Add score_details

milli/src/lib.rs

@@ -17,6 +17,7 @@ mod fields_ids_map;
 pub mod heed_codec;
 pub mod index;
 pub mod proximity;
+pub mod score_details;
 mod search;
 pub mod update;
 

milli/src/score_details.rs

@@ -0,0 +1,314 @@
+use serde::Serialize;
+
+use crate::distance_between_two_points;
+
+#[derive(Debug, Clone, PartialEq)]
+pub enum ScoreDetails {
+    Words(Words),
+    Typo(Typo),
+    Proximity(Rank),
+    Fid(Rank),
+    Position(Rank),
+    ExactAttribute(ExactAttribute),
+    Exactness(Rank),
+    Sort(Sort),
+    GeoSort(GeoSort),
+}
+
+impl ScoreDetails {
+    pub fn local_score(&self) -> Option<f64> {
+        self.rank().map(Rank::local_score)
+    }
+
+    pub fn rank(&self) -> Option<Rank> {
+        match self {
+            ScoreDetails::Words(details) => Some(details.rank()),
+            ScoreDetails::Typo(details) => Some(details.rank()),
+            ScoreDetails::Proximity(details) => Some(*details),
+            ScoreDetails::Fid(details) => Some(*details),
+            ScoreDetails::Position(details) => Some(*details),
+            ScoreDetails::ExactAttribute(details) => Some(details.rank()),
+            ScoreDetails::Exactness(details) => Some(*details),
+            ScoreDetails::Sort(_) => None,
+            ScoreDetails::GeoSort(_) => None,
+        }
+    }
+
+    pub fn global_score<'a>(details: impl Iterator<Item = &'a Self>) -> f64 {
+        Rank::global_score(details.filter_map(Self::rank))
+    }
+
+    /// Panics
+    ///
+    /// - If Position is not preceded by Fid
+    /// - If Exactness is not preceded by ExactAttribute
+    pub fn to_json_map<'a>(
+        details: impl Iterator<Item = &'a Self>,
+    ) -> serde_json::Map<String, serde_json::Value> {
+        let mut order = 0;
+        let mut fid_details = None;
+        let mut details_map = serde_json::Map::default();
+        for details in details {
+            match details {
+                ScoreDetails::Words(words) => {
+                    let words_details = serde_json::json!({
+                            "order": order,
+                            "matchingWords": words.matching_words,
+                            "maxMatchingWords": words.max_matching_words,
+                            "score": words.rank().local_score(),
+                    });
+                    details_map.insert("words".into(), words_details);
+                    order += 1;
+                }
+                ScoreDetails::Typo(typo) => {
+                    let typo_details = serde_json::json!({
+                        "order": order,
+                        "typoCount": typo.typo_count,
+                        "maxTypoCount": typo.max_typo_count,
+                        "score": typo.rank().local_score(),
+                    });
+                    details_map.insert("typo".into(), typo_details);
+                    order += 1;
+                }
+                ScoreDetails::Proximity(proximity) => {
+                    let proximity_details = serde_json::json!({
+                        "order": order,
+                        "score": proximity.local_score(),
+                    });
+                    details_map.insert("proximity".into(), proximity_details);
+                    order += 1;
+                }
+                ScoreDetails::Fid(fid) => {
+                    // copy the rank for future use in Position.
+                    fid_details = Some(*fid);
+                    // For now, fid is a virtual rule always followed by the "position" rule
+                    let fid_details = serde_json::json!({
+                        "order": order,
+                        "attribute_ranking_order_score": fid.local_score(),
+                    });
+                    details_map.insert("attribute".into(), fid_details);
+                    order += 1;
+                }
+                ScoreDetails::Position(position) => {
+                    // For now, position is a virtual rule always preceded by the "fid" rule
+                    let attribute_details = details_map
+                        .get_mut("attribute")
+                        .expect("position not preceded by attribute");
+                    let attribute_details = attribute_details
+                        .as_object_mut()
+                        .expect("attribute details was not an object");
+                    let Some(fid_details) = fid_details
+                    else {
+                        unimplemented!("position not preceded by attribute");
+                    };
+
+                    attribute_details
+                        .insert("query_word_distance_score".into(), position.local_score().into());
+                    let score = Rank::global_score([fid_details, *position].iter().copied());
+                    attribute_details.insert("score".into(), score.into());
+
+                    // do not update the order since this was already done by fid
+                }
+                ScoreDetails::ExactAttribute(exact_attribute) => {
+                    let exactness_details = serde_json::json!({
+                        "order": order,
+                        "matchType": exact_attribute,
+                        "score": exact_attribute.rank().local_score(),
+                    });
+                    details_map.insert("exactness".into(), exactness_details);
+                    order += 1;
+                }
+                ScoreDetails::Exactness(details) => {
+                    // For now, exactness is a virtual rule always preceded by the "ExactAttribute" rule
+                    let exactness_details = details_map
+                        .get_mut("exactness")
+                        .expect("Exactness not preceded by exactAttribute");
+                    let exactness_details = exactness_details
+                        .as_object_mut()
+                        .expect("exactness details was not an object");
+                    if exactness_details.get("matchType").expect("missing 'matchType'")
+                        == &serde_json::json!(ExactAttribute::NoExactMatch)
+                    {
+                        let score = Rank::global_score(
+                            [ExactAttribute::NoExactMatch.rank(), *details].iter().copied(),
+                        );
+                        *exactness_details.get_mut("score").expect("missing score") = score.into();
+                    }
+                    // do not update the order since this was already done by exactAttribute
+                }
+                ScoreDetails::Sort(details) => {
+                    let sort = if details.redacted {
+                        format!("<hidden-rule-{order}>")
+                    } else {
+                        format!(
+                            "{}:{}",
+                            details.field_name,
+                            if details.ascending { "asc" } else { "desc" }
+                        )
+                    };
+                    let value =
+                        if details.redacted { "<hidden>".into() } else { details.value.clone() };
+                    let sort_details = serde_json::json!({
+                        "order": order,
+                        "value": value,
+                    });
+                    details_map.insert(sort, sort_details);
+                    order += 1;
+                }
+                ScoreDetails::GeoSort(details) => {
+                    let sort = format!(
+                        "_geoPoint({}, {}):{}",
+                        details.target_point[0],
+                        details.target_point[1],
+                        if details.ascending { "asc" } else { "desc" }
+                    );
+                    let point = if let Some(value) = details.value {
+                        serde_json::json!({ "lat": value[0], "lng": value[1]})
+                    } else {
+                        serde_json::Value::Null
+                    };
+                    let sort_details = serde_json::json!({
+                        "order": order,
+                        "value": point,
+                        "distance": details.distance(),
+                    });
+                    details_map.insert(sort, sort_details);
+                    order += 1;
+                }
+            }
+        }
+        details_map
+    }
+}
+
+/// The strategy to compute scores.
+///
+/// It makes sense to pass down this strategy to the internals of the search, because
+/// some optimizations (today, mainly skipping ranking rules for universes of a single document)
+/// are not correct to do when computing the scores.
+///
+/// This strategy could feasibly be extended to differentiate between the normalized score and the
+/// detailed scores, but it is not useful today as the normalized score is *derived from* the
+/// detailed scores.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
+pub enum ScoringStrategy {
+    /// Don't compute scores
+    #[default]
+    Skip,
+    /// Compute detailed scores
+    Detailed,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct Words {
+    pub matching_words: u32,
+    pub max_matching_words: u32,
+}
+
+impl Words {
+    pub fn rank(&self) -> Rank {
+        Rank { rank: self.matching_words, max_rank: self.max_matching_words }
+    }
+
+    pub(crate) fn from_rank(rank: Rank) -> Words {
+        Words { matching_words: rank.rank, max_matching_words: rank.max_rank }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct Typo {
+    pub typo_count: u32,
+    pub max_typo_count: u32,
+}
+
+impl Typo {
+    pub fn rank(&self) -> Rank {
+        Rank {
+            rank: self.max_typo_count - self.typo_count + 1,
+            max_rank: (self.max_typo_count + 1),
+        }
+    }
+
+    // max_rank = max_typo + 1
+    // max_typo = max_rank - 1
+    //
+    // rank = max_typo - typo + 1
+    // rank = max_rank - 1 - typo + 1
+    // rank + typo = max_rank
+    // typo = max_rank - rank
+    pub fn from_rank(rank: Rank) -> Typo {
+        Typo { typo_count: rank.max_rank - rank.rank, max_typo_count: rank.max_rank - 1 }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct Rank {
+    /// The ordinal rank, such that `max_rank` is the first rank, and 0 is the last rank.
+    ///
+    /// The higher the better. Documents with a rank of 0 have a score of 0 and are typically never returned
+    /// (they don't match the query).
+    pub rank: u32,
+    /// The maximum possible rank. Documents with this rank have a score of 1.
+    ///
+    /// The max rank should not be 0.
+    pub max_rank: u32,
+}
+
+impl Rank {
+    pub fn local_score(self) -> f64 {
+        self.rank as f64 / self.max_rank as f64
+    }
+
+    pub fn global_score(details: impl Iterator<Item = Self>) -> f64 {
+        let mut rank = Rank { rank: 1, max_rank: 1 };
+        for inner_rank in details {
+            rank.rank -= 1;
+
+            rank.rank *= inner_rank.max_rank;
+            rank.max_rank *= inner_rank.max_rank;
+
+            rank.rank += inner_rank.rank;
+        }
+        rank.local_score()
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub enum ExactAttribute {
+    ExactMatch,
+    MatchesStart,
+    NoExactMatch,
+}
+
+impl ExactAttribute {
+    pub fn rank(&self) -> Rank {
+        let rank = match self {
+            ExactAttribute::ExactMatch => 3,
+            ExactAttribute::MatchesStart => 2,
+            ExactAttribute::NoExactMatch => 1,
+        };
+        Rank { rank, max_rank: 3 }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq)]
+pub struct Sort {
+    pub field_name: String,
+    pub ascending: bool,
+    pub redacted: bool,
+    pub value: serde_json::Value,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, PartialOrd)]
+pub struct GeoSort {
+    pub target_point: [f64; 2],
+    pub ascending: bool,
+    pub value: Option<[f64; 2]>,
+}
+
+impl GeoSort {
+    pub fn distance(&self) -> Option<f64> {
+        self.value.map(|value| distance_between_two_points(&self.target_point, &value))
+    }
+}