From 0300e7272bf4691d2dee24c1fb05e2c2a3f7c59c Mon Sep 17 00:00:00 2001
From: Paul Masurel <paul.masurel@gmail.com>
Date: Sat, 17 Feb 2018 11:56:21 +0900
Subject: [PATCH] Scoring for union.

---
 src/postings/union.rs                     | 23 ++++++++++++++++++++++-
 src/query/boolean_query/boolean_weight.rs | 21 ++++-----------------
 2 files changed, 26 insertions(+), 18 deletions(-)

diff --git a/src/postings/union.rs b/src/postings/union.rs
index 853cae685..6b3de16d4 100644
--- a/src/postings/union.rs
+++ b/src/postings/union.rs
@@ -4,6 +4,7 @@ use postings::SkipResult;
 use common::TinySet;
 use std::cmp::Ordering;
 use DocId;
+use Score;
 use query::score_combiner::{DoNothingCombiner, ScoreCombiner};
 
 const HORIZON_NUM_TINYBITSETS: usize = 32;
@@ -18,6 +19,7 @@ pub struct Union<TScorer, TScoreCombiner=DoNothingCombiner>
     cursor: usize,
     offset: DocId,
     doc: DocId,
+    score: Score,
 }
 
 impl<TScorer, TScoreCombiner> From<Vec<TScorer>>
@@ -44,6 +46,7 @@ impl<TScorer, TScoreCombiner> From<Vec<TScorer>>
             cursor: HORIZON_NUM_TINYBITSETS,
             offset: 0,
             doc: 0,
+            score: 0f32
         }
     }
 }
@@ -89,7 +92,11 @@ impl<TScorer: Scorer, TScoreCombiner: ScoreCombiner> Union<TScorer, TScoreCombin
     fn advance_buffered(&mut self) -> bool {
         while self.cursor < HORIZON_NUM_TINYBITSETS {
             if let Some(val) = self.bitsets[self.cursor].pop_lowest() {
-                self.doc = self.offset + val + (self.cursor as u32) * 64;
+                let delta = val + (self.cursor as u32) * 64;
+                self.doc = self.offset + delta;
+                let score_combiner = &mut self.scores[delta as usize];
+                self.score = score_combiner.score();
+                score_combiner.clear();
                 return true;
             } else {
                 self.cursor += 1;
@@ -129,6 +136,9 @@ impl<TScorer: Scorer, TScoreCombiner: ScoreCombiner> DocSet for Union<TScorer, T
             for obsolete_tinyset in &mut self.bitsets[self.cursor..new_cursor] {
                 *obsolete_tinyset = TinySet::empty();
             }
+            for score_combiner in &mut self.scores[self.cursor*64..new_cursor*64] {
+                score_combiner.clear();
+            }
             self.cursor = new_cursor;
 
             // Advancing until we reach the end of the bucket
@@ -150,6 +160,9 @@ impl<TScorer: Scorer, TScoreCombiner: ScoreCombiner> DocSet for Union<TScorer, T
             for obsolete_tinyset in self.bitsets.iter_mut() {
                 *obsolete_tinyset = TinySet::empty();
             }
+            for score_combiner in self.scores.iter_mut() {
+                score_combiner.clear();
+            }
 
             // The target is outside of the buffered horizon.
             // advance all docsets to a doc >= to the target.
@@ -186,6 +199,14 @@ impl<TScorer: Scorer, TScoreCombiner: ScoreCombiner> DocSet for Union<TScorer, T
     }
 }
 
+impl<TScorer, TScoreCombiner> Scorer for Union<TScorer, TScoreCombiner>
+    where TScoreCombiner: ScoreCombiner,
+          TScorer: Scorer {
+    fn score(&mut self) -> Score {
+        self.score
+    }
+}
+
 #[cfg(test)]
 mod tests {
 
diff --git a/src/query/boolean_query/boolean_weight.rs b/src/query/boolean_query/boolean_weight.rs
index e88ed5168..ab7039d2e 100644
--- a/src/query/boolean_query/boolean_weight.rs
+++ b/src/query/boolean_query/boolean_weight.rs
@@ -11,13 +11,15 @@ use query::RequiredOptionalScorer;
 use query::score_combiner::{SumWithCoordsCombiner, DoNothingCombiner, ScoreCombiner};
 use Result;
 
-fn scorer_union<'a, TScoreCombiner: ScoreCombiner + 'static>(docsets: Vec<Box<Scorer + 'a>>) -> Box<Scorer + 'a> {
+fn scorer_union<'a, TScoreCombiner>(docsets: Vec<Box<Scorer + 'a>>) -> Box<Scorer + 'a>
+    where TScoreCombiner: ScoreCombiner + 'static
+{
     assert!(!docsets.is_empty());
     if docsets.len() == 1 {
         docsets.into_iter().next().unwrap() //< we checked the size beforehands
     } else {
         // TODO have a UnionScorer instead.
-        box ConstScorer::new(Union::<_, TScoreCombiner>::from(docsets))
+        box Union::<_, TScoreCombiner>::from(docsets)
     }
 }
 
@@ -84,21 +86,6 @@ impl BooleanWeight {
             Ok(positive_scorer)
         }
     }
-
-//    fn scorer_if_scoring_enabled<'a>(
-//        &'a self,
-//        reader: &'a SegmentReader,
-//    ) -> Result<Box<Scorer + 'a>> {
-//        let sub_scorers: Vec<Box<Scorer + 'a>> = self.weights
-//            .iter()
-//            .map(|&(_, ref weight)| weight)
-//            .map(|weight| weight.scorer(reader))
-//            .collect::<Result<_>>()?;
-//        let occurs: Vec<Occur> = self.weights.iter().map(|&(ref occur, _)| *occur).collect();
-//        let occur_filter = OccurFilter::new(&occurs);
-//        let boolean_scorer = BooleanScorer::new(sub_scorers, occur_filter);
-//        Ok(box boolean_scorer)
-//    }
 }
 
 impl Weight for BooleanWeight {