use crate::docset::{DocSet, TERMINATED};
use crate::query::term_query::TermScorer;
use crate::query::{EmptyScorer, Scorer};
use crate::{DocId, Score};
pub fn intersect_scorers(mut scorers: Vec<Box<dyn Scorer>>) -> Box<dyn Scorer> {
if scorers.is_empty() {
return Box::new(EmptyScorer);
}
if scorers.len() == 1 {
return scorers.pop().unwrap();
}
scorers.sort_by_key(|scorer| scorer.size_hint());
let doc = go_to_first_doc(&mut scorers[..]);
if doc == TERMINATED {
return Box::new(EmptyScorer);
}
let left = scorers.remove(0);
let right = scorers.remove(0);
let all_term_scorers = [&left, &right]
.iter()
.all(|&scorer| scorer.is::<TermScorer>());
if all_term_scorers {
return Box::new(Intersection {
left: *(left.downcast::<TermScorer>().map_err(|_| ()).unwrap()),
right: *(right.downcast::<TermScorer>().map_err(|_| ()).unwrap()),
others: scorers,
});
}
Box::new(Intersection {
left,
right,
others: scorers,
})
}
pub struct Intersection<TDocSet: DocSet, TOtherDocSet: DocSet = Box<dyn Scorer>> {
left: TDocSet,
right: TDocSet,
others: Vec<TOtherDocSet>,
}
fn go_to_first_doc<TDocSet: DocSet>(docsets: &mut [TDocSet]) -> DocId {
assert!(!docsets.is_empty());
let mut candidate = docsets.iter().map(TDocSet::doc).max().unwrap();
'outer: loop {
for docset in docsets.iter_mut() {
let seek_doc = docset.seek(candidate);
if seek_doc > candidate {
candidate = docset.doc();
continue 'outer;
}
}
return candidate;
}
}
impl<TDocSet: DocSet> Intersection<TDocSet, TDocSet> {
pub(crate) fn new(mut docsets: Vec<TDocSet>) -> Intersection<TDocSet, TDocSet> {
let num_docsets = docsets.len();
assert!(num_docsets >= 2);
docsets.sort_by_key(|docset| docset.size_hint());
go_to_first_doc(&mut docsets);
let left = docsets.remove(0);
let right = docsets.remove(0);
Intersection {
left,
right,
others: docsets,
}
}
}
impl<TDocSet: DocSet> Intersection<TDocSet, TDocSet> {
pub(crate) fn docset_mut_specialized(&mut self, ord: usize) -> &mut TDocSet {
match ord {
0 => &mut self.left,
1 => &mut self.right,
n => &mut self.others[n - 2],
}
}
}
impl<TDocSet: DocSet, TOtherDocSet: DocSet> DocSet for Intersection<TDocSet, TOtherDocSet> {
fn advance(&mut self) -> DocId {
let (left, right) = (&mut self.left, &mut self.right);
let mut candidate = left.advance();
'outer: loop {
loop {
let right_doc = right.seek(candidate);
candidate = left.seek(right_doc);
if candidate == right_doc {
break;
}
}
debug_assert_eq!(left.doc(), right.doc());
for docset in self.others.iter_mut() {
let seek_doc = docset.seek(candidate);
if seek_doc > candidate {
candidate = left.seek(seek_doc);
continue 'outer;
}
}
debug_assert_eq!(candidate, self.left.doc());
debug_assert_eq!(candidate, self.right.doc());
debug_assert!(self.others.iter().all(|docset| docset.doc() == candidate));
return candidate;
}
}
fn seek(&mut self, target: DocId) -> DocId {
self.left.seek(target);
let mut docsets: Vec<&mut dyn DocSet> = vec![&mut self.left, &mut self.right];
for docset in &mut self.others {
docsets.push(docset);
}
let doc = go_to_first_doc(&mut docsets[..]);
debug_assert!(docsets.iter().all(|docset| docset.doc() == doc));
debug_assert!(doc >= target);
doc
}
fn doc(&self) -> DocId {
self.left.doc()
}
fn size_hint(&self) -> u32 {
self.left.size_hint()
}
}
impl<TScorer, TOtherScorer> Scorer for Intersection<TScorer, TOtherScorer>
where
TScorer: Scorer,
TOtherScorer: Scorer,
{
fn score(&mut self) -> Score {
self.left.score()
+ self.right.score()
+ self.others.iter_mut().map(Scorer::score).sum::<Score>()
}
}
#[cfg(test)]
mod tests {
use super::Intersection;
use crate::docset::{DocSet, TERMINATED};
use crate::postings::tests::test_skip_against_unoptimized;
use crate::query::VecDocSet;
#[test]
fn test_intersection() {
{
let left = VecDocSet::from(vec![1, 3, 9]);
let right = VecDocSet::from(vec![3, 4, 9, 18]);
let mut intersection = Intersection::new(vec![left, right]);
assert_eq!(intersection.doc(), 3);
assert_eq!(intersection.advance(), 9);
assert_eq!(intersection.doc(), 9);
assert_eq!(intersection.advance(), TERMINATED);
}
{
let a = VecDocSet::from(vec![1, 3, 9]);
let b = VecDocSet::from(vec![3, 4, 9, 18]);
let c = VecDocSet::from(vec![1, 5, 9, 111]);
let mut intersection = Intersection::new(vec![a, b, c]);
assert_eq!(intersection.doc(), 9);
assert_eq!(intersection.advance(), TERMINATED);
}
}
#[test]
fn test_intersection_zero() {
let left = VecDocSet::from(vec![0]);
let right = VecDocSet::from(vec![0]);
let mut intersection = Intersection::new(vec![left, right]);
assert_eq!(intersection.doc(), 0);
assert_eq!(intersection.advance(), TERMINATED);
}
#[test]
fn test_intersection_skip() {
let left = VecDocSet::from(vec![0, 1, 2, 4]);
let right = VecDocSet::from(vec![2, 5]);
let mut intersection = Intersection::new(vec![left, right]);
assert_eq!(intersection.seek(2), 2);
assert_eq!(intersection.doc(), 2);
}
#[test]
fn test_intersection_skip_against_unoptimized() {
test_skip_against_unoptimized(
|| {
let left = VecDocSet::from(vec![4]);
let right = VecDocSet::from(vec![2, 5]);
Box::new(Intersection::new(vec![left, right]))
},
vec![0, 2, 4, 5, 6],
);
test_skip_against_unoptimized(
|| {
let mut left = VecDocSet::from(vec![1, 4, 5, 6]);
let mut right = VecDocSet::from(vec![2, 5, 10]);
left.advance();
right.advance();
Box::new(Intersection::new(vec![left, right]))
},
vec![0, 1, 2, 3, 4, 5, 6, 7, 10, 11],
);
test_skip_against_unoptimized(
|| {
Box::new(Intersection::new(vec![
VecDocSet::from(vec![1, 4, 5, 6]),
VecDocSet::from(vec![1, 2, 5, 6]),
VecDocSet::from(vec![1, 4, 5, 6]),
VecDocSet::from(vec![1, 5, 6]),
VecDocSet::from(vec![2, 4, 5, 7, 8]),
]))
},
vec![0, 1, 2, 3, 4, 5, 6, 7, 10, 11],
);
}
#[test]
fn test_intersection_empty() {
let a = VecDocSet::from(vec![1, 3]);
let b = VecDocSet::from(vec![1, 4]);
let c = VecDocSet::from(vec![3, 9]);
let intersection = Intersection::new(vec![a, b, c]);
assert_eq!(intersection.doc(), TERMINATED);
}
}