mirror of
https://github.com/meilisearch/MeiliSearch
synced 2024-09-23 09:01:46 +02:00
871 lines
34 KiB
Rust
871 lines
34 KiB
Rust
use std::borrow::Cow;
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use std::cmp::{self, Ordering};
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use std::collections::binary_heap::PeekMut;
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use std::collections::{btree_map, BTreeMap, BinaryHeap, HashMap};
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use std::mem::take;
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use roaring::RoaringBitmap;
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use super::{resolve_query_tree, Context, Criterion, CriterionParameters, CriterionResult};
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use crate::search::criteria::Query;
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use crate::search::query_tree::{Operation, QueryKind};
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use crate::search::{build_dfa, word_derivations, WordDerivationsCache};
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use crate::{Result, TreeLevel};
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/// To be able to divide integers by the number of words in the query
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/// we want to find a multiplier that allow us to divide by any number between 1 and 10.
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/// We chose the LCM of all numbers between 1 and 10 as the multiplier (https://en.wikipedia.org/wiki/Least_common_multiple).
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const LCM_10_FIRST_NUMBERS: u32 = 2520;
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/// To compute the interval size of a level,
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/// we use 4 as the exponentiation base and the level as the exponent.
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const LEVEL_EXPONENTIATION_BASE: u32 = 4;
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/// Threshold on the number of candidates that will make
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/// the system to choose between one algorithm or another.
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const CANDIDATES_THRESHOLD: u64 = 1000;
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type FlattenedQueryTree = Vec<Vec<Vec<Query>>>;
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pub struct Attribute<'t> {
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ctx: &'t dyn Context<'t>,
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state: Option<(Operation, FlattenedQueryTree, RoaringBitmap)>,
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bucket_candidates: RoaringBitmap,
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parent: Box<dyn Criterion + 't>,
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current_buckets: Option<btree_map::IntoIter<u64, RoaringBitmap>>,
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}
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impl<'t> Attribute<'t> {
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pub fn new(ctx: &'t dyn Context<'t>, parent: Box<dyn Criterion + 't>) -> Self {
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Attribute {
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ctx,
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state: None,
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bucket_candidates: RoaringBitmap::new(),
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parent,
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current_buckets: None,
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}
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}
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}
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impl<'t> Criterion for Attribute<'t> {
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#[logging_timer::time("Attribute::{}")]
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fn next(&mut self, params: &mut CriterionParameters) -> Result<Option<CriterionResult>> {
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// remove excluded candidates when next is called, instead of doing it in the loop.
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if let Some((_, _, allowed_candidates)) = self.state.as_mut() {
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*allowed_candidates -= params.excluded_candidates;
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}
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loop {
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match self.state.take() {
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Some((query_tree, _, allowed_candidates)) if allowed_candidates.is_empty() => {
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return Ok(Some(CriterionResult {
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query_tree: Some(query_tree),
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candidates: Some(RoaringBitmap::new()),
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filtered_candidates: None,
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bucket_candidates: Some(take(&mut self.bucket_candidates)),
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}));
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}
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Some((query_tree, flattened_query_tree, mut allowed_candidates)) => {
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let found_candidates = if allowed_candidates.len() < CANDIDATES_THRESHOLD {
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let current_buckets = match self.current_buckets.as_mut() {
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Some(current_buckets) => current_buckets,
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None => {
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let new_buckets = linear_compute_candidates(
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self.ctx,
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&flattened_query_tree,
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&allowed_candidates,
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)?;
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self.current_buckets.get_or_insert(new_buckets.into_iter())
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}
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};
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match current_buckets.next() {
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Some((_score, candidates)) => candidates,
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None => {
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return Ok(Some(CriterionResult {
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query_tree: Some(query_tree),
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candidates: Some(RoaringBitmap::new()),
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filtered_candidates: None,
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bucket_candidates: Some(take(&mut self.bucket_candidates)),
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}));
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}
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}
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} else {
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match set_compute_candidates(
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self.ctx,
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&flattened_query_tree,
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&allowed_candidates,
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params.wdcache,
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)? {
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Some(candidates) => candidates,
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None => {
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return Ok(Some(CriterionResult {
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query_tree: Some(query_tree),
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candidates: Some(RoaringBitmap::new()),
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filtered_candidates: None,
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bucket_candidates: Some(take(&mut self.bucket_candidates)),
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}));
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}
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}
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};
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allowed_candidates -= &found_candidates;
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self.state =
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Some((query_tree.clone(), flattened_query_tree, allowed_candidates));
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return Ok(Some(CriterionResult {
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query_tree: Some(query_tree),
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candidates: Some(found_candidates),
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filtered_candidates: None,
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bucket_candidates: Some(take(&mut self.bucket_candidates)),
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}));
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}
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None => match self.parent.next(params)? {
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Some(CriterionResult {
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query_tree: Some(query_tree),
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candidates,
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filtered_candidates,
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bucket_candidates,
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}) => {
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let mut candidates = match candidates {
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Some(candidates) => candidates,
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None => {
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resolve_query_tree(self.ctx, &query_tree, params.wdcache)?
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- params.excluded_candidates
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}
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};
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if let Some(filtered_candidates) = filtered_candidates {
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candidates &= filtered_candidates;
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}
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let flattened_query_tree = flatten_query_tree(&query_tree);
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match bucket_candidates {
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Some(bucket_candidates) => self.bucket_candidates |= bucket_candidates,
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None => self.bucket_candidates |= &candidates,
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}
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self.state = Some((query_tree, flattened_query_tree, candidates));
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self.current_buckets = None;
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}
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Some(CriterionResult {
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query_tree: None,
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candidates,
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filtered_candidates,
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bucket_candidates,
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}) => {
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return Ok(Some(CriterionResult {
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query_tree: None,
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candidates,
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filtered_candidates,
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bucket_candidates,
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}));
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}
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None => return Ok(None),
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},
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}
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}
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}
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}
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/// WordLevelIterator is an pseudo-Iterator over intervals of word-position for one word,
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/// it will begin at the first non-empty interval and will return every interval without
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/// jumping over empty intervals.
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struct WordLevelIterator<'t, 'q> {
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inner: Box<
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dyn Iterator<Item = heed::Result<((&'t str, TreeLevel, u32, u32), RoaringBitmap)>> + 't,
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>,
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level: TreeLevel,
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interval_size: u32,
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word: Cow<'q, str>,
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in_prefix_cache: bool,
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inner_next: Option<(u32, u32, RoaringBitmap)>,
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current_interval: Option<(u32, u32)>,
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}
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impl<'t, 'q> WordLevelIterator<'t, 'q> {
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fn new(
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ctx: &'t dyn Context<'t>,
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word: Cow<'q, str>,
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in_prefix_cache: bool,
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) -> heed::Result<Option<Self>> {
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match ctx.word_position_last_level(&word, in_prefix_cache)? {
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Some(level) => {
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let interval_size = LEVEL_EXPONENTIATION_BASE.pow(Into::<u8>::into(level) as u32);
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let inner =
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ctx.word_position_iterator(&word, level, in_prefix_cache, None, None)?;
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Ok(Some(Self {
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inner,
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level,
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interval_size,
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word,
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in_prefix_cache,
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inner_next: None,
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current_interval: None,
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}))
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}
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None => Ok(None),
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}
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}
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fn dig(
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&self,
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ctx: &'t dyn Context<'t>,
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level: &TreeLevel,
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left_interval: Option<u32>,
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) -> heed::Result<Self> {
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let level = *level.min(&self.level);
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let interval_size = LEVEL_EXPONENTIATION_BASE.pow(Into::<u8>::into(level) as u32);
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let word = self.word.clone();
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let in_prefix_cache = self.in_prefix_cache;
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let inner =
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ctx.word_position_iterator(&word, level, in_prefix_cache, left_interval, None)?;
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Ok(Self {
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inner,
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level,
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interval_size,
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word,
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in_prefix_cache,
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inner_next: None,
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current_interval: None,
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})
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}
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fn next(&mut self) -> heed::Result<Option<(u32, u32, RoaringBitmap)>> {
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fn is_next_interval(last_right: u32, next_left: u32) -> bool {
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last_right + 1 == next_left
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}
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let inner_next = match self.inner_next.take() {
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Some(inner_next) => Some(inner_next),
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None => self
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.inner
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.next()
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.transpose()?
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.map(|((_, _, left, right), docids)| (left, right, docids)),
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};
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match inner_next {
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Some((left, right, docids)) => match self.current_interval {
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Some((last_left, last_right)) if !is_next_interval(last_right, left) => {
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let blank_left = last_left + self.interval_size;
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let blank_right = last_right + self.interval_size;
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self.current_interval = Some((blank_left, blank_right));
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self.inner_next = Some((left, right, docids));
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Ok(Some((blank_left, blank_right, RoaringBitmap::new())))
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}
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_ => {
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self.current_interval = Some((left, right));
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Ok(Some((left, right, docids)))
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}
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},
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None => Ok(None),
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}
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}
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}
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/// QueryLevelIterator is an pseudo-Iterator for a Query,
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/// It contains WordLevelIterators and is chainned with other QueryLevelIterator.
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struct QueryLevelIterator<'t, 'q> {
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parent: Option<Box<QueryLevelIterator<'t, 'q>>>,
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inner: Vec<WordLevelIterator<'t, 'q>>,
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level: TreeLevel,
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accumulator: Vec<Option<(u32, u32, RoaringBitmap)>>,
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parent_accumulator: Vec<Option<(u32, u32, RoaringBitmap)>>,
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interval_to_skip: usize,
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}
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impl<'t, 'q> QueryLevelIterator<'t, 'q> {
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fn new(
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ctx: &'t dyn Context<'t>,
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queries: &'q [Query],
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wdcache: &mut WordDerivationsCache,
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) -> Result<Option<Self>> {
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let mut inner = Vec::with_capacity(queries.len());
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for query in queries {
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match &query.kind {
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QueryKind::Exact { word, .. } => {
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if !query.prefix || ctx.in_prefix_cache(&word) {
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let word = Cow::Borrowed(query.kind.word());
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if let Some(word_level_iterator) =
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WordLevelIterator::new(ctx, word, query.prefix)?
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{
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inner.push(word_level_iterator);
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}
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} else {
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for (word, _) in word_derivations(&word, true, 0, ctx.words_fst(), wdcache)?
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{
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let word = Cow::Owned(word.to_owned());
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if let Some(word_level_iterator) =
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WordLevelIterator::new(ctx, word, false)?
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{
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inner.push(word_level_iterator);
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}
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}
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}
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}
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QueryKind::Tolerant { typo, word } => {
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for (word, _) in
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word_derivations(&word, query.prefix, *typo, ctx.words_fst(), wdcache)?
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{
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let word = Cow::Owned(word.to_owned());
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if let Some(word_level_iterator) = WordLevelIterator::new(ctx, word, false)?
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{
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inner.push(word_level_iterator);
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}
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}
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}
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}
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}
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let highest = inner.iter().max_by_key(|wli| wli.level).map(|wli| wli.level);
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match highest {
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Some(level) => Ok(Some(Self {
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parent: None,
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inner,
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level,
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accumulator: vec![],
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parent_accumulator: vec![],
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interval_to_skip: 0,
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})),
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None => Ok(None),
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}
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}
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fn parent(&mut self, parent: QueryLevelIterator<'t, 'q>) -> &Self {
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self.parent = Some(Box::new(parent));
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self
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}
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/// create a new QueryLevelIterator with a lower level than the current one.
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fn dig(&self, ctx: &'t dyn Context<'t>) -> heed::Result<Self> {
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let (level, parent) = match &self.parent {
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Some(parent) => {
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let parent = parent.dig(ctx)?;
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(parent.level.min(self.level), Some(Box::new(parent)))
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}
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None => (self.level.saturating_sub(1), None),
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};
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let left_interval = self
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.accumulator
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.get(self.interval_to_skip)
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.map(|opt| opt.as_ref().map(|(left, _, _)| *left))
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.flatten();
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let mut inner = Vec::with_capacity(self.inner.len());
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for word_level_iterator in self.inner.iter() {
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inner.push(word_level_iterator.dig(ctx, &level, left_interval)?);
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}
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Ok(Self {
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parent,
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inner,
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level,
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accumulator: vec![],
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parent_accumulator: vec![],
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interval_to_skip: 0,
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})
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}
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fn inner_next(&mut self, level: TreeLevel) -> heed::Result<Option<(u32, u32, RoaringBitmap)>> {
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let mut accumulated: Option<(u32, u32, RoaringBitmap)> = None;
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let u8_level = Into::<u8>::into(level);
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let interval_size = LEVEL_EXPONENTIATION_BASE.pow(u8_level as u32);
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for wli in self.inner.iter_mut() {
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let wli_u8_level = Into::<u8>::into(wli.level);
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let accumulated_count = LEVEL_EXPONENTIATION_BASE.pow((u8_level - wli_u8_level) as u32);
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for _ in 0..accumulated_count {
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if let Some((next_left, _, next_docids)) = wli.next()? {
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accumulated = match accumulated.take() {
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Some((acc_left, acc_right, mut acc_docids)) => {
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acc_docids |= next_docids;
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Some((acc_left, acc_right, acc_docids))
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}
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None => Some((next_left, next_left + interval_size, next_docids)),
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};
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}
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}
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}
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Ok(accumulated)
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}
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/// return the next meta-interval created from inner WordLevelIterators,
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/// and from eventual chainned QueryLevelIterator.
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fn next(
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&mut self,
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allowed_candidates: &RoaringBitmap,
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tree_level: TreeLevel,
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) -> heed::Result<Option<(u32, u32, RoaringBitmap)>> {
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let parent_result = match self.parent.as_mut() {
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Some(parent) => Some(parent.next(allowed_candidates, tree_level)?),
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None => None,
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};
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match parent_result {
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Some(parent_next) => {
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let inner_next = self.inner_next(tree_level)?;
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self.interval_to_skip += interval_to_skip(
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&self.parent_accumulator,
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&self.accumulator,
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self.interval_to_skip,
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allowed_candidates,
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);
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self.accumulator.push(inner_next);
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self.parent_accumulator.push(parent_next);
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let mut merged_interval: Option<(u32, u32, RoaringBitmap)> = None;
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for current in self
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.accumulator
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.iter()
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.rev()
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.zip(self.parent_accumulator.iter())
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.skip(self.interval_to_skip)
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{
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if let (Some((left_a, right_a, a)), Some((left_b, right_b, b))) = current {
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match merged_interval.as_mut() {
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Some((_, _, merged_docids)) => *merged_docids |= a & b,
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None => {
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merged_interval = Some((left_a + left_b, right_a + right_b, a & b))
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}
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}
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}
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}
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Ok(merged_interval)
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}
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None => {
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let level = self.level;
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match self.inner_next(level)? {
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Some((left, right, mut candidates)) => {
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self.accumulator = vec![Some((left, right, RoaringBitmap::new()))];
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candidates &= allowed_candidates;
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Ok(Some((left, right, candidates)))
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}
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None => {
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self.accumulator = vec![None];
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Ok(None)
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}
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}
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}
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}
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}
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}
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/// Count the number of interval that can be skiped when we make the cross-intersections
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/// in order to compute the next meta-interval.
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/// A pair of intervals is skiped when both intervals doesn't contain any allowed docids.
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fn interval_to_skip(
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parent_accumulator: &[Option<(u32, u32, RoaringBitmap)>],
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current_accumulator: &[Option<(u32, u32, RoaringBitmap)>],
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already_skiped: usize,
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allowed_candidates: &RoaringBitmap,
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) -> usize {
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parent_accumulator
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.iter()
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.zip(current_accumulator.iter())
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.skip(already_skiped)
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.take_while(|(parent, current)| {
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let skip_parent = parent.as_ref().map_or(true, |(_, _, docids)| docids.is_empty());
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let skip_current = current
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.as_ref()
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.map_or(true, |(_, _, docids)| docids.is_disjoint(allowed_candidates));
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skip_parent && skip_current
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})
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.count()
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}
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/// A Branch is represent a possible alternative of the original query and is build with the Query Tree,
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/// This branch allows us to iterate over meta-interval of position and to dig in it if it contains interesting candidates.
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struct Branch<'t, 'q> {
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query_level_iterator: QueryLevelIterator<'t, 'q>,
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last_result: (u32, u32, RoaringBitmap),
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tree_level: TreeLevel,
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branch_size: u32,
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}
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impl<'t, 'q> Branch<'t, 'q> {
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/// return the next meta-interval of the branch,
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/// and update inner interval in order to be ranked by the BinaryHeap.
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fn next(&mut self, allowed_candidates: &RoaringBitmap) -> heed::Result<bool> {
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let tree_level = self.query_level_iterator.level;
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match self.query_level_iterator.next(allowed_candidates, tree_level)? {
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Some(last_result) => {
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self.last_result = last_result;
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|
self.tree_level = tree_level;
|
|
Ok(true)
|
|
}
|
|
None => Ok(false),
|
|
}
|
|
}
|
|
|
|
/// make the current Branch iterate over smaller intervals.
|
|
fn dig(&mut self, ctx: &'t dyn Context<'t>) -> heed::Result<()> {
|
|
self.query_level_iterator = self.query_level_iterator.dig(ctx)?;
|
|
Ok(())
|
|
}
|
|
|
|
/// because next() method could be time consuming,
|
|
/// update inner interval in order to be ranked by the binary_heap without computing it,
|
|
/// the next() method should be called when the real interval is needed.
|
|
fn lazy_next(&mut self) {
|
|
let u8_level = Into::<u8>::into(self.tree_level);
|
|
let interval_size = LEVEL_EXPONENTIATION_BASE.pow(u8_level as u32);
|
|
let (left, right, _) = self.last_result;
|
|
|
|
self.last_result = (left + interval_size, right + interval_size, RoaringBitmap::new());
|
|
}
|
|
|
|
/// return the score of the current inner interval.
|
|
fn compute_rank(&self) -> u32 {
|
|
// we compute a rank from the left interval.
|
|
let (left, _, _) = self.last_result;
|
|
left.saturating_sub((0..self.branch_size).sum()) * LCM_10_FIRST_NUMBERS / self.branch_size
|
|
}
|
|
|
|
fn cmp(&self, other: &Self) -> Ordering {
|
|
let self_rank = self.compute_rank();
|
|
let other_rank = other.compute_rank();
|
|
let left_cmp = self_rank.cmp(&other_rank).reverse();
|
|
// on level: lower is better,
|
|
// we want to dig faster into levels on interesting branches.
|
|
let level_cmp = self.tree_level.cmp(&other.tree_level).reverse();
|
|
|
|
left_cmp.then(level_cmp).then(self.last_result.2.len().cmp(&other.last_result.2.len()))
|
|
}
|
|
}
|
|
|
|
impl<'t, 'q> Ord for Branch<'t, 'q> {
|
|
fn cmp(&self, other: &Self) -> Ordering {
|
|
self.cmp(other)
|
|
}
|
|
}
|
|
|
|
impl<'t, 'q> PartialOrd for Branch<'t, 'q> {
|
|
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
|
|
Some(self.cmp(other))
|
|
}
|
|
}
|
|
|
|
impl<'t, 'q> PartialEq for Branch<'t, 'q> {
|
|
fn eq(&self, other: &Self) -> bool {
|
|
self.cmp(other) == Ordering::Equal
|
|
}
|
|
}
|
|
|
|
impl<'t, 'q> Eq for Branch<'t, 'q> {}
|
|
|
|
fn initialize_query_level_iterators<'t, 'q>(
|
|
ctx: &'t dyn Context<'t>,
|
|
branches: &'q FlattenedQueryTree,
|
|
allowed_candidates: &RoaringBitmap,
|
|
wdcache: &mut WordDerivationsCache,
|
|
) -> Result<BinaryHeap<Branch<'t, 'q>>> {
|
|
let mut positions = BinaryHeap::with_capacity(branches.len());
|
|
for branch in branches {
|
|
let mut branch_positions = Vec::with_capacity(branch.len());
|
|
for queries in branch {
|
|
match QueryLevelIterator::new(ctx, queries, wdcache)? {
|
|
Some(qli) => branch_positions.push(qli),
|
|
None => {
|
|
// the branch seems to be invalid, so we skip it.
|
|
branch_positions.clear();
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
// QueryLevelIterator need to be sorted by level and folded in descending order.
|
|
branch_positions.sort_unstable_by_key(|qli| qli.level);
|
|
let folded_query_level_iterators =
|
|
branch_positions.into_iter().fold(None, |fold: Option<QueryLevelIterator>, mut qli| {
|
|
match fold {
|
|
Some(fold) => {
|
|
qli.parent(fold);
|
|
Some(qli)
|
|
}
|
|
None => Some(qli),
|
|
}
|
|
});
|
|
|
|
if let Some(mut folded_query_level_iterators) = folded_query_level_iterators {
|
|
let tree_level = folded_query_level_iterators.level;
|
|
let last_result = folded_query_level_iterators.next(allowed_candidates, tree_level)?;
|
|
if let Some(last_result) = last_result {
|
|
let branch = Branch {
|
|
last_result,
|
|
tree_level,
|
|
query_level_iterator: folded_query_level_iterators,
|
|
branch_size: branch.len() as u32,
|
|
};
|
|
positions.push(branch);
|
|
}
|
|
}
|
|
}
|
|
|
|
Ok(positions)
|
|
}
|
|
|
|
fn set_compute_candidates<'t>(
|
|
ctx: &'t dyn Context<'t>,
|
|
branches: &FlattenedQueryTree,
|
|
allowed_candidates: &RoaringBitmap,
|
|
wdcache: &mut WordDerivationsCache,
|
|
) -> Result<Option<RoaringBitmap>> {
|
|
let mut branches_heap =
|
|
initialize_query_level_iterators(ctx, branches, allowed_candidates, wdcache)?;
|
|
let lowest_level = TreeLevel::min_value();
|
|
let mut final_candidates: Option<(u32, RoaringBitmap)> = None;
|
|
let mut allowed_candidates = allowed_candidates.clone();
|
|
|
|
while let Some(mut branch) = branches_heap.peek_mut() {
|
|
let is_lowest_level = branch.tree_level == lowest_level;
|
|
let branch_rank = branch.compute_rank();
|
|
// if current is worst than best we break to return
|
|
// candidates that correspond to the best rank
|
|
if let Some((best_rank, _)) = final_candidates {
|
|
if branch_rank > best_rank {
|
|
break;
|
|
}
|
|
}
|
|
let _left = branch.last_result.0;
|
|
let candidates = take(&mut branch.last_result.2);
|
|
if candidates.is_empty() {
|
|
// we don't have candidates, get next interval.
|
|
if !branch.next(&allowed_candidates)? {
|
|
PeekMut::pop(branch);
|
|
}
|
|
} else if is_lowest_level {
|
|
// we have candidates, but we can't dig deeper.
|
|
allowed_candidates -= &candidates;
|
|
final_candidates = match final_candidates.take() {
|
|
// we add current candidates to best candidates
|
|
Some((best_rank, mut best_candidates)) => {
|
|
best_candidates |= candidates;
|
|
branch.lazy_next();
|
|
Some((best_rank, best_candidates))
|
|
}
|
|
// we take current candidates as best candidates
|
|
None => {
|
|
branch.lazy_next();
|
|
Some((branch_rank, candidates))
|
|
}
|
|
};
|
|
} else {
|
|
// we have candidates, lets dig deeper in levels.
|
|
branch.dig(ctx)?;
|
|
if !branch.next(&allowed_candidates)? {
|
|
PeekMut::pop(branch);
|
|
}
|
|
}
|
|
}
|
|
|
|
Ok(final_candidates.map(|(_rank, candidates)| candidates))
|
|
}
|
|
|
|
fn linear_compute_candidates(
|
|
ctx: &dyn Context,
|
|
branches: &FlattenedQueryTree,
|
|
allowed_candidates: &RoaringBitmap,
|
|
) -> Result<BTreeMap<u64, RoaringBitmap>> {
|
|
fn compute_candidate_rank(
|
|
branches: &FlattenedQueryTree,
|
|
words_positions: HashMap<String, RoaringBitmap>,
|
|
) -> u64 {
|
|
let mut min_rank = u64::max_value();
|
|
for branch in branches {
|
|
let branch_len = branch.len();
|
|
let mut branch_rank = Vec::with_capacity(branch_len);
|
|
for derivates in branch {
|
|
let mut position = None;
|
|
for Query { prefix, kind } in derivates {
|
|
// find the best position of the current word in the document.
|
|
let current_position = match kind {
|
|
QueryKind::Exact { word, .. } => {
|
|
if *prefix {
|
|
word_derivations(word, true, 0, &words_positions)
|
|
.flat_map(|positions| positions.iter().next())
|
|
.min()
|
|
} else {
|
|
words_positions
|
|
.get(word)
|
|
.map(|positions| positions.iter().next())
|
|
.flatten()
|
|
}
|
|
}
|
|
QueryKind::Tolerant { typo, word } => {
|
|
word_derivations(word, *prefix, *typo, &words_positions)
|
|
.flat_map(|positions| positions.iter().next())
|
|
.min()
|
|
}
|
|
};
|
|
|
|
match (position, current_position) {
|
|
(Some(p), Some(cp)) => position = Some(cmp::min(p, cp)),
|
|
(None, Some(cp)) => position = Some(cp),
|
|
_ => (),
|
|
}
|
|
}
|
|
|
|
// if a position is found, we add it to the branch score,
|
|
// otherwise the branch is considered as unfindable in this document and we break.
|
|
if let Some(position) = position {
|
|
branch_rank.push(position as u64);
|
|
} else {
|
|
branch_rank.clear();
|
|
break;
|
|
}
|
|
}
|
|
|
|
if !branch_rank.is_empty() {
|
|
branch_rank.sort_unstable();
|
|
// because several words in same query can't match all a the position 0,
|
|
// we substract the word index to the position.
|
|
let branch_rank: u64 =
|
|
branch_rank.into_iter().enumerate().map(|(i, r)| r - i as u64).sum();
|
|
// here we do the means of the words of the branch
|
|
min_rank =
|
|
min_rank.min(branch_rank * LCM_10_FIRST_NUMBERS as u64 / branch_len as u64);
|
|
}
|
|
}
|
|
|
|
min_rank
|
|
}
|
|
|
|
fn word_derivations<'a>(
|
|
word: &str,
|
|
is_prefix: bool,
|
|
max_typo: u8,
|
|
words_positions: &'a HashMap<String, RoaringBitmap>,
|
|
) -> impl Iterator<Item = &'a RoaringBitmap> {
|
|
let dfa = build_dfa(word, max_typo, is_prefix);
|
|
words_positions.iter().filter_map(move |(document_word, positions)| {
|
|
use levenshtein_automata::Distance;
|
|
match dfa.eval(document_word) {
|
|
Distance::Exact(_) => Some(positions),
|
|
Distance::AtLeast(_) => None,
|
|
}
|
|
})
|
|
}
|
|
|
|
let mut candidates = BTreeMap::new();
|
|
for docid in allowed_candidates {
|
|
let words_positions = ctx.docid_words_positions(docid)?;
|
|
let rank = compute_candidate_rank(branches, words_positions);
|
|
candidates.entry(rank).or_insert_with(RoaringBitmap::new).insert(docid);
|
|
}
|
|
|
|
Ok(candidates)
|
|
}
|
|
|
|
// TODO can we keep refs of Query
|
|
fn flatten_query_tree(query_tree: &Operation) -> FlattenedQueryTree {
|
|
use crate::search::criteria::Operation::{And, Or, Phrase};
|
|
|
|
fn and_recurse(head: &Operation, tail: &[Operation]) -> FlattenedQueryTree {
|
|
match tail.split_first() {
|
|
Some((thead, tail)) => {
|
|
let tail = and_recurse(thead, tail);
|
|
let mut out = Vec::new();
|
|
for array in recurse(head) {
|
|
for tail_array in &tail {
|
|
let mut array = array.clone();
|
|
array.extend(tail_array.iter().cloned());
|
|
out.push(array);
|
|
}
|
|
}
|
|
out
|
|
}
|
|
None => recurse(head),
|
|
}
|
|
}
|
|
|
|
fn recurse(op: &Operation) -> FlattenedQueryTree {
|
|
match op {
|
|
And(ops) => ops.split_first().map_or_else(Vec::new, |(h, t)| and_recurse(h, t)),
|
|
Or(_, ops) => {
|
|
if ops.iter().all(|op| op.query().is_some()) {
|
|
vec![vec![ops.iter().flat_map(|op| op.query()).cloned().collect()]]
|
|
} else {
|
|
ops.iter().map(recurse).flatten().collect()
|
|
}
|
|
}
|
|
Phrase(words) => {
|
|
let queries = words
|
|
.iter()
|
|
.map(|word| vec![Query { prefix: false, kind: QueryKind::exact(word.clone()) }])
|
|
.collect();
|
|
vec![queries]
|
|
}
|
|
Operation::Query(query) => vec![vec![vec![query.clone()]]],
|
|
}
|
|
}
|
|
|
|
recurse(query_tree)
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod tests {
|
|
use big_s::S;
|
|
|
|
use super::*;
|
|
use crate::search::criteria::QueryKind;
|
|
|
|
#[test]
|
|
fn simple_flatten_query_tree() {
|
|
let query_tree = Operation::Or(
|
|
false,
|
|
vec![
|
|
Operation::Query(Query { prefix: false, kind: QueryKind::exact(S("manythefish")) }),
|
|
Operation::And(vec![
|
|
Operation::Query(Query { prefix: false, kind: QueryKind::exact(S("manythe")) }),
|
|
Operation::Query(Query { prefix: false, kind: QueryKind::exact(S("fish")) }),
|
|
]),
|
|
Operation::And(vec![
|
|
Operation::Query(Query { prefix: false, kind: QueryKind::exact(S("many")) }),
|
|
Operation::Or(
|
|
false,
|
|
vec![
|
|
Operation::Query(Query {
|
|
prefix: false,
|
|
kind: QueryKind::exact(S("thefish")),
|
|
}),
|
|
Operation::And(vec![
|
|
Operation::Query(Query {
|
|
prefix: false,
|
|
kind: QueryKind::exact(S("the")),
|
|
}),
|
|
Operation::Query(Query {
|
|
prefix: false,
|
|
kind: QueryKind::exact(S("fish")),
|
|
}),
|
|
]),
|
|
],
|
|
),
|
|
]),
|
|
],
|
|
);
|
|
|
|
let expected = vec![
|
|
vec![vec![Query { prefix: false, kind: QueryKind::exact(S("manythefish")) }]],
|
|
vec![
|
|
vec![Query { prefix: false, kind: QueryKind::exact(S("manythe")) }],
|
|
vec![Query { prefix: false, kind: QueryKind::exact(S("fish")) }],
|
|
],
|
|
vec![
|
|
vec![Query { prefix: false, kind: QueryKind::exact(S("many")) }],
|
|
vec![Query { prefix: false, kind: QueryKind::exact(S("thefish")) }],
|
|
],
|
|
vec![
|
|
vec![Query { prefix: false, kind: QueryKind::exact(S("many")) }],
|
|
vec![Query { prefix: false, kind: QueryKind::exact(S("the")) }],
|
|
vec![Query { prefix: false, kind: QueryKind::exact(S("fish")) }],
|
|
],
|
|
];
|
|
|
|
let result = flatten_query_tree(&query_tree);
|
|
assert_eq!(expected, result);
|
|
}
|
|
}
|