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use super::Scorer;
use crate::docset::COLLECT_BLOCK_BUFFER_LEN;
use crate::index::SegmentReader;
use crate::query::Explanation;
use crate::{DocId, DocSet, Score, TERMINATED};
/// Iterates through all of the documents and scores matched by the DocSet
/// `DocSet`.
pub(crate) fn for_each_scorer<TScorer: Scorer + ?Sized>(
scorer: &mut TScorer,
callback: &mut dyn FnMut(DocId, Score),
) {
let mut doc = scorer.doc();
while doc != TERMINATED {
callback(doc, scorer.score());
doc = scorer.advance();
}
}
/// Iterates through all of the documents matched by the DocSet
/// `DocSet`.
#[inline]
pub(crate) fn for_each_docset_buffered<T: DocSet + ?Sized>(
docset: &mut T,
buffer: &mut [DocId; COLLECT_BLOCK_BUFFER_LEN],
mut callback: impl FnMut(&[DocId]),
) {
loop {
let num_items = docset.fill_buffer(buffer);
callback(&buffer[..num_items]);
if num_items != buffer.len() {
break;
}
}
}
/// Calls `callback` with all of the `(doc, score)` for which score
/// is exceeding a given threshold.
///
/// This method is useful for the [`TopDocs`](crate::collector::TopDocs) collector.
/// For all docsets, the blanket implementation has the benefit
/// of prefiltering (doc, score) pairs, avoiding the
/// virtual dispatch cost.
///
/// More importantly, it makes it possible for scorers to implement
/// important optimization (e.g. BlockWAND for union).
pub(crate) fn for_each_pruning_scorer<TScorer: Scorer + ?Sized>(
scorer: &mut TScorer,
mut threshold: Score,
callback: &mut dyn FnMut(DocId, Score) -> Score,
) {
let mut doc = scorer.doc();
while doc != TERMINATED {
let score = scorer.score();
if score > threshold {
threshold = callback(doc, score);
}
doc = scorer.advance();
}
}
/// A Weight is the specialization of a `Query`
/// for a given set of segments.
///
/// See [`Query`](crate::query::Query).
pub trait Weight: Send + Sync + 'static {
/// Returns the scorer for the given segment.
///
/// `boost` is a multiplier to apply to the score.
///
/// See [`Query`](crate::query::Query).
fn scorer(&self, reader: &SegmentReader, boost: Score) -> crate::Result<Box<dyn Scorer>>;
/// Returns an [`Explanation`] for the given document.
fn explain(&self, reader: &SegmentReader, doc: DocId) -> crate::Result<Explanation>;
/// Returns the number documents within the given [`SegmentReader`].
fn count(&self, reader: &SegmentReader) -> crate::Result<u32> {
let mut scorer = self.scorer(reader, 1.0)?;
if let Some(alive_bitset) = reader.alive_bitset() {
Ok(scorer.count(alive_bitset))
} else {
Ok(scorer.count_including_deleted())
}
}
/// Iterates through all of the document matched by the DocSet
/// `DocSet` and push the scored documents to the collector.
fn for_each(
&self,
reader: &SegmentReader,
callback: &mut dyn FnMut(DocId, Score),
) -> crate::Result<()> {
let mut scorer = self.scorer(reader, 1.0)?;
for_each_scorer(scorer.as_mut(), callback);
Ok(())
}
/// Iterates through all of the document matched by the DocSet
/// `DocSet` and push the scored documents to the collector.
fn for_each_no_score(
&self,
reader: &SegmentReader,
callback: &mut dyn FnMut(&[DocId]),
) -> crate::Result<()> {
let mut docset = self.scorer(reader, 1.0)?;
let mut buffer = [0u32; COLLECT_BLOCK_BUFFER_LEN];
for_each_docset_buffered(&mut docset, &mut buffer, callback);
Ok(())
}
/// Calls `callback` with all of the `(doc, score)` for which score
/// is exceeding a given threshold.
///
/// This method is useful for the [`TopDocs`](crate::collector::TopDocs) collector.
/// For all docsets, the blanket implementation has the benefit
/// of prefiltering (doc, score) pairs, avoiding the
/// virtual dispatch cost.
///
/// More importantly, it makes it possible for scorers to implement
/// important optimization (e.g. BlockWAND for union).
fn for_each_pruning(
&self,
threshold: Score,
reader: &SegmentReader,
callback: &mut dyn FnMut(DocId, Score) -> Score,
) -> crate::Result<()> {
let mut scorer = self.scorer(reader, 1.0)?;
for_each_pruning_scorer(scorer.as_mut(), threshold, callback);
Ok(())
}
}