1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159

use crate::fastfield::DeleteBitSet;
use crate::query::explanation::does_not_match;
use crate::query::{Explanation, Query, Scorer, Weight};
use crate::{DocId, DocSet, Score, Searcher, SegmentReader, Term};
use std::collections::BTreeMap;
use std::fmt;

/// `BoostQuery` is a wrapper over a query used to boost its score.
///
/// The document set matched by the `BoostQuery` is strictly the same as the underlying query.
/// The score of each document, is the score of the underlying query multiplied by the `boost`
/// factor.
pub struct BoostQuery {
    query: Box<dyn Query>,
    boost: Score,
}

impl BoostQuery {
    /// Builds a boost query.
    pub fn new(query: Box<dyn Query>, boost: Score) -> BoostQuery {
        BoostQuery { query, boost }
    }
}

impl Clone for BoostQuery {
    fn clone(&self) -> Self {
        BoostQuery {
            query: self.query.box_clone(),
            boost: self.boost,
        }
    }
}

impl fmt::Debug for BoostQuery {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "Boost(query={:?}, boost={})", self.query, self.boost)
    }
}

impl Query for BoostQuery {
    fn weight(&self, searcher: &Searcher, scoring_enabled: bool) -> crate::Result<Box<dyn Weight>> {
        let weight_without_boost = self.query.weight(searcher, scoring_enabled)?;
        let boosted_weight = if scoring_enabled {
            Box::new(BoostWeight::new(weight_without_boost, self.boost))
        } else {
            weight_without_boost
        };
        Ok(boosted_weight)
    }

    fn query_terms(&self, terms: &mut BTreeMap<Term, bool>) {
        self.query.query_terms(terms)
    }
}

pub(crate) struct BoostWeight {
    weight: Box<dyn Weight>,
    boost: Score,
}

impl BoostWeight {
    pub fn new(weight: Box<dyn Weight>, boost: Score) -> Self {
        BoostWeight { weight, boost }
    }
}

impl Weight for BoostWeight {
    fn scorer(&self, reader: &SegmentReader, boost: Score) -> crate::Result<Box<dyn Scorer>> {
        self.weight.scorer(reader, boost * self.boost)
    }

    fn explain(&self, reader: &SegmentReader, doc: u32) -> crate::Result<Explanation> {
        let mut scorer = self.scorer(reader, 1.0)?;
        if scorer.seek(doc) != doc {
            return Err(does_not_match(doc));
        }
        let mut explanation =
            Explanation::new(format!("Boost x{} of ...", self.boost), scorer.score());
        let underlying_explanation = self.weight.explain(reader, doc)?;
        explanation.add_detail(underlying_explanation);
        Ok(explanation)
    }

    fn count(&self, reader: &SegmentReader) -> crate::Result<u32> {
        self.weight.count(reader)
    }
}

pub(crate) struct BoostScorer<S: Scorer> {
    underlying: S,
    boost: Score,
}

impl<S: Scorer> BoostScorer<S> {
    pub fn new(underlying: S, boost: Score) -> BoostScorer<S> {
        BoostScorer { underlying, boost }
    }
}

impl<S: Scorer> DocSet for BoostScorer<S> {
    fn advance(&mut self) -> DocId {
        self.underlying.advance()
    }

    fn seek(&mut self, target: DocId) -> DocId {
        self.underlying.seek(target)
    }

    fn fill_buffer(&mut self, buffer: &mut [DocId]) -> usize {
        self.underlying.fill_buffer(buffer)
    }

    fn doc(&self) -> u32 {
        self.underlying.doc()
    }

    fn size_hint(&self) -> u32 {
        self.underlying.size_hint()
    }

    fn count(&mut self, delete_bitset: &DeleteBitSet) -> u32 {
        self.underlying.count(delete_bitset)
    }

    fn count_including_deleted(&mut self) -> u32 {
        self.underlying.count_including_deleted()
    }
}

impl<S: Scorer> Scorer for BoostScorer<S> {
    fn score(&mut self) -> Score {
        self.underlying.score() * self.boost
    }
}

#[cfg(test)]
mod tests {
    use super::BoostQuery;
    use crate::query::{AllQuery, Query};
    use crate::schema::Schema;
    use crate::{DocAddress, Document, Index};

    #[test]
    fn test_boost_query_explain() {
        let schema = Schema::builder().build();
        let index = Index::create_in_ram(schema);
        let mut index_writer = index.writer_for_tests().unwrap();
        index_writer.add_document(Document::new());
        assert!(index_writer.commit().is_ok());
        let reader = index.reader().unwrap();
        let searcher = reader.searcher();
        let query = BoostQuery::new(Box::new(AllQuery), 0.2);
        let explanation = query.explain(&searcher, DocAddress::new(0, 0u32)).unwrap();
        assert_eq!(
            explanation.to_pretty_json(),
            "{\n  \"value\": 0.2,\n  \"description\": \"Boost x0.2 of ...\",\n  \"details\": [\n    {\n      \"value\": 1.0,\n      \"description\": \"AllQuery\",\n      \"context\": []\n    }\n  ],\n  \"context\": []\n}"
        )
    }
}