/
query_builder.rs
192 lines (163 loc) · 6.03 KB
/
query_builder.rs
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use std::{mem, vec, str, char};
use std::error::Error;
use std::ops::Deref;
use std::hash::Hash;
use group_by::GroupByMut;
use hashbrown::HashMap;
use fst::Streamer;
use rocksdb::DB;
use crate::automaton::{self, DfaExt, AutomatonExt};
use crate::rank::distinct_map::DistinctMap;
use crate::rank::criterion::Criteria;
use crate::database::DatabaseView;
use crate::{Match, DocumentId};
use crate::rank::Document;
fn split_whitespace_automatons(query: &str) -> Vec<DfaExt> {
let has_end_whitespace = query.chars().last().map_or(false, char::is_whitespace);
let mut automatons = Vec::new();
let mut words = query.split_whitespace().map(str::to_lowercase).peekable();
while let Some(word) = words.next() {
let has_following_word = words.peek().is_some();
let lev = if has_following_word || has_end_whitespace {
automaton::build_dfa(&word)
} else {
automaton::build_prefix_dfa(&word)
};
automatons.push(lev);
}
automatons
}
pub struct QueryBuilder<'a, D>
where D: Deref<Target=DB>
{
view: &'a DatabaseView<D>,
criteria: Criteria<D>,
}
impl<'a, D> QueryBuilder<'a, D>
where D: Deref<Target=DB>
{
pub fn new(view: &'a DatabaseView<D>) -> Result<Self, Box<Error>> {
QueryBuilder::with_criteria(view, Criteria::default())
}
}
impl<'a, D> QueryBuilder<'a, D>
where D: Deref<Target=DB>
{
pub fn with_criteria(view: &'a DatabaseView<D>, criteria: Criteria<D>) -> Result<Self, Box<Error>> {
Ok(QueryBuilder { view, criteria })
}
pub fn criteria(&mut self, criteria: Criteria<D>) -> &mut Self {
self.criteria = criteria;
self
}
pub fn with_distinct<F>(self, function: F, size: usize) -> DistinctQueryBuilder<'a, D, F> {
DistinctQueryBuilder {
inner: self,
function: function,
size: size
}
}
fn query_all(&self, query: &str) -> Vec<Document> {
let automatons = split_whitespace_automatons(query);
let mut stream = {
let mut op_builder = fst::map::OpBuilder::new();
for automaton in &automatons {
let stream = self.view.blob().as_map().search(automaton);
op_builder.push(stream);
}
op_builder.union()
};
let mut matches = HashMap::new();
while let Some((input, indexed_values)) = stream.next() {
for iv in indexed_values {
let automaton = &automatons[iv.index];
let distance = automaton.eval(input).to_u8();
let is_exact = distance == 0 && input.len() == automaton.query_len();
let doc_indexes = self.view.blob().as_indexes();
let doc_indexes = &doc_indexes[iv.value as usize];
for doc_index in doc_indexes {
let match_ = Match {
query_index: iv.index as u32,
distance: distance,
attribute: doc_index.attribute,
attribute_index: doc_index.attribute_index,
is_exact: is_exact,
};
matches.entry(doc_index.document_id).or_insert_with(Vec::new).push(match_);
}
}
}
matches.into_iter().map(|(id, matches)| Document::from_matches(id, matches)).collect()
}
}
impl<'a, D> QueryBuilder<'a, D>
where D: Deref<Target=DB>,
{
pub fn query(&self, query: &str, limit: usize) -> Vec<Document> {
let mut documents = self.query_all(query);
let mut groups = vec![documents.as_mut_slice()];
let view = &self.view;
for criterion in self.criteria.as_ref() {
let tmp_groups = mem::replace(&mut groups, Vec::new());
let mut computed = 0;
'group: for group in tmp_groups {
group.sort_unstable_by(|a, b| criterion.evaluate(a, b, view));
for group in GroupByMut::new(group, |a, b| criterion.eq(a, b, view)) {
computed += group.len();
groups.push(group);
if computed >= limit { break 'group }
}
}
}
documents.truncate(limit);
documents
}
}
pub struct DistinctQueryBuilder<'a, D, F>
where D: Deref<Target=DB>
{
inner: QueryBuilder<'a, D>,
function: F,
size: usize,
}
impl<'a, D, F, K> DistinctQueryBuilder<'a, D, F>
where D: Deref<Target=DB>,
F: Fn(DocumentId, &DatabaseView<D>) -> Option<K>,
K: Hash + Eq,
{
pub fn query(&self, query: &str, limit: usize) -> Vec<Document> {
let mut documents = self.inner.query_all(query);
let mut groups = vec![documents.as_mut_slice()];
let view = &self.inner.view;
for criterion in self.inner.criteria.as_ref() {
let tmp_groups = mem::replace(&mut groups, Vec::new());
let mut seen = DistinctMap::new(self.size);
'group: for group in tmp_groups {
group.sort_unstable_by(|a, b| criterion.evaluate(a, b, view));
for group in GroupByMut::new(group, |a, b| criterion.eq(a, b, view)) {
for document in group.iter() {
match (self.function)(document.id, view) {
Some(key) => seen.register(key),
None => seen.register_without_key(),
};
}
groups.push(group);
if seen.len() >= limit { break 'group }
}
}
}
let mut out_documents = Vec::with_capacity(limit);
let mut seen = DistinctMap::new(self.size);
for document in documents {
let accepted = match (self.function)(document.id, view) {
Some(key) => seen.register(key),
None => seen.register_without_key(),
};
if accepted {
out_documents.push(document);
if out_documents.len() == limit { break }
}
}
out_documents
}
}