MeiliSearch/meilisearch-core/src/query_words_mapper.rs

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Rust
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use std::collections::HashMap;
use std::iter::FromIterator;
use std::ops::Range;
use intervaltree::{Element, IntervalTree};
pub type QueryId = usize;
pub struct QueryWordsMapper {
originals: Vec<String>,
mappings: HashMap<QueryId, (Range<usize>, Vec<String>)>,
}
impl QueryWordsMapper {
pub fn new<I, A>(originals: I) -> QueryWordsMapper
where I: IntoIterator<Item = A>,
A: ToString,
{
let originals = originals.into_iter().map(|s| s.to_string()).collect();
QueryWordsMapper { originals, mappings: HashMap::new() }
}
pub fn declare<I, A>(&mut self, range: Range<usize>, id: QueryId, replacement: I)
where I: IntoIterator<Item = A>,
A: ToString,
{
assert!(range.len() != 0);
assert!(self.originals.get(range.clone()).is_some());
assert!(id >= self.originals.len());
let replacement: Vec<_> = replacement.into_iter().map(|s| s.to_string()).collect();
assert!(!replacement.is_empty());
// We detect words at the end and at the front of the
// replacement that are common with the originals:
//
// x a b c d e f g
// ^^^/ \^^^
// a b x c d k j e f
// ^^^ ^^^
//
let left = &self.originals[..range.start];
let right = &self.originals[range.end..];
let common_left = longest_common_prefix(left, &replacement);
let common_right = longest_common_prefix(&replacement, right);
for i in 0..common_left {
let range = range.start - common_left + i..range.start - common_left + i + 1;
let replacement = vec![replacement[i].clone()];
self.mappings.insert(id + i, (range, replacement));
}
{
let replacement = replacement[common_left..replacement.len() - common_right].iter().cloned().collect();
self.mappings.insert(id + common_left, (range.clone(), replacement));
}
for i in 0..common_right {
let id = id + replacement.len() - common_right + i;
let range = range.end + i..range.end + i + 1;
let replacement = vec![replacement[replacement.len() - common_right + i].clone()];
self.mappings.insert(id, (range, replacement));
}
}
pub fn mapping(self) -> HashMap<QueryId, Range<usize>> {
let mappings = self.mappings.into_iter().map(|(i, (r, v))| (r, (i, v)));
let intervals = IntervalTree::from_iter(mappings);
let mut output = HashMap::new();
let mut offset = 0;
// We map each original word to the biggest number of
// associated words.
for i in 0..self.originals.len() {
let max = intervals.query_point(i)
.filter_map(|e| {
if e.range.end - 1 == i {
let len = e.value.1.iter().skip(i - e.range.start).count();
if len != 0 { Some(len) } else { None }
} else { None }
})
.max()
.unwrap_or(1);
let range = i + offset..i + offset + max;
output.insert(i, range);
offset += max - 1;
}
// We retrieve the range that each original word
// is mapped to and apply it to each of the words.
for i in 0..self.originals.len() {
let iter = intervals.query_point(i).filter(|e| e.range.end - 1 == i);
for Element { range, value: (id, words) } in iter {
// We ask for the complete range mapped to the area we map.
let start = output.get(&range.start).map(|r| r.start).unwrap_or(range.start);
let end = output.get(&(range.end - 1)).map(|r| r.end).unwrap_or(range.end);
let range = start..end;
// We map each query id to one word until the last,
// we map it to the remainings words.
let add = range.len() - words.len();
for (j, x) in range.take(words.len()).enumerate() {
let add = if j == words.len() - 1 { add } else { 0 }; // is last?
let range = x..x + 1 + add;
output.insert(id + j, range);
}
}
}
output
}
}
fn longest_common_prefix<T: Eq + std::fmt::Debug>(a: &[T], b: &[T]) -> usize {
let mut best = None;
for i in (0..a.len()).rev() {
let count = a[i..].iter().zip(b).take_while(|(a, b)| a == b).count();
best = match best {
Some(old) if count > old => Some(count),
Some(_) => break,
None => Some(count),
};
}
best.unwrap_or(0)
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn original_unmodified() {
let query = ["new", "york", "city", "subway"];
// 0 1 2 3
let mut builder = QueryWordsMapper::new(&query);
// new york = new york city
builder.declare(0..2, 4, &["new", "york", "city"]);
// ^ 4 5 6
// new = new york city
builder.declare(0..1, 7, &["new", "york", "city"]);
// ^ 7 8 9
let mapping = builder.mapping();
assert_eq!(mapping[&0], 0..1); // new
assert_eq!(mapping[&1], 1..2); // york
assert_eq!(mapping[&2], 2..3); // city
assert_eq!(mapping[&3], 3..4); // subway
assert_eq!(mapping[&4], 0..1); // new
assert_eq!(mapping[&5], 1..2); // york
assert_eq!(mapping[&6], 2..3); // city
assert_eq!(mapping[&7], 0..1); // new
assert_eq!(mapping[&8], 1..2); // york
assert_eq!(mapping[&9], 2..3); // city
}
#[test]
fn original_unmodified2() {
let query = ["new", "york", "city", "subway"];
// 0 1 2 3
let mut builder = QueryWordsMapper::new(&query);
// city subway = new york city underground train
builder.declare(2..4, 4, &["new", "york", "city", "underground", "train"]);
// ^ 4 5 6 7 8
let mapping = builder.mapping();
assert_eq!(mapping[&0], 0..1); // new
assert_eq!(mapping[&1], 1..2); // york
assert_eq!(mapping[&2], 2..3); // city
assert_eq!(mapping[&3], 3..5); // subway
assert_eq!(mapping[&4], 0..1); // new
assert_eq!(mapping[&5], 1..2); // york
assert_eq!(mapping[&6], 2..3); // city
assert_eq!(mapping[&7], 3..4); // underground
assert_eq!(mapping[&8], 4..5); // train
}
#[test]
fn original_unmodified3() {
let query = ["a", "b", "x", "x", "a", "b", "c", "d", "e", "f", "g"];
// 0 1 2 3 4 5 6 7 8 9 10
let mut builder = QueryWordsMapper::new(&query);
// c d = a b x c d k j e f
builder.declare(6..8, 11, &["a", "b", "x", "c", "d", "k", "j", "e", "f"]);
// ^^ 11 12 13 14 15 16 17 18 19
let mapping = builder.mapping();
assert_eq!(mapping[&0], 0..1); // a
assert_eq!(mapping[&1], 1..2); // b
assert_eq!(mapping[&2], 2..3); // x
assert_eq!(mapping[&3], 3..4); // x
assert_eq!(mapping[&4], 4..5); // a
assert_eq!(mapping[&5], 5..6); // b
assert_eq!(mapping[&6], 6..7); // c
assert_eq!(mapping[&7], 7..11); // d
assert_eq!(mapping[&8], 11..12); // e
assert_eq!(mapping[&9], 12..13); // f
assert_eq!(mapping[&10], 13..14); // g
assert_eq!(mapping[&11], 4..5); // a
assert_eq!(mapping[&12], 5..6); // b
assert_eq!(mapping[&13], 6..7); // x
assert_eq!(mapping[&14], 7..8); // c
assert_eq!(mapping[&15], 8..9); // d
assert_eq!(mapping[&16], 9..10); // k
assert_eq!(mapping[&17], 10..11); // j
assert_eq!(mapping[&18], 11..12); // e
assert_eq!(mapping[&19], 12..13); // f
}
#[test]
fn simple_growing() {
let query = ["new", "york", "subway"];
// 0 1 2
let mut builder = QueryWordsMapper::new(&query);
// new york = new york city
builder.declare(0..2, 3, &["new", "york", "city"]);
// ^ 3 4 5
let mapping = builder.mapping();
assert_eq!(mapping[&0], 0..1); // new
assert_eq!(mapping[&1], 1..3); // york
assert_eq!(mapping[&2], 3..4); // subway
assert_eq!(mapping[&3], 0..1); // new
assert_eq!(mapping[&4], 1..2); // york
assert_eq!(mapping[&5], 2..3); // city
}
#[test]
fn same_place_growings() {
let query = ["NY", "subway"];
// 0 1
let mut builder = QueryWordsMapper::new(&query);
// NY = new york
builder.declare(0..1, 2, &["new", "york"]);
// ^ 2 3
// NY = new york city
builder.declare(0..1, 4, &["new", "york", "city"]);
// ^ 4 5 6
// NY = NYC
builder.declare(0..1, 7, &["NYC"]);
// ^ 7
// NY = new york city
builder.declare(0..1, 8, &["new", "york", "city"]);
// ^ 8 9 10
// subway = underground train
builder.declare(1..2, 11, &["underground", "train"]);
// ^ 11 12
let mapping = builder.mapping();
assert_eq!(mapping[&0], 0..3); // NY
assert_eq!(mapping[&1], 3..5); // subway
assert_eq!(mapping[&2], 0..1); // new
assert_eq!(mapping[&3], 1..3); // york
assert_eq!(mapping[&4], 0..1); // new
assert_eq!(mapping[&5], 1..2); // york
assert_eq!(mapping[&6], 2..3); // city
assert_eq!(mapping[&7], 0..3); // NYC
assert_eq!(mapping[&8], 0..1); // new
assert_eq!(mapping[&9], 1..2); // york
assert_eq!(mapping[&10], 2..3); // city
assert_eq!(mapping[&11], 3..4); // underground
assert_eq!(mapping[&12], 4..5); // train
}
#[test]
fn bigger_growing() {
let query = ["NYC", "subway"];
// 0 1
let mut builder = QueryWordsMapper::new(&query);
// NYC = new york city
builder.declare(0..1, 2, &["new", "york", "city"]);
// ^ 2 3 4
let mapping = builder.mapping();
assert_eq!(mapping[&0], 0..3); // NYC
assert_eq!(mapping[&1], 3..4); // subway
assert_eq!(mapping[&2], 0..1); // new
assert_eq!(mapping[&3], 1..2); // york
assert_eq!(mapping[&4], 2..3); // city
}
#[test]
fn middle_query_growing() {
let query = ["great", "awesome", "NYC", "subway"];
// 0 1 2 3
let mut builder = QueryWordsMapper::new(&query);
// NYC = new york city
builder.declare(2..3, 4, &["new", "york", "city"]);
// ^ 4 5 6
let mapping = builder.mapping();
assert_eq!(mapping[&0], 0..1); // great
assert_eq!(mapping[&1], 1..2); // awesome
assert_eq!(mapping[&2], 2..5); // NYC
assert_eq!(mapping[&3], 5..6); // subway
assert_eq!(mapping[&4], 2..3); // new
assert_eq!(mapping[&5], 3..4); // york
assert_eq!(mapping[&6], 4..5); // city
}
#[test]
fn end_query_growing() {
let query = ["NYC", "subway"];
// 0 1
let mut builder = QueryWordsMapper::new(&query);
// NYC = new york city
builder.declare(1..2, 2, &["underground", "train"]);
// ^ 2 3
let mapping = builder.mapping();
assert_eq!(mapping[&0], 0..1); // NYC
assert_eq!(mapping[&1], 1..3); // subway
assert_eq!(mapping[&2], 1..2); // underground
assert_eq!(mapping[&3], 2..3); // train
}
#[test]
fn multiple_growings() {
let query = ["great", "awesome", "NYC", "subway"];
// 0 1 2 3
let mut builder = QueryWordsMapper::new(&query);
// NYC = new york city
builder.declare(2..3, 4, &["new", "york", "city"]);
// ^ 4 5 6
// subway = underground train
builder.declare(3..4, 7, &["underground", "train"]);
// ^ 7 8
let mapping = builder.mapping();
assert_eq!(mapping[&0], 0..1); // great
assert_eq!(mapping[&1], 1..2); // awesome
assert_eq!(mapping[&2], 2..5); // NYC
assert_eq!(mapping[&3], 5..7); // subway
assert_eq!(mapping[&4], 2..3); // new
assert_eq!(mapping[&5], 3..4); // york
assert_eq!(mapping[&6], 4..5); // city
assert_eq!(mapping[&7], 5..6); // underground
assert_eq!(mapping[&8], 6..7); // train
}
#[test]
fn multiple_probable_growings() {
let query = ["great", "awesome", "NYC", "subway"];
// 0 1 2 3
let mut builder = QueryWordsMapper::new(&query);
// NYC = new york city
builder.declare(2..3, 4, &["new", "york", "city"]);
// ^ 4 5 6
// subway = underground train
builder.declare(3..4, 7, &["underground", "train"]);
// ^ 7 8
// great awesome = good
builder.declare(0..2, 9, &["good"]);
// ^ 9
// awesome NYC = NY
builder.declare(1..3, 10, &["NY"]);
// ^^ 10
// NYC subway = metro
builder.declare(2..4, 11, &["metro"]);
// ^^ 11
let mapping = builder.mapping();
assert_eq!(mapping[&0], 0..1); // great
assert_eq!(mapping[&1], 1..2); // awesome
assert_eq!(mapping[&2], 2..5); // NYC
assert_eq!(mapping[&3], 5..7); // subway
assert_eq!(mapping[&4], 2..3); // new
assert_eq!(mapping[&5], 3..4); // york
assert_eq!(mapping[&6], 4..5); // city
assert_eq!(mapping[&7], 5..6); // underground
assert_eq!(mapping[&8], 6..7); // train
assert_eq!(mapping[&9], 0..2); // good
assert_eq!(mapping[&10], 1..5); // NY
assert_eq!(mapping[&11], 2..7); // metro
}
}