Update the criteria to the new ones

meilisearch-core/src/criterion/typo.rs

@@ -0,0 +1,67 @@
+use std::cmp::Ordering;
+
+use compact_arena::SmallArena;
+
+use crate::automaton::QueryEnhancer;
+use crate::bucket_sort::{PostingsListView, QueryWordAutomaton};
+use crate::RawDocument;
+
+use super::{Criterion, prepare_query_distances};
+
+pub struct Typo;
+
+impl Criterion for Typo {
+    fn name(&self) -> &str { "typo" }
+
+    fn prepare<'a, 'tag, 'txn>(
+        &self,
+        documents: &mut [RawDocument<'a, 'tag>],
+        postings_lists: &mut SmallArena<'tag, PostingsListView<'txn>>,
+        query_enhancer: &QueryEnhancer,
+        automatons: &[QueryWordAutomaton],
+    ) {
+        prepare_query_distances(documents, query_enhancer, automatons, postings_lists);
+    }
+
+    fn evaluate(
+        &self,
+        lhs: &RawDocument,
+        rhs: &RawDocument,
+        postings_lists: &SmallArena<PostingsListView>,
+    ) -> Ordering
+    {
+        // This function is a wrong logarithmic 10 function.
+        // It is safe to panic on input number higher than 3,
+        // the number of typos is never bigger than that.
+        #[inline]
+        fn custom_log10(n: u8) -> f32 {
+            match n {
+                0 => 0.0,     // log(1)
+                1 => 0.30102, // log(2)
+                2 => 0.47712, // log(3)
+                3 => 0.60205, // log(4)
+                _ => panic!("invalid number"),
+            }
+        }
+
+        #[inline]
+        fn compute_typos(distances: &[Option<u8>]) -> usize {
+            let mut number_words: usize = 0;
+            let mut sum_typos = 0.0;
+
+            for distance in distances {
+                if let Some(distance) = distance {
+                    sum_typos += custom_log10(*distance);
+                    number_words += 1;
+                }
+            }
+
+            (number_words as f32 / (sum_typos + 1.0) * 1000.0) as usize
+        }
+
+        let lhs = compute_typos(&lhs.processed_distances);
+        let rhs = compute_typos(&rhs.processed_distances);
+
+        lhs.cmp(&rhs).reverse()
+    }
+}