Introduce a new cache for the words fids

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

@@ -0,0 +1,82 @@
+use roaring::RoaringBitmap;
+
+use super::{ComputedCondition, RankingRuleGraphTrait};
+use crate::search::new::interner::{DedupInterner, Interned};
+use crate::search::new::query_term::LocatedQueryTermSubset;
+use crate::search::new::resolve_query_graph::compute_query_term_subset_docids;
+use crate::search::new::SearchContext;
+use crate::Result;
+
+#[derive(Clone, PartialEq, Eq, Hash)]
+pub struct AttributeCondition {
+    term: LocatedQueryTermSubset,
+    nbr_typos: u8,
+}
+
+pub enum AttributeGraph {}
+
+impl RankingRuleGraphTrait for AttributeGraph {
+    type Condition = AttributeCondition;
+
+    fn resolve_condition(
+        ctx: &mut SearchContext,
+        condition: &Self::Condition,
+        universe: &RoaringBitmap,
+    ) -> Result<ComputedCondition> {
+        let AttributeCondition { term, .. } = condition;
+        // maybe compute_query_term_subset_docids should accept a universe as argument
+        let mut docids = compute_query_term_subset_docids(ctx, &term.term_subset)?;
+        docids &= universe;
+
+        Ok(ComputedCondition {
+            docids,
+            universe_len: universe.len(),
+            start_term_subset: None,
+            end_term_subset: term.clone(),
+        })
+    }
+
+    fn build_edges(
+        ctx: &mut SearchContext,
+        conditions_interner: &mut DedupInterner<Self::Condition>,
+        _from: Option<&LocatedQueryTermSubset>,
+        to_term: &LocatedQueryTermSubset,
+    ) -> Result<Vec<(u32, Interned<Self::Condition>)>> {
+        let term = to_term;
+
+        let mut edges = vec![];
+        for word in term.term_subset.all_single_words_except_prefix_db(ctx)? {
+            // ...
+        }
+
+        // Ngrams have a base typo cost
+        // 2-gram -> equivalent to 1 typo
+        // 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..=term.term_subset.max_nbr_typos(ctx) {
+            let mut term = term.clone();
+            match nbr_typos {
+                0 => {
+                    term.term_subset.clear_one_typo_subset();
+                    term.term_subset.clear_two_typo_subset();
+                }
+                1 => {
+                    term.term_subset.clear_zero_typo_subset();
+                    term.term_subset.clear_two_typo_subset();
+                }
+                2 => {
+                    term.term_subset.clear_zero_typo_subset();
+                    term.term_subset.clear_one_typo_subset();
+                }
+                _ => panic!(),
+            };
+
+            edges.push((
+                nbr_typos as u32 + base_cost,
+                conditions_interner.insert(AttributeCondition { term, nbr_typos }),
+            ));
+        }
+        Ok(edges)
+    }
+}