2 typos on words < 9 bytes
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("the quckest brawnert fox jumps over the aziest dog");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[]");
+
+    // 2 typos on words >= 9 bytes: missing letters, missing first letter, replaced letters
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("the extravant fox kyrocketed over the lamguorout dog");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[6]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the extravagant fox skyrocketed over the languorous dog\"",
+    ]
+    "###);
+
+    // 2 typos on words >= 9 bytes: 2 extra letters in a single word, swapped letters + extra letter, replaced letters
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("the extravaganttt fox sktyrocnketed over the lagnuorrous dog");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[6]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the extravagant fox skyrocketed over the languorous dog\"",
+    ]
+    "###);
+}
+
+#[test]
+fn test_phrase_no_typo_allowed() {
+    let index = create_index();
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("the \"quick brewn\" fox jumps over the lazy dog");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @"[]");
+}
+
+#[test]
+fn test_ngram_typos() {
+    let index = create_index();
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("the extra lagant fox skyrocketed over the languorous dog");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[6]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the extravagant fox skyrocketed over the languorous dog\"",
+    ]
+    "###);
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("the ex tra lagant fox skyrocketed over the languorous dog");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @"[]");
+}
+#[test]
+fn test_typo_ranking_rule_not_preceded_by_words_ranking_rule() {
+    let index = create_index();
+    index
+        .update_settings(|s| {
+            s.set_criteria(vec![Criterion::Typo]);
+        })
+        .unwrap();
+
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::Last);
+    s.query("the quick brown fox jumps over the lazy dog");
+    let SearchResult { documents_ids: ids_1, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{ids_1:?}"), @"[0, 23, 7, 8, 9, 22, 10, 11, 1, 2, 12, 13, 4, 3, 5, 6, 21]");
+    let texts = collect_field_values(&index, &txn, "text", &ids_1);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the quick brown fox jumps over the lazy dog\"",
+        "\"the quivk brown fox jumps over the lazy dog\"",
+        "\"the quick brown fox jumps over the lazy\"",
+        "\"the quick brown fox jumps over the\"",
+        "\"the quick brown fox jumps over\"",
+        "\"the quick brown fox jumps over the lackadaisical dog\"",
+        "\"the quick brown fox jumps\"",
+        "\"the quick brown fox\"",
+        "\"the quick brown foxes jump over the lazy dog\"",
+        "\"the quick brown fax sends a letter to the dog\"",
+        "\"the quick brown\"",
+        "\"the quick\"",
+        "\"a fox doesn't quack, that crown goes to the duck.\"",
+        "\"the quickest brownest fox jumps over the laziest dog\"",
+        "\"the quicker browner fox jumped over the lazier dog\"",
+        "\"the extravagant fox skyrocketed over the languorous dog\"",
+        "\"the fast brownish fox jumps over the lackadaisical dog\"",
+    ]
+    "###);
+
+    index
+        .update_settings(|s| {
+            s.set_criteria(vec![Criterion::Words, Criterion::Typo]);
+        })
+        .unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::Last);
+    s.query("the quick brown fox jumps over the lazy dog");
+    let SearchResult { documents_ids: ids_2, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{ids_2:?}"), @"[0, 23, 7, 8, 9, 22, 10, 11, 1, 2, 12, 13, 4, 3, 5, 6, 21]");
+
+    assert_eq!(ids_1, ids_2);
+}
+
+#[test]
+fn test_typo_bucketing() {
+    let index = create_index();
+
+    let txn = index.read_txn().unwrap();
+
+    // First do the search with just the Words ranking rule
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("network interconnection sunflower");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[14, 15, 16, 17, 18, 20]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"netwolk interconections sunflawar\"",
+        "\"network interconnections sunflawer\"",
+        "\"network interconnection sunflower\"",
+        "\"network interconnection sun flower\"",
+        "\"network interconnection sunflowering\"",
+        "\"network interconnection sunflowar\"",
+    ]
+    "###);
+
+    // Then with the typo ranking rule
+    drop(txn);
+    index
+        .update_settings(|s| {
+            s.set_criteria(vec![Criterion::Typo]);
+        })
+        .unwrap();
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("network interconnection sunflower");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[16, 18, 17, 20, 15, 14]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"network interconnection sunflower\"",
+        "\"network interconnection sunflowering\"",
+        "\"network interconnection sun flower\"",
+        "\"network interconnection sunflowar\"",
+        "\"network interconnections sunflawer\"",
+        "\"netwolk interconections sunflawar\"",
+    ]
+    "###);
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("network interconnection sun flower");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[17, 19, 16, 18, 20, 15]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"network interconnection sun flower\"",
+        "\"network interconnection sun flowering\"",
+        "\"network interconnection sunflower\"",
+        "\"network interconnection sunflowering\"",
+        "\"network interconnection sunflowar\"",
+        "\"network interconnections sunflawer\"",
+    ]
+    "###);
+}
+
+#[test]
+fn test_typo_synonyms() {
+    let index = create_index();
+    index
+        .update_settings(|s| {
+            s.set_criteria(vec![Criterion::Typo]);
+
+            let mut synonyms = HashMap::new();
+            synonyms.insert("lackadaisical".to_owned(), vec!["lazy".to_owned()]);
+            synonyms.insert("fast brownish".to_owned(), vec!["quick brown".to_owned()]);
+
+            s.set_synonyms(synonyms);
+        })
+        .unwrap();
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("the quick brown fox jumps over the lackadaisical dog");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[0, 22, 23]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the quick brown fox jumps over the lazy dog\"",
+        "\"the quick brown fox jumps over the lackadaisical dog\"",
+        "\"the quivk brown fox jumps over the lazy dog\"",
+    ]
+    "###);
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("the fast brownish fox jumps over the lackadaisical dog");
+
+    // TODO: is this correct? interaction of ngrams + synonyms means that the
+    // multi-word synonyms end up having a typo cost. This is probably not what we want.
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[21, 0, 22]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the fast brownish fox jumps over the lackadaisical dog\"",
+        "\"the quick brown fox jumps over the lazy dog\"",
+        "\"the quick brown fox jumps over the lackadaisical dog\"",
+    ]
+    "###);
+}

milli/src/search/new/tests/typo_proximity.rs

@@ -0,0 +1,124 @@
+/*!
+This module tests the interactions between the typo and proximity ranking rules.
+
+The typo ranking rule should transform the query graph such that it only contains
+the combinations of word derivations that it used to compute its bucket.
+
+The proximity ranking rule should then look for proximities only between those specific derivations.
+For example, given the the search query `beautiful summer` and the dataset:
+```text
+{ "id": 0, "text": "beautigul summer...... beautiful day in the summer" }
+{ "id": 1, "text": "beautiful summer" }
+```
+Then the document with id `1` should be returned before `0`.
+The proximity ranking rule is not allowed to look for the proximity between `beautigul` and `summer`
+because the typo ranking rule before it only used the derivation `beautiful`.
+*/
+
+use crate::{
+    index::tests::TempIndex, search::new::tests::collect_field_values, Criterion, Search,
+    SearchResult, TermsMatchingStrategy,
+};
+
+fn create_index() -> TempIndex {
+    let index = TempIndex::new();
+
+    index
+        .update_settings(|s| {
+            s.set_primary_key("id".to_owned());
+            s.set_searchable_fields(vec!["text".to_owned()]);
+            s.set_criteria(vec![Criterion::Words, Criterion::Typo, Criterion::Proximity]);
+        })
+        .unwrap();
+
+    index
+        .add_documents(documents!([
+            // trap explained in the module documentation
+            {
+                "id": 0,
+                "text": "beautigul summer. beautiful x y z summer"
+            },
+            {
+                "id": 1,
+                "text": "beautiful summer"
+            },
+            // the next 2 documents set up a more complicated trap
+            // with the query `beautiful summer`, we will have:
+            // 1. documents with no typos, id 0 and 1
+            // 2. documents with 1 typos: id 2 and 3, those are interpreted as EITHER
+            //      - id 2: "beautigul + summer" ; OR
+            //      - id 3: "beautiful + sommer"
+            // To sort these two documents, the proximity ranking rule must use only the
+            // word pairs: `beautigul -- summer` and `beautiful -- sommer` even though
+            // all variations of `beautiful` and `sommer` were used by the typo ranking rule.
+            {
+                "id": 2,
+                "text": "beautigul sommer. beautigul x summer"
+            },
+            {
+                "id": 3,
+                "text": "beautiful sommer"
+            },
+            // The next two documents lay out an even more complex trap.
+            // With the user query `delicious sweet dessert`, the typo ranking rule will return one bucket of:
+            // - id 4: delicitous + sweet + dessert
+            // - id 5: beautiful + sweet + desgert
+            // The word pairs that the proximity ranking rules is allowed to use are
+            // EITHER:
+            //      delicitous -- sweet AND sweet -- dessert
+            // OR
+            //      delicious -- sweet AND sweet -- desgert
+            // So the word pair to use for the terms `summer` and `dessert` depend on the
+            // word pairs explored before them.
+            {
+                "id": 4,
+                "text": "delicitous. sweet. dessert. delicitous sweet desgert",
+            },
+            {
+                "id": 5,
+                "text": "delicious. sweet desgert. delicious sweet desgert",
+            },
+        ]))
+        .unwrap();
+    index
+}
+
+#[test]
+fn test_trap_basic_and_complex1() {
+    let index = create_index();
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("beautiful summer");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[1, 0, 3, 2]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"beautiful summer\"",
+        "\"beautigul summer. beautiful x y z summer\"",
+        "\"beautiful sommer\"",
+        "\"beautigul sommer. beautigul x summer\"",
+    ]
+    "###);
+}
+
+#[test]
+fn test_trap_complex2() {
+    let index = create_index();
+    let txn = index.read_txn().unwrap();
+
+    let mut s = Search::new(&txn, &index);
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    s.query("delicious sweet dessert");
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[5, 4]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"delicious. sweet desgert. delicious sweet desgert\"",
+        "\"delicitous. sweet. dessert. delicitous sweet desgert\"",
+    ]
+    "###);
+}

milli/src/search/new/tests/words_tms.rs

@@ -0,0 +1,437 @@
+/*!
+This module tests the following properties:
+
+1. The `last` term matching strategy starts removing terms from the query
+starting from the end if no more results match it.
+2. Phrases are never deleted by the `last` term matching strategy
+3. Duplicate words don't affect the ranking of a document according to the `words` ranking rule
+4. The proximity of the first and last word of a phrase to its adjacent terms is taken into
+account by the proximity ranking rule.
+5. Unclosed double quotes still make a phrase
+6. The `all` term matching strategy does not remove any term from the query
+7. The search is capable of returning no results if no documents match the query
+*/
+
+use crate::{
+    index::tests::TempIndex, search::new::tests::collect_field_values, Criterion, Search,
+    SearchResult, TermsMatchingStrategy,
+};
+
+fn create_index() -> TempIndex {
+    let index = TempIndex::new();
+
+    index
+        .update_settings(|s| {
+            s.set_primary_key("id".to_owned());
+            s.set_searchable_fields(vec!["text".to_owned()]);
+            s.set_criteria(vec![Criterion::Words]);
+        })
+        .unwrap();
+
+    index
+        .add_documents(documents!([
+            {
+                "id": 0,
+                "text": "",
+            },
+            {
+                "id": 1,
+                "text": "the",
+            },
+            {
+                "id": 2,
+                "text": "the quick",
+            },
+            {
+                "id": 3,
+                "text": "the quick brown",
+            },
+            {
+                "id": 4,
+                "text": "the quick brown fox",
+            },
+            {
+                "id": 5,
+                "text": "the quick brown fox jumps",
+            },
+            {
+                "id": 6,
+                "text": "the quick brown fox jumps over",
+            },
+            {
+                "id": 7,
+                "text": "the quick brown fox jumps over the",
+            },
+            {
+                "id": 8,
+                "text": "the quick brown fox jumps over the lazy",
+            },
+            {
+                "id": 9,
+                "text": "the quick brown fox jumps over the lazy dog",
+            },
+            {
+                "id": 10,
+                "text": "the brown quick fox jumps over the lazy dog",
+            },
+            {
+                "id": 11,
+                "text": "the quick brown fox talks to the lazy and slow dog",
+            },
+            {
+                "id": 12,
+                "text": "the quick brown fox talks to the lazy dog",
+            },
+            {
+                "id": 13,
+                "text": "the mighty and quick brown fox jumps over the lazy dog",
+            },
+            {
+                "id": 14,
+                "text": "the great quick brown fox jumps over the lazy dog",
+            },
+            {
+                "id": 15,
+                "text": "this quick brown and very scary fox jumps over the lazy dog",
+            },
+            {
+                "id": 16,
+                "text": "this quick brown and scary fox jumps over the lazy dog",
+            },
+            {
+                "id": 17,
+                "text": "the quick brown fox jumps over the really lazy dog",
+            },
+            {
+                "id": 18,
+                "text": "the brown quick fox jumps over the really lazy dog",
+            },
+            {
+                "id": 19,
+                "text": "the brown quick fox immediately jumps over the really lazy dog",
+            },
+            {
+                "id": 20,
+                "text": "the brown quick fox immediately jumps over the really lazy blue dog",
+            },
+            {
+                "id": 21,
+                "text": "the quick brown. quick brown fox. brown fox jumps. fox jumps over. over the lazy. the lazy dog.",
+            },
+            {
+                "id": 22,
+                "text": "the, quick, brown, fox, jumps, over, the, lazy, dog",
+            }
+        ]))
+        .unwrap();
+    index
+}
+
+#[test]
+fn test_words_tms_last_simple() {
+    let index = create_index();
+
+    let txn = index.read_txn().unwrap();
+    let mut s = Search::new(&txn, &index);
+    s.query("the quick brown fox jumps over the lazy dog");
+    s.terms_matching_strategy(TermsMatchingStrategy::Last);
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+
+    // 6 and 7 have the same score because "the" appears twice
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[9, 10, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 8, 6, 7, 5, 4, 11, 12, 3]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the quick brown fox jumps over the lazy dog\"",
+        "\"the brown quick fox jumps over the lazy dog\"",
+        "\"the mighty and quick brown fox jumps over the lazy dog\"",
+        "\"the great quick brown fox jumps over the lazy dog\"",
+        "\"this quick brown and very scary fox jumps over the lazy dog\"",
+        "\"this quick brown and scary fox jumps over the lazy dog\"",
+        "\"the quick brown fox jumps over the really lazy dog\"",
+        "\"the brown quick fox jumps over the really lazy dog\"",
+        "\"the brown quick fox immediately jumps over the really lazy dog\"",
+        "\"the brown quick fox immediately jumps over the really lazy blue dog\"",
+        "\"the quick brown. quick brown fox. brown fox jumps. fox jumps over. over the lazy. the lazy dog.\"",
+        "\"the, quick, brown, fox, jumps, over, the, lazy, dog\"",
+        "\"the quick brown fox jumps over the lazy\"",
+        "\"the quick brown fox jumps over\"",
+        "\"the quick brown fox jumps over the\"",
+        "\"the quick brown fox jumps\"",
+        "\"the quick brown fox\"",
+        "\"the quick brown fox talks to the lazy and slow dog\"",
+        "\"the quick brown fox talks to the lazy dog\"",
+        "\"the quick brown\"",
+    ]
+    "###);
+
+    let mut s = Search::new(&txn, &index);
+    s.query("extravagant the quick brown fox jumps over the lazy dog");
+    s.terms_matching_strategy(TermsMatchingStrategy::Last);
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[]");
+}
+
+#[test]
+fn test_words_tms_last_phrase() {
+    let index = create_index();
+
+    let txn = index.read_txn().unwrap();
+    let mut s = Search::new(&txn, &index);
+    s.query("\"the quick brown fox\" jumps over the lazy dog");
+    s.terms_matching_strategy(TermsMatchingStrategy::Last);
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+
+    // "The quick brown fox" is a phrase, not deleted by this term matching strategy
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[9, 17, 21, 8, 6, 7, 5, 4, 11, 12]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the quick brown fox jumps over the lazy dog\"",
+        "\"the quick brown fox jumps over the really lazy dog\"",
+        "\"the quick brown. quick brown fox. brown fox jumps. fox jumps over. over the lazy. the lazy dog.\"",
+        "\"the quick brown fox jumps over the lazy\"",
+        "\"the quick brown fox jumps over\"",
+        "\"the quick brown fox jumps over the\"",
+        "\"the quick brown fox jumps\"",
+        "\"the quick brown fox\"",
+        "\"the quick brown fox talks to the lazy and slow dog\"",
+        "\"the quick brown fox talks to the lazy dog\"",
+    ]
+    "###);
+
+    let mut s = Search::new(&txn, &index);
+    s.query("\"the quick brown fox\" jumps over the \"lazy\" dog");
+    s.terms_matching_strategy(TermsMatchingStrategy::Last);
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+
+    // "lazy" is a phrase, not deleted by this term matching strategy
+    // but words before it can be deleted
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[9, 17, 21, 8, 11, 12]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the quick brown fox jumps over the lazy dog\"",
+        "\"the quick brown fox jumps over the really lazy dog\"",
+        "\"the quick brown. quick brown fox. brown fox jumps. fox jumps over. over the lazy. the lazy dog.\"",
+        "\"the quick brown fox jumps over the lazy\"",
+        "\"the quick brown fox talks to the lazy and slow dog\"",
+        "\"the quick brown fox talks to the lazy dog\"",
+    ]
+    "###);
+
+    let mut s = Search::new(&txn, &index);
+    s.query("\"the quick brown fox jumps over the lazy dog\"");
+    s.terms_matching_strategy(TermsMatchingStrategy::Last);
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+
+    // The whole query is a phrase, no terms are removed
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[9]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the quick brown fox jumps over the lazy dog\"",
+    ]
+    "###);
+
+    let mut s = Search::new(&txn, &index);
+    s.query("\"the quick brown fox jumps over the lazy dog");
+    s.terms_matching_strategy(TermsMatchingStrategy::Last);
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+
+    // The whole query is still a phrase, even without closing quotes, so no terms are removed
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[9]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the quick brown fox jumps over the lazy dog\"",
+    ]
+    "###);
+}
+
+#[test]
+fn test_words_proximity_tms_last_simple() {
+    let index = create_index();
+    index
+        .update_settings(|s| {
+            s.set_criteria(vec![Criterion::Words, Criterion::Proximity]);
+        })
+        .unwrap();
+
+    let txn = index.read_txn().unwrap();
+    let mut s = Search::new(&txn, &index);
+    s.query("the quick brown fox jumps over the lazy dog");
+    s.terms_matching_strategy(TermsMatchingStrategy::Last);
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+
+    // 7 is better than 6 because of the proximity between "the" and its surrounding terms
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[9, 21, 14, 17, 13, 10, 18, 19, 20, 16, 15, 22, 8, 7, 6, 5, 4, 11, 12, 3]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the quick brown fox jumps over the lazy dog\"",
+        "\"the quick brown. quick brown fox. brown fox jumps. fox jumps over. over the lazy. the lazy dog.\"",
+        "\"the great quick brown fox jumps over the lazy dog\"",
+        "\"the quick brown fox jumps over the really lazy dog\"",
+        "\"the mighty and quick brown fox jumps over the lazy dog\"",
+        "\"the brown quick fox jumps over the lazy dog\"",
+        "\"the brown quick fox jumps over the really lazy dog\"",
+        "\"the brown quick fox immediately jumps over the really lazy dog\"",
+        "\"the brown quick fox immediately jumps over the really lazy blue dog\"",
+        "\"this quick brown and scary fox jumps over the lazy dog\"",
+        "\"this quick brown and very scary fox jumps over the lazy dog\"",
+        "\"the, quick, brown, fox, jumps, over, the, lazy, dog\"",
+        "\"the quick brown fox jumps over the lazy\"",
+        "\"the quick brown fox jumps over the\"",
+        "\"the quick brown fox jumps over\"",
+        "\"the quick brown fox jumps\"",
+        "\"the quick brown fox\"",
+        "\"the quick brown fox talks to the lazy and slow dog\"",
+        "\"the quick brown fox talks to the lazy dog\"",
+        "\"the quick brown\"",
+    ]
+    "###);
+
+    let mut s = Search::new(&txn, &index);
+    s.query("the brown quick fox jumps over the lazy dog");
+    s.terms_matching_strategy(TermsMatchingStrategy::Last);
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+
+    // 10 is better than 9 because of the proximity between "quick" and "brown"
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[10, 18, 19, 9, 20, 21, 14, 17, 13, 16, 15, 22, 8, 7, 6, 5, 4, 11, 12, 3]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the brown quick fox jumps over the lazy dog\"",
+        "\"the brown quick fox jumps over the really lazy dog\"",
+        "\"the brown quick fox immediately jumps over the really lazy dog\"",
+        "\"the quick brown fox jumps over the lazy dog\"",
+        "\"the brown quick fox immediately jumps over the really lazy blue dog\"",
+        "\"the quick brown. quick brown fox. brown fox jumps. fox jumps over. over the lazy. the lazy dog.\"",
+        "\"the great quick brown fox jumps over the lazy dog\"",
+        "\"the quick brown fox jumps over the really lazy dog\"",
+        "\"the mighty and quick brown fox jumps over the lazy dog\"",
+        "\"this quick brown and scary fox jumps over the lazy dog\"",
+        "\"this quick brown and very scary fox jumps over the lazy dog\"",
+        "\"the, quick, brown, fox, jumps, over, the, lazy, dog\"",
+        "\"the quick brown fox jumps over the lazy\"",
+        "\"the quick brown fox jumps over the\"",
+        "\"the quick brown fox jumps over\"",
+        "\"the quick brown fox jumps\"",
+        "\"the quick brown fox\"",
+        "\"the quick brown fox talks to the lazy and slow dog\"",
+        "\"the quick brown fox talks to the lazy dog\"",
+        "\"the quick brown\"",
+    ]
+    "###);
+}
+
+#[test]
+fn test_words_proximity_tms_last_phrase() {
+    let index = create_index();
+    index
+        .update_settings(|s| {
+            s.set_criteria(vec![Criterion::Words, Criterion::Proximity]);
+        })
+        .unwrap();
+
+    let txn = index.read_txn().unwrap();
+    let mut s = Search::new(&txn, &index);
+    s.query("the \"quick brown\" fox jumps over the lazy dog");
+    s.terms_matching_strategy(TermsMatchingStrategy::Last);
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+
+    // "quick brown" is a phrase. The proximity of its first and last words
+    // to their adjacent query words should be taken into account
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[9, 21, 14, 17, 13, 16, 15, 8, 7, 6, 5, 4, 11, 12, 3]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the quick brown fox jumps over the lazy dog\"",
+        "\"the quick brown. quick brown fox. brown fox jumps. fox jumps over. over the lazy. the lazy dog.\"",
+        "\"the great quick brown fox jumps over the lazy dog\"",
+        "\"the quick brown fox jumps over the really lazy dog\"",
+        "\"the mighty and quick brown fox jumps over the lazy dog\"",
+        "\"this quick brown and scary fox jumps over the lazy dog\"",
+        "\"this quick brown and very scary fox jumps over the lazy dog\"",
+        "\"the quick brown fox jumps over the lazy\"",
+        "\"the quick brown fox jumps over the\"",
+        "\"the quick brown fox jumps over\"",
+        "\"the quick brown fox jumps\"",
+        "\"the quick brown fox\"",
+        "\"the quick brown fox talks to the lazy and slow dog\"",
+        "\"the quick brown fox talks to the lazy dog\"",
+        "\"the quick brown\"",
+    ]
+    "###);
+
+    let mut s = Search::new(&txn, &index);
+    s.query("the \"quick brown\" \"fox jumps\" over the lazy dog");
+    s.terms_matching_strategy(TermsMatchingStrategy::Last);
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+
+    // "quick brown" is a phrase. The proximity of its first and last words
+    // to their adjacent query words should be taken into account.
+    // The same applies to `fox jumps`.
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[9, 21, 14, 17, 13, 16, 15, 8, 7, 6, 5]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the quick brown fox jumps over the lazy dog\"",
+        "\"the quick brown. quick brown fox. brown fox jumps. fox jumps over. over the lazy. the lazy dog.\"",
+        "\"the great quick brown fox jumps over the lazy dog\"",
+        "\"the quick brown fox jumps over the really lazy dog\"",
+        "\"the mighty and quick brown fox jumps over the lazy dog\"",
+        "\"this quick brown and scary fox jumps over the lazy dog\"",
+        "\"this quick brown and very scary fox jumps over the lazy dog\"",
+        "\"the quick brown fox jumps over the lazy\"",
+        "\"the quick brown fox jumps over the\"",
+        "\"the quick brown fox jumps over\"",
+        "\"the quick brown fox jumps\"",
+    ]
+    "###);
+}
+
+#[test]
+fn test_words_tms_all() {
+    let index = create_index();
+    index
+        .update_settings(|s| {
+            s.set_criteria(vec![Criterion::Words, Criterion::Proximity]);
+        })
+        .unwrap();
+
+    let txn = index.read_txn().unwrap();
+    let mut s = Search::new(&txn, &index);
+    s.query("the quick brown fox jumps over the lazy dog");
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[9, 21, 14, 17, 13, 10, 18, 19, 20, 16, 15, 22]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @r###"
+    [
+        "\"the quick brown fox jumps over the lazy dog\"",
+        "\"the quick brown. quick brown fox. brown fox jumps. fox jumps over. over the lazy. the lazy dog.\"",
+        "\"the great quick brown fox jumps over the lazy dog\"",
+        "\"the quick brown fox jumps over the really lazy dog\"",
+        "\"the mighty and quick brown fox jumps over the lazy dog\"",
+        "\"the brown quick fox jumps over the lazy dog\"",
+        "\"the brown quick fox jumps over the really lazy dog\"",
+        "\"the brown quick fox immediately jumps over the really lazy dog\"",
+        "\"the brown quick fox immediately jumps over the really lazy blue dog\"",
+        "\"this quick brown and scary fox jumps over the lazy dog\"",
+        "\"this quick brown and very scary fox jumps over the lazy dog\"",
+        "\"the, quick, brown, fox, jumps, over, the, lazy, dog\"",
+    ]
+    "###);
+
+    let mut s = Search::new(&txn, &index);
+    s.query("extravagant");
+    s.terms_matching_strategy(TermsMatchingStrategy::All);
+    let SearchResult { documents_ids, .. } = s.execute().unwrap();
+
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[]");
+    let texts = collect_field_values(&index, &txn, "text", &documents_ids);
+    insta::assert_debug_snapshot!(texts, @"[]");
+}