First implementation of the CONTAINS filter

Cargo.lock

@@ -2738,6 +2738,7 @@ dependencies = [
  "logging_timer",
  "maplit",
  "md5",
+ "memchr",
  "memmap2",
  "mimalloc",
  "obkv",

milli/Cargo.toml

@@ -25,10 +25,16 @@ flatten-serde-json = { path = "../flatten-serde-json" }
 fst = "0.4.7"
 fxhash = "0.2.1"
 geoutils = "0.5.1"
-grenad = { version = "0.4.4", default-features = false, features = ["tempfile"] }
+grenad = { version = "0.4.4", default-features = false, features = [
-heed = { git = "https://github.com/meilisearch/heed", tag = "v0.12.5", default-features = false, features = ["lmdb", "sync-read-txn"] }
+    "tempfile",
+] }
+heed = { git = "https://github.com/meilisearch/heed", tag = "v0.12.5", default-features = false, features = [
+    "lmdb",
+    "sync-read-txn",
+] }
 json-depth-checker = { path = "../json-depth-checker" }
 levenshtein_automata = { version = "0.2.1", features = ["fst_automaton"] }
+memchr = "2.5.0"
 memmap2 = "0.5.10"
 obkv = "0.2.0"
 once_cell = "1.17.1"
@@ -39,12 +45,17 @@ rstar = { version = "0.10.0", features = ["serde"] }
 serde = { version = "1.0.160", features = ["derive"] }
 serde_json = { version = "1.0.95", features = ["preserve_order"] }
 slice-group-by = "0.3.0"
-smallstr =  { version = "0.3.0", features = ["serde"] }
+smallstr = { version = "0.3.0", features = ["serde"] }
 smallvec = "1.10.0"
 smartstring = "1.0.1"
 tempfile = "3.5.0"
 thiserror = "1.0.40"
-time = { version = "0.3.20", features = ["serde-well-known", "formatting", "parsing", "macros"] }
+time = { version = "0.3.20", features = [
+    "serde-well-known",
+    "formatting",
+    "parsing",
+    "macros",
+] }
 uuid = { version = "1.3.1", features = ["v4"] }
 
 filter-parser = { path = "../filter-parser" }
@@ -63,13 +74,13 @@ big_s = "1.0.2"
 insta = "1.29.0"
 maplit = "1.0.2"
 md5 = "0.7.0"
-rand = {version = "0.8.5", features = ["small_rng"] }
+rand = { version = "0.8.5", features = ["small_rng"] }
 
 [target.'cfg(fuzzing)'.dev-dependencies]
 fuzzcheck = "0.12.1"
 
 [features]
-all-tokenizations = [ "charabia/default" ]
+all-tokenizations = ["charabia/default"]
 
 # Use POSIX semaphores instead of SysV semaphores in LMDB
 # For more information on this feature, see heed's Cargo.toml

milli/src/search/facet/filter.rs

@@ -4,13 +4,15 @@ use std::ops::Bound::{self, Excluded, Included};
 
 use either::Either;
 pub use filter_parser::{Condition, Error as FPError, FilterCondition, Span, Token};
+use heed::LazyDecode;
+use memchr::memmem::Finder;
 use roaring::RoaringBitmap;
 use serde_json::Value;
 
 use super::facet_range_search;
 use crate::error::{Error, UserError};
 use crate::heed_codec::facet::{
-    FacetGroupKey, FacetGroupKeyCodec, FacetGroupValueCodec, OrderedF64Codec,
+    FacetGroupKey, FacetGroupKeyCodec, FacetGroupValue, FacetGroupValueCodec, OrderedF64Codec,
 };
 use crate::{distance_between_two_points, lat_lng_to_xyz, FieldId, Index, Result};
 
@@ -299,7 +301,22 @@ impl<'a> Filter<'a> {
                 return Ok(all_ids - docids);
             }
             Condition::Contains(val) => {
-                todo!()
+                let finder = Finder::new(val.value());
+                let base = FacetGroupKey { field_id, level: 0, left_bound: "" };
+                // TODO use the roaring::MultiOps trait
+                let mut docids = RoaringBitmap::new();
+                for result in strings_db
+                    .prefix_iter(rtxn, &base)?
+                    .remap_data_type::<LazyDecode<FacetGroupValueCodec>>()
+                {
+                    let (FacetGroupKey { left_bound, .. }, lazy_group_value) = result?;
+                    if finder.find(left_bound.as_bytes()).is_some() {
+                        let FacetGroupValue { bitmap, .. } = lazy_group_value.decode()?;
+                        docids |= bitmap;
+                    }
+                }
+
+                return Ok(docids);
             }
             Condition::StartsWith(val) => {
                 todo!()