feat: Remove the hashbrown dependency for library users

src/database/mod.rs

@@ -189,17 +189,18 @@ impl Database {
 
 #[cfg(test)]
 mod tests {
-    use super::*;
+    use std::collections::HashSet;
     use std::error::Error;
 
     use serde_derive::{Serialize, Deserialize};
-    use hashbrown::HashSet;
     use tempfile::tempdir;
 
     use crate::database::schema::{SchemaBuilder, STORED, INDEXED};
     use crate::database::update::UpdateBuilder;
     use crate::tokenizer::DefaultBuilder;
 
+    use super::*;
+
     #[test]
     fn ingest_one_update_file() -> Result<(), Box<Error>> {
         let dir = tempdir()?;
@@ -367,7 +368,7 @@ mod tests {
 mod bench {
     extern crate test;
 
-    use super::*;
+    use std::collections::HashSet;
     use std::error::Error;
     use std::iter::repeat_with;
     use self::test::Bencher;
@@ -377,12 +378,13 @@ mod bench {
     use rand::{Rng, SeedableRng};
     use serde_derive::Serialize;
     use rand::seq::SliceRandom;
-    use hashbrown::HashSet;
 
     use crate::tokenizer::DefaultBuilder;
     use crate::database::update::UpdateBuilder;
     use crate::database::schema::*;
 
+    use super::*;
+
     fn random_sentences<R: Rng>(number: usize, rng: &mut R) -> String {
         let mut words = String::new();
 

src/database/serde/indexer_serializer.rs

@@ -1,3 +1,8 @@
+use std::collections::HashSet;
+
+use serde::Serialize;
+use serde::ser;
+
 use crate::database::update::DocumentUpdate;
 use crate::database::serde::SerializerError;
 use crate::database::schema::SchemaAttr;
@@ -5,10 +10,6 @@ use crate::tokenizer::TokenizerBuilder;
 use crate::tokenizer::Token;
 use crate::{DocumentId, DocIndex};
 
-use hashbrown::HashSet;
-use serde::Serialize;
-use serde::ser;
-
 pub struct IndexerSerializer<'a, B> {
     pub tokenizer_builder: &'a B,
     pub update: &'a mut DocumentUpdate,

src/database/serde/serializer.rs

@@ -1,4 +1,5 @@
-use hashbrown::HashSet;
+use std::collections::HashSet;
+
 use serde::Serialize;
 use serde::ser;
 

src/database/update/builder.rs

@@ -1,7 +1,7 @@
+use std::collections::HashSet;
 use std::path::PathBuf;
 use std::error::Error;
 
-use hashbrown::HashSet;
 use serde::Serialize;
 
 use crate::database::serde::serializer::Serializer;